Effects of hybrid fibers on properties of desulfurized gypsum-based composite cementitious materials

Basalt fiber (BF) and polyvinyl alcohol fiber (PVAF) were mixed into desulfurized gypsum-based composite cementitious material (DGCCM) by an orthogonal test to prepare hybrid fiber-reinforced DGCCM, whose mechanical properties, water resistance, and durability were studied using visual, range, variance, and microstructure analyses. The results show that combining the two fibers improved the mechanical properties, water resistance, and durability of DGCCM. In terms of mechanical properties, the maximum absolute dry flexural strength and compressive strength increased by 70.05% and 64.52%, respectively, compared with the blank group. PVAF played a better role than BF in crack resistance and toughening, hence contributing more. When the content of PVFA and BF increased to 0.5% and 0.75%, respectively, the water resistance of hybrid fiber-reinforced DGCCM was better. The enhancement showed that BF had a more significant effect on the softening coefficient of DGCCM than PVAF. The incorporation of fibers inhibits the generation of a large number of cracks during the dry-wet and freeze–thaw cycles of DGCCM, which greatly improves its durability. When the content of PVAF and BF were both increased to 0.5%, the durability of hybrid fiber-reinforced DGCCM was better.