Effect of Multi-directional Restraint Induced by Reinforced Steel Bars on ASR Expansion and Bond Performance

Abstract

In this study, we aim to investigate the interaction between alkali-silica reaction (ASR) expansion and multi-directional reinforced steel bars, and to clarify the weakening mechanism of bond performance under the influence of this interaction. First, a series of pullout specimens considering the influence of the steel bar diameter and stirrup number were prepared and then to different degrees of the accelerated ASR test to quantify the multi-directional restraint effect of the reinforced bars. After the accelerated ASR test, pullout tests were conducted to quantify the effect of ASR on the bond performance of the reinforced concrete. The test results show that uniform reinforcement results in a uniform expansion of concrete and a relatively small volumetric expansion rate. Moreover, the specimens without stirrups showed an increase in bond performance when the volumetric expansion rate was lower than 0.2%; however, the bond performance of some specimens with stirrups increased when the volumetric expansion rate was lower than 0.3% because the attenuation of bond performance was delayed by the stirrups. Finally, by comparing the analysis results and the experimental results, a chemo-mechanical analysis method coupled with an ASR expansion model and a poro-mechanical model was verified. This method can accurately predict ASR expansion, stress-strain state, and the bond damage caused by ASR.