Freeze-Thaw Resistance of Lightweight Aggregate Concrete

A freeze-thaw test in water at freezing rates ranging from 2 to 6°C is required to determine the critical spacing factors when a concrete is frozen in water at low rates and also to evaluate the intensity of surface scaling in the absence of deicer salts. The salt frost attack seems to consist of two phases. During the first phase, the combination of salt and water gives rise to surface scaling. The second phase, with accelerated deterioration, probably takes place when the critical degree of saturation is reached in the complete material volume, after a number of cycles and a certain time of water absorption. The freeze-salt resistance is lower with the simultaneous use of air-entraining agent (AEA) and plasticizer than with using AEA only. Vacuum-saturated lightweight aggregate concrete (LWA) (wet) results in severe internal cracking in both scaling and cracking tests after very few cycles, and surface scaling is found to be only little higher in LWA wet than in LWA dry.