On the role of porous aggregates in the fracture mechanisms of lightweight concrete using XCT and Machine Learning

Abstract Replacing limestone aggregates with lightweight ones, such as pumice, results in more sustainable concrete. However, cracking at early ages poses a significant concern for its structural use. In this work, we use X-ray computed tomography to study cylindrical lightweight concrete specimens before and after uniaxial compression to enhance our understanding of how pumice affects the development of tension cracks in the concrete matrix. The results show smaller particles and those with a higher aspect ratio break less. Whilst there’s no proof that the orientation of the particles affects breakage, there are indications that the internal porosity of the particles is highly anisotropic, and its orientation with respect to the loading direction will determine whether the pumice will break or not.