Strength and fracture properties of coral concrete under impact of coral aggregate type and fiber hybridization

Seawater coral aggregate concrete (SCAC) has demonstrated advantages in reducing material cost and energy consumption of marine infrastructure on reefs and islands. However, SCAC exhibits increased brittleness and higher dependency on coral aggregate type as its strength increases. In this study, two types of coral aggregates are used to compare their influence on SCAC performance. Flexible fiber and rigid fiber are blended to improve the strength, toughness, and fracture properties of SCAC. The results show that the compressive strength of SCAC incorporating low-strength coral aggregate is reduced by 30.8% when comparing to that containing high-strength coral aggregate (from 55.6 to 38.5 MPa). Fiber incorporation could mitigate the strength reduction that originated from weaker coral aggregates. A novel constitutive model is proposed to describe the stress-deformation curves of SCAC. Good agreement between the model prediction and test data is observed. Relative to reference group, the fracture energies of SCAC adding 0.1%, 0.2%, and 0.3% polyvinyl alcohol fibers are increased by 10%, 49%, and 88% respectively. The fracture energies of hybrid fiber groups are 46% higher than that of mono fiber groups with the same fiber dosage.