Novel application of sewage sludge ash for sustainable strain-hardening cementitious composites: Mechanical properties, microstructure and environmental impacts

Strain-hardening cementitious composites (SHCC) exhibit strain-hardening behavior and quasi-ductile tensile characteristics, making them promising materials for construction applications.. However, high cement dosage in SHCC leads to high carbon emissions, inhibiting its further development. This study developed a novel low-carbon and high-strength SHCC by substitution of cement clinker with sewage sludge ash (SSA) and limestone. The hydration kinetics , phase assemblage, microstructure, mechanical properties and environmental impacts of the developed limestone sewage sludge ash cement (LS 2 C) based SHCC were comprehensively determined. The findings revealed that the LS 2 C substitution promoted the hydration of SHCC due to the internal curing effect of SSA, reducing the porosity of the matrix and thereby increasing its compressive strength . In addition, LS 2 C-based SHCC demonstrated a significant multi-fissure cracking phenomenon and exhibited a high tensile strain exceeding 7 %. Furthermore, the LS 2 C substitution reduced the inherent material energy and costs, resulting in a reduction of more than 25 % in carbon emissions compared to OPC binders . This research presents a promising avenue for addressing both the pressing issue of SSA disposal and the promotion of sustainable construction practices. • LS 2 C-based SHCC achieves over 25 % carbon emission reduction compared to OPC binders. • Novel LS 2 C enhances SHCC hydration, reducing porosity and improving compressive strength . • LS 2 C-based SHCC shows high tensile strain (7 %) with significant multi-fissure cracking behavior.