混凝土喷射机论文中英文资料外文翻译文献
外文翻译--混凝土结构使用的可靠性
Electronic Journal of Structural Engineering, 1 ( 2001)15 Shrinkage, Cracking and Deflection-the Serviceability of Concrete Structures R.I. GilbertProfessor and Head, School of Civil and Environmental EngineeringThe University of New South Wales, Sydney, NSW, 2052Email: ******************.auABSTRACT This paper addresses the effects of shrinkage on the serviceability of concrete structures. It outlines why shrinkage is important, its major influence on the final extent of cracking and the magnitude of deflection in structures, and what to do about it in design. A model is presented for predicting the shrinkage strain in normal and high strength concrete and the time-dependent behaviour of plain concrete and reinforced concrete, with and without external restraints, is explained. Analytical procedures are described for estimating the final width and spacing of both flexural cracks and direct tension cracks and a simplified procedure is presented for including the effects of shrinkage when calculating long-term deflection. The paper also contains an overview of the considerations currently being made by the working group established by Standards Australia to revise the serviceability provisions of AS3600-1994, particularly those clauses related to shrinkage.KEYWORDSCreep; Cracking; Deflection; Reinforced concrete; Serviceability; Shrinkage.1. IntroductionFor a concrete structure to be serviceable, cracking must be controlled and deflections must not be excessive. It must also not vibrate excessively. Concrete shrinkage plays a major role in each of these aspects of the service load behaviour of concrete structures.The design for serviceability is possibility the most difficult and least well understood aspect of the design of concrete structures. Service load behaviour depends primarily on the properties of the concrete and these are often not known reliably at the design stage. Moreover, concrete behaves in a non-linear and inelastic manner at service loads. The non-linear behaviour that complicates serviceability calculations is due to cracking, tension stiffening, creep, and shrinkage. Of these, shrinkage is the most problematic. Restraint to shrinkage causes time-dependent cracking and gradually reduces the beneficial effects of tension stiffening. It results in a gradual widening of existing cracks and, in flexural members, a significant increase in deflections with time.The control of cracking in a reinforced or prestressed concrete structure is usually achieved by limiting the stress increment in the bonded reinforcement to some appropriately low value and ensuring that the bonded reinforcement is suitably distributed. Many codes of practice specify maximum steel stress increments after cracking and maximum spacing requirements for the bonded reinforcement. However, few existing code procedures, if any, account adequately for the gradual increase in existing crack widths with time, due primarily to shrinkage, or the time-dependent development of new cracks resulting from tensile stresses caused by restraint to shrinkage.For deflection control, the structural designer should select maximum deflection limits that are appropriate to the structure and its intended use. The calculated deflection (or camber) must not exceed these limits. Codes of practice give general guidance for both the selection of the maximum deflection limits and the calculation of deflection. However, the simplified procedures for calculating e J S E Internationaldeflection in most codes were developed from tests on simply-supported reinforced concrete beams and often produce grossly inaccurate predictions when applied to more complex structures. Again, the existing code procedures do not provide real guidance on how to adequately model the time-dependent effects of creep and shrinkage in deflection calculations.Serviceability failures of concrete structures involving excessive cracking and/or excessive deflection are relatively common. Numerous cases have been reported, in Australia and elsewhere, of structures that complied with code requirements but still deflected or cracked excessively. In a large majority of these failures, shrinkage of concrete is primarily responsible. Clearly, the serviceability provisions embodied in our codes do not adequately model the in-service behaviour of structures and, in particular, fail to account adequately for shrinkage.The quest for serviceable concrete structures must involve the development of more reliable design procedures. It must also involve designers giving more attention to the specification of an appropriate concrete mix, particularly with regard to the creep and shrinkage characteristics of the mix, and sound engineering input is required in the construction procedures. High performance concrete structures require the specification of high performance concrete (not necessarily high strength concrete, but concrete with relatively low shrinkage, not prone to plastic shrinkage cracking) and a high standard of construction, involving suitably long stripping times, adequate propping, effective curing procedures and rigorous on-site supervision.This paper addresses some of these problems, particularly those related to designing for the effects of shrinkage. It outlines how shrinkage affects the in-service behaviour of structures and what to do about it in design. It also provides an overview of the considerations currently being made by the working group established by Standards Australia to revise the serviceability provisions of AS3600-1994 [1], particularly those clauses related to shrinkage.2. Designing for ServiceabilityWhen designing for serviceability, the designer must ensure that the structure can perform its intended function under the day to day service loads. Deflection must not be excessive, cracks must be adequately controlled and no portion of the structure should suffer excessive vibration. Shrinkage causes time-dependent cracking, thereby reducing the stiffness of a concrete structure, and is therefore a detrimental factor in all aspects of the design for serviceability.Deflection problems that may affect the serviceability of concrete structures can be classified into three main types:(a)Where excessive deflection causes either aesthetic or functional problems.(b)Where excessive deflection results in damage to either structural or non-structural elementattached to the member.(c)Where dynamics effects due to insufficient stiffness cause discomfort to occupants.3. Effects of ShrinkageIf concrete members were free to shrink, without restraint, shrinkage of concrete would not be a major concern to structural engineers. However, this is not the case. The contraction of a concrete member is often restrained by its supports or by the adjacent structure. Bonded reinforcement also restrains shrinkage. Each of these forms of restraint involve the imposition of a gradually increasing tensile force on the concrete which may lead to time-dependent cracking (in previously uncracked regions), increases in deflection and a widening of existing cracks. Restraint to shrinkage is probably the most common cause of unsightly cracking in concrete structures. In many cases, these problemsarise because shrinkage has not been adequately considered by the structural designer and the effects of shrinkage are not adequately modelled in the design procedures specified in codes of practice for crack control and deflection calculation.The advent of shrinkage cracking depends on the degree of restraint to shrinkage, the extensibility and strength of the concrete in tension, tensile creep and the load induced tension existing in the member. Cracking can only be avoided if the gradually increasing tensile stress induced by shrinkage, and reduced by creep, is at all times less than the tensile strength of the concrete. Although the tensile strength of concrete increases with time, so too does the elastic modulus and, therefore, so too does the tensile stress induced by shrinkage. Furthermore, the relief offered by creep decreases with age. The existence of load induced tension in uncracked regions accelerates the formation of time-dependent cracking. In many cases, therefore, shrinkage cracking is inevitable. The control of such cracking requires two important steps. First, the shrinkage-induced tension and the regions where shrinkage cracks are likely to develop must be recognised by the structural designer. Second, an adequate quantity and distribution of anchored reinforcement must be included in these regions to ensure that the cracks remain fine and the structure remains serviceable.3.1 What is Shrinkage?Shrinkage of concrete is the time-dependent strain measured in an unloaded and unrestrained specimen at constant temperature. It is important from the outset to distinguish between plastic shrinkage, chemical shrinkage and drying shrinkage. Some high strength concretes are prone to plastic shrinkage, which occurs in the wet concrete, and may result in significant cracking during the setting process. This cracking occurs due to capillary tension in the pore water. Since the bond between the plastic concrete and the reinforcement has not yet developed, the steel is ineffective in controlling such cracks. This problem may be severe in the case of low water content, silica fume concrete and the use of such concrete in elements such as slabs with large exposed surfaces is not recommended.Drying shrinkage is the reduction in volume caused principally by the loss of water during the drying process. Chemical (or endogenous) shrinkage results from various chemical reactions within the cement paste and includes hydration shrinkage, which is related to the degree of hydration of the binder in a sealed specimen. Concrete shrinkage strain, which is usually considered to be the sum of the drying and chemical shrinkage components, continues to increase with time at a decreasing rate.Shrinkage is assumed to approach a final value, *sc ε, as time approaches infinity and is dependent onall the factors which affect the drying of concrete, including the relative humidity and temperature, the mix characteristics (in particular, the type and quantity of the binder, the water content and water-to-cement ratio, the ratio of fine to coarse aggregate, and the type of aggregate), and the size and shape of the member.Drying shrinkage in high strength concrete is smaller than in normal strength concrete due to the smaller quantities of free water after hydration. However, endogenous shrinkage is significantly higher.For normal strength concrete (50≤'c f MPa), AS3600 suggests that the design shrinkage (which includes both drying and endogenous shrinkage) at any time after the commencement of drying may be estimated fromb cs cs k .1εε=(1)where b cs .ε is a basic shrinkage strain which, in the absence of measurements, may be taken to be 850 x 10-6 (note that this value was increased from 700 x 10-6 in the recent Amendment 2 of the Standard); k 1 is obtained by interpolation from Figure 6.1.7.2 in the Standard and depends on the time since the commencement of drying, the environment and the concrete surface area to volume ratio. A hypothetical thickness, t h = 2A / u e , is used to take this into account, where A is the cross-sectional area of the member and u e is that portion of the section perimeter exposed to the atmosphere plus half the total perimeter of any voids contained within the section.AS3600 states that the actual shrinkage strain may be within a range of plus or minus 40% of the value predicted (increased from ± 30% in Amendment 2 to AS3600-1994). In the writer’s opin ion, this range is still optimistically narrow, particularly when one considers the size of the country and the wide variation in shrinkage measured in concretes from the various geographical locations. Equation 1 does not include any of the effects related to the composition and quality of the concrete. The same value of εcs is predicted irrespective of the concrete strength, the water-cement ratio, the aggregate type and quantity, the type of admixtures, etc. In addition, the factor k 1 tends to overestimate the effect of member size and significantly underestimate the rate of shrinkage development at early ages.The method should be used only as a guide for concrete with a low water-cement ratio (<0.4) and with a well graded, good quality aggregate. Where a higher water-cement ratio is expected or when doubts exist concerning the type of aggregate to be used, the value of εcs predicted by AS3600 should be increased by at least 50%. The method in the Standard for the prediction of shrinkage strain is currently under revision and it is quite likely that significant changes will be proposed with the inclusion of high strength concretes.A proposal currently being considered by Standards Australia, and proposed by Gilbert (1998) [9], involves the total shrinkage strain, εcs , being divided into two components, endogenous shrinkage, εcse , (which is assumed to develop relatively rapidly and increases with concrete strength) and drying shrinkage, εcsd (which develops more slowly, but decreases with concrete strength). At any time t (in days) after pouring, the endogenous shrinkage is given byεcse = ε*cse (1.0 - e -0.1t ) (2) where ε*cse is the final endogenous shrinkage and may be taken as ε*cse 610)503(-⨯-'=c f , wherec f ' is in MPa. The basic drying shrinkage *csd ε is given by66*1025010)81100(--⨯≥⨯'-=c csd f ε(3) and at any time t (in days) after the commencement of drying, the drying shrinkage may be taken as*1csd csd k εε= (4)The variable 1k is given by )7/(8.08.0541h t t t k k k += (5) where h t e k 005.042.18.0-+= and 5k is equal to 0.7 for an arid environment, 0.6 for a temperate environment and 0.5 for a tropical/coastal environment. For an interior environment, k 5 may be taken as 0.65. The value of k 1 given by Equation 5 has the same general shape as that given in Figure6.1.7.2 in AS3600, except that shrinkage develops more rapidly at early ages and the reduction in drying shrinkage with increasing values of t h is not as great.The final shrinkage at any time is therefore the sum of the endogenous shrinkage (Equation 2) and the drying shrinkage (Equation 4). For example, for specimens in an interior environment with hypothetical thicknesses t h = 100 mm and t h = 400 mm, the shrinkage strains predicted by the above model are given in Table 1. Table 1 Design shrinkage strains predicted by proposed model for an interior environment. h t c f ' *cse ε (x 10-6)*csd ε(x 10-6) Strain at 28 days (x 10-6) Strain at 10000 days (x 10-6) cse ε csd ε cs ε cse ε csd ε cs ε 100 2525 900 23 449 472 25 885 910 50100 700 94 349 443 100 690 790 75175 500 164 249 413 175 493 668 100250 300 235 150 385 250 296 546 4002525 900 23 114 137 25 543 568 50100 700 94 88 182 100 422 522 75175 500 164 63 227 175 303 478 100 250 300 235 38 273 250 182 4323.2 Shrinkage in Unrestrained and Unreinforced Concrete (Gilbert, 1988) [7]Drying shrinkage is greatest at the surfaces exposed to drying and decreases towards the interior of a concrete member. In Fig.1a , the shrinkage strains through the thickness of a plain concrete slab, drying on both the top and bottom surfaces, are shown. The slab is unloaded and unrestrained.The mean shrinkage strain, εcs in Fig. 1, is the average contraction. The non-linear strain labelled ∆εcs is that portion of the shrinkage strain that causes internal stresses to develop. These self-equilibrating stresses (called eigenstresses) produce the elastic and creep strains required to restore compatibility (ie. to ensure that plane sections remain plane). These stresses occur in all concrete structures and are tensile near the drying surfaces and compressive in the interior of the member. Because the shrinkage-induced stresses develop gradually with time, they are relieved by creep. Nevertheless, the tensile stresses near the drying surfaces often overcome the tensile strength of the immature concrete and result in surface cracking, soon after the commencement of drying. Moist curing delays the commencement of drying and may provide the concrete time to develop sufficient tensile strength to avoid unsightly surface cracking.Fig. 1 - Strain components caused by shrinkage in a plain concrete slab.The elastic plus creep strains caused by the eigenstresses are equal and opposite to ∆εcs and are shown in Fig. 1b. The total strain distribution, obtained by summing the elastic, creep and shrinkage strain components, is linear (Fig. 1c) thus satisfying compatibility. If the drying conditions are the same at both the top and bottom surfaces, the total strain is uniform over the depth of the slab and equal to the mean shrinkage strain, εcs . It is this quantity that is usually of significance in the analysis of concrete structures. If drying occurs at a different rate from the top and bottom surfaces, the total strain distribution becomes inclined and a warping of the member results.4. Control of deflectionThe control of deflections may be achieved by limiting the calculated deflection to an acceptably small value. Two alternative general approaches for deflection calculation are specified in AS3600 (1), namely ‘deflection by refined calculation’ (Clause 9.5.2 for beams and Clause 9.3.2 for slabs) and ‘deflection by simplified calculation’ (Clause 9.5.3 for beams and Clause 9.3.3 for slabs). The former is not specified in detail but allowance should be made for cracking and tension stiffening, the shrinkage and creep properties of the concrete, the expected load history and, for slabs, the two-way action of the slab. 呵呵The long-term or time-dependent behaviour of a beam or slab under sustained service loads can be determined using a variety of analytical procedures (Gilbert, 1988) [7], including the Age-Adjusted Effective Modulus Method (AEMM), described in detail by Gilbert and Mickleborough (1997) [12]. The use of the AEMM to determine the instantaneous and time-dependent deformation of the critical cross-sections in a beam or slab and then integrating the curvatures to obtain deflection, is a refined calculation method and is recommended.Using the AEMM, the strain and curvature on individual cross-sections at any time can be calculated, as can the stress in the concrete and bonded reinforcement or tendons. The routine use of the AEMM in the design of concrete structures for the serviceability limit states is strongly encouraged.5. Control of flexural crackingIn AS3600-1994, the control of flexural cracking is deemed to be satisfactory, providing the designer satisfies certain detailing requirements. These involve maximum limits on the centre-to-centre spacing of bars and on the distance from the side or soffit of the beam to the nearest longitudinal bar. These limits do not depend on the stress in the tensile steel under service loads and have been found to be unreliable when the steel stress exceeds about 240 MPa. The provisions of AS3600-1994 over-simplify the problem and do not always ensure adequate control of cracking.With the current move to higher strength reinforcing steels (characteristic strengths of 500 MPa and above), there is an urgent need to review the crack-control design rules in AS3600 for reinforced concrete beams and slabs. The existing design rules for reinforced concrete flexural elements are intended for use in the design of elements containing 400 MPa bars and are sometimes unconservative. They are unlikely to be satisfactory for members in which higher strength steels are used, where steel stresses at service loads are likely to be higher due to the reduced steel area required for strength.6. ConclusionsThe effects of shrinkage on the behaviour of reinforced and prestressed concrete members under sustained service loads has been discussed. In particular, the mechanisms of shrinkage warping in unsymmetrically reinforced elements and shrinkage cracking in restrained direct tension members has been described. Recent amendments to the serviceability provisions of AS3600 have beenoutlined and techniques for the control of deflection and cracking are presented. Reliable procedures for the prediction of long-term deflections and final crack widths in flexural members have also been proposed and illustrated by examples.收缩，开裂和变形–混凝土结构使用的可靠性里吉尔伯特土木及环境工程学校校长兼教授新南威尔士大学，悉尼，新南威尔士州 2052 号电子邮件：******************.au摘要本文讨论收缩对混凝土结构可靠性的影响，它概述了为什么收缩是重要的，它的主要影响，即对结构最终的开裂程度和挠度大小的影响，以及在设计中应该注意什么？有一种模型可以预测在普通混凝土、高强度混凝土、不稳定性普通混凝土和钢筋混凝土中的收缩应变，无论有没有外部约束的情况下，都可以用这种模型来解释。
混凝土工艺中英文对照外文翻译文献
混凝土工艺中英文对照外文翻译文献混凝土工艺中英文对照外文翻译文献混凝土工艺中英文对照外文翻译文献(文档含英文原文和中文翻译) Concrete technology and developmentPortland cement concrete has clearly emerged as the material of choice for the construction of a large number and variety of structures in the world today. This is attributed mainly to low cost of materials and construction for concrete structures as well as low cost of maintenance.Therefore, it is not surprising that many advancements in concrete technology have occurred as a result of two driving forces, namely the speed of construction and the durability of concrete.During the period 1940-1970, the availability of high early strength portland cements enabled the use of high water content in concrete mixtures that were easy to handle. This approach, however, led to serious problems with durability of structures, especially those subjected to severe environmental exposures.With us lightweight concrete is a development mainly of the last twenty years.Concrete technology is the making of plentiful good concrete cheaply. It includes the correct choice of the cement and the water, and the right treatment of the aggregates. Those which are dug near by and therefore cheap, must be sized, washed free of clay or silt, and recombined in the correct proportions so as to make a cheap concrete which is workable at a low water/cement ratio, thus easily comoacted to a high density and therefore strong.It hardens with age and the process of hardening continues for a long time after the concrete has attained sufficient strength.Abrams’law, perhaps the oldest law of concrete technology, states that the strength of a concrete varies inversely with its water cement ratio. This means that the sand content (particularly the fine sand which needs much water) must be reduced so far as possible. The fact that the sand “drinks” large quantities of water can easily be established by mixing several batches of x kg of cement with y kg of stone and the same amount of water but increasing amounts of sand. However if there is no sand the concrete will be so stiff that it will be unworkable thereforw porous and weak. The same will be true if the sand is too coarse. Therefore for each set of aggregates, the correct mix must not be changed without good reason. This applied particularly to the water content.Any drinkable and many undrinkable waters can be used for making concrete, including most clear waters from the sea or rivers. It is important that clay should be kept out of the concrete. The cement if fresh can usually be chosen on the basis of the maker’s certificates of tensile or crushing tests, but these are always made with fresh cement. Where strength is important , and the cement at the site is old, it should be tested.This stress , causing breakage,will be a tension since concretes are from 9 to 11times as strong in compression as in tension, This stress, the modulus of rupture, will be roughly double the direct tensile breaking stress obtained in a tensile testing machine,so a very rough guess at the conpressive strength can be made by multiplying the modulus of rupture by 4.5. The method can be used in combination with the strength results of machine-crushed cubes or cylinders or tensile test pieces but cannot otherwise be regarded as reliable. With these comparisons,however, it is suitable for comparing concretes on the same site made from the same aggregates and cement, with beams cast and tested in the same way.Extreme care is necessary for preparation,transport,plating and finish of concrete in construction works.It is important to note that only a bit of care and supervision make a great difference between good and bad concrete.The following factors may be kept in mind in concreting works.MixingThe mixing of ingredients shall be done in a mixer as specified in the contract.Handling and ConveyingThe handling&conveying of concrete from the mixer to the place of final deposit shall be done as rapidly as practicable and without any objectionable separation or loss of ingredients.Whenever the length of haul from the mixing plant to the place of deposit is such that the concrete unduly compacts or segregates,suitable agitators shall be installed in the conveying system.Where concrete is being conveyed on chutes or on belts,the free fall or drop shall be limited to 5ft.(or 150cm.) unless otherwise permitted.The concrete shall be placed in position within 30 minutes of its removal from the mixer.Placing ConcreteNo concrete shall be placed until the place of deposit has been thoroughly inspected and approved,all reinforcement,inserts and embedded metal properly security in position and checked,and forms thoroughly wetted(expect in freezing weather)or oiled.Placing shall be continued without avoidable interruption while the section is completed or satisfactory construction joint made.Within FormsConcrete shall be systematically deposited in shallow layers and at such rate as to maintain,until the completion of the unit,a plastic surface approximately horizontal throughout.Each layer shall be thoroughly compacted before placing the succeeding layer.CompactingMethod. Concrete shall be thoroughly compacted by means of suitable tools during and immediately after depositing.The concrete shall be worked around all reinforcement,embedded fixtures,and into the comers of the forms.Every precaution shall be taken to keep the reinforcement and embedded metal in proper position and to prevent distortion.Vibrating. Wherever practicable,concrete shall be internally vibrated within the forms,or in the mass,in order to increase the plasticity as to compact effectively to improve the surface texture and appearance,and to facilitate placing of the concrete.Vibration shall be continued the entire batch melts to a uniform appearance and the surface just starts to glisten.A minute film of cement paste shall be discernible between the concrete and the form and around the reinforcement.Over vibration causing segregation,unnecessary bleeding or formation of laitance shall be avoided.The effect spent on careful grading, mixing and compaction of concrete will be largely wasted if the concrete is badly cured. Curing means keeping the concretethoroughly damp for some time, usually a week, until it has reached the desired strength. So long as concrete is kept wet it will continue to gain strength, though more slowly as it grows older.Admixtures or additives to concrete are materials arematerials which are added to it or to the cement so as to improve one or more of the properties of the concrete. The main types are:1. Accelerators of set or hardening,2. Retarders of set or hardening,3. Air-entraining agents, including frothing or foaming agents,4. Gassing agents,5. Pozzolanas, blast-furnace slag cement, pulverized coal ash,6. Inhibitors of the chemical reaction between cement and aggregate, which might cause the aggregate to expand7. Agents for damp-proofing a concrete or reducing its permeability to water,8. Workability agents, often called plasticizers,9. Grouting agents and expanding cements.Wherever possible, admixtures should be avouded, particularly those that are added on site. Small variations in the quantity added may greatly affect the concrete properties in an undesiraale way. An accelerator can often be avoided by using a rapid-hardening cement or a richer mix with ordinary cement, or for very rapid gain of strength, high-alumina cement, though this is very much more expensive, in Britain about three times as costly as ordinary Portland cement. But in twenty-four hours its strength is equal to that reached with ordinary Portland cement in thirty days.A retarder may have to be used in warm weather when a large quantity of concrete has to be cast in one piece of formwork, and it is important that the concrete cast early in the day does not set before the last concrete. This occurs with bridges when they are cast in place, and the formwork necessarily bends underthe heavy load of the wet concrete. Some retarders permanently weaken the concrete and should not be used without good technical advice.A somewhat similar effect,milder than that of retarders, is obtained with low-heat cement. These may be sold by the cement maker or mixed by the civil engineering contractor. They give out less heat on setting and hardening, partly because they harden more slowly, and they are used in large casts such as gravity dams, where the concrete may take years to cool down to the temperature of the surrounding air. In countries like Britain or France, where pulverized coal is burnt in the power stations, the ash, which is very fine, has been mixed with cement to reduce its production of heat and its cost without reducing its long-term strength. Up to about 20 per cent ash by weight of the cement has been successfully used, with considerable savings in cement costs.In countries where air-entraining cement cement can be bought from the cement maker, no air-entraining agent needs to be mixed in .When air-entraining agents draw into the wet cement and concrete some 3-8 percent of air in the form of very small bubbles, they plasticize the concrete, making it more easily workable and therefore enable the water |cement ratio to be reduced. They reduce the strength of the concrete slightly but so little that in the United States their use is now standard practice in road-building where heavy frost occur. They greatly improve the frost resistance of the concrete.Pozzolane is a volcanic ash found near the Italian town of Puzzuoli, which is a natural cement. The name has been given to all natural mineral cements, as well as to the ash from coal or the slag from blast furnaces, both of which may become cementswhen ground and mixed with water. Pozzolanas of either the industrial or the mineral type are important to civil engineers because they have been added to oridinary Portland cement in proportions up to about 20 percent without loss of strength in the cement and with great savings in cement cost. Their main interest is in large dams, where they may reduce the heat given out by the cement during hardening. Some pozzolanas have been known to prevent the action between cement and certain aggregates which causes the aggregate to expand, and weaken or burst the concrete.The best way of waterproof a concrete is to reduce its permeability by careful mix design and manufacture of the concrete, with correct placing and tighr compaction in strong formwork ar a low water|cement ratio. Even an air-entraining agent can be used because the minute pores are discontinuous. Slow, careful curing of the concrete improves the hydration of the cement, which helps to block the capillary passages through the concrete mass. An asphalt or other waterproofing means the waterproofing of concrete by any method concerned with the quality of the concrete but not by a waterproof skin.Workability agents, water-reducing agents and plasticizers are three names for the same thing, mentioned under air-entraining agents. Their use can sometimes be avoided by adding more cement or fine sand, or even water, but of course only with great care.The rapid growth from 1945 onwards in the prestressing of concrete shows that there was a real need for this high-quality structural material. The quality must be high because the worst conditions of loading normally occur at the beginning of the life of the member, at the transfer of stress from the steel to theconcrete. Failure is therefore more likely then than later, when the concrete has become stronger and the stress in the steel has decreased because of creep in the steel and concrete, and shrinkage of the concrete. Faulty members are therefore observed and thrown out early, before they enter the structure, or at least before it The main advantages of prestressed concrete in comparison with reinforced concrete are :①The whole concrete cross-section resists load. In reinforced concrete about half the section, the cracked area below the neutral axis, does no useful work. Working deflections are smaller.②High working stresses are possible. In reinforced concrete they are not usually possible because they result in severe cracking which is always ugly and may be dangerous if it causes rusting of the steel.③Cracking is almost completely avoided in prestressed concrete.The main disadvantage of prestressed concrete is that much more care is needed to make it than reinforced concrete and it is therefore more expensive, but because it is of higher quality less of it needs to be needs to be used. It can therefore happen that a solution of a structural problem may be cheaper in prestressed concrete than in reinforced concrete, and it does often happen that a solution is possible with prestressing but impossible without it.Prestressing of the concrete means that it is placed under compression before it carries any working load. This means that the section can be designed so that it takes no tension or very little under the full design load. It therefore has theoretically no cracks and in practice very few. The prestress is usually applied by tensioning the steel before the concrete in which it isembedded has hardened. After the concrete has hardened enough to take the stress from the steel to the concrete. In a bridge with abutments able to resist thrust, the prestress can be applied without steel in the concrete. It is applied by jacks forcing the bridge inwards from the abutments. This methods has the advantage that the jacking force, or prestress, can be varied during the life of the structure as required.In the ten years from 1950 to 1960 prestressed concrete ceased to be an experinmental material and engineers won confidence in its use. With this confidence came an increase in the use of precast prestressed concrete particularly for long-span floors or the decks of motorways. Whereever the quantity to be made was large enough, for example in a motorway bridge 500 m kong , provided that most of the spans could be made the same and not much longer than 18m, it became economical to usefactory-precast prestressed beams, at least in industrial areas near a precasting factory prestressed beams, at least in industrial areas near a precasting factory. Most of these beams are heat-cured so as to free the forms quickly for re-use.In this period also, in the United States, precast prestressed roof beams and floor beams were used in many school buildings, occasionally 32 m long or more. Such long beams over a single span could not possibly be successful in reinforced concrete unless they were cast on site because they would have to be much deeper and much heavier than prestressed concrete beams. They would certainlly be less pleasing to the eye and often more expensive than the prestressed concrete beams. These school buildings have a strong, simple architectural appeal and will be a pleasure to look at for many years.The most important parts of a precast prestressed concrete beam are the tendons and the concrete. The tendons, as the name implies, are the cables, rods or wires of steel which are under tension in the concrete.Before the concrete has hardened (before transfer of stress), the tendons are either unstressed (post-tensioned prestressing) or are stressed and held by abutments outside the concrete ( pre-tensioned prestressing). While the concrete is hardening it grips each tendon more and more tightly by bond along its full length. End anchorages consisting of plates or blocks are placed on the ends of the tendons of post-tensioned prestressed units, and such tendons are stressed up at the time of transfer, when the concrete has hardened sufficiently. In the other type of pretressing, with pre-tensioned tendons, the tendons are released from external abutments at the moment of transfer, and act on the concrete through bond or archorage or both, shortening it by compression, and themselves also shortening and losing some tension.Further shortening of the concrete (and therefore of the steel) takes place with time. The concrete is said to creep. This means that it shortens permanently under load and spreads the stresses more uniformly and thus more safely across its section. Steel also creeps, but rather less. The result of these two effects ( and of the concrete shrinking when it dries ) is that prestressed concrete beams are never more highly stressed than at the moment of transfer.The factory precasting of long prestressed concrete beams is likely to become more and more popular in the future, but one difficulty will be road transport. As the length of the beam increases, the lorry becomes less and less manoeuvrable untileventually the only suitable time for it to travel is in the middle of the night when traffic in the district and the route, whether the roads are straight or curved. Precasting at the site avoids these difficulties; it may be expensive, but it has often been used for large bridge beams.混凝土工艺及发展波特兰水泥混凝土在当今世界已成为建造数量繁多、种类复杂结构的首选材料。
混凝土工艺中英文对照外文翻译文献
混凝土工艺中英文对照外文翻译文献混凝土工艺中英文对照外文翻译文献(文档含英文原文和中文翻译)Concrete technology and developmentPortland cement concrete has clearly emerged as the material of choice for the construction of a large number and variety of structures in the world today. This is attributed mainly to low cost of materials and construction for concrete structures as well as low cost of maintenance.Therefore, it is not surprising that many advancements in concrete technology have occurred as a result of two driving forces, namely the speed of construction and the durability of concrete.During the period 1940-1970, the availability of high early strength portland cements enabled the use of high water content in concrete mixtures that were easy to handle. This approach, however, led to serious problems with durability of structures, especially those subjected to severe environmental exposures.With us lightweight concrete is a development mainly of the last twenty years.Concrete technology is the making of plentiful good concrete cheaply. It includes the correct choice of the cement and the water, and the right treatment of the aggregates. Those which are dug near by and therefore cheap, must be sized, washed free of clay or silt, and recombined in the correct proportions so as to make a cheap concrete which is workable at a low water/cement ratio, thus easily comoacted to a high density and therefore strong.It hardens with age and the process of hardening continues for a long time after the concrete has attained sufficient strength.Abrams’law, perhaps the oldest law of concrete technology, states that the strength of a concrete varies inversely with its water cement ratio. This means that the sand content (particularly the fine sand which needs much water) must be reduced so far as possible. The fact that the sand “drinks” large quantities of water can easily be established by mixing several batches of x kg of cement with y kg of stone and the same amount of water but increasing amounts of sand. However if there is no sand the concrete will be so stiff that it will be unworkable thereforw porous and weak. The same will be true if the sand is too coarse. Therefore for each set of aggregates, the correct mix must not be changed without good reason. This applied particularly to the water content.Any drinkable and many undrinkable waters can be used for making concrete, including most clear waters from the sea or rivers. It is important that clay should be kept out of the concrete. The cement if fresh can usually be chosen on the basis of the maker’s certificates of tensile or crushing tests, but these are always made with fresh cement. Where strength is important , and the cement at the site is old, it should be tested.This stress , causing breakage,will be a tension since concretes are from 9 to 11times as strong in compression as in tension, This stress, the modulus of rupture, will be roughly double the direct tensile breaking stress obtained in a tensile testing machine,so a very rough guess at the conpressive strength can be made by multiplying the modulus of rupture by 4.5. The method can be used in combination with the strength results of machine-crushed cubes or cylinders or tensile test pieces but cannot otherwise be regarded as reliable. With these comparisons, however, it is suitable for comparing concretes on the same site made from the same aggregates and cement, with beams cast and tested in the same way.Extreme care is necessary for preparation,transport,plating and finish of concrete in construction works.It is important to note that only a bit of care and supervision make a great difference between good and bad concrete.The following factors may be kept in mind in concreting works.MixingThe mixing of ingredients shall be done in a mixer as specified in the contract.Handling and ConveyingThe handling&conveying of concrete from the mixer to the place of final deposit shall be done as rapidly as practicable and without any objectionable separation or loss of ingredients.Whenever the length of haul from the mixing plant to the place of deposit is such that the concrete unduly compacts or segregates,suitable agitators shall be installed in the conveying system.Where concrete is being conveyed on chutes or on belts,the free fall or drop shall be limited to 5ft.(or 150cm.) unless otherwise permitted.The concrete shall be placed in position within 30 minutes of its removal from the mixer.Placing ConcreteNo concrete shall be placed until the place of deposit has been thoroughly inspected and approved,all reinforcement,inserts and embedded metal properly security in position and checked,and forms thoroughly wetted(expect in freezing weather)or oiled.Placing shall be continued without avoidable interruption while the section is completed or satisfactory construction joint made.Within FormsConcrete shall be systematically deposited in shallow layers and at such rate as to maintain,until the completion of the unit,a plastic surface approximately horizontal throughout.Each layer shall be thoroughly compacted before placing the succeeding layer.CompactingMethod. Concrete shall be thoroughly compacted by means of suitable tools during and immediately after depositing.The concrete shall be worked around all reinforcement,embedded fixtures,and into the comers of the forms.Every precaution shall be taken to keep the reinforcement and embedded metal in proper position and to prevent distortion.Vibrating. Wherever practicable,concrete shall be internally vibrated within the forms,or in the mass,in order to increase the plasticity as to compact effectively to improve the surface texture and appearance,and to facilitate placing of the concrete.Vibration shall be continued the entire batch melts to a uniform appearance and the surface just starts to glisten.A minute film of cement paste shall be discernible between the concrete and the form and around the reinforcement.Over vibration causing segregation,unnecessary bleeding or formation of laitance shall be avoided.The effect spent on careful grading, mixing and compaction of concrete will be largely wasted if the concrete is badly cured. Curing means keeping the concretethoroughly damp for some time, usually a week, until it has reached the desired strength. So long as concrete is kept wet it will continue to gain strength, though more slowly as it grows older.Admixtures or additives to concrete are materials are materials which are added to it or to the cement so as to improve one or more of the properties of the concrete. The main types are:1. Accelerators of set or hardening,2. Retarders of set or hardening,3. Air-entraining agents, including frothing or foaming agents,4. Gassing agents,5. Pozzolanas, blast-furnace slag cement, pulverized coal ash,6. Inhibitors of the chemical reaction between cement and aggregate, which might cause the aggregate to expand7. Agents for damp-proofing a concrete or reducing its permeability to water,8. Workability agents, often called plasticizers,9. Grouting agents and expanding cements.Wherever possible, admixtures should be avouded, particularly those that are added on site. Small variations in the quantity added may greatly affect the concrete properties in an undesiraale way. An accelerator can often be avoided by using a rapid-hardening cement or a richer mix with ordinary cement, or for very rapid gain of strength, high-alumina cement, though this is very much more expensive, in Britain about three times as costly as ordinary Portland cement. But in twenty-four hours its strength is equal to that reached with ordinary Portland cement in thirty days.A retarder may have to be used in warm weather when a large quantity of concrete has to be cast in one piece of formwork, and it is important that the concrete cast early in the day does not set before the last concrete. This occurs with bridges when they are cast in place, and the formwork necessarily bends under the heavy load of the wet concrete. Some retarders permanently weaken the concrete and should not be used without good technical advice.A somewhat similar effect,milder than that of retarders, is obtained with low-heat cement. These may be sold by the cement maker or mixed by the civil engineering contractor. They give out less heat on setting and hardening, partly because they harden more slowly, and they are used in large casts such as gravity dams, where the concrete may take years to cool down to the temperature of the surrounding air. In countries like Britain or France, where pulverized coal is burnt in the power stations, the ash, which is very fine, has been mixed with cement to reduce its production of heat and its cost without reducing its long-term strength. Up to about 20 per cent ash by weight of the cement has been successfully used, with considerable savings in cement costs.In countries where air-entraining cement cement can be bought from the cement maker, no air-entraining agent needs to be mixed in .When air-entraining agents draw into the wet cement and concrete some 3-8 percent of air in the form of very small bubbles, they plasticize the concrete, making it more easily workable and therefore enable the water |cement ratio to be reduced. They reduce the strength of the concrete slightly but so little that in the United States their use is now standard practice in road-building where heavy frost occur. They greatly improve the frost resistance of the concrete.Pozzolane is a volcanic ash found near the Italian town of Puzzuoli, which is a natural cement. The name has been given to all natural mineral cements, as well as to the ash from coal or the slag from blast furnaces, both of which may become cements when ground and mixed with water. Pozzolanas of either the industrial or the mineral type are important to civil engineers because they have been added to oridinary Portland cement in proportions up to about 20 percent without loss of strength in the cement and with great savings in cement cost. Their main interest is in large dams, where they may reduce the heat given out by the cement during hardening. Some pozzolanas have been known to prevent the action between cement and certain aggregates which causes the aggregate to expand, and weaken or burst the concrete.The best way of waterproof a concrete is to reduce its permeability by careful mix design and manufacture of the concrete, with correct placing and tighr compaction in strong formwork ar a low water|cement ratio. Even an air-entraining agent can be used because the minute pores are discontinuous. Slow, careful curing of the concrete improves the hydration of the cement, which helps to block the capillary passages through the concrete mass. An asphalt or other waterproofing means the waterproofing of concrete by any method concerned with the quality of the concrete but not by a waterproof skin.Workability agents, water-reducing agents and plasticizers are three names for the same thing, mentioned under air-entraining agents. Their use can sometimes be avoided by adding more cement or fine sand, or even water, but of course only with great care.The rapid growth from 1945 onwards in the prestressing of concrete shows that there was a real need for this high-quality structural material. The quality must be high because the worst conditions of loading normally occur at the beginning of the life of the member, at the transfer of stress from the steel to the concrete. Failure is therefore more likely then than later, when the concrete has become stronger and the stress in the steel has decreased because of creep in the steel and concrete, and shrinkage of the concrete. Faulty members are therefore observed and thrown out early, before they enter the structure, or at least before it The main advantages of prestressed concrete in comparison with reinforced concrete are :①The whole concrete cross-section resists load. In reinforced concrete about half the section, the cracked area below the neutral axis, does no useful work. Working deflections are smaller.②High working stresses are possible. In reinforced concrete they are not usually possible because they result in severe cracking which is always ugly and may be dangerous if it causes rusting of the steel.③Cracking is almost completely avoided in prestressed concrete.The main disadvantage of prestressed concrete is that much more care is needed to make it than reinforced concrete and it is therefore more expensive, but because it is of higher quality less of it needs to be needs to be used. It can therefore happen that a solution of a structural problem may be cheaper in prestressed concrete than in reinforced concrete, and it does often happen that a solution is possible with prestressing but impossible without it.Prestressing of the concrete means that it is placed under compression before it carries any working load. This means that the section can be designed so that it takes no tension or very little under the full design load. It therefore has theoretically no cracks and in practice very few. The prestress is usually applied by tensioning the steel before the concrete in which it is embedded has hardened. After the concrete has hardened enough to take the stress from the steel to the concrete. In a bridge with abutments able to resist thrust, the prestress can be applied without steel in the concrete. It is applied by jacks forcing the bridge inwards from the abutments. This methods has the advantage that the jacking force, or prestress, can be varied during the life of the structure as required.In the ten years from 1950 to 1960 prestressed concrete ceased to be an experinmental material and engineers won confidence in its use. With this confidence came an increase in the use of precast prestressed concrete particularly for long-span floors or the decks of motorways. Whereever the quantity to be made was large enough, for example in a motorway bridge 500 m kong , provided that most of the spans could be made the same and not much longer than 18m, it became economical to usefactory-precast prestressed beams, at least in industrial areas near a precasting factory prestressed beams, at least in industrial areas near a precasting factory. Most of these beams are heat-cured so as to free the forms quickly for re-use.In this period also, in the United States, precast prestressed roof beams and floor beams were used in many school buildings, occasionally 32 m long or more. Such long beams over a single span could not possibly be successful in reinforced concrete unless they were cast on site because they would have to be much deeper and much heavier than prestressed concrete beams. They would certainlly be less pleasing to the eye and often more expensive than the prestressed concrete beams. These school buildings have a strong, simple architectural appeal and will be a pleasure to look at for many years.The most important parts of a precast prestressed concrete beam are the tendons and the concrete. The tendons, as the name implies, are the cables, rods or wires of steel which are under tension in the concrete.Before the concrete has hardened (before transfer of stress), the tendons are either unstressed (post-tensioned prestressing) or are stressed and held by abutments outside the concrete ( pre-tensioned prestressing). While the concrete is hardening it grips each tendon more and more tightly by bond along its full length. End anchorages consisting of plates or blocks are placed on the ends of the tendons of post-tensioned prestressed units, and such tendons are stressed up at the time of transfer, when the concrete has hardened sufficiently. In the other type of pretressing, with pre-tensioned tendons, the tendons are released from external abutments at the moment of transfer, and act on the concrete through bond or archorage or both, shortening it by compression, and themselves also shortening and losing some tension.Further shortening of the concrete (and therefore of the steel) takes place with time. The concrete is said to creep. This means that it shortens permanently under load and spreads the stresses more uniformly and thus more safely across its section. Steel also creeps, but rather less. The result of these two effects ( and of the concrete shrinking when it dries ) is that prestressed concrete beams are never more highly stressed than at the moment of transfer.The factory precasting of long prestressed concrete beams is likely to become more and more popular in the future, but one difficulty will be road transport. As the length of the beam increases, the lorry becomes less and less manoeuvrable until eventually the only suitable time for it to travel is in the middle of the night when traffic in the district and the route, whether the roads are straight or curved. Precasting at the site avoids these difficulties; it may be expensive, but it has often been used for large bridge beams.混凝土工艺及发展波特兰水泥混凝土在当今世界已成为建造数量繁多、种类复杂结构的首选材料。
建筑环境与设备工程毕业论文中英文资料外文翻译文献
建筑环境与设备工程毕业论文中英文资料外文翻译文献篇一：建筑环境与设备工程中英文对照外文翻译文献中英文对照外文翻译文献(文档含英文原文和中文翻译)原文：Ground Source Heat PumpAt present,energy is the most important element for the development of states’economy.Because of the good energy-saving effect,using regenerate resource of energy,and no pollution,the GROUND SOURCE HEAT PUMP AIR-CONDITION is used more and more popular now.In the system of the GROUND SOURCE HEAT PUMP AIR-CONDITION,the terminal devices what include the fan,the deep well pump,the circulate pump are the biggest energy-consumed part except the inner device as well as the compressor motor, etc.So it is very important and significant to make the terminal devices running in the mostenergy-saving condition.In this paper,the author founded on the GROUND SOURCE HEAT PUMP AIR-CONDITION in Guangxi University,based on the actual project condition, made the redesign through the way of frequency conversiontechnology for the old system of GROUND SOURCE HEAT PUMP AIR-CONDITION.At first, the equipments’ running control system were improved following the energy-saving principle of fan and pump,choused Mitsubishi FR series frequency transducer with vector-controlfunction,Mitsubishi FX2N series PLC and other auxiliary parts to make up of the auto-control system for the GROUND SOURCE HEAT PUMP AIR-CONDITION,and then did the emulating analysis for the vector-control mode in the frequency conversion process.In the next based the auto-control system,made the PLC control system designing.This system monitor the temperature and flux in accurate and real time,then input feedback to the plc,finally the terminal device running status will correspond to the customer’s demanded-load,it can wellmeet the goal for saving energy and prolong the life of the motor and other device.At the same time,designed the PLC control process,according to this transformation of the specific programme,programmed for the PLC by using the FX-GP/WIN-C programme software.Researched and analyses the PIDalgorithm and its improved algorithm for the PID Operational module in the PLC.At last,through detailed analysis and accounted for energy-saving effect and the cost of thesystem-reforming,validated the profitability of this redesigned-project,and showed its feasibility and worthBe using renewable geothermal energy in shallow ground layer, a ground source heat pump (GSHP) technology is known as one of air conditioning techniques which have the greatest developmental. The GSHP has great potentials in energy reduction and in reducing CO2emissions to conventional HVAC systems. In China, energy shortage and environmental issues pose a seriouschallenge accompanied by rapid economic growth. GSHP has been spotlighted as both energy efficiency and environmental benefits. Generally, the initial investment for a GCHP system is higher than that of a conventional system. GCHP energy savings will offset the higher installing cost in future. However, there are many aspects affecting the actual amount of energy saved, such as climate, building load, ground heat exchanger, heat pump, control, etc. Recently, a lot of research on the energy performance of GCHP has been carried out. However, most of these previous research projects evaluated the performance of GCHP system based on a laboratory scale or a small capacity system. There is little data documenting the long-term performance of a large-sized GCHP. Evalution and research on real world installed GCHP will provide a more accurate understanding of the current technology’s performance.The paper presented that the energy performance evaluation of two types of GSHPs based on actual operational data. The two types of GSHPs were ground-coupled heat pump system (GCHPs) and groundwater heat pump system (GWHPs) which were,respectively, installed in two apartment buildings of Wuhan, China. In one year, we monitored various operating parameters, including the outdoor temperature, the flow rate, electrical consumption, and the water temperature. The coefficient of performance (COP) values of system and chiller were determined based on a series of measurements. During residential GCHP system operation, the heat injection rate into soil is larger than the heatextraction rate out of soil. The COP of chillers of the GCHPs decreased significantly during the heating season due to the lowering of ground soil temperature. The system power consumption exhibited a strong linear relationship with outdoor temperature in both seasons and this suggests that normalizing power consumption against degree-days is a highly practical index in energy analysis in resident buildings, especially in winter.Some research topics were studied on the two actual cases. An exergy analysis of a ground water heat pump system on the actual operation was conduced. The energy efficiency and exergy loss and efficiency in each of the components of the system are detemined forthe average measured parameters obtained from the monitored results of the hottest month and the coldest month. Inefficient facts are found out and increased energy efficiencies of two proposed improvement measures were estimated. Lower approachtemperature is effective energy saving. In addition to the energy analysis, a full exergy analysis helps to identify the components where inefficiencies occur. An economic analysis model forGWHP was established to calculate energy consumption and operating cost based on a baseline condition. Plate heat exchanger flow rate and groundwater flow rate were optimization parameters according to different water price of the groundwater:GWHP survey data shows the impact of water price on groundwater flow rate in design. The long-term energy performances of theGWHPs and the GCHPs were investigated and compared with conventional HVAC systems and other GSHPs on literature data. A performances model was established base on the two cases to constrast the predictedperformance with the actual performance.Based on superposition theorem of geothermal heat exchangers (GHE), a inverse model for GHE, G-functions interpolationapproach was proposed. Linear interpolation method was adopted to fit G-functions. The method presented here uses the Nelder and Mead simplex algorithm as part of a parameter estimation algorithm to estimate G-function. For verification of G-functions interpolation approach, anumerical experimentation had been conducted where synthetic load on GHE was established. The simulation results with error and no error, were inversely modeled by G-functions interpolation approach and DST calibrated approach. The actual dataset of a small sized and a large sized GSHPs were also used in inverse modeling to verify the results from the G-functions interpolation approach. The small sized GSHPs was from literature. The large sized vertical GSHPs was the monitored case in the paper. A detailed DST model of a GHE has been calibrated to monitored data. The secondyear predicted temperatures calculated by the two models were compared with the measured. The results show the two approaches are reliable and have good performance of error tolerance. The error of GHE water temperature calculated by G-functions interpolation approach was less than DST calibrated approaches. The data error inversely modeled was mainly from recorded day data. As a extension study of the G-functions interpolation model, degree-day G-functions approach was proposed. The model was based on degree-day prediction load and can be applied on the residential buildings. The standard deviation of GHE water temperature by degree-day G-functions approach was larger than DST calibrated approaches. The result shows the appropriateness of degree-day G-functions interpolation approach for the quantitative modeling of GHE.This paper shows that the research on actual performance according measured data and presents two inverse models:G-functions interpolation model, degree-day G-functions model approach, which provides new methods for GHE inverse modelingWith the sustainable development theory being put forward in recent years, people pay more and more attention to energy efficiency and environmental protection. The Ground Source Heat Pump(GSHP) air-conditioning system has been a kind of new technology to save energy and protect environment. This paper gives an overview of technology economy analysis on GSHPAir-conditioning System and optimization design of its ground heat exchanger, which provide helpful suggestion to engineers.First, this paper gives an overview of the history of GSHP system in China and foreign countries. Based on the work principle of the GSHP system, thecharacteristics of three circulations have been proposed, which are the use of renewable energy saving and environmental friendly, etc. hi terms of technology economy, the GSHPair-conditioning system was compared with the air source heat pump system, the water source heat pump system and the traditional central air-conditioningsystem. Main indexes are given to evaluate the technology economy of the GSHP air-conditioning system.A practical project was used as an example for the analysis.Ground-loop heat exchanger is an important part of the GSHP air-conditioning system and deferent from other traditional air-conditioning systems. This paper gave detailed designing method of Ground-loop heat exchanger, including load calculation, pipe layout, choice of tubes and its material, antifreeze method, calculation of pressure drop, etc. Taken the GSHP air-conditioning system in the report room of Shandong Institute of Architecture and Engineering as an example, its design was analyzed and the optimization design of ground-loop heat exchanger was proposed.The people attention to energy efficiency and environmental protection,which decide thesustainable development of the country.The Ground Source Heat Pump(GSHP)air-conditioning system has been a kind of new technology to save energy and protect environment.This paper gives an overview of technologyeconomy analysis on GSHP Air-condition System and optimization design of its ground heat exchanger,which provide helpful suggestion toengineersFirst,this paper gives an overview of GSHP system in China and foreign countries. Based on the work principle of the GSHP system,the characteristics of three circulations have been proposed,which are the use of renewable energy saving and environmental friendly,etc.In teams of technology ,the GSHP air-conditioning system was compared with the air source heat pump system,the water source heat pump system and the traditional central air-conditioning system.Main indexes are given to evaluate the technology economy of GSHP air-conditoning篇二：建筑施工毕业论文中英文资料外文翻译文献建筑施工毕业论文中英文资料外文翻译文献Building construction concrete crack of prevention and processingAbstractThe crack problem of concrete is a widespread existence but again difficult in solve of engineering actual problem, this text carried on a study analysis to a little bit familiar crack problem in the concrete engineering, and aim at concrete the circumstance put forward some prevention, processing measure. Keyword:Concrete crack prevention processing ForewordConcrete is formed by a sand and gravel aggregate,cement,water and other materials but mixed heterogeneous brittle materials.Because the concrete construction transform with oneself, control etc. a series problem, harden model of in the concrete existence numerous tiny hole, spirit cave and tiny crack, is exactly because these beginning start blemish of existence just make the concrete present one some not and all the characteristic of quality.The tiny crack is a kind of harmless crack and accept concrete heavy, impermeable and a little bit other use function not a creation to endanger.But after the concrete besubjected to lotus carry, difference in temperature etc. function, tiny crack would continuously of expand with connect, end formation we can see without the aid of instruments of macro view the crack be also the crack that the concrete often say in the engineering.Concrete building and Component all take sewer to make of, because of crack of existence and development usually make inner part of reinforcing bar etc. materialcreation decay, lower reinforced concrete material of loading ability, durable and impermeable ability, influence building of external appearance, service life, severity will threat arrive people's life and property safety.A lot of all of crash of engineerings is because of the unsteady development of the crack with the result that.Modern age science research with a great deal of of the concrete engineering practice certificate, in the concrete engineering crack problem is ineluctable, also acceptable in certainly of the scope just need to adopt valid of measure will it endanger degree control at certain of scope inside.Thereinforced concrete norm is also explicit provision:Some structure at place of dissimilarity under the condition allow existence certain the crack of width.But at under construction should as far as possible adopt a valid measure control crack creation, make the structure don't appear crack possibly or as far as possible decrease crack of amount and width, particularly want to as far as possible avoid harmful crack of emergence, insure engineering quality thus.Concrete crack creation of the reason be a lot of and have already transformed to cause of crack:Such as temperature variety, constringency, inflation, the asymmetry sink to sink etc. reason cause of crack;Have outside carry the crack that the function cause;Protected environment not appropriate the crack etc. caused with chemical effect.Want differentiation to treat in the actual engineering, work°out a problem according to the actual circumstance.In the concrete engineering the familiar crack and the prevention1.Shrinkage crack and preventionShrinkage crack much appear after the concrete protect be over of a period of time or concrete sprinkle to build to complete behind of around a week.In the cement syrup humidity of evaporate would creation Shrinkage, and this kind of constringency is can't negative.Shrinkage crack of the creation be main is because of concrete inside outside humidity evaporate degree dissimilarity but cause to transform dissimilarity of result:The concrete is subjected to exterior condition of influence, surface humidity loss lead quick, transform bigger, inner part degree of humidity variety smaller transform smaller, bigger surface Shrinkage transform to be subjected to concrete inner part control, creation more big pull should dint but creation crack.The relativehumidity is more low, cement syrup body Shrinkage more big, Shrinkage crack be more easy creation.Shrinkage crack is much surface parallel lines form or the net shallow thin crack, width many between 0.05-0.2 mm, the flat surface part much see in the big physical volume concrete and follow it more in thinner beam plank short to distribute.Shrinkage crackusually the impermeability of influence concrete, cause the durable of the rust eclipse influence concrete of reinforcing bar, under the function of the water pressure dint would creation the water power split crack influence concrete of loading dint etc..Concrete Shrinkage be main with water ash of the concrete ratio, the dosage of the composition, cement of cement, gather to anticipate of the dosage of the property and dosage, in addition etc. relevant.Main prevention measure:While being to choose to use the constringency quantity smaller cement, general low hot water mire and powder ash from stove cement in the adoption, lower the dosage of cement.Two is a concrete of Shrinkage be subjected to water ash ratio of influence more big, water ash ratio more big, Shrinkage more big, so in the concrete match the ratio the design should as far as possible control good water ash ratio of choose to use, the Chan add in the meantime accommodation of reduce water.Three is strict control concrete mix blend with under construction of match ratio, use of concrete water quantity absolute can't big in match ratio design give settle of use waterquantity.Four is the earlier period which strengthen concrete to protect, and appropriate extension protect of concrete time.Winter construction want to be appropriate extension concrete heat preservation to overlay time, and brushing protect to protect.Five is a constitution the accommodation is in the concrete structure of the constringency sew.2.Plastic shrinkage cracking and preventionPlastic shrinkage is the concrete is before condense, surface because of lose water quicker but creation of constringency.The Plastic shrinkage crack is general at dry heat or strong wind the weather appear, crack's much presenting in the center breadth, both ends of the thin and the length be different, with each other not coherent appearance.Shorter crack general long 20-30 cm, the longer crack can reach to a 2-3 m, breadth 1-5 mm.It creation of main reason is:The concrete is eventually almosthaving no strength or strength before the final setting very small, perhaps concrete just eventually final setting but strength very hour, be subjected toheat or compare strong wind dint of influence, the concrete surface lose water to lead quick, result in in the capillary creation bigger negative press but make a concrete physical volume sharply constringency, but at this time the strength of concrete again can't resist its constringency, therefore creation cracked.The influence concrete Plastic shrinkage of the main factors of crack to have water ash ratio, concrete of condense time, environment temperature, wind velocity, relative humidity...etc..Main prevention measure:One is choose to use dry compression value smaller higher silicate of the earlier period strength or common the portland cement.Two is strict the control water ash ratio, the Chan add to efficiently reduce water to increment the collapse of concrete fall a degree and with easy, decrease cement and water of dosage.Three is to sprinkle before building concrete, water basic level and template even to soak through.Four is in time to overlay the perhaps damp grass mat of the plastics thin film, hemp slice etc., keep concrete eventually beforethe final setting surface is moist, perhaps spray to protect etc. to carry on protect in the concrete surface.Five is in the heat and strong wind the weather to want to establish to hide sun and block breeze facilities, protect in time.3.Sink to sink crack and preventionThe creation which sink to sink crack is because of the structure foundation soil quality not and evenly, loose soft or return to fill soil dishonest or soak in water but result in the asymmetry sink to decline with the result that;Perhaps because of template just degree shortage, the template propped up to once be apart from big or prop up bottom loose move etc. to cause, especially at winter, the template prop up at jelly soil up, jelly the soil turn jelly empress creation asymmetry to sink to decline and cause concrete structure creation crack.This kind crack many is deep enter or pierce through sex crack, it alignment have something to do with sinking to sink a circumstance, general follow with ground perpendicular or present 30 °s-45 °Cape direction development, bigger sink tosink crack, usually have certain of wrong, crack width usually with sink to decline quantity direct proportion relation.Crack widthunder the influence of temperature variety smaller.The foundation after transform stability sink to sink crack also basic tend in stability.Main prevention measure:One is rightness loose soft soil, return to fill soil foundation a construction at the upper part structure front should carry on necessity of Hang solid with reinforce.Two is the strength that assurance template is enough and just degree, and prop up firm, and make the foundation be subjected to dint even.Three is keep concrete from sprinkle infusing the foundation in the process is soak by water.Four is time that template tore down to can't be too early, and want to notice to dismantle a mold order of sequence.Five is at jelly soil top take to establish template to notice to adopt certain of prevention measure.4.Temperature crack and preventionTemperature crack much the occurrence is in bigsurface or difference in temperature variety of the physical volume concrete compare the earth area of the concrete structure.Concrete after sprinkling to build, in the hardening the process, cement water turn a creation a great deal of of water turn hot, .(be the cement dosage is in the 350-550 kg/m 3, each sign square the rice concrete will release a calories of 17500-27500kJ and make concrete internal thus the temperature rise to reach to 70 ℃or so even higher)Because the physical volume of concrete be more big, a great deal of of water turn hot accumulate at the concrete inner part but not easy send forth, cause inner part the temperature hoick, but the concrete surface spread hot more quick, so formation inside outside of bigger difference in temperature, the bigger difference in temperature result in inner part and exterior hot the degree of the bulge or cooling dissimilarity, make concrete surface creation certain of pull should dint.When pull should dint exceed the anti- of concrete pull strength extreme limit, concrete surface meeting creation crack, this kind of crack much occurrence after the concrete under constructionperiod.In the concrete of under construction be difference in temperature variety more big, perhaps is a concrete to be subjected to assault of cold wave etc., will cause concrete surface the temperature sharply descend, but creation constringency, surface constringency of the concrete be subjected to inner part concrete of control, creation very big of pull should dint but creation crack, this kind篇三：建筑与环境设备工程外文翻译毕业论文（设计）题系部名称：专业班级：学生姓名：学指导教师：教师职称：外文翻译目：浅谈建筑环境与暖通空调能耗号：XX11014233 讲师 1浅谈建筑环境与暖通空调能耗摘要：研究建筑环境，了解暖通空调负荷产生的原因及影响因素，可以更加合理地提出解决问题的方法。
SPL-4型湿式混凝土喷射机的研究分析
SPL-4型湿式混凝土喷射机的研究分析贺超【摘要】SPL-4型湿式混凝土喷射机全部设计了液压程序控制,采用一种新型的压风和螺旋风送排料结构,可以使湿的混凝土料以稀薄流形态在管路中输送,实现湿式混凝土连续喷射,在煤矿井下锚喷支护中表现出良好的性能.【期刊名称】《煤矿开采》【年(卷),期】2010(015)001【总页数】3页(P83-84,41)【关键词】湿式混凝土喷射机;螺旋风送排料;稀薄流;连续喷射【作者】贺超【作者单位】煤炭科学研究总院建井研究分院,北京,100013;北京中煤矿山工程有限公司,北京,100013【正文语种】中文【中图分类】TU643煤炭科学研究总院建井研究分院,针对当前湿喷机存在的种种问题,经过两年多的研发和一系列的试验、改进,独立研制成功了新型 SPL-4型湿式混凝土喷射机,解决了湿喷机喷腔出料口脉冲现象严重、出料不均、喷浆效率低以及清洗不方便的问题,提高了工作的稳定性和可靠性,是我国煤矿井巷工程的又一项重要科技成果,是喷射混凝土技术的一场彻底变革。
该新产品在开滦集团赵各庄矿业有限公司经过6个月的试验,取得了圆满成功。
主要应用于煤矿井巷工程支护中的喷射混凝土作业,也可适用于冶金矿山、非金属矿山、公路建设、铁路隧道、人防等岩土工程的支护作业,大大提高了湿喷机的工作效率和应用范围[1]。
SPL-4型湿式混凝土湿喷机由主机及速凝剂泵 2大部分组成。
湿喷机主机由进、排料系统,传动系统,液压系统及辅助部分构成,如图 1所示。
由料罐盖、排气阀、料罐、送料螺旋等部件组成。
料罐盖采用滑动开闭方式,在滑动过程中自动完成与料罐口密封压紧及压缩空气释放功能,其压紧力可调,如图 2所示。
双螺旋送料装置 (双罐螺旋及风料混合结构),实现了稀薄流输送,保证了喷射的连续性和均匀性。
推料螺旋通过电动机、减速器及离合器带动,将料罐内混凝土均匀推出,一方面将湿混凝土料进一步搅拌,另一方面减小了混凝土团粒粒径。
混凝土英文论文
Development of Green High Performance Concrete for SustainableDevelopment0706121 29 刘海庆Abstract: With the fast development of society and economy an important factor that affects social and economicdevelopment is environmental pollution. In face of reduction of the natural resources and the growing problem ofenvironmental pollution, the ordinary concrete has not been fit with the need of the social economy; the perfor-mances of concrete are required improvement. So the development of the concrete materials is generally considered with environmental protection, energy conservation, resource saving and the green high performance concrete is developed. The green high performance concrete that is developed in recent years is a new building material. The concept and features of green high performance concrete are introduced, then the categories and current application of it are analyzed and exist problems are proposed, finally it is concluded that the development of green high per-formance concrete is the only way for the sustainable development of the concrete materials.Keywords:green high performance concrete; environmental pollution; sustainable development CLC: TU528 Document code: A Article ID: 1672-2132(2010)Suppl.-0432-040 IntroductionConcrete is the most widely used and the greatest amount of building materials in the con-struction area. However, extensive use of concrete has destroyed unprecedented natural resources so that resources and energy appear crisis. Concrete in the 21st.century not only meets with the re-quirements of the structure, but also minimizes asmuch as possible the damage to the ecological envi-ronment to the need of sustainable development.So, developing the green high performance con-crete is the need of the sustainable develop-ment.1 Connotation and features of green high performance concretenWu Zongwei, academician of Chinese academy of engineering, first proposed the concept of con-crete and he pointed out the green high perfor-mance concrete was the direction of concrete devel-opment. Researchers consider the green high performance concrete should follow conditions as follows:(1) Cement used must be green cement. Sand and stone should be exploited orderly and withoutdamaging the environment.(2) Cement consumption should be saved tothe greatest extent in order to reduce by-products during the course of producing cement, for exam-ple, CO2, SO2, and NO2and so on.(3) Agricultural and industrial waste residueprocessed should be mixed more, such as, ground-ed slag, high-quality fly ash, silica fume and rice husk, to reduce cement, protect environment and improve concrete durability.(4) Industrial waste liquid should be used a lot, especially; water reducing agent made by black paper waste liquid and other composite addi-tive developed should be mixed to help dealing with other liquid.(5) Concrete should be mixed in the mixing station to reduce waste, dust and waster water of mixing concrete in site and waste and water recy-cling should be strengthened.(6) Through enhancing the strength, reduc-ing cross-sectional area or volume of structure, re-ducing concrete volume, cement, sand and stone can be saved. By improving durability of concrete,service life of structure can be lengthened and re-pair and reconstruction cost are further saved andthe indiscriminate use of natural resources will be reduced.(7) A lot of demolition waste should be recy-cled and recycled aggregate concrete should be de-veloped.The concept of green high performance con-crete is to strengthen people′s green awareness and to play an important role of energy saving and en-vironmental protection. It is concluded that the de-velopment of green high performance concrete is the only way for the sustainable development of concrete.2 Classification of the green high performance concrete2.1 Ecological environment-friendly concreteTo meet with the requirements of high strength and high durability, traditional concrete is always in pursuit of its compactness, which will cause concrete structures (lots of buildings and rigid pavement and so on) lack of permeability and permeability, exacerbate urban heat island effect,deteriorate human living environment. So rainwa-ter can not penetrate so that it lowers ground-wa-ter table in the city and affects growth of the sur-face plant, in a result, causes urban ecological sys-tem disorder. Because concrete color is gray, living space built in concrete gives a rough, hard, cold,dark feeling. So it is concluded that the develop-ment of ecological environment-friendly concrete is the only way to solve these problems. Another, e-cological environment-friendly concrete can be di-vided into plant concrete and water-permeability concrete according to different functions.2.2 Recycled aggregate concreteConcrete from the old buildings or structures can be divided into coarse and fine aggregate through breaking and this aggregate take place of some sand and gravel. So this is considered as re-cycled aggregate concrete. The use of recycled ag-gregate has been viewed as one of main measures in the development of green concrete.2.3 High-volume fly ash high performance con-creteFly ash mixed can improve concrete’s strength, impermeability and frost resistance,lower shrinkage; inhibit the effect of the alkali-ag-gregate reaction. High performance concrete which is mixed a great deal of fly ash and the morphologi-cal effects, micro-aggregate effects, volcanic ash effects of fly ash are used fully will lead to greater economic and environmental benefits.2.4 Environmentally mitigatable concrete(1) Environment-protecting concrete: the dif-ferences in composition between this concrete and traditional concrete are that a lot of solid waste,industrial waste residue, waste brick, concrete and solid rubbish and so on and additive produced through industrial waste liquid are mixed by taking certain technical measures to achieve all kinds of waste recycling and reduce environment pollution.(2) Energy-saving concrete: high temperature calcinations siliceous materials (clay or shale) and calcium raw material are needed in the course of ce-ment production, which will consume a large amount of energy. If concrete are prepared through non-burned cement, energy consumption can be reduced significantly.(3) Self-compacting concrete: self-compacting concrete is vibrated and compacted through self-weight. Because of this concrete has sufficient co-hesion so as to ensure disengagement in theprocess of pouring, a large amount of powder are required.3 Engineering application of green high performance concreteThe history of green high performance con-crete is not long, but it has obvious advantages and is paid attention to at home and abroad. Because concrete has been used widely as structural materi-al to date, appearance of green high performance concrete will become the main building structure materials in the 21st.century. Concrete strength in Chicago′s 311 South-walker Building in America with 295m height and 71 layers was C95. 40 mil-lion m3high performance concrete was used in both anchor piers of Akashi Kaikyo Bridge which was the longest suspension bridge at that time.The use of high green performance concretewas started late in China, especially the serious de-fects of the overpass in the Beijing and Tianjin re-gion arouse great concern in the engineering area.Research and application of green high perfor-mance concrete are increasing little by little.C80 high performance concrete are used in high-rise buildings and Jingan Center Building in Shang-hai.4 Existing problems of green high performance concrete4.1 Cost issuesThe cost of concrete is increased by 50% or more because used raw materials, the production and management level and production lines are raised. For example, collecting and preparing re-cycling aggregate must cost a certain machinery and equipment and manpower for recycled con-crete. From the point of economic indicators, the production of recycled aggregate is few profits, no profit, even deficit. If the production of recycled aggregate maintains a certain profit, its retail price will inevitably higher than the natural aggregate.Therefore, it is difficult to be accepted by users.4.2 Early crackingIn recent years cracking of concrete has be-come a hot topic at home and abroad and high per-formance concrete is no exception. That is, crackof concrete is very common. Many factors that in-fluence early cracking of concrete are as follows:self-shrinkage, drying shrinkage, earl y elastic modulus, tensile strength, ultimate tensile strain,creep, water evaporation rate, structural con-straint degree and so on.4.3 Mix problemThe same absolute volume is used with con-ventional concrete. After mixes of various compo-nents are determined, the performance require-ments are proved through experiments. The mix design of green high performance concrete is more difficult than that of common concrete. Comparing with mix design of conventional concrete, the mix design parameters of green high performance con-crete are smaller, such as, less than 0.4~0.42 water-cement ratio, less than 25mm the largest stone diameter (less than 20 mm or even 15 mm),2.6~3.0 sand fineness modulus, 42.5 concretes trength grade (ISO). So mix design will be sim-plified.5 ConclusionThe research of the green high performance technology in China is still in primary stage and the current research is not enough to conclude the laws that directly guide production. So the research and development of green high performance concrete should be increased greatly andquality standards and production specifications should be drawn up.In a word, we should attach great importance to green issues of concrete because these are related to our human survival and development. Through constant exploration and research, it is firmly be-lieved that the green high performance concrete is the only way for the sustainable development of the concrete materials.Reference:[1] CEB-FIP. Environment Design [R]. Lausanne: [s.n.],2004.[2]Malhotra V M. Introduction: Sustainable develop-ment and concrete technology [J].Concrete interna-tional,2002, 24(7):22.[3]吴中伟.绿色高性能混凝土——混凝土的发展方向[J].混凝土与水泥制品,1998,(1):3-6.[4]鄢朝勇.混凝土材料的可持续发展与粉煤灰绿色高性能混凝土[J].国外建材科技,2005,(4):5-7.[5] 王立久,汪振双,赵善宇.绿色生态混凝土技术的研究现状与发展[J].混凝土. 2009,(7):1-3.[6] Kumar M P. Reducing the environmental impact of concrete [J]. Concrete International,2001, 23(10):61-66.[7] Kumar M P. Greening of the concrete industry for sustainable development [J]. ConcreteInternational,2002, 24(7):23-28.[8] 王淑萍,王思远,张春,等.高性能混凝土的研究现状和发展应用[J].北方交通,2007,(4):47-50.[9]周士琼,李益进,尹健,等.复合超细粉煤灰与特种混凝土技术的开发与应用[J].铁道科学与工程学报,2004,(2):39-45.。
欧洲喷射混凝土标准翻译
欧洲喷射混凝土标准1前言《欧洲喷射混凝土标准》是在草案颁布3年后的1996年出版的。
在准备期间，最终出版的标准考虑了大约1000份传阅的草案和搜集到的评论。
自从颁布以来该标准在全世界得到了广泛的应用,并迅速成为行业内的标准参考文件。
规范对喷射混凝土的成功浇筑设施制定了基本要求，而规范对于有关喷射的操作部分进行了详述并单独发行。
这里提出的指南通过给出要求的具体解释对规范做出了评论。
为了有利于指南和规范的相互参照，规范中条款的编号通常是与指南相关的：正如8.2.1，那些斜体字都是指南的下属分支。
2参考资料下面的CEN（欧洲标准化委员会）测试方法代表了与喷射混凝土相关的最新指导，并替代了在欧洲混凝土标准规范中的第二章列表的内容。
混凝土国际标准6784-用压缩法测定静态弹性模量欧洲混凝土测试标准12356-试件和模具的形状,尺寸和其他要求欧洲混凝土测试标准12359-试件抗弯模量的测定欧洲混凝土测试标准12363-硬化混凝土的密度测定欧洲混凝土测试标准12364-水在压力作用下穿透深度的确定欧洲混凝土测试标准12378-新拌混凝土采样欧洲混凝土测试标准12379-制作和养护试件以测试强度欧洲混凝土测试标准12382-稠度和塌落度的测定欧洲混凝土测试标准12390-抗压强度的测定-压缩试验机的规程欧洲混凝土测试标准12394-试件抗压强度的测定欧洲混凝土测试标准12399-拔出力测定欧洲混凝土测试标准12504-空心样本的取样、检测和压缩测试欧洲混凝土结构保护和修复的产品和系统的标准12542-测试方法-拉拔试验测试欧洲混凝土结构保护和修复的产品和系统的标准13057-测试方法-毛细管吸水量的测定另外的一些已发表的参考文献：Austin S. A. and Robins P. J. (eds) .喷射混凝土性能、设计和浇筑 . Whittles出版. UK (ISBN 1-870325-01-X) and McGraw Hill,USA (ISBN 0-07-057148-1).1995.McLeish A .混凝土维修材料和涂膜的标准测试. CIRIA Technical Note 139. 建筑行业研究和信息协会. 伦敦. 1993.Opsahl O.A..强化岩体支撑的钢纤维. BML Report 82.205.建筑材料分类. 挪威理工学院. 特隆赫姆.1983年9月.Melbye T.支撑岩体的喷射混凝土.第四版.1996年1月.4组成材料组成材料的选择应满足技术、健康和安全标准。
土木工程混凝土论文中英文资料外文翻译文献
土木工程混凝土论文中英文资料外文翻译文献外文资料STUDIES ON IMPACT STRENGTH OF CONCRETESUBJECTED TO SUSTAINEDELEVATED TEMPERATUREConcrete has a remarkable fire resisting properties. Damage in concrete due to fire depends on a great extent on the intensity and duration of fire. Spalling cracking during heating are common concrete behaviour observed in the investigation of the fire affected structures. Plenty of literature is available on the studies of concrete based on time temperature cures. In power, oil sectorsand nuclear reactors concrete is exposed to high temperature for considerable period of time. These effects can be reckoned as exposure to sustained elevated temperature. The sustained elevated temperature may be varying from a few hours to a number of years depending upon practical condition of exposures. The knowledge on properties under such conditions is also of prime importance apart from the structures subjected to high intensity fire. Impact studies of structure subjected to sustained elevated temperature becomes more important as it involves sensitive structures which is more prone to attacks and accidents. In this paper impact studies on concrete subjected to sustained elevated temperature has been discussed. Experiments have been conducted on 180 specimens along with 180 companion cube specimens. The temperatures of 100°C, 200°C and 300°C for a duration of exposure of 2 hours 4 hours and 6 hours has been considered in the experiments. The results are logically analyzed and concluded.1. INTRODUCTIONThe remarkable property of concrete to resist the fire reduces the damage in a concrete structure whenever there is an accidental fire. In most of the cases the concrete remains intact with minor damages only. The reason being low thermal conductivity of concrete at higher temperatures and hence limiting the depth of penetration of firedamage. But when the concrete is subjected to high temperature for long duration the deterioration of concrete takes place. Hence it is essential to understand the strength and deformation characteristics of concrete subjected to temperature for long duration. In this paper an attempt has been made to study the variation in Impact Strength of concrete when subjected to a temperature range 100oC, 200oC and 300oC sustained for a period of 2 hrs, 4 hrs and 6 hrs.The review of the literature shows that a lot of research work [1 – 3] has taken place on the effect of elevated temperature on concrete. All these studies are based on time –temperature curves. Hence an attempt has been made to study the effect of sustained elevated temperature on impact strength of concrete and the results are compared with the compressive strength. The experimental programme has been planned for unstressed residual strength test based on the available facilities. Residual strength is the strength of heated and subsequently cooled concrete specimens expressed as percentage of the strength of unheated specimens.2. EXPERIMENTAL INVESTIGATION2.1. TEST SPECIMEN AND MATERIALSA total of 180 specimens were tested in the present study along with 180 companion cubes. An electric oven capable of reaching a maximum temperature of 300oC has been used for investigation. Fine and coarse aggregates conforming to IS383 has been used to prepare the specimen with mix proportions M1 = 1:2.1:3.95 w/c = 0.58, M2 = 1:1.15:3.56 w/c = 0.53, M3 = 1:0.8:2.4 w/c = 0.4.2.2 TEST VARIABLESThe effects of the following variables were studied.2.2.1 Size sSize of Impact Strength Test Specimen was 150 mm dial and 64 mm thickness and size of companion cube 150 x 150 x 150 mm.2.2.2 Maximum TemperatureIn addition to room temperature, the effect of three different temperatures (100oC, 200oC and 300oC) on the compressive strength was investigated.2.2.3 Exposure Time at Maximum TemperatureThree different exposure times were used to investigate the influence of heat on compressive strength; they are 2 hrs, 4 hrs and 6 hrs.2.2.4 Cooling MethodSpecimens were cooled in air to room temperature.3. TEST PROCEDUREAll the specimens were cast in steel moulds as per IS516 and each layer was compacted. Specimens were then kept in their moulds for 24 hours after which they were decoupled and placed into a curing tank until 28 days. After which the specimens were removed and were allowed to dry in room temperature. These specimens were kept in the oven and the required target temperature was set. Depending on the number of specimen kept inside the oven the time taken to reach the steady state was found to vary. After the steady state was reached the specimens were subjected to predetermined steady duration at the end of which the specimens are cooled to room temperature and tested.ACI drop weight impact strength test was adopted. This is the simplest method for evaluating impact resistance of concrete. The size of the specimen is 150 mm dial and 64 mm thickness. The disc specimens were prepared using steel moulds cured and heated and cooled as. This consists of a standard manually operated 4.54 kg hammer with 457 mm drop. A 64 mm hardened steel ball and a flat base plate with positioning bracket and lugs. The specimen is placed between the four guides pieces (lugs) located 4.8 mm away from the sample. A frame (positioning bracket) is then built in order to target the steel ball at the centre of concrete disc. The disc is coated at the bottom with a thin layer of petroleum jelly or heavy grease to reduce the friction between the specimen and base plate. The bottom part of the hammer unit was placed with its base upon the steel ball and the load was applied by dropping weight repeatedly. The loading was continued until the disc failed and opened up such that it touched three of the four positioning lugs. The number of blows that caused this condition is recorded as the failure strength. The companion cubes were tested for cube compression strength (fake).4. ANALYSIS AND RESULTS4.1 RESIDUAL COMPRESSIVE STRENGTH VS. TEMPERATUREFrom Table 1, at 100°C sustained elevated temperature it is seen that the residual strength of air cooled specimens of mixes M1, M2 and M3 has increased in strength 114% for M1 mix, 109% for M2 mix and 111% for M3 mix for 6 hours duration of exposure. When the sustained elevated temperature is to 200°C for air cooled specimens there is a decrease in strength up to 910% approximately for M1 mix for a duration of 6 hours, but in case of M2 mix it is 82% and for M3 mix it is 63% maximum for 6 hours duration of exposure. When the concrete mixes M1, M2 and M3 are exposed to 300°C sustained temperature there is a reduction in strength up to 78% for M1 mix for 6 hour duration of exposure.4.2 RESIDUAL COMPRESSIVE STRENGTH VS DURATION OF EXPOSUREFrom Table 1, result shows that heating up to 100°C for 2 hours and 4 hours, the residual strength of mix M1 has decreased where as the residual strength of mix M2 and M3 has increased. The residual strength is further increased for 6 hours duration of exposure in all the three mixes M1, M2 and M3 even beyond the strength at room temperature. When the specimens of mixes M1, M2 and M3 are exposed to 200°C for 2,4 and 6 hours of duration, it is observed that the residual strength has decreased below the room temperature and has reached 92% for M1 mix, 82 and 73% for M2 and M3 mix respectively. Concrete cubes of mixes M1, M2 and M3 when subjected to 300°C temperature for 2,4 and 6 hours the residual strength for mix M1 reduces to 92% for 2 hours up to 78% for six hours duration of exposure, for M2 mix 90% for 2 hours duration of exposure up to 76% for six hour duration of exposure, for M3 mix 88% up to 68% between 2 and 6 hours of duration of exposure.5. IMPACT STRENGTH OF CONCRETE5.1 RESIDUAL IMPACT STRENGTH VS TEMPERATUREFrom the table 1, it can be observed that for the sustained elevated temperature of 100°C the residual impact strength of all the specimens reduces and vary between 20 and 50% for mix M1, 15 to 40% for mix M2 and M3. When the sustained elevated temperature is 200°C the residual impact strength of all the mixes further decreases. The reduction is around 60-70% for mix M1, 55 to 65% for M2 and M3 mix. When the sustained elevated temperature is 300°C it is observed that the residual impact strength reduces further and vary between 85 and 70% for mix M1 and 85 to 90% for mix M2 and mix M3.5.2 RESIDUAL IMPACT STRENGTH VS DURATION OF EXPOSUREFrom the Table 1 and Figures 1 to 3, it can be observed that there is a reduction in impact strength when the sustained elevated temperature is 100°C for 2 hrs, 4 hrs and 6 hrs, and its range is 15 to 50% for all the mixes M1, M2 and M3. The influence of duration of exposure is higher for mix M1 which decreases more rapidly as compared to mix M2 and mix M3 for the same duration of exposure. When the specimens are subjected to sustained elevated temperature of 200°C for 2,4 and 6 hour of duration, further reduction in residual impact strength is observed as compared to at 100°C. The reduction is in the range of 55-70% for all the mixes. The six hour duration of exposure has a greater influence on the residual impact strength of concrete. When the sustained elevated temperature is 300°C for 2,4 and 6 hours duration of exposure the residualimpact strength reduces. It can be seen that both temperature and duration of exposure have a very high influence on the residual impact strength of concrete which shows a reduction up to 90% approximately for all the mixes.6. CONCLUSIONThe compressive strength of concrete increases at 100oC when exposed to sustained elevated temperature. The compressive strength of concrete decreases when exposed to 200°C and 300°C from 10 to 30% for 6 hours of exposure. Residual impact strength reduces irrespective of temperature and duration. Residual impact strength decreases at a higher rate of 20% to 85% as compared to compressive strength between 15% and 30 % when subjected to sustained elevated temperature. The impact strength reduces at a higher rate as compared to compressive strength when subjected to sustained elevated temperature.混凝土受持续高温影响的强度的研究混凝土具有显着的耐火性能。
2021年最新混凝土搅拌站毕业论文外文翻译（完整版）
一.外文翻译CONCRETE MIXING PLANTThe apparatus of the present invention relates generally to concrete mixing plants and more specifically to such plants utilized to automatically and continuously mix separate concrete components into a wide range of predetermined quantities or batches.Conventional concrete plants and mixer trucks that can normally only be utilized for mixing single large batches of concrete. Such apparatus often are preset to mix a batch that is too large for a specific job. The remaining concrete must either be dumped or resold. If the remaining concrete is to be resold, it often must be watered down before it reaches the second job site.Conventional truck-mounted mixers are necessarily large in volume, to accommodate the labor cost of the individual driver. Furthermore, the concrete must be used within a fixed time span from its receipt in the truck. Delays in transit or unforeseen delay at the site of usage make it difficult to maintain a constant delivery schedule. Usually excess trucks and drivers must be used to assure a ready supply of concrete.Much greater control of concrete consistency and cost is possible by on-site mixing. However, conventional concrete mixers are designed for large scale batch mixing. The mixer described below fills the need for an on-site mixer readily adjustable to meet the instant demands of the user asto quantity and quality.A further problem is that with a premixed batch, it is difficult or impossible to make last minute adjustments in mixture proportions. This difficulty arises frequently in areas where quick climate changes are common and further, where specific building construction techniques call for different concrete stress characteristics.These problems are realized to a limited degree by the apparatus disclosed in U.S. Pat. Nos. 3,339,898 and 3,469,824 granted to Futtyetal. These patents disclosed mixing methods and mixing truck constructions where in concrete components are supplied to an elongated trough. An elongated shaft is provided within the trough having a plurality of spatially disposed mixing paddles and helical feeding screws. Rotation of the shaft simultaneously mixes the particulate ingredients and moves them toward an output end.U.S. Pat. No. 3,310,293 granted to Zimmerman discloses a concrete mixing and delivery system wherein concrete components are held within a plurality of bins supported on a truck frame. The components are held separately within the bins that provide means for dispensing predetermined amounts of the components onto an elongated conveyor belt. The conveyor delivers the separate components to an external mixing trough where water is applied to the dry components and they are mixed by an elongated auger within the mixing trough.Another patent granted to Futty, U.S. Pat. No. 3,336,011, discloses a system and means for selectively mixing concrete and incorporating additives therein which, like the Zimmerman apparatus, deposits concrete components onto a conveyor and delivers them separately to a mixing trough. Water is added to the components at the mixing trough as an auger is rotated to mix the components together. The principal feature of this invention is the provision of separate water supply systems in which either pure water or an antifreeze solution may be selectively applied to the mixture.A further patent granted to Futty, U.S. Pat. No. 3,623,708 discloses a system and means for selectively mixing concrete and incorporating dry additives therein. The apparatus includes means for delivering dry additives to the concrete batch and incorporates a hopper assembly for holding the dry additives. The hopper contains agitator means for mixing and breaking up the dry additive ingredients. A controlled feed means selectively controls the amount of dry additives passed from the hopper into an enclosed auger arrangement. The additives are conveyed by the auger arrangement into an auxiliary mixing trough where they are incorporated into a concrete batch. U.S. Pat. No. 2,976,025 granted to G. M. Pro discloses a combined mixer and conveyor for concrete components. Individual hoppers are used in the Pro apparatus for storing each concrete component. The apparatus includes means for deliveringsand and cement to a helical conveyor within a trough. The materials are received within the trough and tumbled and agitated as they are moved upwardly.Another U.S. Pat. No. 2,946,597, granted to M. W. Simonsen, discloses a fertilizer mixer and spreader with a partition container wherein fertilizer components are kept separately in longitudinally spaced bins. The bins include bottom openings through which the individual components are placed onto a conveyor and delivered to a fertilizer dispensing impeller. The fertilizer dropped onto the impeller is spread across the ground behind the supporting vehicle.U.S. Pat. No. 796,591 granted to W. B. Martin describes a concrete mixer in which individual concrete components are contained within separate hoppers. The apparatus includes means for removing measured amounts of gravel, stone, cement and sand in predetermined quantities and dropping them gravitationally downwardly into a mixing auger.It may be noted that each of the above-cited patents r elating to an apparatus f or mixing separate c oncrete components utilizes an auger or paddled wheel arrangement as means for mixing the components together. The apparatus of the present invention differs from this art in that the mixing of the components is accomplished by impact and shearing action. Mixing by impact is accomplished as the components are propelled against a stationary abutment surface, while mixing by shearing layers orstrata of the components is affected as the components are delivered from storage bins or fall from the abutment surface onto to second conveyor belt or other receiving conveyor.SUMMARY OF THE INVENTIONA concrete mixing plant is described comprising conveyor means for carrying concrete component mater als along a first direction of travel toa discharge point where they are propelled against an upright abutment surface. Supply means is also provided for placing controlled quantitiesof concrete component materials onto an upwardly facing surface of the conveyor means.It is a first object of my invention to provide a concrete mixing plant that is capable of producing a continuous supply of consistent wet concrete.Another object is to provide such a plant that may be controlled while in operation, to change mixture proportions and the consistency of the concrete produced.It is an additional object of my invention to provide such a concrete mixing plant that is relatively simple in3construction and therefore easy to operate. It can be transported to the job site or used as a central mixing plant.A yet further object is to provide such a mixing plant that includesseparate storage bins for each individual concrete component with a metering and discharge mechanism attached to each bin to facilitate control of the quantity of each individual component supplied to the mixture.These and further objects and advantages will become apparent upon reading the following disclosure which, taken with the accompanying drawings, discloses two preferred forms of the present invention.BRIEF DESCRIPTION OF THE DRAWINGSFIG. 1 is a pictorial view of a first embodiment of the mixing plant;FIG. 2 is an enlarged elevational section view taken substantially along line 2—2 in FIG. 1;FIG. 3 is an enlarged elevational section view taken substantially along line 3—3 in FIG. 1;FIG. 4 is an enlarged elevational section view taken substantially along line 4—4 in FIG. 1;FIG. 5 is a fragmentary operational view taken substantially along line 5—5 in FIG. 1;FIG. 6 is a section view illustrating a weighing mechanism utilizedin conjunction with the present invention;FIG. 7 is a plan view of a slurry mixing mechanism incorporated inthe present invention;FIG. 8 is a cross sectional view taken substantially along line 8—8in FIG. 7;FIG. 9 is a plan view of a mixing plant mounted to a truck frame;FIG. 10 is an elevational view of the plant and truck as shown in FIG. 9;FIG. 11 is a sectioned view taken along line 11—11 in FIG. 9; andFIG. 12 is a fragmentary sectioned view taken along lines 12—12 in FIG. 9.DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTSA first embodiment of the concrete mixing plant invention is illustrated in FIGS. 1 through 8 of the attached drawings and is generally designated therein by the reference numeral 10. A mixing plant 10 as shown, is supported by a framework 11. A plurality of component bins 12 and a dry cement bin 12a are located on the framework for receiving and storing individual concrete components such as sand, various size aggregate and, of course, dry cement.The component bins are elements of a supply means whereby the individual concrete components are placed in controlled layered quantities on an upwardly facing surface 13 of first and second conveyor means 14 and 26 respectively. In operation, the supply means is utilized to deliver dry concrete components to the first conveyor means 14 which in turn initially moves the components along a first direction of travel to adischarge end 15. The dry components fall from discharge end 15 ontothe second conveyor means 26. A wet cement slurry is added to the components as they move along on the second conveyor means 26 to a second discharge end 33. The components leave the discharge end 33 as a concrete mixture.混凝土搅拌站本发明的装置本发明一般涉及混凝土搅拌站，更具体地说，涉及这样的植物，利用自动连续到范围广泛的预定量或分批混合单独的混凝土构件。
建筑土木工程外文翻译外文文献英文文献建筑施工混凝土裂痕的预防与处置
Building construction concrete crack ofprevention and processingDimosi M《CANADIAN JOURNAL OF CIVILENGINEERING》Abstract The crack problem of concrete is a widespread existence but again difficult in solve of engineering actual problem, this text carried on a study analysis to a little bit familiar crack problem in the concrete engineering, and aim at concrete the circumstance put forward some prevention, processing measure.Keyword: Concrete crack prevention processingForewordConcrete's ising 1 kind is anticipate by the freestone bone, cement, water and other mixture but formation of the in addition material of quality brittleness not and all the concrete construction transform with oneself, control etc. a series problem, harden model of in the concrete existence numerous tiny hole, spirit cave and tiny crack, is exactly because these beginning start blemish of existence just make the concrete present one some not and all the characteristic of tiny crack is a kind of harmless crack and accept concrete heavy, defend Shen and a little bit other use functionnot a creation to after the concrete be subjected to lotus carry, difference in temperature etc. function, tiny crack would continuously of expand with connect, end formation we can see without the aid of instruments of macro view the crack be also the crack that the concrete often say in the engineering.Concrete building and Gou piece usually all take sewer to make of, because of crack of existence and development usually make inner part of reinforcing bar etc. material creation decay, lower reinforced concrete material of loading ability, durable and anti- Shen ability, influence building of external appearance, service life, severity will threat arrive people's life and property lot of all of crash of engineerings is because of the unsteady development of the crack with the result age science research with a great deal of of the concrete engineering practice certificate, in the concrete engineering crack problem is ineluctable, also acceptable in certainly of the scope just need to adopt valid of measure will it endanger degree control at certain of scope reinforced concrete norm is also explicit provision:Some structure at place of dissimilarity under the condition allow existence certain the crack of at under construction should as far as possible adopt a valid measure control crack creation, make the structure don't appear crack possibly or as far as possible decrease crack of amount and width, particularly want to as far as possible avoid harmful crack of emergence, insure engineering quality thus.Concrete crack creation of the reason be a lot of and have alreadytransformed to cause of crack:Such as temperature variety, constringency, inflation, the asymmetry sink to sink etc. reason cause of crack;Have outside carry the crack that the function cause;Protected environment not appropriate the crack etc. caused with chemical differentiation to treat in the actual engineering, work°out a problem according to the actual circumstance.In the concrete engineering the familiar crack and the prevention.1.Stem Suo crack and preventionStem the Suo crack much appear after the concrete protect be over of a period of time or concrete sprinkle to build to complete behind of around a the cement syrup humidity of evaporate would creation stem Suo, and this kind of constringency is can't Suo crack of the creation be main is because of concrete inside outside humidity evaporate degree dissimilarity but cause to transform dissimilarity of result:The concrete is subjected to exterior condition of influence, surface humidity loss lead quick, transform bigger, inner part degree of humidity variety smaller transform smaller, bigger surface stem the Suo transform to be subjected to concrete inner part control, creation more big pull should dint but creation relative humidity is more low, cement syrup body stem Suo more big, stem the Suo crack be more easy the Suo crack is much surface parallel lines form or the net shallow thin crack, width many between mm, the flat surface part much see in the big physical volume concrete and follow it more in thinner beam plank short to Suo crack usually the anti- Shen of influence concrete,cause the durable of the rust eclipse influence concrete of reinforcing bar, under the function of the water pressure dint would creation the water power split crack influence concrete of loading dint etc..Concrete stem the Suo be main with water ash of the concrete ratio, the dosage of the composition, cement of cement, gather to anticipate of the dosage of the property and dosage, in addition etc. relevant.Main prevention measure:While being to choose to use the constringency quantity smaller cement, general low hot water mire and powder ash from stove cement in the adoption, lower the dosage of is a concrete of stem the Suo be subjected to water ash ratio of influence more big, water ash ratio more big, stem Suo more big, so in the concrete match the ratio the design should as far as possible control good water ash ratio of choose to use, the Chan add in the meantime accommodation of reduce is strict control concrete mix blend with under construction of match ratio, use of concrete water quantity absolute can't big in match ratio design give settle of use water is the earlier period which strengthen concrete to protect, and appropriate extension protect of concrete construction want tobeappropriate extension concrete heat preservation to overlay time, and Tu2 Shua protect to is a constitution the accommodation is in the concrete structure of the constringency sew.Su constringency crack and preventionSu constringency is the concrete is before condense, surface because of lose water quicker but creation of Su constringency crack isgeneral at dry heat or strong wind the weather appear, crack's much presenting in the center breadth, both ends be in the centerthin and the length be different, with each other not coherent crack general long 20-30 cm, the longer crack can reach to a 2-3 m, breadth 1-5 creation of main reason is:The concrete is eventually almost having no strength or strength before the Ning very small, perhaps concrete just eventuallyNing but strength very hour, be subjected to heat or compare strong wind dint of influence, the concrete surface lose water to lead quick, result in in the capillary creation bigger negative press but make a concrete physical volume sharply constringency, but at this time the strength of concrete again can't resist its constringency, therefore creation influence concrete Su constringency open the main factor of crack to have water ash ratio, concrete of condense time, environment temperature,wind velocity, relative humidity...etc.. Main prevention measure:One is choose to use stem the Suo value smaller higher Huo sour salt of the earlier period strength or common the Huo sour brine is strict the control water ash ratio, the Chan add to efficiently reduce water to increment the collapse of concrete fall a degree and with easy, decrease cement and water of is to sprinkle before building concrete, water basic level and template even to soak is in time to overlay the perhaps damp grass mat of the plastics thin film, hemp slice etc., keep concrete eventually before the Ning surface is moist, perhaps spray to protect etc. to carry on protect in the concrete is in the heat and strong wind the weather to want to establish to hide sun and block breeze facilities,protect in time. to sink crack and preventionThe creation which sink to sink crack is because of the structure foundation soil quality not and evenly, loose soft or return to fill soil dishonest or soak in water but result in the asymmetry sink to decline with the result that;Perhaps because of template just degree shortage, the template propped up to once be apart from big or prop up bottom loose move etc. to cause, especially at winter, the templateprop up at jelly soil up, jelly the soil turn jelly empress creation asymmetry to sink to decline and cause concrete structure creation kind crack many is deep enter or pierce through sex crack, it alignment have something to do with sinking to sink a circumstance, general follow with ground perpendicular or present 30 °s-45 ° Cape direction development, bigger sink to sink crack, usually have certain of wrong, crack width usually with sink to decline quantity direct proportion width under the influence of temperature variety foundation after transform stability sink to sink crack also basic tend in stability.Main prevention measure:One is rightness loose soft soil, return to fill soil foundation a construction at the upper part structure front should carry on necessity of Hang solid with is the strength that assurance template is enough and just degree, and prop up firm, and make the foundation be subjected to dintis keep concrete from sprinkle infusing the foundation in the process is soak by is time that template tore down to can't be too early, and want tonotice to dismantle a mold order of is at jelly soil top take to establish template to notice to adopt certain of prevention measure.crack and preventionTemperature crack much the occurrence is in big surface or difference in temperature variety of the physical volume concrete compare the earth area of the concrete after sprinkling to build, in the hardening the process, cement water turn a creation a great deal of of water turn hot, .(be the cement dosage is in the 350-550 kg/m 3, each sign square the rice concrete will release a calories of kJ and make concrete internal thus the temperature rise to reach to 70 ℃or so even higher)Because the physical volume of concrete be more big, a great deal of water turn hot accumulate at the concrete inner part but not easy send forth, cause inner part the temperature hoick, but the concrete surface spread hot more quick, so formation inside outside of bigger difference in temperature, the bigger difference in temperature result in inner part and exterior hot the degree of the bulge cold Suo dissimilarity, make concrete surface creation certain of pull should pull should dint exceed the anti- of concrete pull strength extreme limit, concrete surface meeting creation crack, this kind of crack much occurrence after the concrete under construction the concrete of under construction be difference in temperature variety more big, perhaps is a concrete to be subjected to assault of cold wave etc., will cause concrete surface the temperature sharply descend, but creation constringency, surface constringency of the concrete be subjected to inner part concrete of control,creation very big of pull should dint but creation crack, this kind of crack usually just in more shallow scope of the concrete surface creation.The alignment of the temperature crack usually none settle regulation, big area structure the crack often maneuver interleave;The size bigger structure of the beam plank length, the crack run parallel with short side more;Thorough with pierce through sex of temperature crack general and short side direction parallelism or close parallelism, crack along long side cent the segment appear, in the center more width the size be different, be subjected to temperature variety influence more obvious, winter compare breadth, summer more concrete temperature crack that the heat inflation cause is usually in the center the thick both ends be thin, but cold Suo crack of thick thin variety not too emergence of the this kind crack will cause the rust eclipse of reinforcing bar, the carbonization of concrete, the anti- jelly which lower concrete melt, anti- tired and anti- Shen ability etc..Main prevention measure:One is as far as possible choose to use low hot or medium hot water mire, like mineral residue cement, powder ash from stove cement...etc..Two is a decrease cement dosage, cement dosage as far as possible the control is in the 450kg/m 3 is to lower water ash ratio, water ash of the general concrete ratio control below is improvement the bone anticipate class to go together with, the Chan add powder ash from stove or efficiently reduce water etc. to come to reduce cement dosage and lower water to turn is animprovement concrete of mix blend to process a craft, lower sprinkle of concrete to build is the in addition that the Chan add a have of fixed amount to reduce water and increase Su, slow Ning etc. function in the concrete, improvement the concrete mix to match a thing of mobility, protect water, lower water to turn hot, postpone hot Feng of emergence is the heat season sprinkle to build can the adoption take to establish to hide sun plank etc. assistance measure control concrete of Wen Sheng, lower to sprinkle temperature of build the is the temperature of big physical volume concrete should the dint relate to structure size, concrete structure size more big, temperature should dint more big, so want reasonable arrangement construction work preface, layering, cent the piece sprinkle to build, for the convenience of in spread hot, let up is at great inner part constitution of the physical volume concrete cool off piping, cold water perhaps cold air cool off, let up concrete of inside outside difference in is the supervision which strengthen concrete temperature, adopt to cool off in time, protection istoreserve temperature constringency to is to let up to control, sprinkle proper before building concrete in the Ji rock and old concrete top build a 5 mm or so sand mat a layer or usage asphalt etc. material Tu2 is to strengthen concrete to protect, the concrete after sprinkle build usemoist grass Lian in time, hemp slice's etc. overlay, and attention sprinkle water to protect, appropriate extension protect time, assurance the concrete surface be slow-moving cool the cold season, concrete surfaceshould constitution heat preservation measure, in order to prevent cold wave is the allocation be a little amount in the concrete of reinforcing bar perhaps add fiber material concrete of temperature crack control at certain of scope inside.and prevention that the chemical reaction causeAlkali bone's anticipating the crack that reaction crack and reinforcing bar rust eclipse cause is the most familiar in the reinforced concrete structure of because of chemical reaction but cause of crack. The concrete blend a future reunion creation some alkalescence ion, these ion with some activity the bone anticipate creation chemical reaction and absorb surroundings environment in of water but the physical volume enlarge, make concrete crisp loose, inflation open this kind of crack general emergence concrete structure usage period, once appear very difficult remediable, so should at under construction adopt valid the measure carry on of prevention measure:While being to choose to anticipate with the alkali activity small freestone is the in addition which choose to use low lye mire with low alkali or have no is the Chan which choose to use accommodation with anticipate to repress an alkali bone to anticipate reaction.Because the concrete sprinkle to build, flap Dao bad perhaps is a reinforcing bar protection layer thinner, the harmful material get into concrete to make reinforcing bar creation rust eclipse, the reinforcing bar physical volume of the rust eclipse inflation,cause concrete bulge crack, the crack of this kind type much is a crack lengthways, follow the position of reinforcing bar of prevent measure from have:One is assurance reinforcing bar protection the thickness of the is a concrete class to go together with to want is a concrete to sprinkle to note and flap Dao airtight is a reinforcing bar surface layer Tu2 Shua antisepsis coating.Crack processingThe emergence of the crack not only would influence structure of whole with just degree, return will cause the rust eclipse of reinforcing bar, acceleration concrete of carbonization, lower durable and anti- of concrete tired, anti- Shenaccording to the property of crack and concrete circumstance we want differentiation to treat, in time processing, with assurance building of safety usage.The repair measure of the concrete crack is main to have the following some method:Surface repair method, infuse syrup, the Qian sew method, the structure reinforce a method, concrete displacement method, electricity chemistry protection method and imitate to living from heal method. Surface repair the method be a kind of simple, familiar of repair method, it main be applicable to stability and to structure loading the ability don't have the surface crack of influence and deep enter crack of processing measure that is usually is a surface in crack daubery cement syrup, the wreath oxygen gum mire or at concrete surface Tu2 Shua paint, asphaltetc. antisepsis material, at protection of in the meantime for keeping concrete from continue under the influence of various function to open crack, usually can adoption the surface in crack glue to stick glass fiber cloth etc. measure.1, infuse syrup, the Qian sew methodInfuse a syrup method main the concrete crack been applicable to have influence or have already defend Shen request to the structure whole of repair, it is make use of pressure equipments gum knot the material press into the crack of concrete, gum knotthe material harden behind and concrete formation one be whole, thus reinforce of in common use gum knot material has the cement the syrup, epoxy, A Ji CXi sour ester and gather ammonia ester to equalize to learn material.The Qian sew a method is that the crack be a kind of most in common use method in, it usually is follow the crack dig slot, the Qian fill Su in the slot or rigid water material with attain closing crack of in common use Su material has PVC gum mire, plastics ointment, the D Ji rubber etc.;In common use rigid water material is the polymer cement sand syrup.2, the structure reinforce a methodWhen the crack influence arrive concrete structure of function, will consideration adopt to reinforce a method to carry on processing to the concrete structure reinforce medium in common use main have thefollowing a few methodThe piece of enlargement concrete structure in every aspect accumulate, outside the Cape department of the Gou piece pack type steel, adoption prepare should the dint method reinforce, glue to stick steel plate to reinforce, increase to establish fulcrum to reinforce and jet the concrete compensation reinforce.3, concrete displacement methodConcrete displacement method is processing severity damage concrete of a kind of valid method, this method be first will damage of the concrete pick and get rid of, then again displacement go into new of concrete or other in common use displacement material have:Common concrete or the cement sand syrup, polymer or change sex polymer concrete or sand syrup.4, the electricity chemistry protection methodThe electricity chemistry antisepsis is to make use of infliction electric field in lie the quality of electricity chemical effect, change concrete or reinforced concrete the environment appearance of the place, the bluntness turn reinforcing bar to attain the purpose of protection method, chlorine salt's withdrawing a method, alkalescence to recover a method is a chemistry protection method in three kinds of in common use but valid advantage of this kind of method is a protection method under the influence of environment factor smaller, apply reinforcing bar, concrete of long-term antisepsis, since can used for crack structure already can also used for new set up structure.5, imitate to living from legal moreImitate to living from heal the method be a kind of new crack treatment, its mimicry living creature organization secrete a certain material towards suffering wound part auto, but make the wound part heal of function, join some and special composition(suchas contain to glue knot of the liquid Xin fiber or capsule) in the concrete of the tradition the composition, at concrete inner part formation the intelligence type imitate to living from heal nerve network system, be the concrete appear crack secrete a parts of liquid Xin fiber can make the crack re- heal.ConclusionThe crack is widespread in the concrete structure existence of a kind of phenomenon, it of emergence not only will lower the anti- Shen of building ability, influence buildingof usage function, and will cause the rust eclipse of reinforcing bar, the carbonization of concrete, lower the durable of material, influence building of loading ability, so want to carry on to the concrete crack earnest research, differentiation treat, adoption reasonable of the method carry on processing, and at under construction adopt various valid of prevention measure to prevention crack of emergence and development, assurance building and Gou piece safety, stability work.译文：建筑施工混凝土裂痕的预防与处置迪默斯M《加拿大土木工程学报》摘要混凝土的裂缝问题是一个普遍存在而又难于解决的工程实际问题本文对混凝土工程中常见的一些裂痕问题进行了探讨分析并针对具体情况提出了一些预防、处置办法。
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混凝土喷射机论文中英文资料外文翻译文献Summarization and improvement of concrete-ejecting machinesAbstract :The text introduces the principle ,style and development process of dry and wet type concrete-ejecting machines. It analyzes domesticandforeign application instance ,allkindsofconcrete-ejecting machinesmostly merit and flaw. Also it introduces somerepresentational wetcon-crete-ejecting machines domestic developed. Some flaws ofconcrete-ejecting machines are improved.Keywords:concrete-ejectingmachines,frame characteristic ,operating principles , highway.Concrete is the use of compressed air jet, will be allocated a certain level and good water-cement ratio mixing concrete materials, through the pipeline by the jet nozzle, and high speed jet out to the surface by spraying a concrete suppor-t Layer is sprayed concrete construction equipment operations in the main. Asa concrete spraying technology saving concrete and steel, timber, labour-saving and improve construction efficiency and reduce costs, and other characteristics, the concrete applican of the jet increasingly common. Has now been widely us-ed in railway, highway, water conservancy, construction, coal and other buildi -ng works in construction, a tunnel solution, road slope, construction pit, unde-rground works of temporary and permanent care to support the construction m-achinery operations. [ 1 ]1 The work of sprayed concrete mechanism and the development trendIn sprayed concrete operations, the overwhelming majority of the use of concrete-rotor aircraft, such as jet structure is simple, reliable performance, a small, lightweight, easy to operate and maintenance。
Dry jet principle and structure are: the rotor with a liner to a certain speed of rotation, and the combination of pressure plates fixed on the liner fixed, with a board connected into the wind pipe and discharging elbow, when Rotor equipped with materials in the various materials Cup rotation and into the wind to the elbow and discharging the same time, in the role of gas under pressure, and materials through the elbow and expected to lose the material transported to the nozzle a nd nozzle in the water Blasting away.Dry concrete jet of the main advantages is a long distance carrier, simple equipment, durable, but because it is so dry nozzles, mixing concrete mixed with water, and therefore the construction dust, are more resilient, dry spraying operations against workers in the dust Health, in particular the narrow roadway construction, dust pollution is more serious [2]。
From the 1960s onwards, in Western developed countries, wet spraying began gradually introducing the technology, all kinds of wet concrete Jets also be developed, sprayed concrete and dry the main difference is that enough (in water-cement ratio requirements should be The volume of) the opportunity to join the mixing of different water。
Wet sprayed concrete is expected lose their access to the former Mixture has added a foot of water mixing, the loser in the delivery of the cylinder is the wet concrete; dry sprayed concrete is lost in the transmission of the material did not join the mixing Water dry material (ground humidity mixing natural materials or drying materials), and in sufficient volume nozzle before mixing with water, dry mixture and mix quickly after the whole wet concrete delivered to the nozzle, speed up the coagulation of the doped Afte r the jet to beam a material of construction [3].At the national level, as people's environmental awareness and enhance the quality of sprayed concrete requirements of the increase, an increasing number of wet concrete into the use of jet aircraft. In recent years, some domestic units also began to develop several wet concrete jet, but the scale of production is still to be expanded. To sum up, jet wet concrete of the main advantages are the following:1) greatly reduced the plane and next to the nozzles of dust concentration and eliminate the health hazards to workers.2) high productivity. Dry concrete Jets general no more than 53 m3 / h, and the use of jet wet concrete, artificial operations up to 103 m3 / h, a mechanical manual, up to 203 m3 / h.3) The rebound was low. Jet Dry, concrete rebound of up to 15 percent to 50 percent, the wet spray technical rebound rate can be reduced to below 10%.4) wet spray, easy to control because of water-cement ratio, a high degree of concrete hydration, it can significantly improve the quality of sprayed concrete and improve quality of the concrete absorbed.2 Wet concrete Jets and the type of work principleConcrete Pumping main piston pump-jet spray and a wet-wet spraying machine screw pump two categories. Piston pump-jet aircraft will be wet plunger-wet concrete as a concrete pump the basic body jet, with the export pipeline to the nozzle and in this Access to compressed gas will jet out of concrete, wet spray such a heavy machine general However, long distance transmission, Second Beach, the Xiaolangdi Water Conservancy Project and other large-scale use of the aircraft's main disadvantage is that low productivity, and screw the stator sets of wear and tearmore serious, there was little scope of application.3 Domestic wet concrete Jets3. 1 SPZ26-wet concrete JetsSPZ26-wet concrete jet sent to a gas-rotor aircraft wet concrete, and its working principle of Liwa 280 Ruishi A similar model, by its rotor rotary motor driven by reducer, the aircraft equipment less investment, high productivi ty, light weight , Good mobility [4].3. 2 PZ25B Concrete jet aircraft to spray dry, wet spray and spray tide. It automatically clean, non-stick block, cutting speed, little more than expected, h igh efficiency.3.3 impeller wet concrete wet concrete impeller jet aircraft is a new wet spraying machine, it adopted a impeller feeding device, a reliable, long life, to aggregate size of the big advantages. At present, China's development of the wet concrete pumping and dual-use spray-spray-wet concrete tunnel construction is indispensable to engineering equipment, the main impeller and rotor piston-type pumps and wet spraying machine. Impeller and rotor piston wet spraying machine short-distance transportation, displacement of small, fragile pieces of short life, serious leakage pulp, cleaning a long time [5].4 Jet promote the use of wet concrete in some of the issues to be resolvedAt present, due to wet jet technology has obvious advantages, wet concrete Jets in the project is also an increasing number of applications, but because there are some outstanding issues, the wet concrete to promote the use of jet played a certain obstacles Role, even in China, currently the main sprayed concrete operations is still dry spray.1) use of wet concrete jet of liquid condensate, a joint venture of imports and higher prices (up to 6000 yuan / t ~ 8 000元/ t), and domestic liquid condensate of no production, should be relatively dry Spray of powder and quick-setting low price (more than 1000 yuan / t).2) low labor costs and people's environmental awareness to be increased.3) wet concrete jet operations, more complex equipment, operation and maintenance of jet aircraft for less than dry. 4) the use of wet concrete jet operations, higher equipment investment.5 Improvement of concrete-ejecting machines5.1 After the concrete improvement of the characteristics of a jet1) dust better. The improved use of the seal can not be dust, has greatlyimproved the working conditions of workers, increased labor productivity.2) increase the flexibility of high-adhesive rubber material cavity. Concretecan be an effective solution to the problem of bonded easily, remove theconcrete to reduce the number of bonded and improve labor efficiency.3) use of wear-resistant rubber pads. Rubber mats more than double the wearresistance, a decrease of rubber pads to reduce the frequency of the use ofreplacement cost.4) the overall change from the original drive shaft composed of three parts,not easy to solve the demolition, the problem of maintenance.5.2 Improve the difference between before and after the concrete Jets1) the original concrete jet rotating body formed by the wear-resistant castiron foundry, without treatment, after the rust-bonding, improved afterthe jet cavity spraying anti-rust treatment and greatly reduce thepossibility of a bond.2) the original concrete jet rotation of direct contact with the materialI, Mifengbuyan; feed mouth without sealing device, improved toincrease a wear-res istant rubber pads and mouth and feed ring.3）In rotating body and mouth spray to increase flexible rubber material, and the rotation of the original concrete jet spray and a flexible rubbermouth cavity. Concrete work of a high-pressure jet of air cavity,flexible rubber in the air cavity under the pressure of being compressed,rotating body is constantly rotating, when the rotation of the chamberpassed a flexible rubber pressure zone, the pressure disappeared,flexible Rubber cavity in the stretch under its own restitution due to thehigh flexibility of rubber attached to the cavity on the concrete andscattered by squeezing down, automatic removal of the concretebonding, in order to facilitate maintenance and replacement of therotating flexible rubber Liu cavity, the overall 12 will be split into fourcavity, each of the three cavity. The same token, I expected to increasein a flexible rubber material cavity.4) the original concrete jet drive shaft for the overall structure, cleaningup the rotating body cavity or replacement work flexible rubbermaterial cavity, to be screened in Shangzuo body and can also Xiediao,will improve the entire shaft is divided into three parts , The middle ofa connecting shaft, through the home side, connecting shaft, the pinwill be linked to the two-axis, demolition, only to tear down the shaftcan be connected in blocks of lift, the replacement of flexible rubberbody cavity or clean-up rotation, Province when the effort, boosted byincreasing the flexibility of rubber rubber seal cavity and the driveshaft connected to the body structure and effective solution to the dustand inconvenience to the demolition of concrete and bond issues,some use from the scene, has been made Good results.6 The endconclusion of a wave while spraying can reduce dust concentration and reduce the rate of rebound, but the dust hazard still exists, still higher rates rebound from the required standard there is still a considerable distance. All countries in the world of wet concrete of the jet at the same time, developed a jet of wet concrete, and increasingly mature, many countries have started to use a lot. China's current wet-spray method is still in testing stage and not yet fully promote the application level. Mainly wet spraying machine size, complexity of the aggregate demand high, and China's production of liquid condensate, the admixture of poor, the impact of the wet jet promotion and application. In this regard China's many units have begun research, and has made big progress. Development of reliable performance, small size, for the scene to promote the use of the wet spraying machine is still the future of sprayed concrete technology one of the main direction.中文译文混凝土喷射机的概述及改进摘要:介绍了干式和湿式混凝土喷射机的工作原理、类型、发展过程,分析了国内外应用情况和各类混凝土喷射机的优缺点,并对近年来国内研制开发的几种具有代表性的湿式混凝土喷射机作了介绍,对混凝土喷射机的问题进行了技术改进。