Published Article / Corrosion of rebar in concrete is commonly associated with the free chloride in the pore water in the cement matrix. Knowing the quantity of chloride in concrete is important because chloride can promote corrosion of steel reinforcement when moisture and oxygen are present. The problem ofphysical extraction and the measurement of the free chloride content in pore water solutions extracted from cement pastes has received attention in literature but has not been explained in full detail. However, the variability of results obtained from the different methods used by various investigators only serves to confuse the issue. This investigation describes the use of a tumbler designed to prepare homogeneous samples and the use of a pore water expression device designed to extract free chloride in cement paste and concrete samples.