Improvement in the physical properties of solid bricks by adding household glass waste

Abstract

The extensive consumption of clayey soils to manufacture bricks has caused the depletion of these non-renewable natural resources. In this paper, in a bid to reduce clay consumption and recycle waste glass, 20 wt% crushed household glass was added to clayey soils from Jun and Guadix (Granada, Spain) to manufacture handmade and extruded bricks fired at 800, 950 and 1100 ◦C. The presence of carbonates in the soil from Jun favored the development of new Ca-(Mg) silicates such as gehlenite, diopside, wollastonite and anorthite, while mullite developed in the bricks made with clay from Guadix. The addition of glass altered the porous system of the bricks, which absorbed less water and dried more quickly than conventional bricks. As regards the manufacturing procedure, extruded bricks turned out to be less porous than handmade ones. The porosity of both handmade and extruded bricks fell as the firing temperature increased. Bricks with added glass were more resistant to compressive strength tests than those made exclusively with clay. These results were confirmed by ultrasound measurements from which we observed that the compactness of bricks increases in line with the increase in the firing temperature and by adding glass. Accelerated ageing tests (freeze-thaw, salt crystallization and wet-dry) revealed that the addition of glass provides the bricks with more compactness, strength and durability than those without glass fired at the same temperature. 20 wt% proved to be the ideal proportion for waste glass added to the clay used in the production of high-quality compact bricks.