"Resistance to Chloride Ion Penetration of Concretes Containing Fly Ash, Silica Fume, or Slag"

Abstract

The effects of two pozzolanic admixtures, fly ash and silica fume, and a ground granulated blast furnace slag on the chloride ion intrusion of concretes prepared with low water to cementitious material ratios (w/c) (0.35 to 0.45) were investigated. Results of the rapid permeability test (AASHTO T 277) showed that the resistance of concrete to the penetration of chloride ions increases significantly as the w/c is decreased for the same proportion of solid ingredients. Usually, concretes with pozzolans or slag exhibited higher resistance to chloride ion penetration than the control concretes containing portland cement as the cementitious material. Results of the 90 day ponding test (similar to aashto t 259), which was conducted with 0.40 w/c concretes only, indicated minimal choride content at depths below 3/4 inch (19 mm) for all the test concretes. Strength values for all concretes made with the pozzolans and slag at 90 days were in excess of 5,000 psi (34.5 Mpa), which is satisfactory (a).