Efficient utilization of waste marine clay for fine aggregate to develop sustainable and cost-effective strain-hardening cement-based composites

The prevalent overreliance on silica sand within strain-hardening cement-based composites (SHCC) underscores the urgency to address the depletion of natural resource. To address this concern, a novel approach involving the utilization of waste marine clay (WMC), an underutilized construction waste residue, is explored. This study marks the first application of high-volume calcined WMC as a substitute for silica sand within sustainable and cost-effective strain-hardening cement-based composites (SC-SHCC). The investigation encompasses a comprehensive analysis of SC-SHCC, covering mechanical properties, hydration, shrinkage, and cost. The results showed that the integration of calcined WMC instead of silica sand had noticeable improvements in the mechanical properties of SC-SHCC due to the notable pozzolanic activity and filling effect of calcined WMC. The developed SC-SHCC replacing two-thirds of the silica sand with calcined WMC exhibited a compressive strength of 76.34 MPa, a tensile strength of 14.63 MPa, and a tensile strain capacity of 5.99%, which successfully pushed the performance of conventional SHCC. Key indicators such as compressive strength, flexural strength, and tensile strength exhibited promising enhancements as calcined WMC dosage increased. The incorporation of calcined WMC contributed to heightened ettringite formation, thereby improving the tensile strength, and tensile strain energy of SC-SHCC. Besides, SC-SHCC exhibited pronounced drying shrinkage, primarily attributable to the free water evaporation and capillary pore development associated with calcined WMC. Furthermore, substituting calcined WMC for silica sand led to reducing the costs within SC-SHCC production. Therefore, the findings of this study hold promise for advancing the field of SHCC while promoting the environmentally friendly utilization of waste materials.