Experimental Studies of mechanical and corrosion properties in concrete using mineral admixtures

ABSTRACT The phenomenon of wide spread deterioration of concrete structures during the past two decades has become a matter of global concern. The deterioration of reinforced concrete structures is often due to the corrosion of the reinforcing steel embedded in the concrete. Corrosion of steel in concrete occurs when the outside environment influences the change in composition of the pore solution. The permeability of concrete is one of the main reason by which the change in the PH of the pore solution takes place. The chloride ion diffusion into the concrete affects the passivity of steel rebar and consequently accelerates the corrosion. In addition Co2 and oxygen can easily diffuse through the concrete and thus destroy the passive film formed on the steel surface by lowering the PH of the pore solution. Therefore the microstructure and the impermeability of the concrete may be altered, with a high packing density of concrete as the key for obtaining durable concrete. This has been achieved and studied by incorporating mineral and chemical admixtures in the concrete. Fly ash and Micro silica are one such mineral admixtures used in concrete as the supplementary cementitious material to enhance the impermeability characteristics of concrete and thus reduce the risk of corrosion of the embedded steel. An attempt has made to study the mechanical and corrosion properties in more than 100 specimens using flyash and microsilica.