Mechanical and restrained shrinkage behaviors of cement mortar incorporating waste tire rubber particles and expansive agent

Abstract

The evaluation of early shrinkage behavior and cracking potential is an indispensable subject in today's concrete research. This study was conducted to evaluate of synergetic effect of two sizes of waste tire rubber particles and a united expansive agent (UEA) on the mechanical strength, restrained shrinkage, and microstructure characteristics of cement mortar. A reduced scale of restrained squared eccentric ring device (RSERD) was utilized to evaluate the restrained shrinkage behavior of the mortar mixture. The cracking time, cracking location, and shrinkage strain of the specimen were monitored, counted, and analyzed. It was found that rubber particles and UEA have further improvements in reducing cracking risks. The synergistic effect of the combination of these two additives in resisting cracking was observed. In addition, the incorporation of rubber particles with a smaller size reduced loss in strength and contributed more to shrinkage reduction. The cracks of 48 square-eccentric ring specimens were restricted to the expected area. Moreover, the transient response relationship of the restrained shrinkage strain in three areas tended to be constant over time. The findings in this study will, to some extent, promote the development and application of crumb rubber concrete modified with expansive agent in shrinkage control and risk reduction.