Performance And Service Life Analysis Of Silane Impregnated Concrete

Reinforced concrete is widely used in various engineering structures because of its good durability at present. However, concrete as a porous material with high permeability, seawater intrusion on the concrete structure in the marine environment can bring a large number of harmful substances especially the erosion of chforide ton, which could lead to steel corrosion of concrete structure. Thus, the service life of concrete structure is also significantly reduced, which will cause serious waste of resources. Meanwhile, with the increasing requirements of modern project to the performance of concrete, the durability problem of concrete is becoming more and more serious. Therefore, how to effectively improve the durability and the service life of concrete structures has become a major issue.Water erosion is an important reason for the reduction of concrete structure durability, and the destruction of concrete structures is mostly related to the intrusion of water. Therefore, most of the disease problem ofconcrete structure could be solved effectively as long as the external moisture can be prevented from entering reinforced concrete structure. Silane material, as a kind of high permeability waterproof material, has been used in the protection of concrete structure in 1980s. Compared with other concrete structures, silane impregnation has the advantages of simple operation and the longer service life, and a more long-term protective effect on concrete structure.In this paper, the effect of silane impregnation on the protection of concrete structure is studied, and the influence of silane materials on water absorption rate, silane impregnation depth, resistance to chloride ion penetration (flux, chloride ion diffusion coefficient), carbonation resistance, salt freezing resistance of different type concrete is tested. The concrete type used includes three strength grades (C35, C40, C45) Portland cement concrete and a strength grade (C35) composite cement concrete. On this basis, COMSOL Multiphysics is used to simulate and analyze the service life of concrete structure based on chloride ion erosion. Sensitivity factor analysis was taken to analyze the effect of four different factors on the final chloride ion concentration on reinforced bar surface by the orthogonal test method. The four influence factors are silane impregnation depth, thickness of concrete protective layer, concrete diffusion coefficient, initial concentration of chloride ion. Finally, the single factor analysis was carried out.Research results show that, silane impregnation can significantly reduce concrete water absorption rate, and the reduce rate can reach nearly 90%. Silane impregnation depth is roughly between 5-10mm. The smaller concrete strength is, the greater silane impregnation depth is and the decrease amplitude of concrete water absorption is. The effect of silane impregnation on ordinary portland cement concrete is more obvious. Silane impregnation can effectively improve the resistance to chloride ion penetration of concrete. The decrease amplitude of silane impregnation on concrete flux value and chloride diffusion coefficient is between 20%-40%, and its effect on composite cement concrete is greater. The influence of silane impregnation on concrete carbonation resistance is not obvious,28d carbonation depth of concrete before and after silane impregnation has little difference.Silane impregnation can obviously improve the salt freezing resistance of concrete. The higher the concrete strength grade is, the more obvious the effect of silane impregnation. Before silane impregnation, the surface layer of concrete salt freezing surface is seriously peeled off after 28 times of freeze-thaw cycle test, however, there is only a small part of the spalling on concrete salt freezing surface, basically remaining in good condition after silane impregnation. Silane impregnation can significantly reduce the mass loss per unit area of concrete after salt freeze-thaw cycles, and the reduction ratio after 28 salt freeze-thaw cycles can reach more than 90%, but its effect on relative dynamic elastic modulus loss is not obvious.The simulation results indicate that, the greatest influence on concrete structure service life is the initial chloride ion concentration, followed in turn by thickness of concrete protective layer, silane impregnation depth, and the influence of concrete diffusion coefficient is the least.