Investigation of the effect of nano-silica deposition on cellulose fibers , the mechanical properties of autoclaved cement composites in industrial scale

In this study, the surface modification of cellulose fibers and its effect on the mechanical properties of fiber-cement composite was evaluated. The fiber modification was conducted through deposition of nano-silica at two levels 3 and 5 wt % (based on dry weight of cement) on the surface. The fibers and composites were characterized by emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectrum (EDS), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Also, mechanical in wet and dry state of cement fiber composites was investigated. FE-SEM and EDS analysis of the modified fibers showed that the nano-silica deposited on the fiber surface, as observed by the increase of the Si peak in the EDS measurement, which proved the effective modification of cellulose fibers with well dispersed nano-silica on the fiber surface. The reaction of the hydroxyl groups of the cellulose fibers and chemical bonding between cellulose and silica was formed after superficial modification examined by FT-IR analysis. The crystallinity index of the fibers was reduced 15%. The mechanical results showed that the presence of nano-silica treated fibers in the matrix increased the modulus of rupture (MOR) in wet and dry states.