Cracking of cover concrete due to non-uniform corrosion of corner rebar: A 3D meso-scale study

Abstract

Corrosion of steel in concrete structures is one of the main causes of structural durability failure. In order to study the rust cracking behavior of the concrete protective layer, a three-dimensional meso-scale model of concrete was established. In the approach, the concrete was regarded as a three-phase composite composed of coarse aggregates, mortar matrix and the interfacial transition zones (ITZs). The non-uniform radial displacement method was used to characterize the mechanical effect of steel rust on the surrounding concretes. The cracking behavior of concrete cover caused by non-uniform corrosion of corner reinforcement was simulated based on the meso-scale method. The rust expansion pressures on the surrounding concretes due to non-uniform corrosion of corner rebar were explored. Moreover, the influences of steel bar diameter, cover thickness and corrosion distribution mode on the cracking of cover concrete were investigated. The simulation results indicate that the non-uniform rust pattern of the steel bar makes rust expansion pressure smaller than the uniform rust. The random distribution of aggregates has little effect on the cracking mode of the concrete protective layer. With the increase of the ratio of the thickness of concrete cover to the diameter of steel bar, the maximum rust expansion pressure of concrete increases. Bar diameter has a negligible influence on the cracking pattern of concrete.