Properties of rubberized concrete modified by using silane coupling agent and carboxylated SBR

Using waste rubbers as aggregates in concrete is a feasible approach to recycle the material. However, due to the poor adhesion of rubber to cement paste, the replacement of normal aggregate with rubber will lead to a reduction in the mechanical strength of concrete. This paper presents a new approach to overcome this deficiency by treating waste rubbers with silane coupling agent (SCA) and carboxylated styrene-butadiene rubber (CSBR) latex to develop chemical bonds between rubbers and cement paste. This study investigates the influence of this surface treatment on the mechanical strength and chloride penetration resistance of rubberized concrete. Experiments were conducted with six different volume fractions of rubbers (between 0% and 30%) to replace fine aggregate in the concrete. The experimental results showed that the compressive strength and flexural strength of concretes incorporating proper amount of treated rubbers could be improved by 4% and 13% respectively as compared to the control concrete with no rubbers. Moreover, the chloride penetration resistance was also improved by 35%. The good adhesion of waste rubbers to cement paste, the formation of rubber networks and the embedding effect of rubbers as shown in SEM images are explanations for the enhancement in the mechanical strength and durability for the treated rubber concrete.