Damage Analysis And Experimental Study Of Reinforced Concrete Structures With Rebar Corrosion

Steel corrosion is one of the most predominant deterioration mechanisms in reinforced concrete structures. The serviceability and durability of concrete structures can be heavily affected by the corrosion of reinforcing steel. After steel depassivation, the formation of the corrosion products will induce a pressure on the surrounding concrete and generate stresses in the concrete cover. As the volume of corrosion products increases, cracks initiate at the steel/concrete interface and propagate outwards and eventually spread to the surface of the concrete cover. These cracks in turn provide a path for more rapid ingress of aggressive agents to the reinforcement, which can accelerate the corrosion process. Therefore, investigation on the corrosion-induced cracking process is very important for the prediction of the serviceability and durability of reinforced concrete structures. This paper focuses on the corrosion-induced cracking process by experimental studies and analytical studies. The main work in this paper can be summarized as follows:(1) Considering different damage along the radial direction of the concrete cover due to cracks and the mechanical properties of the rust products, an analytical model for corrosion-induced concrete cracking process in reinforced concrete structures has been developed based on damage mechanics and elastic mechanics. The elastic mechanics is utilized to analyze the whole concrete cover subject to corrosion expansion at the early stage. Once the inner crack between the concrete and steel occurs, the concrete cover is divided into two regions. One is the inner cracked part and the other is the outer intact part. The elastic mechanics is used for analyzing the intact part and the damage mechanics is applied to deal with the cracked part. Damage variable is adopted to describe the different damage along the radial direction of the concrete cover. Based on this model. the expansive pressure and the radial loss of steel bar are discussed. Parametric studies are carried out to examine the effects of the correlative factors on the expansive pressure and the steel loss.(2) An electrochemical accelerated method was used during the corrosion of reinforced concrete specimens. The thickness of the rust layer at the inner cracking and surface cracking were tested in this experiment and the experimental results have been compared with the calculation results of the proposed model. The composition of the oxidation products at steel/concrete interface and the distribution of corrosion products in the corrosion-induced cracks were observed using SEM.(3) A reinforced concrete specimen subjected to chloride ingress in an artificial environment for 2 years was cut into slices to investigate the mode of the corrosion-induced cracks and the distribution of the corrosion products in the cracks. The total circumferential crack width at different radius and the total crack width at the surface of the concrete cover were measured. The development process of the cracks and the corrosion products are obtained and a model is established.