Role of heterogeneities on local stresses and strains in concrete using x-ray computed tomography imaging, 3D x-ray diffraction measurements and mesoscale simulations

The mechanics of concrete can be understood comprehensively only if its heterogeneous microstructure is considered in experiments and simulations. The influence of heterogeneities on local stress and strain fields remains under-explored with no experimental validation. We combine mesoscale modeling, in-situ X-ray computed tomography imaging, digital volume correlation and in-situ 3D X-ray diffraction measurements for one of the first times to investigate the role of heterogeneities on macroscopic and microscopic responses in concrete. The focus of this talk is on heterogeneities at the micron scale: aggregates, cement paste, interfacial transition zone, high-density phases, and voids. We specifically seek to answer whether all levels of heterogeneities are essential in predicting: (a) elastic macroscopic stress-strain response, (b) microscopic elastic stress-strain localizations, and (c) representative volume element size for elastic responses. The results demonstrate significant influence of heterogeneities on local strains in matrix phases and minimal influence of heterogeneities on stresses in individual grains.