Mechanical and microstructural properties of cement pastes with rice husk ash coated with carbon nanofibers using a natural polymer binder

This study investigated a new approach to dispersion of carbon nanofibers (CNFs) in cement paste by coating rice husk ash (RHA) particles using a natural polymer binder. Light Chitosan with low molecular weight was used to provide bonding between CNFs and SiO2 from the RHA substrate. Mechanical properties namely, compressive strength and flexural properties of paste specimens were assessed to evaluate the efficiency of the applied method. Microstructural analysis was carried out using FTIR, XRD, TGA, and SEM to investigate the effects of the coating process on the hydration products and to explain the mechanical properties of specimens with the modified RHA. The results showed that 15% and 5% modified RHA increased the compressive strength and flexural strength of paste specimens at 28 days by 53% and 187%, respectively. Microstructural analysis showed that the coating process delayed the hydration, however, the physical crosslinking effect of carbon nanofibers enhanced the mechanical properties at all ages.