Effect of CaCl2 on the hydration characteristics of the different cement pastes using ordinary Portland cement (OPC) and blended Portland cement with ground clay bricks (GCB) was studied. Various mixes were prepared using a water/solid ratio (W/S) of 0.25 (by weight). Three ratios of CaCl2 (0.25, 0.5 and 0.75% by weight of the solid binder) are used; the CaCl2 used was dissolved in the mixing water. The hydration characteristics of the different mixes are tested via determination of the combined water content, phase composition, compressive strength, total porosity (P%) and X-ray diffraction analysis (XRD) at different time intervals up to 180 days. Differential thermal analysis (DTA) was used to give more information about qualitative analysis. The results showed that calcium chloride accelerates cement hydration in all systems studied. The optimum ratio for the highest compressive strength can be considered the ratio of 0.50 CaCl2 for pastes containing 10% GCB.