Mechanical performances, chloride permeability, and microstructure of wollastonite microfiber reinforced cement-based composite incorporated with zeolite powder

Abstract

Wollastonite microfiber (WM) with a unique fiber structure and zeolite powder (ZP) with a high pozzolanic effect can improve the performances of cement-based composite owing to the same calcium silicate system. This study aimed to analyze the effects of WM and ZP on the properties of cement-based composite by compressive test, flexural test, shear test, rapid chloride migration (RCM) test, fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), mercury intrusion porosimetery (MIP) and scanning electron microscopy (SEM). Results showed that utilizing WM and ZP was found to be beneficial for improving mechanical performances and impermeability. WM had a more significant effect on enhancing flexural and shear properties, which can be attributed to the fact that the WM as a fibrous structure could provide skeleton support and bridging crack resistance in the matrix, and an addition of 5% WM (by mass) in the matrix could increase the 60-day flexural strength, shear strength and tensile strength by 24%, 13% and 4%. Additionally, ZP had a more significant impact on improving the late compressive strength and chloride permeability because of the particle filling effect and pozzolanic effect. The pozzolanic ingredient (such as active SiO2 and Al2O3) in ZP can take secondary hydration reaction with Ca(OH)2 to produce C–S(A)-H, this can refine the pore size and reduce the porosity, especially for the large pore.