Mechanical and environmental performance of high-strength strain-hardening cementitious composites with high-dosage ternary supplementary cementitious materials: Fly ash, limestone, and calcined clay

Abstract

Strain-Hardening/Engineered Cementitious Composites (SHCC/ECC) are emerging as cementitious composites with high deformation capacity and excellent crack control ability. However, the high cement dosage (typically 1000–1500 kg/m3) in conventional high-strength SHCC leads to high environmental impacts, while using high-dosage conventional supplementary cementitious materials (SCM) to replace cement typically leads to low strength. This study aims to solve this conflict by using ternary SCM to develop high-strength SHCC with satisfactory mechanical properties and environmental performance. High dosages of ternary SCM (50–80 % by weight of binder) were explored, with 10–70 % fly ash and 0–40 % limestone calcined clay (LCC). Test results showed that with 30 % Portland cement, 50 % fly ash, and 20 % LCC, SHCC achieved compressive strength of 96.89 MPa, tensile strength of 11.24 MPa, ultimate tensile strain of 6.71 %, and average crack width of 78 µm. Additionally, the embodied carbon and energy per unit tensile strength of the developed SHCC is much lower than that of conventional SHCC. To assess the overall performance of SHCC for sustainable construction, seven key performance indices were comprehensively compared, encompassing mechanical properties, environmental impact and economic viability. This new version of sustainable high-strength SHCC holds great potential for reducing carbon footprint in various practical applications.