Investigation on the dynamic tensile behaviour of rubberized mortar using the Brazilian disc method

Abstract

The use of tire rubber particles as a partial substitute for fine aggregate in cement-based materials has been proven to potentially have both environmental and economic benefits. Although the studies on the physical and mechanical properties of rubberized mortar are abundant, those related to the dynamic tensile behaviour are scarce. In this study, rubber powders with three sizes (0.125 mm, 0.180 mm, and 0.425 mm) are used to fabricate the Brazilian disc rubberized mortar specimen, with rubber volume percentages up to 40%. A 50 mm-diameter split Hopkinson pressure bar (SHPB) apparatus is then adopted to conduct the dynamic split tension tests, and the static tensile tests are also conducted for comparison purposes. Experimental results show that the dynamic split tensile strength of the rubberized mortar linearly increases with increasing the loading rate, whereas decreases with the increase of the rubber volume percentage. The mortars with smaller rubber powder at the same percentage exhibit more significant dynamic strength loss. As compared with the static tests, the reduction ratio of the dynamic split tensile strength of mortar with different rubber content is much smaller. The dynamic increase factors of the rubberized mortar are more sensitive to the loading rate, and positively correlated to both the rubber volume and the powder size. Besides, the occurring time of the primary crack initiation gradually decreases with increasing the loading rate and rubber size, whereas increases with increasing the rubber volume percentage. In addition, the dissipated energy density of the rubberized mortar is positively correlated with the rubber volume percentage, and the addition of the smaller rubber powder can enhance the dynamic energy absorption capacity.