外文翻译---混凝土施工温度与裂缝的探讨(编辑修改稿)

外文翻译---混凝土施工温度与裂缝的探讨(编辑修改稿)内容摘要：

109 页 temperature gradient, so an additional one on the surface tensile stress, thermal stress superposition and hydration, coupled with the shrinkage of concrete, Tensile stress to reach the surface of great value, there is the danger of lead to cracks, but if in a timely manner after the removal of the template on the surface coverage of a light insulating material, such as foam sponge and so on, have a concrete surface to prevent excessive tensile stress, with significant results. Reinforced concrete on the large volume of thermal stress has little effect because the large volume of concrete reinforced with a very low rate. Only on the general impact of reinforced concrete. Not too high in temperature and stress below the yield limit under the condition of the properties of steel is stable, and with the stress, time and temperature has nothing to do. Linear expansion coefficient of steel and concrete linear expansion coefficient difference between the small changes in temperature between the two with only a very small stress. Since the modulus of elasticity of steel to concrete elastic modulus of 7 ~ 15fold, when the stress reached the tensile strength of concrete and cracking, the steel stress will not exceed 100 ~ 200kg/cm2 .. So , Want to use in reinforced concrete to prevent the emergence of small cracks is difficult. However, after the reinforced structure of the number of cracks in general has bee more than a small distance, a smaller width and depth. And if the diameter of steel thin and close spacing, the crack resistance of concrete to enhance the effect of better. Concrete and reinforced concrete structure of the surface often occur cracks in thin and shallow, most of them belonging to shrinkage cracks. While this is generally shallow cracks, but its strength and durability of the structure is still a certain impact. In order to ensure the quality of concrete to prevent cracking and improve the durability of concrete, the proper use of admixtures is also one of the measures to reduce cracking. Such as the use of anticracking agent and water, in practice, its major role in concluding as follows: (1) the existence of a large number of pores in the concrete that, after evaporation of water generated by capillary capillary tension, deformation of the concrete shrinkage. Pores increased capillary diameter can reduce the surface tension, but would reduce the strength of concrete. (2) the impact of watercement ratio is an important factor for concrete shrinkage, the use of anticracking agent can reduce water consumption reduced by 25% concrete. (3) the amount of cement concrete is also an important factor in shrinkage, water 第 110 页 addition and subtraction mixed concrete cracking agent in maintaining the strength of concrete under the condition of 15 percent can reduce the amount of cement, aggregate size, by increasing the amount to supplement. (4) anticracking agent and water can improve the consistency of cement slurry to reduce the bleeding of concrete, reduce shrinkage deformation Shen. (5) to improve and cement bonded aggregate, and enhance the anticracking performance of concrete. (6) concrete bound in the contraction produced by tensile stress, when the tensile stress is greater than the tensile strength of concrete will be produced when the cracks. Waterreducing agent can be an effective anticracking of the concrete tensile strength to increase, a substantial increase in anticracking performance of concrete. (7) mixingpacting concrete admixtures can, and can effectively improve the carbonation resistance of concrete to reduce the carbonation shrinkage. (8)doped waterreducing agent after the concrete cracking retardation time due, in the effecti。