The effect of styrene-butadiene rubber and ethylene vinyl acetate polymers on the mechanical properties of Engineered Cementitious Composites

Nowadays, the application of the Engineered Cementitious Composites (ECC) is increasing. An alternative way to use un-oiled fibers in ECC is the coating fibers with hydrophobic oil. Coating of fibers with hydrophobic oil in high volumes of concrete is not practical and is almost impossible. In this study, to increase the mechanical properties of ECC with the use of unoiled fibers, the polymers of styrene butadiene rubber (SBR) and ethylene vinyl acetate (EVA) were used. The cement was replaced by the polymers in order to strengthen the tensile and flexural properties. In sum, 7 mix proportions were prepared for the intended tests. The ECC for compressive strength, the uniaxial tensile and three-point bending were examined and tested. The results of the present research indicated that the use of polymers boosts the tensile and flexural properties of the ECC with unoiled fibers. The tensile strain in this study increased by more than 3% after the application of the polymers. Furthermore, the compressive strength increased by more than 47 MPa, and the deflection at the mid-span reached more than 9 mm in the bending test. On the other hand, these results also proved that the SBR latex is more compatible with the use of ECC in comparison of EVA powder.