Wet swelling effect on crack performance of facing concrete for rockfill dams

Abstract

The swelling of aged concrete is a significant issue in the operation of dams such as concrete-faced rockfill dams (CFRDs). Swelling of concrete is one cause of tensile stress, which is typically related to water movement in concrete pores, especially around the water surface. In this study, the change in the interior relative humidity and deformation in aged concrete specimens around the surface of the water were measured. The experimental results revealed that the swelling of the concrete above the water surface was correlated with an increase in interior relative humidity due to water diffusion, while the swelling of the concrete submerged in the water developed in early and late stages and was dominated by capillary absorption and diffusion. A new theoretical swelling model was developed to predict the deformation development, and the theoretical predictions were validated by the experimental data. The swelling model was applied in a finite-element analysis of a CFRD to obtain more realistic stress distributions. The analysis indicated that the wet swelling of concrete had a significant impact on the increase in tensile stress distribution in the concrete slab around the water surface.