The mechanical strength of sulphoaluminate cement-gypsum composite material reinforced with polypropylene fibers synergistically modified by KH570 and nano-SiO2

The polypropylene (PP) fibers were modified by silane coupling agent (KH570) or synergistically modified by KH570 and nano-SiO2 in this paper. The modification effect of PP fibers was evaluated by SEM and FTIR. The reinforcing effect of PP fibers and the modified PP fibers on sulphoaluminate cement-gypsum composites (SGC) was investigated. The results show that KH570 can undergo an autohydrolysis reaction and wrap on the surface of the PP fibers, which makes the hydrophilicity of PP fibers improved. Nano-SiO2 can further improve the hydrophilicity and roughness of the PP fiber surface by polycondensation reaction with KH570. KH570 and nano-SiO2 synergistically modified PP (KH570-SiO2-PP) fibers obviously increase the compressive strength and flexural strength of the hardened SGC compared with PP fibers or KH570 modified PP (KH570-PP) fibers. The SEM images show that PP-KH570-SiO2 fibers have better adhesion with the matrix than PP fibers and KH570- PP fibers.