High-temperature, freeze–thaw, and sulfate resistance of mortars incorporating ternary blends of fly ash, chromite, and waste glass

The demand for sustainable construction materials promotes the use of industrial waste in cement-based systems. This study examines mortars incorporating fly ash (FA) (0%, 7.5%, and 15%), waste glass, and chromite aggregates for mechanical and durability performance. Specimens underwent compressive strength, freeze–thaw, high-temperature, sulfate attack, and ultrasonic pulse velocity tests, while microstructure was characterized by x-ray diffraction, thermogravimetric analysis, and scanning electron microscopy–energy-dispersive spectroscopy. Mortars with 7.5% FA exhibited relatively high compressive strength and improved freeze–thaw resistance. The combined use of chromite and FA improved strength retention at 800°C, reaching 23 MPa with 7.5% FA and 50% chromite. The greatest sulfate resistance occurred in mortars containing 15% FA and 15% waste glass, maintaining compressive strengths of 61 and 70.9 MPa after MgSO4 and Na2SO4 exposure, respectively.