Pomace from the wine industry as an additive in the production of traditional sustainable lightweight eco-bricks

This research examines fired clay bricks made with waste pomace from the wine industry as an additive in brick production. To this end, we analyse and discuss the chemical, mineralogical, textural and physical-mechanical behaviour of fired bricks made with three concentrations of wine pomace (2.5, 5 and 10 wt%) and at three different firing temperatures (800, 950 and 1100 °C) and evaluate their durability to salt crystallization. Variations in colour were also examined. The firing process resulted in the decomposition of phyllosilicates and carbonates, the crystallization of Fe oxides and the appearance of high-temperature Ca- (and Mg-) silicates phases such as gehlenite, wollastonite, anorthite and diopside. The bricks made with added wine pomace had very similar mineralogy to the control samples made without it. The bricks made with added wine pomace were lighter than the control samples and underwent less linear shrinkage during the drying process. Particles in the wine pomace were consumed during firing, leading to the appearance of voids. The bricks made with this additive had higher levels of water absorption and poorer mechanical strength. The greatest colour differences were detected after increasing the amount of waste, which generally resulted in yellower bricks. The increase in firing temperature resulted in an improvement in mechanical resistance regardless of the composition of the bricks. However, bricks fired at 1100 °C made without additive are more resistant to damage caused by salts than those made with wine pomace.