外文翻译(中英文word版)废弃混凝土再生新技术探索
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。
国外再生混凝土的应用前沿及标准
国外再生混凝土的应用前沿及标准一、前言再生混凝土（Recycled Concrete）是将废弃混凝土经过加工后再利用于新的混凝土中的一种可持续发展的建筑材料。
在全球环保意识不断增强的情况下，再生混凝土的应用越来越受到重视。
本文将介绍国外再生混凝土的应用前沿及标准，以期为国内相关产业提供参考。
二、国外再生混凝土的应用前沿1. 混凝土的再生利用率不断提高在欧洲和北美地区，混凝土的再生利用率不断提高。
欧洲的再生混凝土利用率已经达到了70%以上，而在北美地区，再生混凝土的利用率也在逐年增长。
这是由于在这些发达国家，政府对环保的重视程度较高，对建筑废弃物的回收和再利用也有着更严格的要求。
2. 再生混凝土的技术不断创新随着技术的不断发展，再生混凝土的质量也在不断提高。
在欧洲和北美地区，一些研究机构和企业已经开发出了一些高性能的再生混凝土。
这些混凝土不仅可以满足常规混凝土的使用要求，而且还具有更好的性能，如更好的耐久性、更高的承载能力等。
3. 再生混凝土的应用范围不断扩大在国外，再生混凝土已经广泛应用于公路、桥梁、隧道、机场、码头等基础设施建设中。
此外，再生混凝土还可以用于预制构件、地基、填充等领域。
三、国外再生混凝土的标准1. 欧洲标准欧洲标准EN 206：2013规定了混凝土的性能要求和材料性质，包括混凝土的抗压强度、抗拉强度、抗弯强度、耐久性、可加工性等方面。
此外，欧洲标准还要求再生混凝土的性能应满足与常规混凝土相同的要求，并且要求再生混凝土的使用量应不超过混凝土总量的30%。
2. 美国标准美国标准ACI 555R-01规定了再生混凝土的性能要求和应用要求，包括再生混凝土的抗压强度、抗拉强度、抗弯强度、耐久性等方面。
此外，美国标准还要求再生混凝土的使用应符合环保要求，并且需要进行全面的质量控制和检测。
3. 日本标准日本标准JIS A 5021-2003规定了再生混凝土的性能要求和应用要求，包括再生混凝土的抗压强度、抗拉强度、抗弯强度、耐久性等方面。
外文翻译 (自动保存的)
能源和建筑在MWC的热性能和机械性能研究：提高混凝土制品环境可持续性克里斯蒂娜Becchio ，斯特凡诺保罗Corgnati ，安德烈Kindinis ，西莫内塔Pagliolico能量学系（DENER ），都灵理工大学，科索公爵阿布鲁齐24 ，10129都灵，意大利材料科学与工程化学（DISMIC ），都灵理工大学，科索公爵阿布鲁齐24 ，10129意大利都灵系文章信息文章历史：2009年3月13日修改稿2009年5月13日2009年5月29日关键词：木材聚集轻质混凝土热式质量电导率抗压强度摘要本研究以构成一个更可持续的轻质混凝土，矿化木混凝土（MWC）上，由木工生产废料替代天然骨料的可能性。
利用这种类型的聚集体，三重目的已经达到：保存天然原料，节约能源和废物的再利用。
此外，使用木材聚集的性能，试图建立一个可持续的混凝土具有高的热惯量，高耐热性和低体重。
在本文中，对混凝土的机械性能和热性能的添加木聚集体的影响进行了研究。
机械性能进行了调查与抗压强度的测试，而一维热流模型已被用于预测MWC的热导率。
这个方案具有良好的绝缘围护结构的需求，同时具有高的热质量：使用MWC可以用不同的类型学比较重的建筑围护结构的想法有关。
一系列其他的值可以得出：重量轻，环保，易产业化，便于现场浇注。
因此，在建筑结构木器，混凝土的应用程序可能是为了提高可持续性和建筑节能一个有趣的解决方案。
2009爱思唯尔B.V.保留所有权利。
1 、介绍促进可持续发展带来了压力采取适当的方法，以保护环境各个行业，包括建筑。
在建设过程中需要能量的高支出，并导致广泛的可量化的环境影响，包括气体排放，水资源利用和固体和液体废物。
能源消耗的提取，运输，加工和装配的原材料，以及所连接的二氧化碳和温室气体排放占建设[1-3]所有生命周期的多变，但相当大的比率。
还有一系列既通过施工过程和建设的网站上的存在，包括土地的干扰，生态系统改变，植被破坏，占领一个潜在的资源网站的结果，产生不易量化局部环境的影响地下水干扰。
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。
钢筋混凝土结构中英文对照外文翻译文献
中英文对照外文翻译(文档含英文原文和中文翻译)Reinforced ConcreteConcrete and reinforced concrete are used as building materials in every country. In many, including the United States and Canada, reinforced concrete is a dominant structural material in engineered construction. The universal nature of reinforced concrete construction stems from the wide availability of reinforcing bars and the constituents of concrete, gravel, sand, and cement, the relatively simple skills required in concrete construction, and the economy of reinforced concrete compared to other forms of construction. Concrete and reinforced concrete are used in bridges, buildings of all sorts underground structures, water tanks, television towers, offshore oil exploration and production structures, dams, and even in ships.Reinforced concrete structures may be cast-in-place concrete, constructed in their final location, or they may be precast concreteproduced in a factory and erected at the construction site. Concrete structures may be severe and functional in design, or the shape and layout and be whimsical and artistic. Few other building materials off the architect and engineer such versatility and scope.Concrete is strong in compression but weak in tension. As a result, cracks develop whenever loads, or restrained shrinkage of temperature changes, give rise to tensile stresses in excess of the tensile strength of the concrete. In a plain concrete beam, the moments about the neutral axis due to applied loads are resisted by an internal tension-compression couple involving tension in the concrete. Such a beam fails very suddenly and completely when the first crack forms. In a reinforced concrete beam, steel bars are embedded in the concrete in such a way that the tension forces needed for moment equilibrium after the concrete cracks can be developed in the bars.The construction of a reinforced concrete member involves building a from of mold in the shape of the member being built. The form must be strong enough to support both the weight and hydrostatic pressure of the wet concrete, and any forces applied to it by workers, concrete buggies, wind, and so on. The reinforcement is placed in this form and held in place during the concreting operation. After the concrete has hardened, the forms are removed. As the forms are removed, props of shores are installed to support the weight of the concrete until it has reached sufficient strength to support the loads by itself.The designer must proportion a concrete member for adequate strength to resist the loads and adequate stiffness to prevent excessive deflections. In beam must be proportioned so that it can be constructed. For example, the reinforcement must be detailed so that it can be assembled in the field, and since the concrete is placed in the form after the reinforcement is in place, the concrete must be able to flow around, between, and past the reinforcement to fill all parts of the form completely.The choice of whether a structure should be built of concrete, steel, masonry, or timber depends on the availability of materials and on a number of value decisions. The choice of structural system is made by the architect of engineer early in the design, based on the following considerations:1. Economy. Frequently, the foremost consideration is the overall const of the structure. This is, of course, a function of the costs of the materials and the labor necessary to erect them. Frequently, however, the overall cost is affected as much or more by the overall construction time since the contractor and owner must borrow or otherwise allocate money to carry out the construction and will not receive a return on this investment until the building is ready for occupancy. In a typical large apartment of commercial project, the cost of construction financing will be a significant fraction of the total cost. As a result, financial savings due to rapid construction may more than offset increased material costs. For this reason, any measures the designer can take to standardize the design and forming will generally pay off in reduced overall costs.In many cases the long-term economy of the structure may be more important than the first cost. As a result, maintenance and durability are important consideration.2. Suitability of material for architectural and structural function.A reinforced concrete system frequently allows the designer to combine the architectural and structural functions. Concrete has the advantage that it is placed in a plastic condition and is given the desired shape and texture by means of the forms and the finishing techniques. This allows such elements ad flat plates or other types of slabs to serve as load-bearing elements while providing the finished floor and / or ceiling surfaces. Similarly, reinforced concrete walls can provide architecturally attractive surfaces in addition to having the ability to resist gravity, wind, or seismic loads. Finally, the choice of size of shape is governed by the designer and not by the availability of standard manufactured members.3. Fire resistance. The structure in a building must withstand the effects of a fire and remain standing while the building is evacuated and the fire is extinguished. A concrete building inherently has a 1- to 3-hour fire rating without special fireproofing or other details. Structural steel or timber buildings must be fireproofed to attain similar fire ratings.4. Low maintenance.Concrete members inherently require less maintenance than do structural steel or timber members. This is particularly true if dense, air-entrained concrete has been used forsurfaces exposed to the atmosphere, and if care has been taken in the design to provide adequate drainage off and away from the structure. Special precautions must be taken for concrete exposed to salts such as deicing chemicals.5. Availability of materials. Sand, gravel, cement, and concrete mixing facilities are very widely available, and reinforcing steel can be transported to most job sites more easily than can structural steel. As a result, reinforced concrete is frequently used in remote areas.On the other hand, there are a number of factors that may cause one to select a material other than reinforced concrete. These include:1. Low tensile strength.The tensile strength concrete is much lower than its compressive strength ( about 1/10 ), and hence concrete is subject to cracking. In structural uses this is overcome by using reinforcement to carry tensile forces and limit crack widths to within acceptable values. Unless care is taken in design and construction, however, these cracks may be unsightly or may allow penetration of water. When this occurs, water or chemicals such as road deicing salts may cause deterioration or staining of the concrete. Special design details are required in such cases. In the case of water-retaining structures, special details and / of prestressing are required to prevent leakage.2. Forms and shoring. The construction of a cast-in-place structure involves three steps not encountered in the construction of steel or timber structures. These are ( a ) the construction of the forms, ( b ) the removal of these forms, and (c) propping or shoring the new concrete to support its weight until its strength is adequate. Each of these steps involves labor and / or materials, which are not necessary with other forms of construction.3. Relatively low strength per unit of weight for volume.The compressive strength of concrete is roughly 5 to 10% that of steel, while its unit density is roughly 30% that of steel. As a result, a concrete structure requires a larger volume and a greater weight of material than does a comparable steel structure. As a result, long-span structures are often built from steel.4. Time-dependent volume changes. Both concrete and steel undergo-approximately the same amount of thermal expansion and contraction. Because there is less mass of steel to be heated or cooled,and because steel is a better concrete, a steel structure is generally affected by temperature changes to a greater extent than is a concrete structure. On the other hand, concrete undergoes frying shrinkage, which, if restrained, may cause deflections or cracking. Furthermore, deflections will tend to increase with time, possibly doubling, due to creep of the concrete under sustained loads.In almost every branch of civil engineering and architecture extensive use is made of reinforced concrete for structures and foundations. Engineers and architects requires basic knowledge of reinforced concrete design throughout their professional careers. Much of this text is directly concerned with the behavior and proportioning of components that make up typical reinforced concrete structures-beams, columns, and slabs. Once the behavior of these individual elements is understood, the designer will have the background to analyze and design a wide range of complex structures, such as foundations, buildings, and bridges, composed of these elements.Since reinforced concrete is a no homogeneous material that creeps, shrinks, and cracks, its stresses cannot be accurately predicted by the traditional equations derived in a course in strength of materials for homogeneous elastic materials. Much of reinforced concrete design in therefore empirical, i.e., design equations and design methods are based on experimental and time-proved results instead of being derived exclusively from theoretical formulations.A thorough understanding of the behavior of reinforced concrete will allow the designer to convert an otherwise brittle material into tough ductile structural elements and thereby take advantage of concrete’s desirable characteristics, its high compressive strength, its fire resistance, and its durability.Concrete, a stone like material, is made by mixing cement, water, fine aggregate ( often sand ), coarse aggregate, and frequently other additives ( that modify properties ) into a workable mixture. In its unhardened or plastic state, concrete can be placed in forms to produce a large variety of structural elements. Although the hardened concrete by itself, i.e., without any reinforcement, is strong in compression, it lacks tensile strength and therefore cracks easily. Because unreinforced concrete is brittle, it cannot undergo large deformations under load and failssuddenly-without warning. The addition fo steel reinforcement to the concrete reduces the negative effects of its two principal inherent weaknesses, its susceptibility to cracking and its brittleness. When the reinforcement is strongly bonded to the concrete, a strong, stiff, and ductile construction material is produced. This material, called reinforced concrete, is used extensively to construct foundations, structural frames, storage takes, shell roofs, highways, walls, dams, canals, and innumerable other structures and building products. Two other characteristics of concrete that are present even when concrete is reinforced are shrinkage and creep, but the negative effects of these properties can be mitigated by careful design.A code is a set technical specifications and standards that control important details of design and construction. The purpose of codes it produce structures so that the public will be protected from poor of inadequate and construction.Two types f coeds exist. One type, called a structural code, is originated and controlled by specialists who are concerned with the proper use of a specific material or who are involved with the safe design of a particular class of structures.The second type of code, called a building code, is established to cover construction in a given region, often a city or a state. The objective of a building code is also to protect the public by accounting for the influence of the local environmental conditions on construction. For example, local authorities may specify additional provisions to account for such regional conditions as earthquake, heavy snow, or tornados. National structural codes genrally are incorporated into local building codes.The American Concrete Institute ( ACI ) Building Code covering the design of reinforced concrete buildings. It contains provisions covering all aspects of reinforced concrete manufacture, design, and construction. It includes specifications on quality of materials, details on mixing and placing concrete, design assumptions for the analysis of continuous structures, and equations for proportioning members for design forces.All structures must be proportioned so they will not fail or deform excessively under any possible condition of service. Therefore it is important that an engineer use great care in anticipating all the probableloads to which a structure will be subjected during its lifetime.Although the design of most members is controlled typically by dead and live load acting simultaneously, consideration must also be given to the forces produced by wind, impact, shrinkage, temperature change, creep and support settlements, earthquake, and so forth.The load associated with the weight of the structure itself and its permanent components is called the dead load. The dead load of concrete members, which is substantial, should never be neglected in design computations. The exact magnitude of the dead load is not known accurately until members have been sized. Since some figure for the dead load must be used in computations to size the members, its magnitude must be estimated at first. After a structure has been analyzed, the members sized, and architectural details completed, the dead load can be computed more accurately. If the computed dead load is approximately equal to the initial estimate of its value ( or slightly less ), the design is complete, but if a significant difference exists between the computed and estimated values of dead weight, the computations should be revised using an improved value of dead load. An accurate estimate of dead load is particularly important when spans are long, say over 75 ft ( 22.9 m ), because dead load constitutes a major portion of the design load.Live loads associated with building use are specific items of equipment and occupants in a certain area of a building, building codes specify values of uniform live for which members are to be designed.After the structure has been sized for vertical load, it is checked for wind in combination with dead and live load as specified in the code. Wind loads do not usually control the size of members in building less than 16 to 18 stories, but for tall buildings wind loads become significant and cause large forces to develop in the structures. Under these conditions economy can be achieved only by selecting a structural system that is able to transfer horizontal loads into the ground efficiently.钢筋混凝土在每一个国家，混凝土及钢筋混凝土都被用来作为建筑材料。
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。
废弃混凝土资源化再生利用的新技术及其应用
废弃混凝土资源化再生利用的新技术及其应用一、背景介绍近年来，城市化进程加快，建设活动频繁，建筑垃圾产生量急剧增加。
其中，废弃混凝土是建筑垃圾中产量最大的一类。
传统处理方式是填埋，但填埋会占用大量土地资源，同时也会对环境造成污染。
因此，废弃混凝土资源化再生利用已成为一个热门话题。
二、废弃混凝土再生利用技术1. 混凝土碎石再生利用技术混凝土碎石再生利用技术是将废弃混凝土进行破碎、筛分等处理后，用于制造再生混凝土、路基、路面等建筑材料。
这种技术能够有效地减少废弃混凝土的填埋量，同时降低了新原材料的使用量，对环境和资源的保护具有重要意义。
2. 水泥混凝土回收技术水泥混凝土回收技术是指将废弃混凝土进行粉碎、筛分、洗涤等处理后，回收其中的水泥和砂石颗粒，用于制造新的混凝土。
这种技术能够有效地降低建筑垃圾的填埋量，同时还可以减少新原材料的使用量，节约资源。
3. 生态混凝土制备技术生态混凝土制备技术是指将废弃混凝土进行处理后，加入一定的生态骨料和其他辅料，制备出新型混凝土。
这种混凝土具有较好的生态环保性能，能够在一定程度上解决城市建设中的生态环保问题。
三、废弃混凝土再生利用应用案例1. 上海环球中心上海环球中心是一座集商业、文化、娱乐等多功能于一体的超高层建筑。
在建设过程中，废弃混凝土资源化再生利用技术得到了广泛应用。
根据统计，此项目共处理了约10万吨废弃混凝土，其中近70%被再生利用。
再生利用后的废弃混凝土被用作路基、路面、基础等建筑材料，有效地减少了建筑垃圾的填埋量，节约了大量的原材料。
2. 北京大兴国际机场北京大兴国际机场是中国首个“四横四纵”民航枢纽和世界上最大的单体航站楼。
在建设过程中，废弃混凝土资源化再生利用技术也得到了广泛应用。
据统计，此项目共处理了约23万吨废弃混凝土，其中近80%被再生利用。
再生利用后的废弃混凝土被用作路基、路面、基础等建筑材料，有效地减少了建筑垃圾的填埋量，节约了大量的原材料。
混凝土结构修复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)对混凝土修复过程中的真正理解或误解摘要：在最近的一段时间内，在世界的很多地方，早期钢筋的腐蚀而对混凝土结构产生的早期恶化和损坏，已经成为混凝土结构方面的主要问题。
加速这个恶化过程的一个主要因素是混凝土结构所存在的环境和气候状况。
恶劣的环境与低质量的混凝土加上有或无缺陷的设计和建设惯例，这都使结构恶化的过程变得具有交互性，累积得非常迅速，进而形成一种恶性的发展，而且很难被停止。
很多混凝土结构耐久性差的性能正引起结构产生裂缝.而在补救工作的支出，则使物主和社会所不能承担，并且他们也不希望看到悲剧重演。
这篇文章仅提出一些对钢筋腐蚀和保护选择的初步认识，而对混凝土和混凝土修理的抑制混合物腐蚀的影响则进行了详细讨论。
与抑制剂在修理效力有关的复杂论文已经发表，其中主要对基于电化学活动在新结构和修复结构方面之间差别进行了分析。
随着盲目的对需要修理的混凝土使用那些适用于新建筑的保护方法，文章断定："修复混凝土"的生意将会越来越好。
一种对新的和需要修理的混凝土之间的电化学差别的更广泛理解认为对修理的结构使用有效的钢筋保护是必要的。
关键词：碱度腐蚀保护耐久性抑制剂强化1 序言这是一个不幸的事实。
全世界范围内,大量混凝土结构都处在恶化/ 危险状态的阶段。
同时，必须承认的是，很多被修理的混凝土结构在几年后，一修再修。
被修理混凝土结构的保持性能的长久表现则最大限度的取决于它们的设计，建设，维护和使用。
与建筑在修理的几年之后出现裂缝相比，几乎没有问题能加剧公众与政府之间的冲突，并且导致他们对我们提供的建筑物用途的功能感到不满意。
然而与预期相反，不管是恶劣的环境状况还是适合的环境状态,在混凝土修理过程中,腐蚀的问题已经变得非常普遍.因而，混凝土修理业正面临一项主要的挑战：怎样制止全世界物质基础设施的腐坏。
它是如此重要，对当今的混凝土修复，我们要迫切检查腐蚀和腐蚀保护措施的发行，且探索在不久的将来它有可能改进的地方，即：如何使现在的修理能耐用到将来。
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废弃混凝土再生新技术探索【摘要】本文对目前废弃混凝土再生技术的研究做了论述,并指出了其中存在的一些问题。
结合混凝土各组成部分的结构特点,提出了通过低温煅烧对废弃混凝土综合利用的新方法。
在750℃温度条件下煅烧1h,可以实现水泥浆与骨料的分离。
脱水后的水泥浆可以重新获得水化活性。
得到的混凝土骨料可以满足使用要求。
【关键词】废弃混凝土;再生技术;煅烧;水化活性;压碎指标【中图分类号】TU352·8【文献标识码】A【文章编号】1001-6864(2009)09-0004-02国家“十五计划”纲要指出:“坚持资源开发与节约并举,把节约放在首位,法保护和合理使用资源,提高资源利用率,实现永续利用。
推进资源综合利用技术研究开发,加强废旧物资回收利用,加快废弃物处理的产业化,促进废弃物转化为可用资源。
”保护环境、节约能源、减少废料、以持续的方式使用可再生资源是可持续发展战略的重要内容。
建材工业是典型的基础原料工业,在国民经济发展中具有重要作用。
建材工业又是典型的资源、能源消耗型工业,在其快速发展的同时,面临着资源、能源的过度消耗和环境的严重污染。
建筑和建材行业的根本出路就是走可持续发展的道路[1]。
起初,我国对混凝土的利用仅是简单的破碎充当再生粗骨料,这种生产的再生骨料性能与天然粗骨料的性能存在一定差异,主要表现在密度低、吸水率高、压碎指标大,表明再生骨料的空隙率高,强度低,这主要是由于其表面附着有大量水泥砂浆及在破碎过程中引入一定量的微裂纹的缘故[2],生成的混凝土性能低,耐久性、抗冻融、抗腐蚀能力差。
研究者根据再生骨料再利用过程中存在的问题,对再生骨料进行了物理、化学改性以及整形改性。
如朱崇绩等通过整形除去再生骨料表面的砂浆,使颗粒变得光滑,需水量降低,使所配制的混凝土收缩降低,但仍高于天然骨料混凝土[3]。
没有解决再生骨料中微裂纹带来的弊端。
目前有研究者对废弃混凝土进行了综合利用研究,通过筛分获得砌筑砂浆或进步筛分生产具有水化活性的再生水泥。
如孙荣光等[4]对旧水泥浆高温处理后的再水化胶凝特性研究,得出再生水泥具有再水化的能力,同时生成C-S-H凝胶、Aft和CH等物质,说明水化产物结构相同,但由于大量脱水相的存在使水化速度快。
余睿等[5]通过对水泥浆的研究得出石膏和粉煤灰组成改性剂能延长活化水泥浆的初凝时间,增强其抗压强度,但不能减少活化水泥浆的标准稠度需水量。
由于易水化的水泥石脱水需要时间,所以煅烧时间和脱水温度对再生水泥性能不容忽视。
1．废弃混凝土裂解温度确定混凝土是由水泥、粗细集料、矿物掺合料等加水拌合,经水化硬化而形成的一种微观不均匀,宏观均匀的人造石。
废弃混凝土在低温煅烧时的温度由水泥脱水温度与石灰石分解温度共同决定。
1·1水泥水化产物脱水温度文献认为,含水矿物中普通吸附水的脱水温度一般为100~110℃,存在于层状硅酸盐结构中的层间水或胶体矿物中的胶体水多数要在200~300℃以内脱水,个别要在400℃以内脱水;架状结构的硅酸盐结构水则要在400℃左右才大量脱出。
结晶水在不同结构中的矿物中结合程度不同,其脱水温度也不同。
结构水是矿物中结合最牢的水,脱水温度较高,一般要在450℃以上才脱水[5]。
为了确定废弃混凝土的低温煅烧温度,保证在该温度条件下骨料和水泥浆能够充分分离,水泥石完全脱水,本课题对水泥浆进行了热重分析(TGA),热失重曲线及(TG)及差热曲线(DTG)如图1所示。
从图1可以看出,水泥浆在100℃前后分别有一个明显的失重过程,理论上应当是失去自由水和弱吸附水所形成的过程。
在500℃以前又有一个明显的失重过程,该失重过程温度范围较窄,但失重速度较快,从水泥石的组成看应当是Ca(OH)2失水形成的。
另一个水泥石脱水过程发生在682~775℃之间,脱水的峰值速率发生在740℃。
这一过程脱水过程剧烈,持续时间较长,这一失水过程使C-S-H凝胶分解,重新生成为具有潜在水化活性的胶凝材料。
温度继续升高,直至1000℃再无明显的吸热峰出现。
另外,温度再渡升高可能影响混凝土骨料的结构。
因此,混凝土分解温度确定为750℃。
经过高温处理的水泥浆因脱水而重新获得水化活性,这一性能已在实验中得到证实。
1·2碎石分解温度粗骨料(碎石)的成分主要由CaCO3和在少量的MgCO3组成,其中MgCO3的分解温度较低,600℃就开始剧烈反应,CaCO3剧烈分解温度则更高达到900℃左右,但其开始分解温度较低,在650℃就开始分解。
所以在550~900℃范围内煅烧混凝土时,随着温度的升高,骨料发生分解的量增大,使骨料的强度降低。
过渡区是混凝土的薄弱环节,一方面搅拌时在骨料表面被水膜覆盖,妨碍了水泥粒子与骨料表面接触,骨料周边水灰比变大,另一方面,水化反应溶出的迁移性大的Ca2+、Al3+、SO4-3离子为使浓度平衡向骨料表面扩散。
在骨料表面附近,六角板状结晶的氢氧化钙和针状结晶的钙钒石的析出比较显著,形成大且连续的空隙构造[8]。
使过渡区的水分也几乎以层间水及自由水的形式存在,所以在较低的煅烧温度就可实现骨料与水泥砂浆的分离,理论上在300℃以上即可实现分离。
为了探究煅烧温度对骨料强度的影响,本试验分别对600、700、800℃煅烧温度时所得到的粗骨料压碎值进行了研究,并与天然碎石和直接破碎的混凝土进行了比较,实验结果如图所示。
从图2可知在燃烧温度600℃时,碎石的压碎指标略高于天然碎石,而随燃烧温度的提高,压碎指标明显增大,标志着骨料强度降低。
但在800℃所得到的骨料强度仍高于混凝土直接破碎得到的骨料强度,所以在混凝土煅烧温度不超过800℃时是可行的。
2结语根据混凝土各组分的结构特点,采取煅烧的方法把骨料和水泥浆分离是可行的。
经分解后的粗骨料可以在新拌混凝土中应用,其强度高于混凝土直接破碎得到的再生骨料。
经分离得到的水泥浆重新获得了再次水化的活性。
为废弃混凝土的回收以及骨料和水泥浆的再生和利用开辟了一条新的途径。
参考文献[1]水中和,曹蓓蓓,万惠文.废弃混凝土再生利用技术及其发展前景[J]·资源节约与综合利用,2006,(3):8-11·[2]王耀新.混合应用天然与再生骨料混凝土的基本性能[J]·混凝土,2005,(8):49-53·[3]朱崇绩,李秋义,李云霞.颗粒整形对再生骨料混凝土耐久性的影响[J]·水泥与混凝土,2007,(3):6-10·[4]孙荣光,余睿,玄东兴,水中和.旧水泥浆高温处理后的再水化胶凝特性研究[J].武汉理工大学学报,2007,(9):115-118·[5]余睿,水中和,玄东兴.再生水泥浆的改性研究[J]·2009,(4):104-107·[6]SidneyMindess·混凝土(原著第二版)[M].吴科如,等译·北京:化学工业出版社,2005·1·[7]王培铭,许乾慰.材料研究方法[M].北京:科学出版社,2005,236-249·[8]徐新生,徐卫生.混凝土过渡区对混凝土物质渗透性影响[J]·山东建材,1999,(3):10-13·EXPLORATION ON RECYCLING TECHNOLOGY OF WASTE CONCRETEMA Xin-wei1,ZHANG Dong-qing2,YINWei-feng2,LI Ning2 (1·Department of Civil Engineering, Harbin Institute ofTechnology at Weihai, Shandong Weihai 264209, China;2·School ofMaterials Science and Engineering, Harbin Institute ofTechnology, Harbin 150001, China)Abstract:The current research situation on the recycling technology ofwaste concrete and existing problems in applicationwas summarized·Consideringthe structural characteristics of cement paste and aggregate, a new recycling technology through calcination is presented·The cement paste and aggregates could be separated at 750℃for one hour·The dehydrated cement paste can have reactivity again, and the aggregates can meet the requirement of application·Key words:waste concrete;recyclyingte;chnology;calcination;reactivity;crushing indexNational "tenth five-year plan" outline pointed out: "insists resource development and save the save itself, in the first place, protect and rationally use method of resources, and improve the resource utilization rate, to achieve sustainable use. Push technology research and development resources comprehensive utilization of waste materials, strengthen recycling, accelerate the industrialization, promote waste disposal of waste into usable resources." Protect the environment and save energy, reducing waste, with continuous way, using renewable resource is the important content of strategy of sustainable development. The building materials industry is typical of basic raw materials industry in the national economy development, plays an important role. The building materials industry is typical resources, energy consumption industries in its rapid development, at the same time, facing the excessive consumption of resources, energy and environmental pollution. Construction and building materials industry is the fundamental way to walk the path of sustainable development [1].At first, the use of concrete in the crushing only a simple as recycled coarse aggregate, the production of natural regeneration aggregate performance and the performance of coarse aggregate, main show there is some difference in density low, bibulous rate is high, crush index is big, show the gap regeneration aggregate rate high, low intensity, and it is mainly because the surface adhesion has large cement mortar and crushing process in certain micro cracks of introducing the sake [2] and generated concrete performance low, durability, freezing-thawing resisting, corrosion resistance is poor. The researchers based on renewable aggregate reuse the problems existing in the process of recycled aggregate, carried on the physical and chemical modification and plastic modification. As such ZhuChong performance by plastic toremove the mortar, renewable aggregate surface water that particles, smooth, prepared by reducing shrinkage of concrete lower, but still higher than the natural aggregate concrete [3]. Not solve the regeneration aggregate micro cracks in the malpractices. Currently have researchers of the waste comprehensive utilization of concrete research, through the screening get bonding mortar or progress screening production of renewable cement hydration activity with. If SunRongGuang etc [4] to the old cement. after high temperature treatment of slurry rehydration characteristics study gel, it is concluded that renewable cement with a rehydration ability, while generating C - S - H gel, Aft and CH that hydration products such material, but same structure dehydrated phases because of the existence of hydration speed to. YuRui etc [5] for water mud through the research that fly ash and composition modifier gypsum slurry can extend the initial setting activation time and strengthen the compressive strength, however does not reduce activation of standard slurry water viscosity. Due to easy hydration of cement stone dehydration need time, so calcining time and dehydration temperature of recycled cement performance cannot be ignored.1. Determine the decomposition temperature of waste concreteConcrete is made of cement, thick aggregate, such as mineral admixture, the water hydration sclerosis regarding mix-proportion formed a microscopic uneven, macro uniform man-made stone. Abandoned the concrete in low temperature calcination temperature by cement dehydration temperature decomposition temperatures decided together with limestone.1 · 1 cement hydration products dehydration temperatureLiterature in minerals that water cut the dehydration temperature ordinary adsorption water for 100 ~ 110 ℃commonly, exists in layer silicate structure between layers of the colloid water or colloid mineral water in 200 ~ 300 much ℃in within dehydration, individual ℃400 within dehydration; Frame shape structure of silicate structure in 400 ℃water is only around large emerge. The minerals in different structure gesso combination of different degree, the dehydration temperature is different. Structure combination of water is mineral water, the most jail dehydration temperature is higher, typically in 450 ℃above just dehydration [5]. In order to determine the low temperature calcining temperature waste concrete, guarantee the temperature conditions in slurry aggregates, and can be fully separation, cement stone completely dehydration, this topic to the slurry thermogravimetric analysis (TGA), thermo-gravimetric curve and (TG) and differential thermal curve (DTG) as shown in figure 1 below.Temperature（℃）Slurry thermogravimetric analysis curvesFrom figure 1 in 100 ℃, water slurry before an obvious weightlessness, respectively, in theory should be losing process of free water and weak adsorption water by the formation of the process. In 500 ℃ago and have an obvious of weightlessness process, this weightlessness process temperature range is narrower, but weightlessness faster, the composition of the cement paste.the watch from shall be the Ca (OH) 2 water loss formation. Another cement stone anhydration process occurs in 682 ~ 775 ℃between, dehydration rate occurred in 740 ℃peak. This process a severe dehydration process, continues for a long time, the water loss process makes C - S - H gel decomposition, born again into a potential hydration activity of cementitious material. Temperature continues to rise again until 1000 ℃, has no obvious heat-sink peak appearing. In addition, temperature rise again crossing may influence the structure of concrete aggregate. Therefore, concrete decomposition temperature determined for 750 ℃. The slurry high-temperature processing for dehydration and regain hydration activity, this performance has been confirmed in the experiment.1 ·2 gravel decomposition temperatureThe coarse aggregate (gravel) mainly by the ingredients in a small amount of CaCO3 and MgCO3 composition, which MgCO3 decomposition temperature is lower, 600 ℃began to react vigorously CaCO3 decomposition temperatures, severe ℃is high reached 900 around, but its start decomposing temperature is lower, at 650 ℃began to decompose. So in 550 ~ 900 ℃ scope when calcined concrete, with the rise of temperature, aggregate ratio increases occurred decomposition, aggregate strength decreased. Transitional zone is the concrete and the weak link in aggregate, on one hand, mixing the surface is water film covering, hampered cement particles and aggregate surface contact, aggregate peripheral water-cement ratio change, on the other hand, the transference of hydration reaction dissloution Ca2 +, big Al3 +, SO4-3 ion to make to the aggregate balance of surface concentration of diffuse. In aggregate, hexagonal near the surface plate crystallization of calcium hydroxide and needle crystal stone precipitation of calcium vanadium, forming a notable large andcontinuous space structure [8]. Make the moisture in the transition between layers also almost free water and water exists in the form of lower, so in the calcining temperature can achieve aggregate and cement mortar in the separation of more than 300 ℃, the theory can be realized separation. In order to explore calcining temperature effect on the strength of aggregate respectively, and the test of 600, 700, 800 ℃ calcining temperature get the coarse aggregate crush values are studied, and directly with natural gravel and broken concrete were compared, and the experiment results as shown.600 700 800Natural aggregate broken concreteFrom graph 2 600 ℃in combustion temperature that when the crush index, gravel, and slightly higher than the natural macadam with combustion temperature rise, crush index increased, marked the aggregate strength decreased. But in 800 ℃obtained aggregate strength is still higher than the aggregate concrete crushing get directly in the concrete intensity, so no more than 800 ℃calcination temperature is feasible.2 .EpilogueAccording to the structure characteristics of various components of the concrete methods of, take the aggregate and pellets slurry separation is feasible. After the decomposition of coarse aggregate in concrete in new mix, its strength of concrete application of crushing get directly than renewable aggregate. The slurry isolated from getting the hydration activity again. For the collection and aggregate concrete waste water and mud regeneration and use open a new way.References[1] water and CaoBeiBei, WanHuiWen. Abandoned, recycled technology and its development of concrete [J] prospect, conservation of resources and comprehensive utilization, 2006, (3) : 8-11 ·[2] WangYaoXin. Mix with application of natural regeneration aggregate concrete, basic properties of concrete [J], 2005, (8) : 49-53 ·[3] ZhuChong performance LiQiuYi, LiYunXia. Particles, of recycled aggregate concrete durability plastic [J], the influence of cement and concrete, 2007, (3) : 6-10 ·[4] SunRongGuang, YuRui, XuanDongXing, the water and the mud. Old water high temperature treatment rehydration gelling properties research [J]. Journal of wuhan university of technology, 2007, (9) : 115-118 ·[5] YuRui, the water and the mud. XuanDongXing renewable water, modified study [J] DE 2009, (4) : 104-107 ·[6] SidneyMindess ·concrete (original second edition) [M]. WuKeRu, etc, Beijing: chemical industry translation press, 2005 · 1 ·[7] WangPeiMing, research methods XuQian comfort. Materials [M]. Beijing: science press, 2005,236-249 ·[8] XuXinSheng, XuWeiSheng transition region. Concrete of concrete material [J], osmotic influence of shandong building materials, 1999, (3) : 10-13 ·。