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英译汉（英文）Discuss the construction temperature and crack of the concrete lightly The summary , 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 Control 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 cant be ignored on the stress state of the structure. Whom 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. 1、Reason of a crack Have 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 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 hardenned, 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 concrete too. 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 arent 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 ones shoulder or back limit when draw out of shape to have *104 only , is it carry on ones shoulder or back limit location when stretch out of shape to there is *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 to congeal present the stress of drawing in the structure in plain concrete, must rely on the concrete oneself to bear . Require to avoid the stress of drawing or only very small stress of drawing appears of the 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. 2、Analysis of 2 temperature stresses Can be divided into following three stages according to the forming process of the temperature stress: (1)It is early: Build concrete is it is it over basically to send out heat to cement to begin , generally one one day by oneself. 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 cause mainly, these stresses and first two kinds of remnants stresseses are changed and added . Can be divided into two kinds according to the reason why the temperature stress causes: (1)Spontaneous stress: There are not any restraint 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,cant out of shape and stress not cause not free. Such as case roof beam roof concrete and guardrail concrete. 3、Control and preventing the measure of the crack of 3 temperature For 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. 4、Early maintenance of 4 concrete Practice 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 to keep warm followingly: (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 ones 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. 5、Conclusions Construction temperature and relation of crack in concrete the above carry on preliminary 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 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. 英译汉（汉字）浅谈混凝土的施工温度与裂缝摘 要 通过多年的现场观察，通过查阅有关混凝土内部应力方面的专著，对混凝土温度裂缝产生的原因、现场混凝土温度的控制和预防裂缝的措施进行等进行阐述。关键词 混凝土 温度应力 裂缝 控制混凝土在现代工程建设中占有重要地位。而在今天，混凝土的裂缝较为普遍，在桥梁工程中裂缝几乎无所不在。尽管我们在施工中采取各种措施，小心谨慎，但裂缝仍然时有出现。究其原因，我们对混凝土温度应力的变化注意不够是其中之一。在大体积混凝土中，温度应力及温度控制具有重要意义。这主要是由于两方面的原因。首先，在施工中混凝土常常出现温度裂缝，影响到结构的整体性和耐久性。其次，在运转过程中，温度变化对结构的应力状态具有显著的不容忽视的影响。我们遇到的主要是施工中的温度裂缝，因此本文仅对施工中混凝土裂缝的成因和处理措施做一探讨。1、裂缝的原因混凝土中产生裂缝有多种原因，主要是温度和湿度的变化，混凝土的脆性和不均匀性，以及结构不合理，原材料不合格（如碱骨料反应），模板变形，基础不均匀沉降等。混凝土硬化期间水泥放出大量水化热，内部温度不断上升，在表面引起拉应力。后期在降温过程中，由于受到基础或老混凝上的约束，又会在混凝土内部出现拉应力。气温的降低也会在混凝土表面引起很大的拉应力。当这些拉应力超出混凝土的抗裂能力时，即会出现裂缝。许多混凝土的内部湿度变化很小或变化较慢，但表面湿度可能变化较大或发生剧烈变化。如养护不周、时干时湿，表面干缩形变受到内部混凝土的约束，也往往导致裂缝。混凝土是一种脆性材料，抗拉强度是抗压强度的110左右，短期加荷时的极限拉伸变形只有（0.61.0）104， 长期加荷时的极限位伸变形也只有（1.22.0）104.由于原材料不均匀，水灰比不稳定，及运输和浇筑过程中的离析现象，在同一块混凝土中其抗拉强度又是不均匀的，存在着许多抗拉能力很低，易于出现裂缝的薄弱部位。在钢筋混凝土中，拉应力主要是由钢筋承担，混凝土只是承受压应力。在素混凝土内或钢筋混凝上的边缘部位如果结构内出现了拉应力，则须依靠混凝土自身承担。一般设计中均要求不出现拉应力或者只出现很小的拉应力。但是在施工中混凝土由最高温度冷却到运转时期的稳定温度，往往在混凝土内部引起相当大的拉应力。有时温度应力可超过其它外荷载所引起的应力，因此掌握温度应力的变化规律对于进行合理的结构设计和施工极为重要。2、温度应力的分析根据温度应力的形成过程可分为以下三个阶段：（1）早期：自浇筑混凝土开始至水泥放热基本结束，一般约30天。这个阶段的两个特征，一是水泥放出大量的水化热，二是混凝上弹性模量的急剧变化。由于弹性模量的变化，这一时期在混凝土内形成残余应
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