Frost Resistance of Alkali-Activated Combined Slag and Fly Ash Concrete Cured at Ambient Temperature.

Alkali-activated slag/fly ash concretes were tested regarding their resistance to freezing-and-thawing cycles and deicing salt scaling. Different fly ash contents, added water dosages, and air-entraining admixture (AEA) dosages were tested. The deicing salt-scaling resistance tests were conducted on different types of surfaces (troweled, formed, saw cut). The tested alkali-activated slag/fly ash concretes showed excellent performances to freezing and thawing (300 cycles) with statistically identical values of relative dynamic modulus of elasticity averaging 100%. The performance was also good for specimens tested without addition of AEA. However, they exhibited poor scaling resistance to deicing salts with only one mixture satisfying the 0.50 kg/m2 (0.102 lb/ft2) limit of the Bureau de normalisation du Québec (BNQ) test procedure, with a value of 0.49 kg/m2 (0.100 lb/ft2). Finished surfaces underwent more scaling than formed or saw-cut surfaces. The curing of the specimens and the scaling test itself may not be suitable to test alkali-activated concrete. [ABSTRACT FROM AUTHOR]