FRPs for the rehabilitation of concrete beams exhibiting alkali-aggregate reactions

摘要

A recently established technique for strengthening reinforced concrete structures is the external bonding of fibre reinforced polymers (FRPs). Indeed, this promising rehabilitation technology has the potential to be one of the most effective repair methods in the future. This paper deals with the use of FRPs as a rehabilitation method for concrete beams affected by alkali-aggregate reactions (AARs). Numerous corrective techniques have been developed to inhibit alkali-aggregate reactions in concrete structures. However, most of the existing techniques do not allow the structures to recover their initial mechanical properties. In order to investigate the effectiveness of FRPs for beams exhibiting alkali-aggregate reactions, laboratory simulations are required. In this study, the effectiveness of FRPs as external reinforcement for reinforced concrete beams affected by AARs is investigated. The time schedule for the installation of the FRPs and for the flexural tests was determined in order to evaluate the composite's contribution in reducing AAR-related beam expansion and to assess the effect of FRP on flexural strength. The effect of AARs on the behaviour of beams depends on the internal steel reinforcement, which reduces the concrete expansion and thus diminishes losses in mechanical properties. Futhermore, the development of AARs is inversely proportional to the size of the specimens. In our study we have used small-scale reinforced concrete beams (100 x 150 x 1220 mm) with two different longitudinal steel ratios (0.24 and 0.42% respectively). The concrete mix and the exposure conditions have been selected to rapidly develop the AARs. This investigation focuses on the measurements of strength variations. Also, experimental measurements of beam expansion with time will be discussed.