Effects of bitumen emulsion (POLYCOAT) on the mechanical properties of cement mortar

Abstract

This paper aims to study the effect of partial replacement of cement with bitumen emulsion (BE) commercially known as POLYCOAT on the mechanical properties and microstructure of cement mortar. For compressive strength, a decrease of 20 % was observed at 2.5 %, 5 % and 7.5 % replacement, while it decreased by 30 % at 10 %. This is due to the cement absorbing water from the bitumen, and forming a bituminous layer that reduces the compressive strength. As for tensile strength, it increased by 19 % at 7.5 % replacement by weight of cement, which reduces porosity and improves internal density, but when the percentage increases further, the tensile strength decreases. This was proven by studying the porosity using Image J software, which showed a slight increase in porosity with BE. Fourier transform infrared spectroscopy (FTIR) analyses showed that the addition of BE did not change the chemical composition of the hydration products. These results confirm that the main effect of adding bitumen is a physical effect that enhances the properties of the material by modifying the microstructure and increasing the density of the bonds without forming new compounds. The results of this study showed that it is possible to use cement-bitumen mortar as a cushion layer that reduces noise and vibration in concrete structures. This may open the way to study the properties of this material and the possibility of using it as inhibitors in the field of railways and bridges, which means the need for more studies and laboratory tests.