Influence of Alkali-Silica reaction (ASR) on aggregate interlock and shear-friction behavior of reinforced concrete members

Alkali-silica reaction (ASR) is one of the most damaging mechanisms affecting concrete structures worldwide. ASR effects on the durability and serviceability of damaged concrete are widely known and fairly well understood. However, the structural implications are still unclear, and a number of contradictory data are found in the literature, especially regarding shear behavior. The influence of ASR distressed reinforced concrete on aggregate interlock is presented in this paper. Push-off specimens having different transverse reinforcement ratios were fabricated with ASR reactive coarse aggregates. The specimens were monitored over time and displayed different levels of expansion. Results indicated that ASR-induced expansion and damage were affected by the transverse reinforcement ratio. However, little to no aggregate interlock reduction was observed on ASR-affected specimens up to moderate expansion levels (about 0.12%). It was found that there were two controlling and competing mechanisms that affected aggregate interlock for ASR-affected specimens: the beneficial effects of chemical prestressing and the detrimental ASR-induced damage.