Effect of Curing and Type of Cement on the Resistance of Concrete to Freezing in Deicing Salt Solutions

Experimental studies on the resistance of concretes to freezing and thawing in a saturated sodium chloride solution are described. The concretes were made of various types of cement differing in content of blast furnace slag. They were cured in water for 1 to 48 days and subsequently stored in air with and without carbon dioxide. Also the effect of curing, carbonation and type of cement on the structure of hydrated cement pastes was studied by mercury intrusion porosimetry. The results indicated that for air-entrained portland cement concretes a comparatively short curing period is sufficient to obtain high durability. Prolonged storage in water may reduce durability. Carbonation may have a positive effect. For concretes made of blast furnace slag cements the required curing time increases with increasing slag content. For cements with a high slag content air-entrainment did not result in improved resistance to freezing and thawing, and carbonation substantially reduced it. The observed behavior of concrete specimens can be interpreted in terms of microstructural changes of the hydrated cement pastes. (Author/TRRL)