Functionalized PP fiber to improve compressive strength and solidification/stabilization performance of cement with heavy metals

To deal with the increasing amount of hazardous solid wastes, a functionalized PP (AM-PP) fiber was prepared and used with cement to solidify these wastes. PP fiber was firstly functionalized with amine groups and then characterized by SEM, FT-IR and XPS analyses. Mechanical property tests indicated that, compared with unmodified PP, AM-PP exhibited lower breaking strength while possessed a higher elongation at break no matter in dry or wet state, as the modification imparted AM-PP lower crystallinity and more amorphous phase. Compressive strength of cement samples containing heavy metals was evidently improved when AM-PP was added, which was owing to the adsorption and bonding of metal ions onto AM-PP and thus reduced the adverse effect of heavy metals on cement hydration. Hydration heat and thermogravimetry analyses also confirmed more hydration products were generated when AM-PP was added, especially in early age. Leaching test showed the amount of Cu²⁺, Zn²⁺ and Pb²⁺ leached from cement samples with heavy metals and AM-PP added was much lower than that from samples without AM-PP. Therefore, the prepared AM-PP fiber could effectively contribute to waste reutilization and environmental sustainability.