Analysis of the Modifying Effect of Styrene Butadiene Rubber Latex Copolymer on Strength and Permeability Properties of Structural Light Aggregate Concrete

Polymers not only possess repairing functions concerning the concrete structures, but also due to their properties are used in making different types of polymer cements and improving the matrix structure of cement materials, enhancing the viscosity, mechanical, and stability power of concretes. Today, there is limited knowledge on the use of SBR in structural light aggregate concrete. In the present research, light expanded clay aggregate was used to produce light weight concrete weighing 1740 to 1780 kg/M3. Unlike the previously conducted studies in which the desirable properties of concrete were achieved by increasing the compressive strength, in the current study we have used C25 light concrete without any cement supplements. SBR latex copolymer was incorporated in concrete directly (additive) and indirectly (light aggregates coating) each based on a combinational performance of 28 and 60 days. The results revealed that based on the used cement matrix, the optimal performance of the latex in the direct method was enhanced by increasing the bending and tensile strength rather than the compressive strength. The indirect presence of latex not only imposed a new limit in ITZ, but also had no interfering role in modifying the chemical mechanism of cement hydration. Thus, the behavior of this concrete did not show any enhancement in the mechanical properties as it did in the case of direct implication of latex. The study also showed that the presence of latex in both methods led to reduced permeability of the concrete. This research also looked into the impact of cement matrix capability, latex consumption rate, curing age and method and the effect of copolymer ratio on improving the light weight concrete stability and mechanical properties.