Influence of PFA, slag and microsilica on chloride induced corrosion of reinforcement in concrete

Abstract Steel reinforcement electrodes embedded in different matrices of concrete were exposed to simulated marine splash zone exposure for about 600 days (1200 cycles) after initial curing in air for 14 days. The corrosion potentials and polarisation resistance were monitored at regular intervals to determine the state and rate of corrosion. The concrete matrices included different cement replacement levels of pfa, ground granulated blast furnace slag (BFS) and microsilica, at a water/(cement+blend) ratio of 0.58. The Cl− and OH− concentration in pore fluid and the acid soluble Cl− in concrete were also determined. The results show that maximum protection against rebar corrosion is provided at 60% replacement of cement by BFS and at 10 and 15% replacement by microsilica. The corrosion rates are more sensitive to Cl− concentration in the matrix than to the Cl−/OH− ratio.