Effect of alkali-silica reaction on the fracture properties of confined concrete

•Confined alkali-silica reaction (ASR) generates anisotropic expansion.•Angle between ASR crack orientation and splitting force affects fracture properties.•ASR cracks oriented parallel to splitting force increase fracture energy.•ASR cracks oriented perpendicular to splitting force decrease fracture properties. Alkali-silica reaction (ASR), which was recently discovered in nuclear power plant structures commonly without shear reinforcement, has previously been shown to induce anisotropic expansion in confined concrete. The fracture properties (strength, stiffness, and specific fracture energy) of ASR-induced anisotropically-damaged concrete specimens were quantified by varying both the damage level and relative direction of the ASR-induced cracking orientation against the loading direction corresponding to the fracture propagation. The effect of different orientations (0, 45, and 90° relative to the notch of the specimen) of expected ASR-induced cracks on the fracture properties was investigated using a wedge-splitting test (WST). Specimens without ASR expansion generally showed the highest fracture properties; however, the specific fracture energy was highest for ASR-affected specimens in which the expected orientation of ASR-induced cracks was perpendicular to the WST specimen notch. Specimens in which the ASR-induced cracks were parallel to the notch exhibited the lowest strength and fracture energy.