Title: Long-term Performance of Pozzolanic materials in Resisting Corrosion of Reinforcement in Concrete

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Publication: CIA

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Date: 2/28/2011

Abstract:
Chlorides are the single factor that most adversely affects the reinforcement corrosion process. Recent studies indicate that rehabilitation of structures along the Australian coast, cost about $200 Million (AUD) every year as a result of reinforcement corrosion. Pozzolanic materials are being used to make concrete durable although the mechanisms of their effects are not fully understood. This paper presents a combination of a microstructural and performance investigation with the objective of optimizing the utilisation of some of the more commonly used pozzolanic materials. In this study, fly ash and blast furnace slag (BFS) were used systematically in the increased percentages of 25, 50, and 70% of total cementitious materials. Silica fume was mixed at the rate of 10% forming various binary and ternary blends. Reinforced concrete slabs were cast and ponded for two years with 3% NaCl solution simulating sea water salinity. Pore size distribution was utilized to evaluate the hydration mechanism in these blends. The results indicate that 25% replacement of cement with fly ash and addition of 10% silica fume is the optimum percentage in fly ash blends. The ternary blend with 70% BFS and 10% silica fume exhibited larger total pore volume compared to other binary and ternary blends of slag, however, finer pore structure was observed in this blend beyond 400 Å pore diameter.