Use of nano-SiO2 to develop a high performance green lightweight engineered cementitious composites containing fly ash cenospheres
Bin Xi, Yingwu Zhou, Kequan Yu, Biao Hu, Xiaoxu Huang, Lili Sui, Feng Xing
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.