Assessing alkali-silica reaction damage to concrete with non-destructive methods: From the lab to the field

The effectiveness of any non-destructive (ND) procedure for evaluating the damage to concrete depends on the relation between physical and mechanical properties. With this attempt, this paper deals with the application of three ND methods (ultrasonic wave velocities, dynamic Young modulus measured with resonant frequency and electrical resistivity) for the evaluation of concrete cores drilled from a large hydraulic structure affected by alkali-silica reaction (ASR). In parallel, the concrete was tested for its mechanical properties and petrographic examinations were also performed. ND results were compared with those obtained from concrete specimens made in the lab and showing various levels of deterioration associated with ASR.Results from all methods (except electrical resistivity) showed that the overall condition of the concrete remains of good quality, in spite of the significant expansion rates measured on the structure. On the one hand, damage is mainly located within the first two meters from the surface. On the other hand, concrete deterioration at the bottom of the structure was very low.The electrical resistivity did not appear to be appropriate for evaluating the damage level related to ASR. Dynamic Young modulus and ultrasonic pulse velocity yielded better results. The best correlation was obtained between the P-wave velocities and the static Young modulus. This study emphasizes that laboratory results cannot be directly extrapolated to field results.