【正文】 In these, can produce various forms of concrete cracks. To grasp the construction process of raw materials, in pouring process configuration of progress and thickness, grasp timely maintenance work well, which can avoid concrete cracks. A, The cause of the tear initial defects of concrete Concrete is posed of cement, sand aggregate, mixed with water and other materials and formation of heterogeneity brittle materials. In the beginning, because hardened concrete construction and deformation, a series of problems, such as constraint in the concrete shape sclerosis will exist numerous micropores, airpocket and micro cracks of concrete that usually called initial defects. Micro cracks is usually a cracks in the concrete, bearing, and some other function not harm. But under load, temperature of concrete, shrinkage and function, micro cracks will be expanded and connectivity, and finally form the visible cracks of concrete, macroscopic crack, said it was the use of concrete structure, properties and durability of adverse effects. load factor Due to the tensile strength of concrete structure or structures, small as a part of the external effects of stress than concrete tensile strength, will crack. Therefore, the concrete in the load and the load, can produce a crack. To load the crack, can produce by reasonable design and construction to prevent. For the load of crack, due to reasons, it is hard to handle and prevent. The more mon than load factors have temperature, dry shrinkage, settling contraction deformation, plastic shrinkage deformation, etc, in these function, can make concrete inside tensile stress. volume concrete crack formation reasons Massive concrete cracking reasons can be divided into two types: one is the structural cracks, is caused by external load, 2 it is material of crack is not caused by the changes of deformation and temperature stress and is mainly posed of concrete39。s shrinkage. This article mainly discussed type materials. One specific reasons are as follows: The temperature stress caused by fracture (temperature crack) temperature cracks in the main reason is caused by temperature difference. Temperature can be divided into three types: early concrete pouring, produce large amounts of the hydration heat, due to the concrete is a poor conductor of heat accumulation in concrete, the hydration heat to send out, often make internal temperatures rise, concrete and reinforced concrete surface temperature for outdoor environment temperature, it is formed, the temperature and temperature inside of condensate in early concrete tensile stress when more than concrete pressive strength, will cause cracking in concrete, In addition, in the dismantling formwork, surface temperature and reduce the temperature caused by fast, and will cause cracking. When the concrete temperature, maximum heat radiates to the minimum temperature, temperature, or use them with the highest temperature difference is the internal temperature, These three temperature will produce temperature crack. In these three temperature, is mainly caused by hydration heat and the temperature. Shrinkage crack contraction there are many causes, including drying shrinkage, plastic shrinkage, shrinkage, carbonation contraction, etc. Here mainly introduces drying shrinkage and plastic shrinkage. After drying shrinkage of concrete sclerosis, in dry environment, the water concrete to the loss caused by inside extroversion, concrete the shrinkage deformation cracks. The plastic shrinkage of cement and concrete in the activity of higher temperature, or in low watercement condition exacerbate cause craze. When the concrete surface water obviously decreased, lactation evaporation of water cannot get the timely supplements, then concrete is still in a state of plastic, by a concrete surface tension, uneven distribution will appear the cracks of concr