To promote the use of unconventional coarse aggregates in cementitious materials, the authors carried out experiments on concrete mixtures containing 100% unconventional aggregates, either industrial byproducts (sintered fly ash, crumb rubber and copper slag) or C&D waste (blue brick), as replacements for normal coarse aggregates in concrete and, to determine the mechanical performance and non destructive properties of concrete containing these aggregates. In addition, the micro-mechanical damage behaviour of the prepared mixtures under drop-weight impact loading were quantitatively analyzed using the X-ray computed tomography coupled with digital image analysis based on the changes in the air void distributions before and after the loading. It was proven that one effect of the aggregate on the resulting damage after impact loading is seen in the change in the porosity which is manifested in the level of pore connectivity from a micro-structure point of view. It was also concluded that the hydrophobic nature, softness, porosity and rigidity of the unconventional aggregates are of paramount importance for the performance and design of concrete with these aggregates. (C) 2018 Elsevier Ltd. All rights reserved.