1、 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, shou
2、ld 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 a
3、nd 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 treatment In building construction, concrete cracks is a widespread problem, crac
4、ks 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 preve
5、ntion 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 peoples lives and property safety . Crack is impossible to comple
6、tely 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 ef
7、fectively 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 cracks The concrete is a brittle material of a gravel aggregate, cement, water and other additional material formed by mix
8、ing 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 . Mi
9、cro-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 ofte
10、n 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 i
11、n the concrete are the following: (1) shrinkage cracks； plastic shrinkage cracking； (3) settlement cracks； temperature cracks； chemical reaction caused by cracks. 2.Concrete cracks and prevention 2.1 Shrinkage cracks and prevention of Shrinkage cracks appear in a week or so after the end of the conc
12、rete 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 d
13、eformation 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 c
14、racks. 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 f
15、lat-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-c
16、ement ratio of the concrete, cement component, the amount of cement used, the nature 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.
