Fragmentation modes of single coral particles under uniaxial compression: Microstructural insights

Abstract

Coral soils are being used increasingly as construction and building materials in ocean engineering. Because of their biological origins, coral soils have unique properties compared to rock and silica sands with physical or chemical origins. One of the most important properties of coral soils is particle breakage. The particle breakage behavior of coral soil exerts significant control over its mechanical properties including strength, stiffness, and hydraulic features, but despite extensive studies into coral particle breakage, the relationship between fragmentation mode and coral microstructure remains to be revealed. This paper reports uniaxial compression tests on single coral particles with various microstructural characteristics. How mineralogy, chemical composition, coral particle shape and size, water content, and loading rate affect coral particle breakage behavior is discussed. The test results reveal that the fragmentation mode of coral is controlled predominantly by the coral microstructure, with particle irregularity also playing a role. While underwater immersion does not alter the corresponding fragmentation mode of coral particles, it dramatically reduces the particle crushing strength and leads to a higher degree of particle breakage. An fragmentation mode classification system that considers the force–displacement responses, particle fragmentation features, and coral microstructural properties is proposed. The classification applies to not only coral particles but also other granular materials. This paper improves the understanding of the particle crushing mechanism of coral soils.