DEVELOPMENT OF CORROSION LAYER OF STEEL BAR IN CONCRETE AND ITS MECHANICAL AND ELECTROCHEMICAL EFFECTS

摘要

Corrosion of steel bar in concrete can be caused under environment of chlorideattack,porosity of the steel-concrete interface offer a space for diffusing of the expansive rust.The diffusion of the rust transforms the porous steel-concrete interface into the dense mixedlayer composed of concrete and rust,the layer is called corrosion layer for short in this paper.The development of the corrosion layer leads to mechanical effect on corrosion cracking andelectrochemical effect on retardation of oxygen and water transportation. The dense corrosionlayer resists rust diffusion,and then produces an expansive force which forms corrosioncracking finally. The dense corrosion layer retards transporting oxygen and water to thesurface of the steel bar,and than the corrosion rate is slows down. This paper describes thecomposition and distribution of the corrosion layer along the bar surface,presents thedistribution model of expansive force and reveal time-depended process of the variation ofcorrosion rate of the steel bar in concrete,and discusses the mechanism of mechanical andelectrochemical effects.