Geotechnical properties and durability of geopolymer-bound recycled waste glass

This paper presents an experimental investigation into the geotechnical properties and durability of a novel composite material introduced using recycled waste glass (RWG). Since the aim is to apply the composite for ground improvement, a geopolymer-based binder is developed to increase the adhesion between RWG aggregates. Durability is assessed by measuring the unconfined compressive strength (UCS) after immersion in water for varying durations to assess the resistance to degradation when exposed to groundwater interactions. The results indicate a 32.5% reduction in strength, attributed to the dissolution of highly soluble crystalline silicate hydrates, thermonatrite, and natrite within the first 24 h of immersion. Beyond this initial period, the UCS stabilised at ∼9 MPa, indicating that prolonged immersion does not significantly contribute to further material degradation. Consolidated drained triaxial tests show that the material has a secant modulus of 980 MPa after 24 h of immersion. The stress–strain response of the material is characterised by post-peak softening followed by a distinct ultimate strength state, similar to cement-mixed soils, but with comparatively higher stiffness and strength. Therefore, the strength parameters corresponding to both peak and ultimate states are critical for the performance evaluation of the proposed new composite material.