Effect of waste glass content on resistance of geopolymer binders to sulfuric acid attack

Geopolymers, known for their enhanced resistance to aggressive environment, are the subject of a new study to further increase their resistance by incorporating various raw materials. This research investigates the influence of waste glass content on the properties of alkali-activated binders exposed to an aggressive environment. The waste glass, replacing slag and metakaolin, was added in varying amounts ranging from 0 to 30 mass% . Sodium water glass, in the mass ratio of 4:5 to the binder, was used as the alkaline activator. The resistance to acid attack was assessed by immersing mortars in a sulfuric acid solution. The samples underwent analysis for appearance, mass and longitudinal change, compressive strength, and loss of alkalinity. Phase composition and microstructure were analysed using X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy techniques. Acid and water leachate was analysed by inductively coupled plasma mass spectrometry. The findings of the study revealed that incorporating waste glass content up to 20 mass% reduced porosity and affected the formation of gypsum. Gypsum results from the reaction between the binder and sulfuric acid and contributes to the surface deterioration of the specimens. Consequently, this research demonstrates that waste glass incorporation in the mix design can enhance the resistance of geopolymers to sulfuric acid, thus extending the service life of concrete structures.