Sustainable lightweight engineered cementitious composites using limestone calcined clay cement (LC3)

Abstract

Engineered cementitious composites (ECC) have superior ductility and durability. The intensive use of ordinary Portland cement (OPC) in ECC, however, yields significant burdens on eco-system. To reduce the cement usage and improve the environmental performance of ECC, this study proposes to replace OPC and silica sand with limestone calcined clay cement (LC3) and fly ash cenosphere (FAC) to produce sustainable lightweight engineered cementitious composites (LW-ECC). The effect due to the weight fraction of LC3 (0%, 35%, 50%, and 65%) on the mechanical properties and microstructure of LC3-based LW-ECC were investigated. To understand the synergistic reaction mechanism, the thermal gravimetric analysis (TGA), mercury intrusion porosimeter (MIP), environmental scanning electronic microscope (SEM) and X-ray diffraction (XRD) analysis were conducted. Replacing OPC with LC3 slightly decreased compressive and tensile strength, and increased ductility. The high reactivity of LC3 decreased porosity and pore size. Life cycle assessment (LCA) was conducted to investigate the environmental performance. LC3-based LW-ECC achieved substantially lower environmental impacts than conventional ECC due to the replacement of cement with LC3. Though having negligible weight fraction, PE fiber and plasticizer dominated environmental impact in certain aspects.