Permeability Effects on the Sulfate Resistance of Concrete

A laboratory study was conducted to determine the effect of permeability on the sulfate resistance of concrete containing fly ash. Concrete specimens were moist cured for 7 and 100 days before being submerged in a 10 percent solution of sodium sulfate, according to the Bureau of Reclamation Test Procedure 4906-86. A low calcium and a high calcium fly ash were used at 25 and 35 percent volumetric replacement levels to study the relationship between permeability and sulfate resistance of concrete containing fly ash. At the time of initial exposure, the permeability of the concrete was measured using the AASHTO T277 Rapid Chloride Ion Permeability Test Procedure. The results of this study indicate that decreased permeability is not sufficient to prevent the degradation of concrete exposed to a sulfate environment Low permeability concrete may suffer from sulfate attack despite the appearance of high quality construction.