Use of nano-SiO2 to develop a high performance green lightweight engineered cementitious composites containing fly ash cenospheres

Abstract

To further improve the utilization rate of fly ash cenospheres (FAC) in cement-based systems, this paper introduced adopting nano-SiO2 (NS) particles to develop a new high performance green lightweight engineered cementitious composites (HPGLW-ECC) incorporating FAC. The effects of NS at different dosages (0%, 1%, 2%, 3% and 4% by cement weight) on the mechanical properties and microstructure of lightweight ECC (LW-ECC) were investigated. High performance of NS treated LW-ECC was observed, e.g., the compressive strength, tensile stress and strain capacity at 28 d reached 56 MPa, 8 MPa and 10%, respectively. To understand the reaction mechanism, the thermal gravimetric analysis (TGA) and X-ray diffraction (XRD) analysis were conducted. Besides, the mercury intrusion porosimetry (MIP) analysis indicated that the NS particle effectively restrained the porosity and further refined the pore structure in LW-ECC mortar. The morphology observed by a scanning electronic microscope (SEM) uncovered that NS made the matrix denser and improved the interface transition zone (ITZ) between the FAC and the mortar.