Durability of silica fume concrete exposed to chloride in hot climates

The premature deterioration of reinforced concrete structures is a serious problem in hot coastal environments. Most of this deterioration is caused b y chloride ingress through the concrete, resulting in the corrosion of the reinforcing steel. Since the mid 1990s the practice of specifying silica fu me in concrete has widened in the Middle East. as engineers work to improve the durability of concrete, which is subjected to the extreme exposure con ditions in the region. Current practice is to use mixtures with a maximum w ater/cement ratio of 0.4 and to replace 5% to 10% of the cement with silica fume depending on the degree of exposure. Are these small amounts of silic a fume sufficient to maintain an appropriate life span for concrete structu res tinder the varying exposure conditions, and how much cover is required to the reinforcement to protect the steel from corrosion? In this paper, mo dels are proposed to estimate the chloride ion ingress into portland cement concrete and silica-fume-enriched concrete under different exposure condit ions. The results show that small amounts of silica fume are sufficient as long as appropriate concrete covers to reinforcement are maintained and chl oride exposure to the concrete is correctly assessed.