Prof. Gamal Elsayed Abdelaziz :: Publications:

This paper aims to elucidate the effectiveness of the artificial local-made pozzolanic materials on the degradation processes of reinforced concrete exposed to various aggressive conditions containing sulphate or/and chloride ions. Two series of mortar and reinforced concrete samples made with different Silica Fume (SF) or Rice Husk Ash (RHA) content (0, 10 and 20%, by weight of OPC) were prepared and exposed to various predetermined aggressive aqueous solutions (10% sodium sulphate or/and 5% sodium chloride). The % expansion and weight gain of exposed test samples and the corrosion activity of reinforcing steel bars imbedded in concrete samples were regularly monitored every two weeks along a period of one year of exposure. It was concluded that the inclusion of either SF or RHA into OPC matrix has led to reducing the level of degradation of reinforced concrete, where the corrosion activity of reinforcing steel and % expansion and weight gain were significantly reduced. The beneficial effect of SF on reducing the degree of degradation of reinforced concrete was fairly close to that of RHA. However, the maximum degradation in the hardened paste matrix in concrete, from the volume and weight change point of view, was produced when it was subjected to environment containing sulphate ions only, while the maximum degradation in the reinforcement, from the corrosion point of view, can be produced at the environment containing both sulphate and chloride ions together.