A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Civil Engineering

Thesis (M. Eng.) - Asian Institute of Technology, 2000

Corrosion of reinforcing steel is the main cause of deterioration of high strength reinforced concrete structures as well as normal strength one. This study takes up corrosion of reinforcement in the high strength concrete as a subject and effects of reinforcement corrosion on load bearing capacity, ductility, toughness etc of reinforced high strength concrete structures are examined experimentally. The experimental framework consists of total of twenty beams in two experimental series, hereafter called Series-A and Series-B. In Series-A, ten singly reinforced beams and in Series-B, ten doubly reinforced beams with shear reinforcements undergoing different degrees of corrosion are investigated. Corrosion is introduced on reinforcing bars by an accelerating corrosion technique using constant current apparatus as a power source. Degree of reinforcement corrosion is varied in each specimen respectively from 0 to 7.5 percent, which is expressed as percentage reduction in reinforcing bar diameter. The experimental results show that the load bearing capacity, ductility and toughness of high strength concrete beams are significantly influenced by reinforcement corrosion. Especially, for the load bearing capacity, not only the remarkable reduction of the capacity itself but also, the change of failure modes with difference in flexural cracking pattern occurred in higher corrosion condition. Main causes of these degradations are the reduction of reinforcement bar diameter and the breakdown of bond property at steel/concrete interface due to the corrosion cracks induced by corrosion of reinforcement. Certain assumptions are put forward for predicting the residual load-bearing capacity of corroded high strength reinforced concrete beams. These assumptions show conservative value in predicting residual load bearing-capacity of corroded concrete beams. Furthermore, the mechanical properties of high strength concrete structures are less influenced than the normal strength concrete structures due to the corrosion of reinforcement.