Investigating the influence of PVA and PP fibers on the mechanical, durability, and microstructural properties of one-part alkali-activated mortar: An experimental study

Alkali-activated materials (AAMs) have gained significant attention in recent years due to their potential for sustainable construction and outstanding strength and durability characteristics. However, their wide application is constrained by their weak behavior under flexure and tensile loading, leading to brittleness. This study examines the formulation of an alkali-activated fiber-reinforced mortar, using fly ash and hydrated lime as main precursors, and investigates the capacity when reinforced with polyvinyl alcohol (PVA) and polypropylene (PP) fibers. The performance was measured through experimental investigation in terms of flowability, setting time, compressive strength (CS), water absorption, flexure strength (FS), and load-displacement curve under flexure loading. The durability was assessed through acid and sulfate attack tests after 120 days. The findings showed that adding both types of fibers improved the mechanical and durability performance of the one-part AAM. The highest CS of 44.95 MPa and 42.04 MPa and FS of 7.8 MPa and 6.9 MPa were achieved for PVA and PP fibers at a 1.5% fiber content. The FS was increased by 18.94% and 28.2% for PP1.5 and PVA1.5 fibers respectively. The control sample, PP 1.5 and PVA 1.5 recorded 31.1%, 12.5%, and 11% loss in CS after the acid attack test, respectively, after 120 days. A reduction of 15.3% and 13.3% was recorded in flow diameter with the addition of PP and PVA fibers at 2%. Overall, mortars reinforced with PVA fibers have shown better flowability, mechanical strength, and chemical resistance than PP fibers.