Mechanical properties of alkali-activated ladle slag reinforced by polypropylene fibers

This experimental investigation deals with the effects of short polypropylene fibers (PP) on the mechanical properties of alkali-activated ladle slag (AALS). Borax was employed as retardant (0.2% wt. binder) to delay the rapid setting of AALS. The mechanical properties of multifilament fiber-reinforced mortar (2% v/v fiber addition) were compared to the plain unreinforced material considering flexural, compressive and tensile properties, as well as the fracture toughness. The PP reinforcement led to important improvement in the mechanical performance. Fracture energy and fracture toughness of the reinforced AALS were approximately 90 and 2.5 times higher, respectively, compared to the plain material. Furthermore, the flexural strength of the composite increased by roughly 300% while compressive strength was not affected. Additionally, the fibrous reinforcement changed the flexural post-peak behavior of AALS composite with an extended ‘softening’ behavior.