The influence of high temperature on microstructural damage and residual properties of nano-silica-modified (NS-modified) self-consolidating engineering cementitious composites (SC-ECC) using response surface methodology (RSM)

In this study, nano-silica (NS) has been incorporated into self-consolidating engineered cementitious composites (SC-ECC) for improving materials utilization and performance. Accordingly, the experimental results of the influence of nano-silica (NS) and polyvinyl alcohol (PVA) fibre on the high temperature resistance and microstructure of NS-modified SC-ECC is reported. Standard ECC mix (ECC M45) was adopted to develop mix matrix of composites with PVA fibre at 0.5%, 1%, 1.5%, and 2%, while NS at 1%, 2%, 3%, and 4% with the aim of investigating the behaviour of the materials at high temperatures. The NS-modified SC-ECC specimens were considered at various high temperatures up to 400 °C for residual compressive strength assessment using response surface methodology (RSM). While the microstructure of the mix containing 2% each of NS and PVA fibre at a high temperature up to 400 °C were investigated for microstructural properties through mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM). The incorporation of NS and PVA fibre improved the performance of ECC due to the physiochemical effects and microcracks’ bridging ability of NS and PVA fibres, respectively, which was further confirmed by the microstructural studies. The developed prediction model using RSM shows a strong degree of correlation and predictability between the dependent (residual compressive strength) variable and the independent (NS, and PVA) variables after high temperatures exposure. The multi-objective optimization results revealed that the criteria settings at 2% each of NS and PVA fibre achieved a residual compressive strength of about 101 MPa while optimizing the high temperature resistance up to about 293 °C.