In an aggressive environment, corrosion of steel reinforcement is one of the major causes of deterioration in reinforced concrete (RC) beams that can lead to significant area loss of reinforcement resulting in premature failure. Shear reinforcement (stirrups) with smaller concrete cover is more likely to be corroded earlier than the main reinforcement. Significant area loss of shear reinforcement alters the structural performance of the RC beam and requires immediate repair and strengthening.

The conventional repair method is to lap additional rebar to the corroded reinforcement, which is time-consuming and uneconomical due to high labor costs. In some cases, due to limited depth of the member, there is insufficient lap length for stress transfer from corroded stirrup to the new rebar....[ Read more ]

In an aggressive environment, corrosion of steel reinforcement is one of the major causes of deterioration in reinforced concrete (RC) beams that can lead to significant area loss of reinforcement resulting in premature failure. Shear reinforcement (stirrups) with smaller concrete cover is more likely to be corroded earlier than the main reinforcement. Significant area loss of shear reinforcement alters the structural performance of the RC beam and requires immediate repair and strengthening.

The conventional repair method is to lap additional rebar to the corroded reinforcement, which is time-consuming and uneconomical due to high labor costs. In some cases, due to limited depth of the member, there is insufficient lap length for stress transfer from corroded stirrup to the new rebar. The present study explores a new repair approach using high-strength strain-hardening cementitious composites (HS-SHCC) which can carry sufficient tensile loading up to high strain levels. In this research, the design of HS-SHCC to compensate for the loss in load-carrying capacity due to stirrup corrosion is first discussed. Contrary to the conventional repair method, the proposed HS-SHCC technique does not require the lapping of the additional stirrup and the associated removal of a large amount of concrete.

Reinforced concrete (RC) beams containing stirrups with reduced area and patched with HS-SHCC were cast and tested under four-point bending together with control beams to demonstrate the novel repair method. The shear span-to-depth ratio of the specimen was kept at 2.5:1. Finite element models were also designed and employed to perform numerical simulation on both the control and repaired beams. Good agreement between experimental and simulated load vs displacement relations was achieved. From the results, it was found that the HS-SHCC patch can effectively recover the load-carrying capacity for beams with severely corroded shear stirrups. The potential of the novel repair method for practical applications is hence demonstrated.