Effect of acids and freeze-thaw on the durability of modified rubberized concrete with optimum rubber crumb content

Investigations of the effect of acids and freeze-thaw on pozzolanic cement-based rubberized concrete after surface treatment of rubber crumbs are limited. Rubberized concrete's mechanical and durability properties (water absorption, acid attack resistance, and freeze-thaw attack resistance) are evaluated. Six rubber crumbs content (0%, 10%, 15%, 20%, 25%, and 30%) and particle size 0.6-2.36 mm are used to replace fine aggregate in concrete partially, and 15% replacement level of rubber crumb is found to be the optimum quantity in concrete. Structural analyses show that the specimens remain in the crystalline phase after being submerged in H2SO4 and HCl acid. When rubberized concrete is immersed in H2SO4 and HCl solution with equal concentrations and duration, specimens immersed in HCl solution have been found to have less surface erosion, less weight loss, and lower compressive strength loss. When the conventional concrete mix is immersed in H2SO4 and HCl solution, the losses in compressive strength are 74.56% and 30.34%, but in rubberized concrete, the losses are 60.01% and 24.22% only. No apparent microcracks and no spalling on the surfaces of the specimens are found up to 90 freeze-thaw cycles. Rubberized concrete's ultrasonic velocity decreases slightly up to 90 freeze-thaw cycles, but it still has good concrete quality.