外文翻译---浅谈混凝土的施工过程中温度与裂缝控制

南京理工大学紫金学院毕业设计(论文)外文资料翻译系：机械系专业：土木工程外文出处：《 CANADIAN JOURNAL OF CIVI ENGINEERING 》(用外文写)附件： 1.外文资料翻译译文；2.外文原文。

指导教师评语：签名：年月日注：请将该封面与附件装订成册。

附件1：外文资料翻译译文建筑施工混凝土裂缝的预防与处理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。

浅谈混凝土的施工温度与裂缝混凝土裂缝威胁着工程质量，文章通过阐述裂缝产生的原因，分析温度应力，提出控制温度和预防裂缝的措施，以及防止裂缝对混凝土进行早期养护，从混凝土裂缝的角度为工程安全提出参考依据。

标签：温度裂缝养护0 引言长期以来，混凝土在建筑施工中始终发挥着举足轻重的作用。

但是混凝土裂缝问题也是长期困扰建筑、施工单位的一大难题，桥梁工程裂缝问题尤为严重。

尽管在施工阶段已采取了防治措施，但裂缝仍时有发生。

在混凝土施工中，温度应力和温度控制对裂缝防治意义重大，具体体现在：一是混凝土结构的整体性和耐久性受温度产生的裂缝的影响较大；另一方面结构的应力状态受温度变化的影响明显。

1 裂缝产生的原因在混凝土施工中，原材料的选择、温湿度变化、混凝土的脆性和不均匀性、地基发生不均匀沉陷等等诸多因素都有可能引发混凝土裂缝，因此在施工中要加强各环节、各工序的质量控制。

由于混凝土水花作用会产生大量水化热，致使混凝土内、外部形成温度差，进而导致混凝土表面产生拉应力。

降温时，基础混凝土与旧混凝土相互制约，导致混凝土的内部出现大于混凝土本身抗裂能力的拉应力，进而引发结构裂缝。

混凝土作为一种脆性材料，抗拉强度不均匀，在混凝土的内部存在许多抗拉能力低、极易出现裂缝的薄弱部位。

另外，由于原材料拌合不均匀，水灰比不稳定，以及混凝土出现离析现象，在混凝土内部由钢筋承担拉应力，混凝土只承受压应力。

但是在钢筋混凝土的边缘和素混凝土内部，这部分拉应力职能由混凝土本身承担。

因此，浇筑过程中，要严格控制浇筑质量，尽量避免混凝土构件产生拉应力。

但是在施工过程中，由于混凝土温度的变化，导致混凝土内部产生拉应力。

为了确保结构设计的合理性，熟悉温度应力的变化规律。

2 温度应力的分析形成温度应力过程分为早期、中期、晚期三个阶段：①早期：大约需要30天，是指从开始浇筑混凝土到水泥完成放热。

此时混凝土表现出两个特征：一是弹性模量发生急剧变化；二是水泥产生大量水化热。

浅谈混凝土的施工温度与裂缝的成因与控制【摘要】在如今的工程建设中，混凝土构件占有相当大的比重。

但因为混凝土的抗拉强度比较低，所以在混凝土构件中会经常会出现一些裂缝，而这些裂缝的存在会严重影响混凝土构件的使用效能，甚至会造成一定的安全危害。

这些裂缝主要是因为混凝土温度应力的变化而引起的。

本文将结合察汗乌苏水电站大坝工程对混凝土的施工温度和裂缝的成因与控制进行探讨。

【关键词】混凝土；施工温度；裂缝；成因；控制1.引言混凝土广泛应用于现代工程建设当中，混凝土裂缝问题是混凝土施工过程当中常见的问题。

混凝土裂缝的出现会导致混凝土浸水而腐蚀内部构件，从而降低混凝土材料的耐久性、抗渗透性以及承载力，同时还会影响混凝土结构的使用寿命以及外观，严重的甚至会对人们的生命财产安全产生危害。

在混凝土施工过程中，施工人员通常会采取各种办法防止混凝土裂缝的产生，但混凝土裂缝问题仍会出现。

这主要是由于不重视对混凝土的温度应力的控制。

混凝土的体积一般比较大，会产生大量的水化热，但混凝土的内部结构和外部结构散热速度不一致以及混凝土会受到各种约束，从而会在混凝土内部产生较大的温度应力，进而导致混凝土裂缝的产生。

这些裂缝的存在是很严重的质量隐患。

因而，在混凝土施工过程中，对混凝土的施工温度控制是控制混凝土裂缝产生的关键。

2.工程概况趾板砼设计宽度有6m、8m、10m，厚度有60cm、80cm、100cm、130cm，共分42个浇筑块，砼方量共计4898m3。

趾板锚筋（Φ28）长分别有5.2m、4.9m、4.85m、4.7m，锚筋深入基岩4m。

右岸在1600m高程以上设计有高趾墙，左岸在1646.500m高程以上设计有高趾墙。

趾板混凝土标号为C25W12F300，级配为二级配。

砼浇筑严格执行DL/T5144-2001，施工坍落度控制在3～7cm。

施工方案：趾板砼浇筑顺序为先河床段，后岸坡段，岸坡段趾板砼随坝体升高超前8～10m浇筑。

趾板砼共分为42个浇筑块，施工时由上而下依次跳仓浇筑，各道工序穿插进行，流水作业。

山东交通学院2015届毕业生毕业论文外文翻译院别交通土建工程学院专业土木工程班级土木111学号姓名指导教师二○一五年六月混凝土裂缝成因及控制摘要: 针对目前建筑混凝土的裂缝问题, 分别从温度应力、原材料质量、收缩形变、钢筋锈蚀以及施工工艺质量几个方面论述了开裂原因, 并提出了相应的控制措施。

关键词: 混凝土; 裂缝; 原因; 控制混凝土出现裂缝的原因多种多样, 通常情况下,裂缝的存在不会影响构件的正常使用( 宽度< 0. 05 mm ) , 但如果裂缝过大就会降低结构的安全性和耐久性, 本文主要针对后者进行讨论。

1 混凝土裂缝成因1. 1 温度裂缝当外部温度或结构内部温度发生变化, 混凝土将发生形变, 若变形受到约束, 结构内将产生应力,当应力超过混凝土抗拉强度时将产生温度裂缝。

通常情况下, 温度应力主要有3 种形成方式:1) 大体积混凝土(厚度超过2 m ) 浇注之后由于水泥水化放热产生温度应力; 此外, 由于混凝土弹性模量的急剧变化也会在其内部形成残余应力;2) 当水泥放热基本结束后, 由于混凝土的冷却以及外界气温变化引起温度应力;3) 在使用过程中, 由于突发降水、冷空气侵袭或日落等致使混凝土结构外表面温度突然下降, 内部温降相对较慢而产生温度应力。

1. 2 原材料质量引起的裂缝配制混凝土时所采用原材料质量不合格, 也可能导致结构出现裂缝。

1. 2. 1 水泥如果水泥安定性不合格, 其中的游离氧化钙含量超标, 则由于氧化钙在凝结过程中水化很慢, 在混凝土凝结后仍然继续起水化作用, 可破坏已硬化的水泥石, 使混凝土抗拉强度下降。

若水泥出厂时强度不足, 水泥受潮或过期, 亦可能使混凝土强度不足, 导致混凝土开裂。

1. 2. 2 砂、石集料1) 砂石的粒径、级配、杂质含量如果砂石粒径太小、级配不良, 将导致水泥和拌和水用量加大, 使混凝土收缩加大, 影响混凝土的强度; 如果使用超出规定的特细砂, 后果将更加严重。

浅谈混凝土的施工温度与裂缝控制混凝土是一种常见的建筑材料，在建筑工程中使用广泛。

混凝土的施工温度是混凝土在浇筑和养护过程中的温度。

混凝土施工温度对混凝土的力学性能、耐久性以及裂缝控制起着重要的作用。

一、混凝土施工温度对混凝土性能的影响混凝土的强度及其它力学性能受施工温度的影响较大。

施工温度过高或过低均会影响混凝土的强度和耐久性。

1.施工温度过高当混凝土浇筑时，由于施工温度过高，混凝土内部的水分蒸发过快，使混凝土失去一定的流动性，使混凝土浇筑成型品质降低，甚至会导致表面龟裂、脱落等现象。

当混凝土在热天时间内浇筑施工时，混凝土表面干燥速度过快，由于混凝土内部空隙温度差异而产生的收缩留下很强的甚至是深层龟裂，好比新鲜的面团刚刚加水和发酵，如果太阳直射整个盆，开裂就是不可避免的。

同时，高温还会降低混凝土的强度和耐久性，减缓和延长混凝土的硬化时间，以及增加混凝土表面和内部的温度差异。

这些问题都会对混凝土的性能造成负面影响。

2.施工温度过低当混凝土浇筑时，如果温度过低，将会延缓混凝土的硬化时间，影响混凝土的强度的形成。

还会影响混凝土的耐久性，导致混凝土易龟裂、渗漏、变形等现象的产生，降低混凝土的使用寿命。

施工温度过高或过低，均会影响混凝土的强度和耐久性，因此，在混凝土的施工中，需要注意施工温度的控制。

二、混凝土的裂缝控制混凝土的裂缝问题一直是一个难解决的问题，在施工中常常因为温度问题而导致混凝土裂缝，这种问题会降低混凝土的强度和水密性。

在混凝土浇筑时，需要注意以下几点，从而控制混凝土的裂缝。

1. 控制施工温度在混凝土施工中，需要适当控制施工温度。

混凝土的施工温度应该在适宜的范围内，户外施工建议在混凝土浇筑前，首先确定好混凝土温度，以便掌握室内水泥浆料温度。

混凝土表层蒸发记录、养护天数以及养护时段都是需要记录的任务。

2. 减少温度温跃变化在混凝土浇筑时，避免热、冷交替引起的温度温跃变化，可以采用以下几种方式：确保混凝土内温度均匀，使用适当的混凝土配合比例控制水灰比，加有机物超塑剂、熟石灰等减少水泥对混凝土的影响，以减少液体表面张力。

外文翻译---浅谈混凝土的施工过程中温度与裂缝控制外文翻译一、原文Discuss the construction temperature andcrack of the concrete lightlyThe summary: In order to prevent the owners of the concrete work of claims, we must do a good job in the construction process in the temperature and crack control, through observation live for many years, through consulting the monograph about stress within the concrete, explain to concrete temperature reason, on-the-spot concrete control and measure, prevention of crack of temperature that crack produce. Keyword Concrete Temperature stress Crack Control1. The concrete occupies the important position in modern engineering construction. But today, the crack of the concrete is comparatively general, the cracks are nearly omnipresent in the science of bridge building. Though we take various kinds of measures in constructing, careful, but the crack still occurs now and then. Tracing it to its cause, it is one of them incompletely that our change to concrete temperature stress pays attention to. In the large volume concrete, temperature stress and temperature control are significant. This is mainly because of the reason of two respects. First of all, concrete often appear the temperature crack in not constructing, influence the globality and durability of the structure. Secondly, in the course of operating, the temperature change has remarkable influence that can't be ignored on the stress state of the structure. We meet to construct temperature crack in mainly, so only to origin cause of formation and treatment measure, concrete of crack make a discussion in constructing this text.Reason of a crackIt has many kinds of reasons to produce the crack in the concrete, it is mainly the changes of temperature and humidity, fragility and disparity of the concrete, and the structure is unreasonable, the raw materials is not up to standard (if the alkali aggregate react), the template is out of shape, the foundation does not subside etc. evenly. The cement emits a large amount of heat of hydration when the concrete is hardened, inside temperature is rising constantly, cause the stress of drawing on the surface. In the course of lowering the temperature, is it congeal foundation pay restrain to mix always later stage, will present the stress of drawing within the concrete. Reducing of temperature can surface cause heavy stress of drawing very in concretetoo. When these draw the stress and go beyond resisting the ability of splitting of concrete, namely will present the crack. A lot of inside humidity of concrete change very light or change relatively slow, surface humidity might change heavy the violent change takes placing. Such as maintaining thoroughly, when getting wetter when not doing, contract surface there aren't deformation doing, often cause the crack too. The concrete is a kind of fragility material, tensile strength is about 1/10 of the compression strength, is it carry on one's shoulder or back limit when draw out of shape to have （0.6～1.0）×104 only, is it carry on one's shoulder or back limit location when stretch out of shape to there is（1.2～2.0）×104 to add for a long time to add a short time. Because raw materials even, water dust than unstable, transport and build phenomenon of emanating of course, its tensile strength is not even in the same concrete, a lot of resist the ability of drawing very low, it is apt to present the weak position of the crack. Among armored concrete, draw stress to undertake by reinforcing bar mainly, concrete bear stress of keeping just. Or reinforcing bar mix if edge position gone to congeal presents the stress of drawing in the structure in plain concrete must rely on the concrete oneself to bear. Require avoiding the stress of drawing or only very small stress of drawing appears of the general design. But the concrete is cooled from maximum temperature to the steady temperature of operating period in constructing, often cause sizable to draw the stress within the concrete. The temperature stress can exceed other outsides and load the stresses caused sometimes, know change law, temperature of stress for carry on reasonable structural design and construct extremely important.Analysis of 2 temperature stressesIt can be divided into following three stages according to the forming process of the temperature stress:(1)It is early: It needs generally 30 day from beginning building concrete to finishing sending out heat basically by cement. There are two characteristics at this stage, first, the cement emits a large amount of heat of hydration, second, mix and congeal the changing sharply of elastic model quantity. Because of the change of elastic model quantity, form the remaining stress in the concrete in this period.(2)Middle period: Up till the concrete is cooled until stability temperature from cement send out heat function basically when expiring, in this period, the temperature stress is mainly because the cooling of the concrete and external temperature change cause, these stresses and remnants stresses that is formed in early days are superposed, mix and congeal the elastic mould amount that goes to and does not change much during this period.(3)Later period: Operation period after the complete cooling of concrete. Temperature stress whether external temperature change causes mainly, these stresses and first two kinds of remnants stresses are changed and added.It can be divided into two kinds according to the reason why the temperature stress causes:(1)Spontaneous stress: There are not any restraints or totally static structure at the border, if inside temperature is non-linear distribution, temperature stress appearing because structure restrains from each other. For example, the body of mound of the bridge, the physical dimension is relatively large, surface temperature is low when the concrete is cooled, inside temperature is high, present the stress of drawing on the surface, present the stress of pressing in the middle.(2)Restrain the stress: All of the structure ones or it restrain external one some border, can't out of shape and stress not cause not free. Such as case beam roof concrete and guardrail concrete.These two kinds of temperature stresses draw back stresses caused to act on with the doing of concrete together frequently. It is a more complicated job to want to analyse the distribution, size of the temperature stress accurately according to known temperature. In case of great majority, need to rely on the model test or the number value to calculate. To is it make temperature stress have sizable limp to creep concrete, at the stress accounting temperature, must consider the influence that creep, calculate concretely that no longer states thinly here.Control and preventing the measure of the crack of 3 temperatureFor prevent crack, lighten temperature stress can from control temperature and is it is it set about to restrain terms from two to improve.The measure of controlling temperature is as follows:(1)Is it improve aggregate grade mix, is it do rigid concrete to spend, mix mixture to adopt, is it guide angry pharmaceutical or plastification pharmaceutical, etc. measure in order to reduce cement consumption of concrete to add;(2)Add water or the water to cool the broken stone in order to reduce the temperature of building of the concrete while mixing and shutting the concrete;(3)Reduce the thickness of building while building the concrete on hot day, utilize and build the aspect to dispel the heat;(4)Bury the water pipe underground in the concrete, enter the cold water to lower the temperature openly;(5)Stipulate rational form removal time, the temperature keeps warm the surface while lowering suddenly, in case that the rapid temperature gradient takes place in the concrete surface;(6)The concrete with medium and long-term and exposed construction builds a piece of surface or thin wall structure, take the measure of keeping warm in cold season;The measure of improving condition of restraining is:(1)Divide and sew and divide one rationally;(2)Prevent the foundation from rising and falling too big;(3)Rational arrangement construction process, prevent the too big discrepancy in elevation and side from exposing for a long time;In addition, improve the performance of the concrete and improve and resist the ability of splitting, strengthen maintenance, prevent the surface from being done and contracted, especially guarantee the quality of the concrete is very important to preventing the crack, should pay special attention to avoiding producing and running through the crack, the globality resumed its structure after appearing is very difficult, so should rely mainly on preventing the emergence of the running through crack while constructing.In construction of concrete, for raise turnover rate of template, demand concrete form removal as soon as possible that build newly often. Should consider form removal time properly when concrete temperature is higher than the temperature, so as not to cause the superficial early crack of concrete. Building the early form removal newly, cause very large stress of drawing on the surface, the phenomenon that "temperature is assaulted" appears. Build initial stage in concrete, because heat of hydration is sent out, the surface causes sizable to draw the stress, surface temperature is also higher than temperature at this moment, remove the template at this moment, surface temperature is lowered suddenly, must cause temperature gradient, thus add and draw the stress on the surface, change and add with the heat of hydration stress, in addition, the concrete dries and contracts, the superficial stress of drawing reaches very great number value, have danger of causing the crack, but cover a light-duty heat insulator with on the surface in time after removing the template, for instance foam sponge, etc. , for prevent concrete surface from produce the too big stress of drawing, have remarkable results.Add muscle influence to large volume temperature stress of concrete very light, because large volume concrete include muscle to be rate very much low. Just have influence on the general armored concrete. On terms that temperature is not very high and the stress is less than limit of surrendering, every performance of the steel is steady, and have nothing to do with stress state, time and temperature. Line bloated coefficient of steel and concrete line bloated coefficient difference very light, take place little internal stress very only between the two while changing in temperature. Because elastic mould amount of steel concrete elastic mould 7~15 of quantity, reach as interior concrete stress tensile strength and when fracturing, the stress of the reinforcing bar will not exceed 10000kg/cm2. So is it is it prevent tiny appearance difficulty very much of crack from to make use of reinforcing bar to want among concrete. But the crack in the structure generally becomes numerous, the interval is little, the width and depth are smaller after adding the muscle. And if diameter of reinforcing bar detailed and when interval dense, to improve concrete resist result of person who split better.Concrete and surface, armored concrete of structure can take place detailed and shallow crack often, among them the great majority belong to and do and draw back the crack. Though this kind of crack is generally all relatively light, it stills have certain influence on the intensity and durability of the structure.In order to guarantee concrete project quality, prevent fracturing, improve the durability of the concrete, use the admixture to reduce one of the measures that fractures correctly. Whether is it reduce water is it split pharmaceutical to defend, I summarize his main function in practice to use.(1)There is a large number of capillary in the concrete, produce capillary tension in the capillary after water is evaporated, make concrete is it contract out of shape to do. Increasing the thin aperture of hair can reduce the capillary surface tension, but will make the intensity of concrete reduce. This surface tension theory has already been confirmed in the world as far back as the sixties.(2)Water dust than influence important factor that concrete shrink, is it reduce water is it split pharmaceutical can make concrete water consumption reduce by 25% to defend to use.(3)Cement consumption important factor, concrete of person who shrink too, is it add and subtract water is it split concrete reducible 15% of the cement consumption on terms that keep the intensity of concrete of pharmaceutical to defend to mix, its volume is supplemented by increasing aggregate consumption.(4)Reduce water is it split pharmaceutical can improve consistency of grout, reduce concrete secrete ink to defend, reduce and sink and draw back deforming.(5)Improve gluing the strength of forming of the grout and aggregate, the concrete improved resists the performance of splitting.(6)Concrete is it produce stress of drawing to restrain from while shrinking, crack when drawing the stress and is greater than concrete tensile strength can produce. Reduce water is it split pharmaceutical effective concrete tensile strength of improvement very to defend, improve resisting the performance of splitting of concrete by a wide margin.(7)It can make the concrete density good to add the admixture to mix, can improve resisting carbonization of concrete effectively, reduce carbonization to shrink.(8)Is it reduce water is it split slow coagulation time proper concrete under pharmaceutical to defend, on the basis of preventing the fast water of cement from sending out heat effectively to mix, prevent the plasticity shrink that brings because the cement is not congealed for a long time from increasing.(9)Mix admixture concrete and getting easy and kind, surface easy to feel flat, form little membrane, reduce the moisture to evaporate, reduce drily and shrink. A lot of admixtures all have the functions of slow coagulation, increasing and apt, improvement plasticity, the experiment that we should carry on in this respect more inthe project practice is compared with and studied, than lean against not improving terms more simple, may getting simple and more direct, economy.Early maintenance of 4 concretePractice has proved, the common crack of concrete , most is the surface crack of different depth, main reason its whether temperature gradient cause cold temperature of area lower too easy to form crack suddenly. So say the warm-keeping of the concrete is especially important to preventing the early crack of surface.From the viewpoint of temperature stress, should reach and require keeping warm following:1)Prevent concrete internal and external temperature poor and concrete surface gradient from, prevent the surface crack.2)Prevent concrete from to be ultra and cold , should is it is it make the minimum temperature is not lower than the steady temperature of concrete service time construction time in concrete to try to try one's best.3)Prevent the old concrete subcooling, in order to reduce the restraint among the old and new concrete.The early maintenance of the concrete, the main purpose lies in keeping the suitable warm and humid condition, in order to get the result of two respects, on the other hand make the concrete avoid the invasion and attack of the unfavorable and warm, humidity out of shape, the ones that prevent from harmfully are cold to contract and do to contract. On one hand make cement water function go on smoothly, is in the hope of reaching the intensity designed and resisting the ability of splitting.The suitable warm damp condition is interrelated. Mix warm-keeping measure paid to congeal often protects wet results too. Analyse, water concrete include moisture can meet demand, cement of water have enough and to spare newly theoretically. But because the reason of evaporating etc. often causes losses of the moisture, thus postpone or hinder water of the cement from, the surface concrete receives this kind of adverse effect easiestly and directly. Key period when maintained in initial a few days after so the concrete is built should pay attention to conscientiously in constructing.2. Quality control of waterproof concrete constructionCombined with experience, from formwork design, fabrication and installation, assembling reinforcement, pouring and curing of concrete and other aspects construction technology of fair-faced concrete is introduced as well as quality control measures and standards in order to reduce engineering cost to acquire satisfied economic and social benefits.The factors of influencing waterproof-concrete quality are very many. Any links does not pay attention to the water-proof concrete of field loss hinders the water function without exception jointly with degree. Engineering construction in the basement adopts secondary form board fabrication and installation, reinforced barfabrication and bind, concrete stirring and mixing system and transport, concrete covibration beat with a stick, construction joint practice, concrete curing and dismantle model and being ready for backfill and so on aspects. These are very critical to quality method to ensure that water-proof concrete self water-proof, and the way of practice has wan out.Method being under construction2.1 Fabrication and InstallationAccording to the concert of closely knit, demand of reason why to form board since the water-proof also concrete have made and have assembled corresponding rise is special, be to require that not leaving out thick fluid, firm closely knit block of wood deformation, water absorption Character should be small and ought to give priority to select and using bamboo slab rubber form board or the steel form.. Strict control form board room gap size, necessary exceeding 2 mms uses foam rubber or plastic to squeeze a crack in, porous form board nonutility without exception to board face Be ready for wall post at the same time rotting the prevention and cure job adopt the cement mortar pouring same, indicia in before the root segment sticking the foam rubber or plastic strip, the bottom puts on a cement mortar, concrete a concrete, first 5cm~10cm. Since water-proof, concrete structure wall thickness is mostly more infertile. Be to ensure that component geometry dimension, Chang adopt the inside and outside bolt to pull the measure meeting attention to, responds to on play receive bolt centre interpose stop water iron plate, to prevent water from forming pilotage passage along bolt leakage.2.2 Assembling reinforcementWater-proof concrete structure has demanding as follows to the reinforced bar:1)Reinforced bar should adopt twisted steel as far as possible, increases by hold wrap a force composing in reply a water ability2)Reinforced bars connect should try one's best to adopt to solder connection, stop using and being needless to bind connection to the full3)When binding a reinforced bar, the iron wire head responds to inner bending.4)Strict control reinforced bars protective layer thickness.Minimal thickness of water-proof concrete reinforced bar protective layer is not smaller than 25mms, the protective layer welcoming water surface especially inadmissibility to disappoint error. The iron wire and reinforced bar that application buries in advance within mortar piece while using mortar heel block as protective layer, are bound solid. When the cavalry puts up the fixed reinforced bar if adopt a reinforced bar, also need to increase solders water iron plate or fixation just goes ahead, to strengthen water-proof effect in the heel block. This project uses new materials nylon to have fixed there is an effect's had guarded against reinforced bar protective layer deviation piece big mass common failings.2.3 The concrete stirring and mixing makes and transportsSince the water-proof concrete requires that higher closely knit, reason why stir and mix system also need to have the fairly good homogeneity, should be ready for burning as follows almost for this purpose:1)Ensures that mixing time, mixing at every time are secondary jump into a expect the general ejection of compact block of wood less than 2mins.2)Should use the apposition agent, the solution queen who should manufacture certain thickness from apposition agent adds the mixer inner, the dried powder or high concentration solution will add an agent extra not to adds the mixer inner directly, prevent from mixing is uneven but part concentrates, both lose the apposition agent effect, and affect concrete mass.3)Responds to the assured source of life degree having a spot test on the admeasurement concrete at the regular intervals collapsing in the process being under construction, construction is middle if Yu rains or other cause, respond to the ratio determining whose water ratio, and adjusting the composition being under construction in time when change happened in sandstone moisture content.4)Project uses the commodity concrete, has boundary have raised a concrete stirring mass and of all kinds effect apposition agent adulterating falls when amounts, the water ash having controlled a concrete strictly collapsing.5)Concretes adopt a pump to have given handicraft, effective avoiding a concrete producing the phenomenon isolating bleeding and leaving out thick fluid in the process of transportation.2.4 Matters needing attention in being under construction1)Construction school assignment soft and floury is divided. Water-proof concreting should stratify strictly being in progress, and a continuous construction is completed The front and back and high and low connect between the tier should subjugate within the cement initial setting time, For this purpose, with handling a worker dividing into several, at the same time each other, school assignment group faces or it is all right for each other, carry on the back.2)Achieve strictly fixed point determines the amounts of the components of a substance material down According to the vehicle capacities stratifying concrete altitude and the means of transport, the quantify carrying out fixed point strictly is able to go down one important ring expecting that this is to improve water-proof concreting mass.3)Concretes vibrating beat one important ring being to ensure that the concrete is closely knit, defend against to seep with a stick. Also, should adopt fixed point vibrating, handle meticulously on basis expecting that under determining the amounts of the components of a substance homogeneously in fixed point. Pay attention to high and low tier of linking up. Now that needing to prevent from miss and vibrating, notvibrating enough, being going to prevent a fault from vibrating again, Need to forbid using prying the method coming to aid to vibrate moving a reinforced bar or shaking a reinforced bar especially, such separates to making the front already concrete the reinforced bar and concrete shaking the reality part, causes serious consequences.4)Being ready for the assured source of life degree taking over thick fluid measure, and adjusting in time to collapse seriously. Average water-proof concrete structure construction, the construction joint being under construction respectively, composing namely on erecting wall sells be bottom board and vertical wall at reduced prices. Should irrigate thick a layer of 5cm~10cms surname indicia cement mortars in seam place first linking up closely knitting tier, in order to ensuring that the seam place vibrates when concrete vertical wall. Simultaneous, improve step by step with concrete an altitude, should fall off step by step with the water yield, diminish collapsing to fall degree prevent from concrete insist to be short but the cement paste is partial to much phenomenon to aggregate appearing on upper part.2.5 Dismantling model and curing of concreteThe water-proof concreting queen maintains goodness and badness working, not only affecting the intensity arriving at a concrete, moreover the impervious function affecting to the concrete. Evidence, water-proof concrete early phase dehydration or curing process lack for water, will reduce whose impervious function by a wide margin. Water-proof concrete curing responds to the block of wood less than 14ds. The water-proof concrete dismantles a model demanding to be unable to compare high, dismantle model time unsuitable untimely, respond to when dismantling a model handle meticulously, prevent an iron rod from using to pry stiffly, that the sledgehammer is knocked suddenly and forcibly pries, uses a concrete meet with destroy.2.6 Do good well at backfillWater-proof architectural backfill is a final working procedure, it be sometimes ignored, this is a very big faults in fact under the ground. When the water-proof structure job is over queen responds to the construction carrying out backfill immediately. Most important, we should take backfill seriously self mass; Secondly, backfill varia and ponding should clear up the pit bottom in the front, respond to densification with layers when backfill. Water-proof structure vicinity layer pounds true backfill, self is a reliable and economical as well water proofing drapery under the ground. In project basement engineering construction Shanghai, since organizing water proofing down to earth strictly with all above seven passes, the concrete is under construction, effect is comparatively ideal. The percolating water phenomenon does not appear.ConclusionsConstruction temperature and relation of crack in concrete the above carry onpreliminary discussion of theory and practice, though the academia has different theories to origin cause of formation and computing technology of the concrete crack, but to concrete prevention and improving the measure suggestion to relatively unify, application in practice result fine too at the same time, concrete to is it observe, compare more by us to want in constructing, analyse more, summarize more after going wrong, combine many kinds of prevention and deal with the measure, the crack of the concrete can be avoided.一、翻译浅谈混凝土的施工过程中温度与裂缝控制摘要为了防止业主对混凝土工程的索要赔偿,我们就必须做好过程中的温度与裂缝控制。

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。

浅析混凝土施工过程中的温度及裂缝控制混凝土在工程施工中扮演着重要的角色，它广泛应用于建筑、桥梁、道路等工程中。

混凝土的温度和裂缝控制一直是工程施工中需要重点考虑的问题。

温度和裂缝对混凝土结构的安全和耐久性都具有重要影响，因此在混凝土施工过程中，需要合理控制温度并采取有效措施来防止裂缝的产生。

一、混凝土施工中的温度控制1. 温度的影响混凝土的温度对混凝土的强度、收缩、开裂等性能都会有影响。

一般来说，混凝土的温度过高会导致混凝土强度降低，收缩率增加，易裂性增加；温度过低也会影响混凝土的强度和耐久性。

在混凝土施工过程中，需要合理控制混凝土的温度，以保证混凝土的质量和工程的安全。

2. 控制温度的措施在混凝土施工中，常用的控制温度的措施有：水泥的选择、水泥用量的控制、控制拌合料温度、加入减水剂等。

水泥的选择和用量的控制是最为关键的。

不同种类的水泥适用的温度范围不同，因此在选择水泥时需要根据施工环境和要求来选择合适的水泥。

控制水泥的用量也是非常重要的，过多或过少的水泥用量都会对混凝土的温度产生影响。

控制拌合料的温度也是需要重点考虑的问题，因为拌合料的温度会直接影响混凝土的温度。

在炎热的夏季，需要采取措施来控制拌合料的温度，以保证混凝土的质量。

2. 控制裂缝的措施在混凝土施工中，控制裂缝的措施有很多种，常用的措施包括：合理设计梁板结构、采用预应力混凝土、使用增强混凝土等。

合理设计梁板结构是防止裂缝产生的最为基本的措施。

在设计结构时，需要合理设置构件的截面积和配筋，以及设置适当的支撑和支座，以避免混凝土受到过大的内力和变形而产生裂缝。

采用预应力混凝土和增强混凝土也是控制裂缝的有效措施。

预应力混凝土能够在混凝土中设置预应力钢筋，使混凝土在受力时产生一定的压应力，从而减小混凝土的张应力，减少裂缝的产生；而增强混凝土则是利用增强材料来提高混凝土的抗拉强度和抗裂性能，降低混凝土的裂缝宽度和数量。

The causes, prevention and treatment of cracks in concrete Abstract:In the building construction concrete cracks a quality common problem, the causes of cracks in concrete, prior prevention, as well as after the repair process is a more common phenomenon in the process of building production, should be taken seriously enough. The concrete is a brittle material of a gravel aggregate, cement, water and other additional material formed by mixing a non-homogeneous. Concrete construction and deformation constraints and a series of problems, there are a large number of micro-porosity, cavitation and micro-cracks in the concrete hardening molding. The author combines his engineering work experience, summed up the cracks in concrete causes and prevention measures.Keywords: causes of cracks in concrete preventive treatmentIn building construction, concrete cracks is a widespread problem, cracks solution is a more difficult problem. Cracks in concrete reasons are manifold, deformation: such as contraction, expansion, settlement and other causes cracks; external load caused by: improper maintenance of concrete; cracks caused by the external additive problems.Concrete cracks, if not prevention measures to solve, extending its further development will lead to the internal reinforcement corrosive, reducing the carrying capacity of the reinforced concrete structure, impermeability, durability useful life, and even affect people's lives and property safety . Crack is impossible to completely eliminate the engineering specification expressly provides some structure in which the different conditions, allowing the existence of a certain width and depth of the crack. But in the construction process should be as far as possible to take effective preventive and technical safeguards to effectively control the cracks, as little as possible or minimize crack width, depth, and in particular to avoid in key positions or harmful cracks.1.Causes and types of concrete cracksThe concrete is a brittle material of a gravel aggregate, cement, water and other additional material formed by mixing a non-homogeneous. Hardening molding concrete concrete construction and deformation constraints there are a large number of micro-porosity, cavitation and micro-cracks, precisely because of the existence of these initial defects before the concrete showing some heterogeneity characteristics . Micro-cracks is usually a harmless cracks on concrete load-bearing, seepage and use the function does not cause harm. But in the concrete under load, temperature effects, the micro-cracks will continue to expand and connectivity, and ultimately the formation of visible macro cracks, the cracks is often said that the concrete works.Many cracks in concrete cracks caused by deformation: such as temperature change, shrinkage, expansion, uneven subsidence caused cracks; external load induced cracks; cracks caused by improper conservation of the environment and chemical action, etc. .Common cracks in the concrete are the following: (1) shrinkage cracks; ②plastic shrinkage cracking; (3) settlement cracks; ④temperature cracks; ⑤chemical reaction caused by cracks.2.Concrete cracks and prevention2.1 Shrinkage cracks and prevention ofShrinkage cracks appear in a week or so after the end of the concrete curing period of time or after concrete pouring. The evaporation of the water in the slurry will produce shrinkage, and the shrinkage is irreversible. Drying shrinkage cracks are mainly caused due to the different degree of evaporation of the moisture inside and outside the concrete result of deformation of the type: concrete affected by the influence of external conditions, excessive surface moisture loss, large deformation, internal humidity changes smaller deformation smaller, the larger the surface shrinkage deformation by concrete internal constraints, have a greater tensile stress cracks. The lower the relative humidity, the greater the shrinkage of cement paste shrinkage cracks are easy to produce. Shrinkage cracks parallel to the surface of the linear or reticular light fine cracks, width of more than 0.05 to 0.2 mm between the flat parts more common in mass concrete, thin flat-slab along the short to distribution. Shrinkage cracks usually affect the impermeability of concrete, causing corrosion of steel affect the durability of concrete, water pressure will produce hydraulic fracturing affecting concrete bearing capacity. The concrete shrinkage main and to the water-cement ratio of the concrete, cement component, the amount of cement used, thenature and amount of aggregate, the amount of admixture.The main preventive measures:(1)Selection of a smaller amount of shrinkage cement, commonly used in low heat cement and fly ash cement, reduce the amount of cement.(2)Concrete shrinkage by water-cement ratio, the greater the water-cement ratio, the greater the shrinkage in the concrete mix design should try to control the selection of a good water-cement ratio, while mixing the water-reducing agent .(3)Strict control than with concrete mixing and construction, concrete water consumption must not be greater than the amount of water given by the mixture ratio design.(4)To strengthen the early curing of concrete and appropriate to extend the concrete curing time. Appropriate to extend the winter construction concrete insulation cover, and brushing curing agent curing.(5) Set the appropriate contraction joints in concrete structures2.2 Plastic shrinkage cracks and preventionThe plastic shrinkage refers to the before condensation, the concrete surface due to rapid dehydration resulting contraction. Plastic shrinkage cracking is generally hot and dry or windy weather, the cracks mostly wide in the middle, both ends of the thin and vary in length, non-coherentstate. Short cracks as long as 20 to 30cm the longer cracks of up to 2 to 3 m, width of 1 to 5 mm. Main causes: the concrete before the final setting almost no strength or intensity is very small or just the final setting concrete small strength, high temperature or a larger wind, the concrete surface excessive water loss, resulting in capillary have a greater negative pressure of the concrete volume of a sharp contraction, but this time the strength of the concrete can not resist its own contraction, resulting in cracking. The main factors affecting the plastic shrinkage cracking water-cement ratio, the setting time of the concrete, the ambient temperature, wind speed, relative humidity, and so on.The main preventive measures:(1) Selection of shrinkage values smaller high early strength Portland cement or ordinary Portland cement.(2) Strict control of water-cement ratio, to increase the slump and workability of the concrete, to reduce the amount of cement and water mixed with superplasticizer.(3) Pouring concrete before watering the grass roots and templates evenly soaked.(4) Timely covered by plastic film or wet straw, hemp sheet to maintain final setting of concrete the moist front surface or the surface of the concrete spraying curing agent for conservation.To set the sun and wind facilities .(5) At high temperatures and windy weather, timely conservation.2.3 subsidence cracks and preventionSubsidence cracks caused by structural foundation soil is uneven, soft, or backfill or flooding due to uneven settlement; template stiffness, the template support spacing is too large or the bottom of the support as a result of loose, especially in the template support winter on the frozen ground, permafrost thaw uneven settlement, resulting in the concrete structure cracks. Such cracks are deep into or through the cracks, toward subsidence, generally along the perpendicular to the ground or in the form of an angle of 30 °to 45 °direction, subsidence cracks tend to have a certain amount of dislocation, crack width is often and is proportional to the amount of the settlement. Crack width was less affected by temperature changes. Ground deformation stability, subsidence cracks basically stabilized.The main preventive measures:(1)on the soft soil, filling foundation should be carried out prior to the construction of the superstructure necessary compaction and reinforcement.(2)to ensure that the template has a sufficient strength and stiffness, and firmly support the foundation uniform force.(3) prevent the process of concreting the foundation is immersed inwater.(4) template removal time can not be too early, and pay attention to the order form removal.(5) in the erection of the template on the permafrost to take certain precautions.2.4 Temperature cracks and preventionTemperature cracks occurred in mass concrete surface or larger changes in temperature regions in concrete structures. Concrete pouring, in the hardening process of cement hydration reaction to produce large amounts of heat of hydration (when the amount of cement per cubic meter of concrete will release 17,500 27500kJ heat at 350 to 550 kg/m3, so that the internal temperature of the concrete SITA about 70 °C or higher). Cause the internal temperature to rise sharply due to the larger volume of concrete, the accumulation of a large amount of heat of hydration within the concrete and easy to distribute, and rapid cooling of the surface of the concrete, thus forming a larger temperature difference inside and outside, the larger the temperature difference caused by the internal and external different degrees of thermal expansion and contraction of the concrete surface tensile stress (Practice has proved that when the temperature difference between inside and outside of the concrete itself is 25 ° C to 26 °C, will produce roughly about10MPa concrete tensile stress). When the tensile stress exceeds the ultimate tensile strength of the concrete, the concrete surface cracks, cracks occurred in the concrete construction in the late. Concrete construction when the temperature changes, or concrete attacked by the cold wave will lead to concrete surface temperature sharp decline, and contraction, contraction of the concrete surface bound by internal concrete, will produce large tensile stress. cracks, such cracks are generated in the the shallow concrete surface within the range of usually only.The trend of temperature cracks usually certain rules, often criss-cross a large area of structural cracks; the length of the beam and plate size larger structures, cracks parallel to the short side; deep and penetrating temperature cracks are generally parallel or nearly parallel to the direction of the short side , cracks along the longest edge segments appear more dense middle. Crack width sizes, affected by temperature changes more obvious, summer, winter wide narrow. The high temperature expansion caused by the concrete temperature is usually middle coarse fine at both ends, while the the shrink cracks thickness less obvious changes. The emergence of such cracks can cause corrosion of steel, concrete carbonation, reduce freeze-thaw resistance of concrete, anti-fatigue and impermeability.The main preventive measures:(1) try to use low heat or moderate heat cement, slag cement, fly ash cement.(2) reduce the amount of cement to try to control the amount of cement 450kg/m3.(3) reduce the water-cement ratio, generally water-cement ratio of concrete is controlled below 0.6.(4) improve the aggregate gradation, fly ash or superplasticizer to reduce the amount of cement, lower heat of hydration.(5) improve the concrete mixing process, "secondary air" traditional "cold" on the basis of new technology, reduce the temperature of concrete pouring.(6)a certain amount of concrete admixture having less water, plasticizers, retarding admixture role to improve the fluidity of the concrete mixture, water retention, reduce the heat of hydration, delaying the time of occurrence of the thermal peak.(7)hot season puts up visor and other auxiliary measures to control the temperature rise of the concrete pouring, to reduce pouring concrete temperature.(8)mass concrete temperature stress associated with the structure size, the larger the size of the concrete structure, the greater the temperature stress, so reasonable arrangements for the construction process, hierarchical, block pouring, to facilitate cooling, reducingconstraints.2.5 chemical reaction caused cracks and preventionAlkali-aggregate reaction cracks and steel corrosion cracks caused by the most common due to the chemical reaction caused by cracks in the reinforced concrete structure. Concrete mixing will produce some of the alkaline ions, these ions produce a chemical reaction with certain reactive aggregate and absorbs water in the surrounding environment and the volume increases, resulting in concrete crisp, expansion cracking. Such cracks usually appear in the concrete structure during use, in the event difficult to remedy, should take effective measures to prevent it in the construction. Concrete pouring poor vibrators or reinforced protective layer is thin, harmful substances into the concrete reinforcing bars from corrosion, the corroded reinforcement volume expansion, leading to concrete Splitting the cracks of this type of longitudinal cracks along the location of reinforcement .The main preventive measures:(1) selection of the alkali reactivity of small sand and gravel aggregate.(2) selection of low-alkali cement and admixtures of low-alkali or alkali.(3) selection of a suitable admixture AAR with.3 crack treatmentCracks in concrete remedial measures mainly the following methods: surface repair method, grouting, caulking closure method, structural reinforcement, concrete replacement method, electrochemical protection and legal bionic self-healing.3.1 Surface repair methodSurface repair method is a simple, common repair method, the action is in the cracks in the surface of the painting grout, epoxy mortar or concrete surface coating paint, anti-corrosion materials such as asphalt, concrete protection at the same time in order to prevent various The Effect of cracking, usually can paste in cracks in the surface of the glass fiber cloth and other measures.3.2 grouting, caulking closure methodThe grouting method is the use of pressure equipment cementing material is pressed into the cracks in the concrete, the cementing material hardened concrete to form a whole, and thus play the purpose of plugging consolidation. Top cementing material grout, epoxy, methacrylate, polyurethane and other chemical materials. The filleting gouges along the cracks in the tank filled, the plastic or rigid sealing material, in order to achieve the purpose of closed cracks. Commonly used plastic materialsare PVC, clay, plastic ointment, butyl rubber, etc.; rigid sealing material is a polymer cement mortar.3.3 Structural reinforcement methodWhen the the cracks impact on the performance of concrete structures, to take structural reinforcement concrete structure. Commonly used in the following ways: structural reinforcement to increase the cross-sectional area of the concrete structure, corner in the component outsourcing steel, prestressed Reinforcing paste the steel reinforcement, additional the fulcrum reinforcement and shotcrete reinforcement.3.4 Concrete replacement methodThe concrete substitution method is an effective method for dealing with serious damage to the concrete, this method is deteriorated concrete is removed first, and then replaced into the new concrete or other materials. Top replacement materials: of Ordinary concrete or cement mortar, polymer or polymer modified concrete or mortar.3.5 electrochemical Protection ActCathodic protection, chloride extraction, alkaline recovery method, the use of the electrochemical action of the applied electric field in the medium, to change concrete or reinforced concrete in which the state of the environment, passivated steel, in order to achieve the purpose ofanti-corrosion.3.6 biomimetic self-healing legalBionic self-healing legitimate the traditional components of the concrete in some special components such as liquid-core fibers or capsules containing binder, formed within the concrete the intelligent bionic self-healing neural network system, when the concrete cracks secreted part of the liquid core fiber cracks can heal again. Conclusion:Cracks is a common phenomenon in the concrete structure, its appearance will not only reduce the impermeability of the building, affect the use of the building, and would lead to corrosion of steel, concrete carbonation, reduce the durability of the materials, the impact the carrying capacity of the building, so to carefully study the concrete cracks, be treated differently, using a reasonable method for processing to take effective preventive measures to prevent the emergence and development of cracks in the construction, to ensure the safety of buildings and structures and stable work.混凝土裂缝的成因、预防及处理摘要：在建筑工程施工中混凝土裂缝的产生是一项质量通病，因此对混凝土裂缝的成因分析、事先预防，以及产生后的修补处理是建筑生产过程中较为普遍的现象，应引起足够的重视。

中文5153字附录A论建筑工程中混凝土裂缝的预防与处理作者：阿西夫·哈米德摘要：混凝土裂缝是建筑工程中普遍存在的一种不良现象，它直接影响到混凝土结构的使用功能和耐久性。

对建筑工程中一些常见的混凝土裂缝进行了分类探讨，并对具体情况提出了一些预防和处理措施。

关键词：混凝土；裂缝；预防；处理1 前言建筑工程施工中，如果混凝土构件出现裂缝，就会影响混凝土构件的刚度和建筑物结构的整体抵抗能力，即使裂缝的出现不会导致混凝土构件的破坏或建筑物的倒塌，也会影响到建筑外观，当裂缝宽度超出一定限度时，也会造成钢筋锈蚀，影响结构构件的耐久性能。

本文介绍混凝土工程施工中几种常见裂缝的预2 常见裂缝分类混凝土裂缝产生的原因是多方面的，情况较为复杂，综合因素较多。

对于某种裂缝的出现，人们很难给予一个准确明晰的原因分析。

工程实践证明，裂缝形成的原因主要来自三个方面：变形、荷载以及不均匀沉降。

一般由温差、收缩、不均匀沉降等引起的变形赞成的裂缝约占80%，荷载等造成的约占20%，当然还需要考虑其综合原因。

根据这些主要影响因素，人们常把混凝土裂缝归纳为收缩裂缝、温度裂缝、沉降裂缝、徐变裂缝、应力裂缝和施工裂缝等几大类。

3 常见裂缝分析及预防3.1混凝土塑性收缩裂缝及预防塑性收缩是指混凝土在凝结前期。

表面因失水过快而产生的收缩。

一般在干热和大风天气裂缝较为常见，形状多为中间宽、两端细、互不连贯且长短不一，较长的裂缝可达2m－3m，宽度可达0.5cm，严重影响混凝土的抗渗性和耐久性。

主要预防措施：一是选用干缩值较小、早期强度较高的硅酸盐或普通硅酸盐水泥。

二是严格控制水灰比，在保证混凝土施工所需坍落度和和易性的前提下尽量减少水的用量，必要时掺入减水剂。

三是浇筑混凝土之前，将基层和模板均匀浇水湿透。

四是及时覆盖握料薄膜或者潮湿的草垫、麻片等，保持混凝土凝结前表面湿润，或者在混凝土表面喷洒养护剂等进行养护。

3.2 沉陷裂缝及预防沉陷裂缝的产生主要是由于结构地基浸水、土质不匀或回填土不密实等原因引起不均匀沉降所致；另外在混凝士硬化过程中由于模板刚度不足或支撑底部不牢固也会引起沉陷裂缝。