Combination of Structural Monitoring and Laboratory Tests for Assessment of Alkali-Aggregate Reaction Swelling: Application to Gate Structure Dam

Since 1964, the Temple-sur-Lot Dam, built in southwest France in 1948, has been subject to continuous alkali-aggregate reaction (AAR)-induced displacements despite low and relatively constant alkali content in the concrete and nonsignificant residual swelling test results. It has been assumed that a substitution process between alkali and calcium in the alkali-aggregate reactive gel could explain this long-term behavior As the calcium substitution phenomenon is very slow, it cannot be detected using a conventional residual swelling test, so an original method to assess the AAR kinetics and the residual swelling capability is proposed. This method first involved a laboratory test dealing with the silica consumption kinetics and, second, a numerical finite element inverse analysis of the dam, which included the consumption kinetics measured in the laboratory. The final swelling amplitude was thus fitted from only one observed structural displacement rate at a given period The model prediction capability was validated through the comparison between the displacement of instrumented points predicted by the calculations (not used for the fitting) and the variations measured on the dam. Finally, calculations were performed to predict the future displacements and damage fields of the dam.