Influence of Air Content on the Behavior of RC Beams Subjected to Freezing and Thawing

Abstract Research on concrete durability during prolonged use has been ongoing due to concrete’s widespread use in construction. Freeze–thaw cycles exert a significant impact on concrete durability, especially in regions with harsh climates. While existing studies primarily focus on material aspects, research on the performance degradation of reinforced concrete (RC) structures is limited. This limitation is attributed to the inadequacy of current freeze–thaw testing standards for large structures like RC structures. Therefore, there is a need to propose freeze–thaw testing methods tailored for RC members. This study investigates the influence of air content and freeze–thaw cycles on the material and structural properties of RC beams, proposing a novel rapid freeze–thaw testing method for RC members. The study compares this new method (N test) with the conventional ASTM C666/C666M-15 rapid freeze–thaw testing procedure (A test), aiming to establish a correlation between the two experiments. Concrete mixtures with air content ranging from 0 to 9% underwent two types of freeze–thaw tests, followed by flexural testing of RC beams. The results were analyzed for air content, slump, compressive strength, mass loss, crack patterns, and failure modes, and they offer insights into the relationship between air entrainment, freeze–thaw resistance, and the structural behavior of RC under diverse environmental conditions.