Ground waste glass–carbide lime as a sustainable binder stabilising three different silica sands

Waste glass is a solid residue usually available near urban centres, where it is discarded after being used as a container for one of several products. Carbide lime (CL) is a by-product of the manufacture of acetylene gas. The present research evaluates the potential of combining these two wastes as a possible hydraulic cement to enhance the behaviour of sands. Pozzolanic reactions occur between silica in its amorphous phases (found in GG) and Ca⁺⁺ (present in CL) in an alkaline environment. The effect of the amount of GG, the CL content and the porosity of the blend on the strength, stiffness and durability of compacted sand–GG–CL mixes is quantified for three distinct sands. An original parameter, termed the porosity/binder index (η/B_iv), can be used to normalise the behaviour of the unconfined compressive strength (q_u), the shear modulus at small strains (G₀) and the accumulated loss of mass (ALM) of the compacted mixes, considering GG + CL as the binder. Results have shown unique normalised tendencies for q_u, G₀ and ALM with η/B_iv for the three studied compacted sand–GG–CL blends, even though each sand has a distinct grain size distribution.