Study of bond between epoxy, steel reinforcing bars and concrete affected by alkali-silica reaction

Installation of drilled-in epoxy bonded reinforcing barsis generally an effective strengthening method for deficient concretestructures. However, this method of rehabilitation has largely been studied and tested on sound concrete elements, i.e. without any pathological damage, which raisesthe question of bond capabilities inexisting damaged elements. This investigation studies the influence of alkali-silica reaction (ASR) onthe capacity of epoxy bonded anchors. ASR, which is very common in eastern Canada, results from the chemical reaction between the alkali hydroxides in the concrete’s pore solution and some siliceous mineral phases inthe aggregates. Pull-out tests on epoxy bonded anchors havingembedded lengths offourtimes the bar diameter(Ø= 16 mm)have demonstrated a drop in bond strength when concrete is affected by ASR. In addition, the study revealed that the progression of concrete expansion due to ASR, leads to a confinement of the epoxy bonded anchor and increases the bond strength. These conclusions are therefore considered for the development of a model for the design of epoxy bonded anchors in existing concrete infrastructure affected by ASR