Concrete Expansion Induced by Alkali-Silica Reaction in a Small Arch Dam

摘要

Alkali-aggregate reaction in concrete structures consists of a chemically deleterious reaction between alkalis liberated during the cement hydration and reactive minerals present in the aggregates like silica, silicate or carbonate. The process leads to the formation of a gel, which expands in the presence of hydroxyl ions, causing cracks and volumetric variation in the concrete. In this study, we employ a chemo-mechanical parametric model for long-term simulation of orthotropic concrete expansion caused by alkali-silica reaction, considering the influence of the stress state on the expansion. The model relies on an equation that represents the basic characteristics of an alkali-silica reaction (ASR) expansion. An optimization process is employed to adjust the numerical results to the field measurements. The orthotropic concrete expansion due to ASR in the three principal directions are taken independently of each other, as a simplifying assumption, but still leading to reasonable results for evaluating orthotropic concrete swelling. This is accomplished in a validation example and in a rather complex dam structure, which presents ASR for over 50 years.