Mechanical and thermal properties of green lightweight engineered cementitious composites

This study reports the development of green lightweight engineered cementitious composites (GLECC) with high volume of industrial wastes. Three types of industrial wastes including iron ore tailings, fly ash, and fly ash cenosphere were used as aggregates, mineral admixture, and lightweight filler, respectively, in the production of GLECC. The influences of fly ash and fly ash cenosphere contents on the physical, mechanical, and thermal properties of GLECC mixtures were experimentally investigated. Fly ash cenosphere was most advantageous in reducing the density and thermal conductivity, while improving the tensile ductility of GLECC with only a slight reduction in compressive strength. The GLECC mixtures in this study exhibit density of 1649-1820 kg/m³, tensile strain capacity of 3.3-4.3%, tensile first cracking strength of 2.5-3.6 MPa, ultimate tensile strength of 4.8-5.9 MPa, and compressive strength of 25.0-47.6 MPa at 28 days, depending on the contents of iron ore tailings, fly ash, and fly ash cenosphere. The GLECC mixtures developed in this study utilize industrial wastes up to about 89% by volume of total solid matrix materials and weigh under 1850 kg/m³ (limit for lightweight concrete classification); yet their mechanical properties are similar to ultra-ductile ECC with added advantage of lower thermal conductivity for energy conservation when used as a building material.