Effects of fibers on mechanical properties and freeze-thaw resistance of phosphogypsum-slag based cementitious materials

Cementitious materials made primarily with phosphogypsum (PG) and ground-granulated blast-furnace slag (GGBFS, or slag) are studied. Mineral, glass and polypropene (PP) fibers with various dosages are incorporated into this PG-slag (PGS) system. The anti-impact work, flexural strength, and freeze-thaw (F-T) resistance of these fiber-reinforced PGS mixes are evaluated, and the microstructures of these fiber-reinforced PGS mixes are also examined. The results show that addition of any of these fibers can significantly increase the flexural strength, anti-impact work, water resistance, and freezing-thawing resistance of PGS. Among the three fibers studied, the PP fiber is the easiest to disperse, and it also has a good bond with the PGS matrix. Addition of 1.35% (by volume) of the PP fiber has increased the flexural strength of the PGS twice and increased the anti-impact work up to 7 times. At the optimal fiber content, the PP fiber provides a better overall performance than mineral and glass fibers.