WASTE GLASS POWDER-BASED ALKALI-ACTIVATED MORTAR

Abstract

The global warming ensues from the emission of large amount of greenhouse gases in the atmosphere. The part of the carbon footprint attributed to the concrete becomes more and more important due to the cement content and the increase of the worldwide demand for concrete. Although much is done to reduce the environmental impact of concrete with the use of supplementary cementitious materials, the best alternative can be the development of new Portland cement-free binder through alkali-activation of waste products. This paper deals with the development of waste glass powder (GP) based alkali-activated mortar. Metakaolin (MK) is used to replace a part of glass powder in order to introduce Al and also to stabilize alkali ions in the system. The effect of NaOH concentration and MK content on the mechanical and microstructural properties of mortars are studied. Results show a gradual increase in the mechanical properties of the mortar with more cohesion between the paste and sand aggregates when MK is added up to 8%. In contrast, without MK or with less than 3% of MK content, the compressive strength decreases with the time with a poor cohesion between the paste and aggregates. Moreover, the NaOH concentration of 5M is enough to activate the studied system as a high level of concentration induces a delay in the geopolymer gel formation. According to the first results, this glass powder based geopolymer seems promising and further studies need to be carried out.