外文翻译(中英文word版)废弃混凝土再生新技术探索
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·
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EXPLORATION ON RECYCLING TECHNOLOGY OF WASTE CONCRETE
MA 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 index
National "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 to
remove 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 concrete
Concrete 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 temperature
Literature 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 curves
From 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 temperature
The 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 and
continuous 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 concrete
From 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 .Epilogue
According 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 ·
机械手机械设计论文中英文资料对照外文翻译
中英文资料对照外文翻译 机械设计 摘要： 机器由机械和其他元件组成的用来转换和传输能量的装置。比如：发动机、涡轮机、车、起重机、印刷机、洗衣机和摄影机。许多机械方面设计的原则和方法也同样适用于非机械方面。术语中的“构造设计”的含义比“机械设计”更加广泛，构造设计包括机械设计。在进行运动分析和结构设计时要把产品的维护和外形也考虑在机械设计中。在机械工程领域中，以及其它工程领域，都需要机械设备，比如：开关、凸轮、阀门、船舶以及搅拌机等。 关键词：设计流程设计规则机械设计 设计流程 设计开始之前就要想到机器的实用性，现有的机器需要在耐用性、效率、重量、速度，或者成本上得到改善。新的机器必需能够完全或部分代替以前人的功能，比如计算、装配、维修。 在设计的初级阶段，应该充分发挥设计人员的创意，不要受到任何约束。即使有一些不切实际的想法，也可以在设计的早期，即在绘制图纸之前被改正掉。只有这样，才不致于阻断创新的思路。通常,必须提出几套设计方案,然后进行比较。很有可能在这个计划最后指定使用某些不在计划方案内的一些想法的计划。 一般当产品的外型和组件的尺寸特点已经显现出来的时候，就可以进行全面的设计和分析。接着还要客观的分析机器性能、安全、重量、耐用性，并且成本也要考虑在内。每一个至关重要的部分要优化它的比例和尺寸，同时也要保持与其它组成部分的平衡。 选择原材料和工艺的方法。通过力学原理来分析和实现这些重要的特性，如稳定和反应的能量和摩擦力的利用，动力惯性、加速度、能量；包括材料的弹性强度、应力和刚度等物理特性，以及流体的润滑和驱动器的流体力学。设计的过程是一个反复与合作的过程，无论是正式的还是非正式的，对设计者来说每个阶段都很重要。。产品设计需要大量的研究和提升。许多的想法,必须通过努力去研究成为一种理念,然后去使用或放弃。
英文文献翻译
中等分辨率制备分离的 快速色谱技术 W. Clark Still,* Michael K a h n , and Abhijit Mitra Departm(7nt o/ Chemistry, Columbia Uniuersity,1Veu York, Neu; York 10027 ReceiLied January 26, 1978 我们希望找到一种简单的吸附色谱技术用于有机化合物的常规净化。这种技术是适于传统的有机物大规模制备分离，该技术需使用长柱色谱法。尽管这种技术得到的效果非常好，但是其需要消耗大量的时间，并且由于频带拖尾经常出现低复原率。当分离的样本剂量大于1或者2g时，这些问题显得更加突出。近年来，几种制备系统已经进行了改进，能将分离时间减少到1-3h，并允许各成分的分辨率ΔR f≥（使用薄层色谱分析进行分析）。在这些方法中，在我们的实验室中，媒介压力色谱法1和短柱色谱法2是最成功的。最近，我们发现一种可以将分离速度大幅度提升的技术，可用于反应产物的常规提纯，我们将这种技术称为急骤色谱法。虽然这种技术的分辨率只是中等（ΔR f≥），而且构建这个系统花费非常低，并且能在10-15min内分离重量在的样本。4 急骤色谱法是以空气压力驱动的混合介质压力以及短柱色谱法为基础，专门针对快速分离，介质压力以及短柱色谱已经进行了优化。优化实验是在一组标准条件5下进行的，优化实验使用苯甲醇作为样本，放在一个20mm*5in.的硅胶柱60内，使用Tracor 970紫外检测器监测圆柱的输出。分辨率通过持续时间（r）和峰宽（w,w/2）的比率进行测定的（Figure 1），结果如图2-4所示，图2-4分别放映分辨率随着硅胶颗粒大小、洗脱液流速和样本大小的变化。
外文翻译---混凝土,钢筋混凝土和预应力混凝土
Concrete, Reinforced Concrete, and PrestressedConcrete Concrete is a stone like material obtained by permitting a carefully proportioned mixture of cement, sand and gravel or other aggregate, and water to harden in forms of the shape and dimensions of the desired structure. The bulk of the material consists of fine and coarse aggregate. Cement and water interact chemically to bind the aggregate particles into a solid mass. Additional water, over and above that needed for this chemical reaction, is necessary to give the mixture workability that enables it to fill the forms and surround the embedded reinforcing steel prior to hardening. Concretes with a wide range of properties can be obtained by appropriates adjustment of the proportions of the constituent materials. Special cements, special aggregates, and special curing methods permit an even wider variety of properties to be obtained. These properties depend to a very substantial degree on the proportions of the mix, on the thoroughness with which the various constituents are intermixed, and on the conditions of humidity and temperature in which the mix is maintained from the moment it is placed in the forms of humidity and hardened. The process of controlling conditions after placement is known as curing. To protect against the unintentional production of substandard concrete, a high degree of skillful control and supervision is necessary throughout the process, from the proportioning by weight of the individual components, trough mixing and placing, until the completion of curing. The factors that make concrete a universal building material are so pronounced that it has been used, in more primitive kinds and ways than at present, for thousands of years, starting with lime mortars from 12,000 to 600 B.C. in Crete, Cyprus, Greece, and the Middle East. The facility with which , while plastic, it can be deposited and made to fill forms or molds of almost any practical shape is one of these factors. Its high fire and weather resistance are evident advantages. Most of the constituent materials, with the exception of cement and additives, are usually available at low cost locally or at small distances from the construction site. Its compressive strength, like that of natural stones, is high, which makes it suitable for members primarily subject to compression, such as columns and arches. On the other hand, again as in natural stones, it is a relatively brittle material whose tensile strength is small compared with its compressive strength. This prevents its economical use in structural members that ate subject to tension either entirely or over part of their cross sections. To offset this limitation, it was found possible, in the second half of the
机械设计外文翻译(中英文)
机械设计理论 机械设计是一门通过设计新产品或者改进老产品来满足人类需求的应用技术科学。它涉及工程技术的各个领域，主要研究产品的尺寸、形状和详细结构的基本构思，还要研究产品在制造、销售和使用等方面的问题。 进行各种机械设计工作的人员通常被称为设计人员或者机械设计工程师。机械设计是一项创造性的工作。设计工程师不仅在工作上要有创造性，还必须在机械制图、运动学、工程材料、材料力学和机械制造工艺学等方面具有深厚的基础知识。如前所诉，机械设计的目的是生产能够满足人类需求的产品。发明、发现和科技知识本身并不一定能给人类带来好处，只有当它们被应用在产品上才能产生效益。因而，应该认识到在一个特定的产品进行设计之前，必须先确定人们是否需要这种产品。 应当把机械设计看成是机械设计人员运用创造性的才能进行产品设计、系统分析和制定产品的制造工艺学的一个良机。掌握工程基础知识要比熟记一些数据和公式更为重要。仅仅使用数据和公式是不足以在一个好的设计中做出所需的全部决定的。另一方面，应该认真精确的进行所有运算。例如，即使将一个小数点的位置放错，也会使正确的设计变成错误的。 一个好的设计人员应该勇于提出新的想法，而且愿意承担一定的风险，当新的方法不适用时，就使用原来的方法。因此，设计人员必须要有耐心，因为所花费的时间和努力并不能保证带来成功。一个全新的设计，要求屏弃许多陈旧的，为人们所熟知的方法。由于许多人墨守成规，这样做并不是一件容易的事。一位机械设计师应该不断地探索改进现有的产品的方法，在此过程中应该认真选择原有的、经过验证的设计原理，将其与未经过验证的新观念结合起来。 新设计本身会有许多缺陷和未能预料的问题发生，只有当这些缺陷和问题被解决之后，才能体现出新产品的优越性。因此，一个性能优越的产品诞生的同时，也伴随着较高的风险。应该强调的是，如果设计本身不要求采用全新的方法，就没有必要仅仅为了变革的目的而采用新方法。 在设计的初始阶段，应该允许设计人员充分发挥创造性，不受各种约束。即使产生了许多不切实际的想法，也会在设计的早期，即绘制图纸之前被改正掉。只有这样，才不致于堵塞创新的思路。通常，要提出几套设计方案，然后加以比较。很有可能在最后选定的方案中，采用了某些未被接受的方案中的一些想法。
土木工程外文翻译参考3篇
学校 毕业设计（论文）附件 外文文献翻译 学号： xxxxx 姓名： xxx 所在系别： xxxxx 专业班级： xxx 指导教师： xxxx 原文标题： Building construction concrete crack of prevention and processing 2012年月日 .
建筑施工混凝土裂缝的预防与处理1 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缝问题进行了探讨分析，并针对具体情况提出了一些预防、处理措施。 关键词：混凝土裂缝预防处理 前言 混凝土是一种由砂石骨料、水泥、水及其他外加材料混合而形成的非均质脆性材料。由于混凝土施工和本身变形、约束等一系列问题，硬化成型的混凝土中存在着众多的微孔隙、气穴和微裂缝，正是由于这些初始缺陷的存在才使混凝土呈现出一些非均质的特性。微裂缝通常是一种无害裂缝，对混凝土的承重、防渗及其他一些使用功能不产生危害。但是在混凝土受到荷载、温差等作用之后，微裂缝就会不断的扩展和连通，最终形成我们肉眼可见的宏观裂缝，也就是混凝土工程中常说的裂缝。 混凝土建筑和构件通常都是带缝工作的，由于裂缝的存在和发展通常会使内部的钢筋等材料产生腐蚀，降低钢筋混凝土材料的承载能力、耐久性及抗渗能力，影响建筑物的外观、使用寿命，严重者将会威胁到人们的生命和财产安全。很多工程的失事都是由于裂缝的不稳定发展所致。近代科学研究和大量的混凝土工程实践证明，在混凝土工程中裂缝问题是不可避免的，在一定的范围内也是可以接受的，只是要采取有效的措施将其危害程度控制在一定的范围之内。钢筋混凝土规范也明确规定：有些结构在所处的不同条件下，允许存在一定宽度的裂缝。但在施工中应尽量采取有效措施控制裂缝产生，使结构尽可能不出现裂缝或尽量减少裂缝的数量和宽度，尤其要尽量避免有害裂缝的出现，从而确保工程质量。 混凝土裂缝产生的原因很多，有变形引起的裂缝：如温度变化、收缩、膨胀、不均匀沉陷等原因引起的裂缝；有外载作用引起的裂缝；有养护环境不当和化学作用引起的裂缝等等。在实际工程中要区别对待，根据实际情况解决问题。 混凝土工程中常见裂缝及预防: 1.干缩裂缝及预防 干缩裂缝多出现在混凝土养护结束后的一段时间或是混凝土浇筑完毕后的一周左右。水泥浆中水分的蒸发会产生干缩，且这种收缩是不可逆的。干缩裂缝的产生主要是由于混凝土内外水分蒸发程度不同而导致变形不同的结果：混凝土受外部条件的影响，表面水分损失过快，变形较大，内部湿度变化较小变形较小，较大的表面干缩变形受到混凝土内部约束，产生较大拉应力而产生裂缝。相对湿度越低，水泥浆体干缩越大，干缩裂缝越易产 1原文出处及作者：《加拿大土木工程学报》
土木外文翻译--高温下钢筋混凝土中钢筋的性能
土木外文翻译--高温下钢筋混凝土中钢筋的性能
外文原文： Research Letters in Materials Science Volume 2008 (2008), Article ID 814137, 4 pages doi:10.1155/2008/814137 Research Letter Properties of Reinforced Concrete Steel Rebars Exposed to High Temperatures ?lker Bekir Top?u and Cenk Karakurt Department of Civil Engineering, Eski?ehir Osmangazi University, 26480 Eski?ehir, Turkey Received 12 February 2008; Accepted 31 March 2008 Academic Editor: Rajiv S. Mishra Copyright ? 2008 ?lker Bekir Top?u and Cenk Karakurt. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The deterioration of the mechanical properties of yield strength and modulus of elasticity is considered as the primary element affecting the performance of steel structures under fire. In this study, hot-rolled S220 and S420 reinforcement steel rebars were subjected to high temperatures to investigate the fire performance of these materials. It is aimed to determine the remaining mechanical properties of steel rebars after elevated temperatures. Steels were subjected to 20, 100, 200, 300, 500, 800, and 9 5 0 ° C temperatures for 3 hours and tensile tests were carried out. Effect of temperature on mechanical behavior of S220 and S420 were determined. All mechanical properties were reduced due to the temperature increase of the steel rebars. It is seen that mechanical properties of S420 steel was influenced more than S220 steel at elevated temperatures.
机械专业外文翻译中英文翻译
外文翻译 英文原文 Belt Conveying Systems Development of driving system Among the methods of material conveying employed，belt conveyors play a very important part in the reliable carrying of material over long distances at competitive cost．Conveyor systems have become larger and more complex and drive systems have also been going through a process of evolution and will continue to do so．Nowadays，bigger belts require more power and have brought the need for larger individual drives as well as multiple drives such as 3 drives of 750 kW for one belt(this is the case for the conveyor drives in Chengzhuang Mine)．The ability to control drive acceleration torque is critical to belt conveyors’ performance．An efficient drive system should be able to provide smooth，soft starts while maintaining belt tensions within the specified safe limits．For load sharing on multiple drives．torque and speed control are also important consideratio ns in the drive system’s design. Due to the advances in conveyor drive control technology，at present many more reliable．Cost-effective and performance-driven conveyor drive systems cov ering a wide range of power are available for customers’ choices[1]. 1 Analysis on conveyor drive technologies 1．1 Direct drives Full-voltage starters．With a full-voltage starter design，the conveyor head shaft is direct-coupled to the motor through the gear drive．Direct full-voltage starters are adequate for relatively low-power, simple-profile conveyors．With direct fu11-voltage starters．no control is provided for various conveyor loads and．depending on the ratio between fu11- and no-1oad power requirements，empty starting times can be three or four times faster than full load．The maintenance-free starting system is simple，low-cost and very reliable．However, they cannot control starting torque and maximum stall torque；therefore．they are
废弃混凝土的回收利用分解创新
建筑垃圾的处理和合理利用的思考 摘要目前我国建筑垃圾已占到城市垃圾总量的30~40%,,其中很大一部分是旧房拆除过程中所产生的废旧混凝土构件和块体。传统的建筑垃圾处理方法将占用大量耕地,造成一定的环境污染,如何合理处理这部分建筑垃圾成为摆在我们面前的一个重要课题。本文根据大量国内外调查资料和研究分析,从材料、技术和经济等方面论述了生产再生混凝土和在建筑工程中应用再生混凝土的可行性,给出了再生混凝土生产的技术要求和经济指标,对建筑垃圾的处理具有一定的指导意义。 关键词废弃混凝土再生骨料破碎与分级技术 1前言 随着城市公用与民用建筑及市政设施的更新、改造和建设,在建设过程中,大量旧建筑物被拆除,从而产生大量的建筑垃圾,目前我国建筑垃圾数量已占到城市垃圾总量的30~40%。根据有关资料,经过砖混结构、全现浇结构和框架结构等建筑的施工材料损耗的粗略估计,每万平方米建筑的施工过程中,仅建筑废渣就会产生500~600吨,若据此测算,我国每年仅施工建设所产生和排出的建筑废渣就有4000万吨。而建筑垃圾中又尤其以废弃混凝土占得比重最多，因此,在建筑废弃物回收再利用当中,解决占绝大多数的废弃混凝土是至关重要的。建国初期我国处理废弃混凝土的办法:一是运往郊外掩埋;二是运往河道倾倒,这些都带来了一定的不利影响。近年来, 国内专家学者们在废弃混凝土方面开展了一些基础性研究。但研究深度不够, 再加上施工应用者的认识不足, 特别是没有标志性工程的示范和相关技术标准、规程的指导。因此, 目前我国建筑垃圾资源化再生循环利用步伐缓慢, 综合高效利用率尚不足 5%。然而，由于美国、日本和欧洲等发达国家和地区对建筑垃圾尤其是废弃混凝土等的再生循环利用研究开展得较早, 目前废弃混凝土的再生利用率均在 90%以上。因此我国在废弃混凝土方面的研究与发展还有很大的进步空间，本文通过国内外对废弃混凝土的研究和经济效益方面的评价阐述废弃混凝土对城市的可持续发展所起到的重中之重的意义。 2.国内对废弃混凝土的研发与利用 目前,我国对于建筑废弃物的处理办法主要是运往郊外露天堆放或填埋,即使是回收也只是作为建筑物或道路的基础材料等低级利用,这样不仅会占用大量土地,造成环境污染,而且还会导致资源的严重浪费。一方面我国是一个资源匮乏的国家,经济增长越来越受到资源和环境的约束;另一方面我国要贯彻和谐社会、可持续发展战略,因此建筑垃圾处理及应用技术的研究势在必行。
外文翻译(中英文word版)废弃混凝土再生新技术探索
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
随时间变化的钢筋混凝土阻力分析外文翻译
随时间变化的钢筋混凝土阻力分析外文翻译 Prepared on 24 November 2020
毕业设计(论文)外文资料翻译 系（部）：建筑工程系 专业：土木工程 班级： B070704 姓名： 123 学号： 123 外文出处：Journal of Wuhan University 附件： 1. 原文； 2. 译文 2010年12月29日 附件1：原文 随时间变化的钢筋混凝土阻力分析 摘要∶对钢筋混凝土材料时间相关性的分析方法进行介绍，讨论钢筋混凝土的作用 机理，然后再研究随时间而定的钢筋混凝土抵抗力。此外，钢筋混凝土结构中的钢材腐 蚀也是需要被分析的。鉴定随时间而变的抵抗力的实际统计方法，包括物质的材料，结 构尺寸，影响计算的确定。另外，范例中估计随时间而变钢筋混凝土结构构件的抵抗力 是给的。 关键字∶不定分析；随时间变化的抵抗力；钢筋混凝土 1．介绍： 因为钢筋混凝土材料适用于很多地方，并且价格便宜，所以它在土木工程中是一种 非常有用的材料。因此，这种材料大量的被使用。然而，传统的建筑结构设计和钢筋混
凝土材料的研究很少注意到钢筋混凝土强度和时间的关系，尤其是作用在材料上的不同影响作用几乎是不予研究的。直到近年来，在建筑施工中的一些研究才涉及这个问题——关于钢筋混凝强度与时间相关性的。已做过的关于钢筋混凝土柱破坏概率的研究表明低强度的钢筋混凝土柱破坏概率低于偶然的荷载作用下的破坏概率。并且这种计算方法已经被运用到随时间而变化的破坏概率的计算上。低强度的和Liu[4] 混凝土结构耐久性上的研究认为这种作用加速了其的破坏。并且Lu [6]等已经论述钢筋腐蚀的情况。一般而言，依赖不同因素的钢筋混凝土抵抗力明显减小。在对混凝土结构安全性校核上,基础理论为钢筋混凝土耐久性分析提供了建议。研究随时间而变的钢筋混凝土结构的性质的是必要的。 ２．影响钢筋混凝土机理的因素 许多因素对钢筋混凝土抵抗力都产生影响。在水区域内存在着超过50种化学腐蚀元素,水在其中工作并且起调节作用。获得一次相关钢筋混凝土模型的实际方法是一种多因素理解方法。通常，对于单一的因素，许多结果只考虑到混凝土的碳化作用，碳化的厚度可以用下面公式来表示： 可以写为：D ( t) = K t (1) 式中D ( t)，K和t分别为厚度，速度系数与碳化的时间。 到目前为止，虽然有许多模型被运用到钢筋的断裂，疲劳破坏中，但是还没有大家都认可的结论存在。一般而言，能够降低钢筋混凝土的抵抗力的变量有钢筋的几何尺寸，周边环境情况以及随时间而变的抵抗力等。显而易见，钢筋混凝土抵抗力的变化是的一个随机函数过程或者说是一系列材料和结构变量的相互作用。钢筋混凝土在空气中的碳化被称之为中和反应。它是合成物与在空中的CO2以及钢筋混凝土中的碱性材料缓慢中和的过程。在空气中完全地碳化密实混凝土中的钢筋保护层需要花费几十年的时
外文翻译英文
A Distributed Approach for Track Occupancy Detection Abstract This paper investigates the problem of track occupancy detection in distributed settings. Track occupancy detection determines which tracks are occupied in a railway system. For each track, the Neyman–Pearson structure is applied to reach the local decision. Globally, it is a multiple hypotheses testing problem. The Bayesian approach is employed to minimize the probability of the global decision error. Based on the prior probabilities of multiple hypotheses and the approximation of the prior probabilities of multiple hypotheses and the approximationofthereceiving operation characteristic curve of the local detector, a person-by-person optimization method is implemented to obtain the fusion rule and the local strategies off line. The results are illustrated through an example constructed from in situ devices. Key Words:Track occupancy detection,Neyman–Pearson, Generalized likelihood ratio test, Bayesian approach,Distributed detection 1Introduction With respect to the majority of railway systems in China, a quasi-moving block method is employed to specify the safe zone of a train. A key piece of knowledge to be determined is the set of track segments that are occupied, i.e., track occupancy detection. Then the speed restriction curves for the following trains are calculated accordingly. When there are misdetections, collisions may happen; additionally, false alarms may lead to declines of line capacity. Track occupancy detection is achieved by a set of track circuits. The track circuit is a crucial device mainly composed of a transmitter–receiver pair and a track segment. The measurement is the receiving signal at the end of the track. For each segment, a decision is made locally and individually, which leads to frequent ambiguities on which tracks are occupied for the whole line. It means that the false alarm rate of the line increases greatly. Besides, for the next generation of railway systems, a moving block method is adopted. Such a method requires the exact position and velocity of the train. However, those data are not provided in the current detection mechanism.
混凝土相关外文翻译
英文译文 在桥梁覆盖中的聚丙烯酰胺改性混凝土在实验室材料性能测试和有 限元建模结构中的反应 Qinwu Xu1; Zengzhi Sun2; Hu Wang3; and Aiqin Shen4 摘自： Qinwu https://www.360docs.net/doc/1d14531514.html,boratory Testing Material Property and FE Modeling Structural Response of PAM-Modified Concrete Overlay on Bridges[J]. ASCE:Journal of bridge engineering,2009,14(1):26-35 摘要： 在开裂困扰和界面脱粘的影响下，波特兰水泥混凝土通过反复装载车辆和温度循环进行覆盖桥面。为了提高覆盖性能，本研究运用聚丙烯酰胺聚合物能修改混凝土力学的性能。直接剪切和耐冲击性试验，旨在分别衡量界面结合强度和动态性能。弯曲强度和弯曲疲劳根据标准进行试验。同时，在交通的负荷下，为了分析应激反应和提高结构设计，建立T梁和箱梁桥三维有限元模型，通过一个分析模型弯曲应力的开发来验证有限元模拟结果。在有限元模型设计中，橡胶垫能够吸收弯曲应力。实验室测试结果表明，聚丙烯酰胺可以显著提高混凝土的抗折强度，粘结强度，耐冲击和疲劳寿命。含8％聚丙烯酰胺的改性混凝土对水泥质量比混凝土与其他PAM的百分比提出了更高的抗弯强度和耐冲击性。有限元模拟结果表明，一个关键覆盖厚度的存在能够减小在结构设计中应该避免的最大界面剪应力，橡胶垫能够有效地减轻弯曲应力。 关键词：桥梁；化验结果；有限元法；材料特性；结构响应；波特兰水泥；混凝土 导言 波特兰水泥混凝土已被用于桥面表面结构的覆盖，以支持车辆装载和保护桥梁结构。在反复车辆装载，温度循环，收缩和化学反应的影响下桥梁的覆盖可能遇到开裂的
土木工程钢筋混凝土结构中英文对照外文翻译文献
中英文翻译
原文： DESIGN OF REINFORCED CONCRETE STRUCTURES 1. BASIC CONCERPTS AND CHARACERACTERISTICS OF REINFORCED CONCRETE Plain concrete is formed from hardened mixture of cement, water , fine aggregate , coarse aggregate (crushed stone or gravel ) , air and often other admixtures . The plastic mix is placed and consolidated in the formwork, then cured to accelerate of the chemical hydration of hen cement mix and results in a hardened concrete. It is generally known that concrete has high compressive strength and low resistance to tension. Its tensile strength is approximately one-tenth of its compressive strength. Consequently, tensile reinforcement in the tension zone has to be provided to supplement the tensile strength of the reinforced concrete section. For example, a plain concrete beam under a uniformly distributed load q is shown in Fig . 1.1(a), when the distributed load increases and reaches a value q=1.37KN/m , the tensile region at the mid-span will be cracked and the beam will fail suddenly . A reinforced concrete beam if the same size but has to steel reinforcing bars (2φ16) embedded at the bottom under a uniformly distributed load q is shown in Fig.1.1(b). The reinforcing bars take up the tension there after the concrete is cracked. When the load q is increased, the width of the cracks, the deflection and the stress of steel bars will increase . When the steel approaches the yielding stress ?y , the deflection and the cracked width are so large offering some warning that the compression zone . The failure load q=9.31KN/m, is approximately 6.8 times that for the plain concrete beam. Concrete and reinforcement can work together because there is a sufficiently strong bond between the two materials, there are no relative movements of the bars and the surrounding concrete cracking. The thermal expansion coefficients of the two materials are 1.2×10-5K-1 for steel and 1.0×10-5~1.5×10-5K-1 for concrete . Generally speaking, reinforced structure possess following features : Durability .With the reinforcing steel protected by the concrete , reinforced concrete