Influence the use of glass sludge on the thermal diffusivity of structural mor-tars using thermography

ABSTRACT Soda-lime-silica glass is a material with high recycling potential. However, its processing generates microparticles that are suspended in the water used for cooling the tools. This residue is inert and generally not reused. For disposal, the microparticles of glass are decanted using flocculants and the mud produced is deposited in landfills. According to the literature, these glass microparticles could act as supplementary cementitious material in Portland cement production. However, information on the thermal performance of these materials is scarce. This study investigates the thermal diffusivity of mortars for structural purposes made with Portland cement and pozzolanic soda-lime-silica glass mud. The mortars were produced with and without cement replacement for 10 and 20% natural mud and washed mud to remove the flocculant. The mortars were characterized for compressive strength and thermal diffusivity. The specific mass, the thermal conductivity and the heating profile of the mortars were also determined, requirements to evaluate the thermal diffusivity. The results indicate that glass mud with and without flocculant could be used in place of cement without compromising compressive strength due to its pozzolanic characteristics. In mortars with 10% mud without flocculant an increase of approximately 8% in compressive strength is observed. However, in all samples with glass mud, washed or not, there is a decrease of 3 to 4% in the specific mass and 17 to 18% in the thermal conductivity, indicating that the pozzolanic reaction did not occur to its full extent. Diffusivity, determined with the aid of infrared thermography, presents results compatible with the literature and indicates that the use of the residue does not significantly influence the thermal inertia of the mortars. Thus, glass mud in place of 10% and 20% Portland cement could be used in structural mortars without compromising the thermal performance of the system, in addition to contributing to the environment by providing adequate destination to the waste and reducing the withdrawal of raw materials for cement production.