Effect of the chemical composition of different types of recycled glass used as aggregates on the ASR performance of cement mortars

- Glass chemical composition strongly influences the reactivity.
- Different amounts of modifiers and stabilizer oxides influence the solubility of glasses.
- The chemical composition of ASR gels depends on chemical composition of the original glass.
- Cullets from fluorescent lamps expand without the contribution of external alkali.

Glass with different chemical compositions, deriving from separate collection, has been used as fine aggregate to formulate cementitious mortars, substituting natural sand. Glass coming from cathode-ray tube monitors, fluorescent lamps, and crystal glass (from production of home décor items) along with glass deriving from soda-lime glass containers, which has been taken as a reference, have been investigated. Glass solubility has been determined in alkaline environment similar to the one inside the cementitious composite. Alkali silica reaction has been tested on glass modified cement mortar in different accelerated conditions. Mortar samples containing glass with chemical composition different with respect to soda-lime glass are subjected to alkali silica reaction. This behaviour is largely dependent on the ratio among modifier and stabilizer oxides in the glass. The same ratio affects glass solubility and consequently composition of expanding gels when alkali silica reactions take place.