The Synergistic Effect of Surface Coating SCA/SiO2 NPs on the Degradation Resistance and Interfacial Bond of Sisal Fibers in Cementitious Composites

The primary concern for natural fiber reinforced cementitious composites (NFRCC) is fiber degradation and weak fiber-matrix interface. This paper presents the effects of surface coating of silane coupling agent and SiO2 nano-particles (SCA/SiO2 NPs) on enhancing the degradation resistance and interfacial bond of sisal fibers in NFRCC. SCA/SiO2 NPs were coated on the surface of sisal fibers via dip-coating method and the dispersibility, morphology and stability of the coating were characterized microscopically. The influence of SCA/SiO2 NPs on the wetting ability, water absorption capacity, and resistance to Ca2+ ingress of the sisal fibers is characterized quantitatively. The degradation resistance of the sisal fibers in NFRCC was studied by testing the residual tensile strength of the embedded fiber after aging cycles. The fiber-matrix interfacial bond strength was obtained by the modified pull-out method. The results show that the combined coating of hydrophobic SCA with pozzolanic SiO2 NPs can generate synergistic effects that significantly improve the degradation resistance and the interfacial bond property of sisal fibers in NFRCC.