Effect of Water Content on Volumetric and Mechanical Properties of Cement Bitumen Emulsion Mixture

Water greatly affects the mechanical properties of cement bitumen emulsion mixture (CBEM). Its content is usually determined by the minimum voids content of CBEM. However, its effect on the mechanical properties of CBEM has not gained much attention. The effect of water content on volumetric and mechanical properties of CBEM was thoroughly studied to determine a more suitable water content for better mechanical properties. The voids content, indirect tensile strength (ITS), failure tensile strain, stiffness modulus, and critical strain energy density (CSED) of CBEM with different cement contents were investigated. Results indicate that the maximum strength of CBEM does not appear at the water content of the minimum voids content. The water content of CBEM with maximum strength is much lower than that of CBEM with minimum voids content. This is because the strength of CBEM highly depends on the microstructure of hardened cement bitumen emulsion binder. Low water content can help to form a dense microstructure and continual bitumen membrane in cement bitumen emulsion binder, which is beneficial to the strength of CBEM. The mechanical properties of CBEM in both conditions of minimum voids content and maximum strength were compared. CBEM has the maximum ITS and CSED and relatively high failure strain and stiffness modulus in the condition of maximum ITS, the cracking resistance of which can be better than that in the condition of minimum voids content. It is recommended that the optimum water content of CBEM should be determined by the maximum ITS in the mix design.