Elevating key performance of ecological high ductility cementitious composites by coral: The role of exclusive microstructure

The use of local materials is becoming more prominent in the construction of oceanic islands and reefs. In this study, for the first time, a coral-based ecological high ductility cementitious composite (CE-HDCC) was introduced and prepared from coral powder and coral sand. The unique microstructure of coral enabled its splitting along the aragonite fiber growth surface under tensile stress. This phenomenon reduced the crack tip toughness ( J tip ) without significantly affecting the material's strength and notably enhanced the ductility of the CE-HDCC. The ductility of the CE-HDCC was positively correlated with the dosage of coral powder. At a high substitution level of 40%, the tensile strain rate reached 8.1%, and the ultimate mid-span deflection was 26.5 mm, representing increases of 88.4% and 103.8%, respectively, with respect to the undoped group. When the average crack width was less than 100 μm, the absolute permeability of CE-HDCC following damage was significantly reduced. Additionally, the coupling of X-ray computed tomography (X-CT) and digital image correlation (DIC) was used to establish a quantitative relationship between the average crack width and spatial damage volume.