Boundary Effects Considerations for Concrete Hydraulic Facilities Affected by Alkali-Silica Reaction

The influence of boundary effects on the experimental results of concrete specimens is a phenomenon known for several decades. They are believed to be the main cause of size effects affecting physico-chemical concrete parameters assessed in the laboratory. For the specific context of hydraulic structures affected by ASR, they have a considerable impact on the predictions of numerical multi-physical simulations. This work highlights and quantifies the chemical and mechanical boundary effects that have arisen during a large experimental program to characterize the mechanical properties and ASR kinetics of a reactive mass concrete mixture used in the construction of an existing hydro-electric facility (maximum aggregate size of 76 mm). The focus is made on the fracture energy and the ASR free expansion curve, two important parameters for constitutive macro chemo-mechanical concrete models. Influence of specimen free boundary effects is highlighted on both parameters using a chemical-mechanical analogy. Also, the laser-induced breakdown spectroscopy (LIBS) with fast high-resolution scan technology is explored for the context of concrete samples affected by ASR. LIBS was found in this work in-progress study, as an interesting quantitative tool to characterize the chemical size effects.