Analysis of Freeze-Thaw Damage of Lightweight Aggregate Concrete

Since lightweight aggregate usually accounts for a higher percentage of the concrete by volume, the properties of lightweight aggregate can significantly influence the properties of the resulting concrete. In this study, we investigated the effects of the water content of lightweight coarse aggregate (LCA) on freeze-thaw resistance of lightweight aggregate concrete (LC) and analyzed how to control the fatal frost damage - cracks in LC. The results showed that the freeze-thaw resistance of LC was determined by the water content of LCA. It is clear that lowering the water content of LCA below 17% is the key method to secure the freeze-thaw resistance of LC. The study showed that the higher the water content of LCA, the higher the weight loss and the larger pore volume of LCA, the bigger the length expansion and the lower the durability factors of LC after freezing and thawing. Internal cracks occurred only in the concrete specimens that contained LCAs with higher water content when subjected to freezing and thawing. Expansion pressure occurred easily in the higher water content LCAs and micro-cracks formed initially in the weak grains. Then micro-cracks enlarged and spread to the mortar as the number of freeze-thaw cycles increased. This process eventually caused LC expansion and damage.