The effect of specimen size and the number of exposed surfaces on the drying shrinkage of concrete

Recently, unexpected deformations have been reported in concrete structures due to shrinkage and creep. These deformations have been attributed to non-uniform moisture conditions within the cross-section. Although current design specifications account for drying shrinkage using uniform coefficients, they do not reflect internal moisture variations. To address this limitation, this study experimentally investigates drying shrinkage behavior. Mortar specimens of two sizes were prepared, with four surfaces of each specimen sealed to simulate non-uniform moisture conditions. A specimen with two surface seals was also prepared for comparison. All specimens were placed in a controlled environment, and axial strains at both the surface and interior were measured. The results revealed differences in strain depending on measurement position, confirming that non-uniform shrinkage developed within a single cross-section.