Effects of the initial water curing time on the corrosion behavior of steel bar corrosion in fly ash concrete

Concrete specimens made of 30% fly ash (FA) replacement ratio and ordinary Portland cement (OPC) were fabricated to study the effects of the initial water curing time on the corrosion behavior of the embedded steel bar. The specimens were cured in water tank for 5days, 7days, 14days and 28days respectively at a normal temperature of 20□, then taken out and stored at an indoor natural environment. At the exposure time of 60days, 120days and 180days, steel barsʹ corrosion current densities icorr, corrosion potentials Ecorr in FA and OPC concrete specimens and their electrical resistivities ρc were tested. Results indicate that the initial wet curing time has important effects on steel barsʹ corrosion behaviors in both FA concrete and OPC concrete. With the increase of the initial wet curing time, steel barsʹ icorr all tend to decrease and Ecorr tend to increase. The longer the initial wet curing time, the higher the protective ability of FA concrete, compared to OPC concrete. Under the normal temperature, the shorter initial wet curing time of 5days and 7days for FA concrete showed worse protective ability than OPC concrete. However, when the initial wet curing time surpasses 14days, FA concrete behaves better than OPC concrete.