Waterglass (sodium silicate) is a commodity industrial chemical, sold as a powder or water solution, and used in compound formulations, for processing textiles and lumber, and in the manufacture of ceramics, silica gel and other materials. Waterglass is prepared by melting together soda (Na2CO3) and quartz/silica sand (SiO2), in an energy-demanding process (1100-1200 °C) to produce an amorphous material known as cullet. The cullet is then mixed with water and pressurised steam to produce an aqueous solution. The development of a robust technology for making waterglass from waste glass is highly desired by the bulk industrial chemical industry.

GUITAR will demonstrate a manufacturing process for waterglass suitable for producing "cementless" concrete products when used together with cement bypass flue dust (a waste stream from the manufacture of cement) and/or Ground Granulated Blast Furnace Slag (GGBS, a by-product from steel production). The end products will be autoclaved aerated concrete building blocks, normal density blocks, and a pre-bagged one part binder (GGBS with waterglass) that do not use any Portland cement, instead using waste materials to replace it.

These products will have a significantly lower environmental impact those currently on the market.

The project will explore the preparation and purification strategies required to deliver waterglass equivalent to that produced as a commodity bulk chemical for use in detergents (the largest single market for waterglass) and paper production. The 2016 global market size of sodium silicate was estimated at $8.6 billion and is projected to reach $11.0 billion by 2022, with the EU sharing approximately 20% of the market. EU production capacity exceeds 2 million tonnes per annum.

The competitive advantage of the new waterglass production process arises from its lower environmental impact and its lower cost of production. There are two-fold environmental benefits: lower process temperature (around 150 °C instead of \>1100°C) and use of waste glass cullet rather than virgin material (pure quartz/silica sand). The production cost for waterglass from the waste glass cullet is estimated at £100 £/tonne (about 95% cost being NaOH). In comparison, the market price of commercially available sodium silicate solution is of the order $500-$1000/tonne, and it is expected to further increase with increasing penalties for C02 emissions and consequent energy input costs.