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.