Influences of surface-area-to-volume ratio on the early-age thermal cracking characteristics of mass concrete, with a special focus on the foundation continuously poured by two different heat generation mixes

This study investigates the influence of structural geometry, represented by the surface-area-to-volume (A/V) ratio, on the early-age thermal cracking behavior of mass concrete foundations cast continuously using two distinct heat-generation mixtures. An extensive numerical investigation was conducted on three structural geometry groups, each analyzed under six different A/V ratios. The relationships between the A/V ratio and three key indicators of thermal cracking risk, including the peak temperature, maximum temperature differential, and minimum thermal cracking index, were systematically evaluated. The results demonstrate that thermal cracking behavior of mass concrete depends primarily on the A/V ratio rather than specific structural geometry. A decrease in the A/V ratio leads to higher peak temperatures and larger maximum temperature differentials, while reducing the minimum thermal cracking index, thereby indicating an increased risk of thermal cracking in larger structures. Moreover, structures with smaller A/V ratios require longer times to reach peak temperature conditions and maintain elevated temperatures and gradients for extended periods, indicating the need for delayed removal of formwork and insulation to avoid thermal shock. Strong geometry-independent linear relationships between the A/V ratio and all three thermal cracking indicators highlight the feasibility of using smaller-scale models with equivalent A/V ratios to assess cracking risks in larger structures.