Enhancing the properties of coral aggregates through integrated modification techniques: Mechanisms and applications

The transportation of natural aggregates to remote islands incurs substantial logistical costs, driving increased utilization of locally available coral aggregates (CA) in marine construction. However, CA application in coral aggregate concrete (CAC) remains constrained by the material's inherent limitations, including low mechanical strength, high porosity, and elevated salt content. While existing studies predominantly focus on singular modification strategies, understanding the synergistic mechanisms of combined modification techniques remains insufficient. This research systematically examines five modification methods, specifically contrasting individual treatments with composite approaches. Results demonstrate that, the composite technique integrating cement paste coating and corrosion inhibitor (CI) immersion (C-CI) yielded the most pronounced improvements: cylinder compressive strength surged by 91.9 %, and the crushing index decreased by 19.2 % compared to untreated CA. Additionally, the use of this method resulted in a 31.0 % increase in the compressive strength of CAC. These improvements stem from synergistic pore-filling, chloride adsorption, and enhanced bonding at the interfacial transition zone (ITZ) between CA and cement matrix. The research establishes a methodology for optimizing CAC in marine engineering through integrated modification approaches that address CA's intrinsic deficiencies.