Effect of seawater mixing on the properties of Island Reefs Ecological High Ductility Cementitious Composites: Tensile performance, microstructure, and carbon emissions
Yingjie Chu, Liping Guo, Jiayi Li, Xiang-Peng Fei, Jie Lu, Guo-Tai Zhao
Abstract
This paper presents the first preparation of a low-carbon, low-cost Island Reefs Ecological High Ductility Cementitious Composites (IRE-HDCC) with high proportions of waste coral micropowder, coral sand, and seawater . Seawater mixing was found to enhance the hydration process of IRE-HDCC, resulting in an excessive increase in crack tip toughness (J tip ), a significant reduction in the strain-hardening energy index (PSH energy ), and a decrease in the ultimate tensile strain . However, the negative effect of seawater on fiber-bridging stress was mitigated by partially replacing cement with waste coral micropowder. When more than 20 % of the cement was replaced with waste coral micropowder, the dilution effect on hydration became dominant, promoting beneficial defects in the matrix. This led to an increase in the strain-hardening strength index (PSH strength ) and improved the composite’s ultimate tensile strain . At 40 % cement replacement with waste coral micropowder and seawater mixing, the SW40 group achieved a compressive strength of 123.7 MPa, a tensile elongation of 9.0 %, and an average crack width of 81 μm. Additionally, compared with the Control group, the SW40 group presented significant environmental and economic advantages, including a 43 % reduction in energy consumption, a 48.1 % decrease in embodied carbon , a 39 % reduction in material costs, and a 60 % reduction in transportation costs. These findings highlight the potential of IRE-HDCC for sustainable engineering applications .