Accelerated ASR testing of recycled concrete

Abstract

The work involves research on investigating techniques and procedures to assess the Alkali Silica Reactivity (ASR) expansion potential for concrete made from recycled concrete aggregate (RCA) which was known to have ASR, or is capable of ASR under conditions of increased alkali. Laboratory testing was done to evaluate various testing procedures designed to accelerate the ASR reaction. This included evaluating prisms with variable surface to volume ratios, increased moisture state, and microwave energy. Standard 280 mm prisms with 76.2 mm faces cast with four 6.35 mm parallel longitudinal holes were shown to not only accelerate ASR but also to lower the coefficient of variation of the expansion data. Expansion of 76.2 mm concrete cubes was found to be significantly accelerated as compared to that of a standard prism. Sealing prisms in evacuated plastic bags with water was also found to effectively accelerate ASR expansion. Concrete prisms were subjected to ASTM C 1260 and ASTM C 1293 conditions and the results were compared to those from modified versions of the same tests including the use of microwaves.