Analyses on the Scaling Effect of Cementitious Specimens Exposed to Internal Swelling Mechanisms

Laboratory studies on internal swelling reactions are typically conducted on small-size samples, and their results may not fully replicate the conditions experienced by massive concrete structures. This study revisits expansion data from two specimen groups exposed to aggregate-silica reaction and delayed ettringite formation. The groups include large mock-up blocks and core samples extracted from the blocks after around 200 days of exposure, with samples subjected to the same conservation conditions for each investigated mechanism. The study aims to (i) analyze the experimental expansion data of laboratory specimens and large mock-ups exposed to internal swelling mechanisms, (ii) correlate the behavior of real-scale massive structures with the residual expansion of core samples, and (iii) provide recommendations for predicting the long-term expansion of massive concrete structures based on residual strain analysis. Possible explanations for the inconsistent expansion at various scales are mentioned, considering differences in moisture degree, leaching degree of alkalis/calcium, temperature gradient, the occurrence of microcracks due to the high-speed action of the drill, and the restraint from the end support. The main reason for the varied behavior across scales is believed to be the restraint effect induced by concrete self-weight and metal support. Calculations of swelling stress and expansion predictions are conducted in this study, incorporating the restraint effect into constitutive equations coupled with a damage model.