Evaluation of the induced mechanical deterioration of ASR-affected concrete under varied moisture and temperature conditions

Moisture and temperature are critical for developing alkali-silica reaction (ASR) in concrete. However, the influence of these exposure conditions on ASR-induced deterioration, specifically mechanical property losses, has not been well studied. To further our understanding, concrete cylinders made with Spratt reactive coarse aggregates and boosted in alkalis to 5.25 kg/m³ ${Na}_2{O}_{eq}$ were manufactured and stored at three different temperatures (i.e., 21 °C, 38 °C, and 60 °C) under numerous relative humidities (i.e., 100 %, 90 %, 82 %, 75 %, and 62 %). The reduction in mechanical properties was assessed using the stiffness damage test (SDT), direct shear and compressive strength tests. Overall, most results for mechanical properties showed a strong linear trend with expansion, with the exception of the modulus of elasticity and shear strength. In low moisture conditions that experienced both drying shrinkage and ASR, the expansion level associated with a given mechanical property loss differs from that in high moisture conditions due to early age cracks that developed in the cement paste. In most published research, expansion is the primary criteria used in assessing role of exposure conditions. However, it was found that expansion levels alone are not reliable indicators of induced deterioration due to the coupled mechanism. Furthermore, the impact of this phenomenon varies with the different mechanical properties assessed. Additionally, the moisture threshold required for the reaction was evaluated by considering the impact on mechanical properties.