Investigation of the Physicochemical Properties of Metakaolin-Based Geopolymer Filled with Extraction Sludge-Based Wastes

Abstract

The global demand to reduce waste disposal has led to an increase in scientific research regarding sustainable waste-based materials. In this context, metakaolin-based geopolymers, or amorphous aluminosilicate polymers, have been synthesized in the presence of 20 wt.% of extraction sludges from food supplement production (W1) and from partially stabilized industrial waste (W2), used as filler after metakaolin activation with alkaline solution. A comparison study in terms of physicochemical properties has been conducted between the geopolymer control (GP0) and those with the two fillers (i.e., GPW1 and GPW2). Fourier-transform infrared spectroscopy (FT-IR) was used to follow geo-polymerization occurrence, while integrity test and compressive strength were used to understand the differences between the synthesized samples. Eventually, the leaching test and antimicrobial activity were also carried out. The main findings revealed that the wastes do not influence the geo-polymerization and the GPW1 and GPW2 had a stable macroscopic structure. The presence of alumina in W2 led to a gas formation with a hardened highly porous structure and a decreased compressive strength. GPW1 showed a higher compressive strength than GP0. None of the geopolymers released heavy metals suggesting that the matrices were able to inertize the wastes. Finally, both wastes and geopolymers revealed antimicrobial properties.