Experimental Study on Compressive Behaviors of Concrete Exposed to Alkali-Silica Reaction Under Multidirectional Restraints

The aim of this study is to investigate the cracking anisotropy and mechanical performance of alkali-silica reaction (ASR)-expanded concrete under multiaxial restraint conditions. Uniaxially and biaxially restrained specimens were prepared using a newly fabricated fixture, and ASR expansion acceleration and compression tests were performed. Expansion and cracking anisotropy were observed for different restraint conditions. In addition, a decreasing tendency in the mechanical performance was observed in the subsequent compression test when the specimens were loaded in the direction perpendicular to the cracks. The remaining mechanical properties were significantly related to the expansion parallel to the loading direction. Next, the quantitative extraction of crack characteristics on the cut surface was attempted using an image detection technique. Each crack was isolated, and its angle was calculated. The trend of the reduced mechanical performance was summarized using information on the angle of cracks in the cross-section. By using the crack information extracted via image detection analysis, a more quantitative prediction of the mechanical performance of ASR-expanded concrete can be achieved.