Are large volume concrete members more or less susceptible to thermal cracking compared to small volume members?

In the context of concrete structures, large volume members are actually more susceptible to thermal cracking than smaller volume members. This increased susceptibility is primarily due to the factors associated with mass concrete. Large volumes of concrete generate a significant amount of heat during the curing process due to hydration, and as the concrete cures, it can experience temperature differentials between the interior and exterior.

The larger the volume, the greater the potential for temperature gradients. When the surface cools and the interior remains hot, the resulting stresses can lead to cracking. This phenomenon is exacerbated in large pours where the surface area to volume ratio is lower, allowing the internal temperature to rise significantly compared to the surface.

Additionally, the properties of concrete can further enhance this effect. Larger masses of concrete tend to retain heat longer, increasing the duration of the temperature differential and enhancing the potential for thermal cracking. In contrast, smaller volume members tend to cool more uniformly and have less drastic differences in temperature, leading to a lower risk of cracking. This understanding emphasizes the importance of thermal control measures in large pours to minimize the risks associated with thermal cracking.