Used Lamps Recycling in Geopolymers

Geopolymers, a class of largely amorphous aluminosilicate binder materials, have been extensively studied over the several past decades. New metakaolin-based geopolymer formulations were elaborated by addition of lamp waste glass and with sodium silicate/NaOH activation. The influence on the microstructure and mechanical properties of compositional variation with partial replacement of metakaolin by lamp waste glass (0, 25, 50, and 75%) and Si/Al ratio (3.5 and 4) were studied. From 1 to 7 days of curing, the combination of these two amorphous materials (metakaolin and glass) exhibited suitable compressive strength values reaching 17 MPa. At higher Si/Al ratio (3.5–4), these values are largely superior to metakaolin-based one (around 4 MPa). At higher percentage of waste (25% metakaolin, 75% glass), the mechanical resistance tends to decrease due to the higher reactivity of metakaolin with alkaline solution. This behavior is also observed when more curing time is applied to the studied geopolymers (28 days).