Mesoscopic investigation of the matrix pores and ITZ effects on the mechanical properties of seawater sea-sand coral aggregate concrete

Abstract

In this study, the matrix pores and ITZ effects on the mechanical properties of seawater sea-sand coral aggregate concrete (SSCAC) were investigated via the meso-element equivalent method. The effective modulus and strength of aggregate and matrix in SSCAC at different scale level were derived via the Voigt model and Mori-Tanaka method. A three-step equivalence process was established to consider the influence of the matrix pores. The surface permeability zone for coral aggregate was proposed to explain the strength enhanced effect of the interface transition zone (ITZ) in SSCAC. A comparisons study was carried out to analyze the difference between SSCAC and ordinary Portland concrete about the stress-strain relationships, failure patterns, and failure mechanisms. Finally, the impact of porosity variations on the mechanical properties development of SSCAC have been investigated, which indicate that the compressive and splitting tensile strengths of SSCAC present distinct three-stage variations with respect to porosity. A sensitive range of ITZ effect was proposed to reveal that as porosity within 7%–18%, the variation of porosity can influence the ratio of splitting tensile strength to compressive strength of SSCAC remarkably. To ensure optimal performance in both splitting tensile strength and compressive strength, it is recommended to maintain the porosity of SSCAC within the range of 5%–10%.