Sodium silicate from waste glass cullet as an activator for cement-less concrete

Waste glass is a significant problem with almost 200,000 tonnes of glass from construction sites in the UK alone sent to landfill in 2018. Furthermore, proper recycling of all building glass waste could avoid 925,000 tonnes of landfilled waste every year and save around 1.23 million tonnes of primary raw materials annually. This study was undertaken to find an alternative use of waste glass cullet as an activator for alkali activated materials. Not only will this make use of waste glass otherwise destined for landfill, but alkali activated materials have shown a possible reduction of 30% - 80% of global warming compared to Portland cement concrete. The study used a mixture of waste domestic glass and flat glass from a local refuse collector. The waste glass was milled to a powder and combined with sodium hydroxide to form a crude glass-derived sodium silicate activator. This activator was successfully used for the activation of blended precursors containing Ground Granulated Blast Furnace Slag (GGBS) and Fly Ash (FA) that performed similarly in terms of compressive strength to the same precursors activated with commercial activators. Furthermore, the activator was used for the casting of normal density concrete building blocks that reached an impressive strength of 15.6 MPa.