Testing specimen effect on shrinkage of lightweight concrete

The shape and size of the testing specimen influence the measured shrinkage strain of concrete at different ages. This study compares the shrinkage strain of lightweight concrete containing treated expanded polystyrene beads measured by prism (285 × 75 × 75 mm) and cylindrical (150 × 300 mm) specimens for 225 d after 7 and 14 d of moist-curing, respectively. The shape of the specimen had a distinct effect on the shrinkage, especially immediately before and after the age of 60 d. The increasing trend of the shrinkage strain in the prism and cylinder specimens was different. Considering the specimen shape, a relationship is proposed and verified by the existing models and experimental data to predict the shrinkage strain of lightweight concrete.