Mechanical properties of modified coral aggregate seawater sea-sand concrete: Experimental study and constitutive model

The use of corals, seawater, and sea-sand to prepare concrete can effectively solve the problem of raw material transportation in constructing remote sea islands and reefs. Corals have the disadvantages of high porosity, high water absorption, and low crushing strength, which adversely affect the performance of concrete. In this study, corals were modified by a superfine cement paste, and the modified coral aggregate seawater sea-sand concrete was prepared by replacing gravel aggregates proportionally with modified coral aggregates. The cubic compressive, splitting tensile, flexural, and axial compressive properties of modified coral aggregate seawater sea-sand concrete with five aggregate replacement ratios were studied. The results showed that the coral aggregate was divided into two parts after the concrete failed. The higher the replacement ratio of the aggregates, the smoother the splitting failure surface of the concrete. The modification measures could not significantly improve the compressive and tensile strengths of coral aggregate concrete, and the increasing rate was less than 10%. The compressive strength of concrete using modified coral aggregates was approximately 30% lower than that of concrete using gravel. Based on the experimental results, a prediction model, which can simulate the compressive stress-strain relationship of coral aggregate concrete under different replacement ratios, was proposed.