Mesoscopic characteristics and macroscopic mechanical properties of coral aggregates.

• Coral aggregates sampled from different positions of coral cluster. • Morphology and pore characteristics of coral aggregates. • Quasi-static compressive behaviors of coral aggregates. • X-CT tests for mesoscopic characteristics of coral aggregates. • 3D mesoscale modelling of coral aggregate samples based on X-CT image data. Coral aggregate is a type of porous and light-weight construction material with intense prospects for the engineering applications in remote ocean islands. However, its macroscopic properties is directly determined by the mesoscopic characteristics, such as texture, porosity, etc. Thus, the mesoscopic characteristics and macroscopic properties of coral aggregates are investigated in the present work. Three types of coral aggregates sampled at different positions of coral clusters, such as the tip-, stem- and root segments, are selected for investigation. The zoom-stereo microscope and X-ray computed tomography (XCT) facility are used to conduct the morphology observations for coral aggregates. Afterwards, the pore information (i.e., size, number and connectivity) of different coral aggregates are tested and analyzed quantitatively according to the XCT scanning data. Besides, the uniaxial compressive properties of coral aggregates are studied using cylinder aggregate samples with dimension of φ10mm × 20 mm. The effect of porosity characteristic on the compressive strengths of coral aggregates is discussed comprehensively. Furthermore, based on the XCT scanning data, a series of algorithms are developed to establish the mesoscale models for different coral aggregate samples. Employing the established mesoscale models and the Mohr-Coulomb criterion, the uniaxial compressive tests of coral aggregates are simulated. Results indicate that there are high reliabilities for the developed mesoscale model and the determined material model parameters of different coral aggregates, providing further insights into the mechanical properties of coral aggregates. [ABSTRACT FROM AUTHOR]