Chloride attack is the most significant mechanism of deterioration for reinforced concrete. The corrosion of steel in such an environment is initiated once a critical concentration of chlorides is reached at the level of the reinforcing steel. Many chlorides may have been chemically or physically bound and are unable to play an active part in initiating corrosion. However, the chlorides in the pore fluid, known as the free chlorides, are paramount in assessing the corrosion risk of reinforced concrete as these ions are in solution and are free to initiate corrosion. An investigation using various cement blends, viz. ordinary Portland cement containing 30% PFA, 50% GGBS, 10% MK, 10% MS and 100% OPC, were used to cast mortar specimens, which were subjected to a chloride environment for 24 weeks. The pore fluid from the specimens was extracted at various depths up to 20 mm and the chloride concentration of the fluid was determined. The specimens were also fractured and sprayed with silver nitrate to identify visually the depth to which the chlorides have penetrated.