Influence of Temperature on the Microstructural Properties of ASR-Affected Concrete

Alkali-silica reaction (ASR) reduces the serviceability of affected structures, and temperature significantly enhances the development of the deterioration mechanism. The assessment of the role of temperature in the reaction is however incomplete without the evaluation of induced internal damage. Although the Damage Rating Index (DRI) has proven to be a reliable tool for assessing internal damage in ASR-affected concrete, its applicability over a range of exposed temperatures has not been explored. This study exposed 36 concrete cylinders containing a highly reactive aggregate to three storage temperatures (21 ℃, 38 ℃, and 60 ℃) and 100% relative humidity. The kinetics was monitored over time, and ASR-induced inner damage was evaluated using an extended version of the DRI. Results show that the petrographic features of ASR-affected concrete are significantly influenced by the exposed temperature, even at similar expansion levels. Moreover, an increase in temperature induced a difference in microstructural properties, such as crack width, length and density.