"Comparative results of utilization of fly ash, silica fume and GGBFS in reducing the chloride permeability of concrete"

This research project was undertaken to determine the effect on the chloride permeability of concretes of increasing amounts of fly ash in low water/cementitious material ratio concrete, as compared with comparable high quality concretes containing combinations of portland cement, silica fume and ground granulated blast furnace slag. The test method utilized was the Rapid Determination of the Chloride Permeability of Concrete (AASHTO T-277). Fifteen superplasticized concrete mixtures were evaluated for compressive strength at ages of 28 and 56 days, and for chloride permeability at 56 days. The inclusion of fly ash, silica fume, and ground granulated blast furnace slag all significantly reduced the chloride permeability of concrete, as compared with concrete containing portland cement only. Increasing amounts of fly ash generally showed decreased permeability in the tests conducted.