Cement Asphalt Emulsion Composites (CAEC) are mixtures of bitumen emulsion, cement, water and aggregates that harden at ambient temperature. They are mixed at ambient temperature and harden due to breaking of the emulsion, water evaporation and cement hydration. Potential advantages of CAEC are lower temperature susceptibility than asphalt concrete and higher flexibility than cement concrete. To quantify the effects of cement hydration on the mechanical properties of CAEC, two different emulsions (cationic and anionic) mixed with either 0%, 3% and 6% Ordinary Portland Cement (OPC) by mass of dry aggregates were studied by isothermal calorimetry and Marshall tests. By monitoring the mass of the specimens and estimating the amount of water bound by the cement, the water content was calculated. This study shows that bitumen emulsion has no significant effect on the degree of cement hydration. Cement hydration, however, significantly contributes to the hardening of CAEC. Moreover, a higher amount of cement added to the mixture results in a higher amount of bound, adsorbed and capillary water in the CAEC.