Durability of sisal fiber-reinforced mortar with glass powder as cement substitute in aggressive environment

Mortar plays a crucial role in construction, serving as a binder in masonry, plastering, and repairs. However, durability remains a key challenge, especially under harsh environmental conditions. This study investigates the durability and mechanical performance of sisal fiber reinforced-mortar (FR-M) incorporating waste glass powder (GP) as a partial cement replacement. Mortar mixes with 0–20% GP and 1% sisal fiber were prepared, and their properties were evaluated under exposure to magnesium sulfate (MgSO₄). Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD) analyses revealed that GP enhanced the formation of C–S–H gel, reduced porosity, and promoted a denser matrix, which correlated with improved strength and sulfate resistance. The results demonstrated that the balanced mix, which is 7.5% GP with 1% fiber, showed the highest compressive strength (18 MPa) and flexural strength (6.7 MPa) after 90 days of curing. Furthermore, this mix exhibited superior sulfate resistance, with only 13.8% and 14.8% loss in compressive and flexural strengths, respectively, and minimal expansion (0.096 mm). In contrast, higher GP levels (15% and 22.5%) led to reduced strength and durability. This study highlights the combined effect of GP and sisal fiber in improving both the mechanical properties and sulfate resistance of mortar, offering a sustainable solution for durable construction materials.