Unveiling the Potential of Diatomaceous Earth for the Synthesis of Sustainable Geopolymer Binders

Abstract

This study explored the use of natural diatomaceous earth (ND) and brewery waste diatomaceous earth (BWD) as precursors for the synthesis of geopolymeric binders, with a focus on optimizing the developed compositions and analyzing their physico-mechanical and microstructural properties. Geopolymers were synthesized using various precursor combinations, with adjustments to their SiO2/Al2O3 molar ratios. ND exhibited high reactivity as a precursor, yielding compositions with compressive strengths of up to 28.59 MPa after 24 hours of curing and low porosity. This performance was attributed to the formation of an amorphous gel with a high density of Si–O–Si(Al) bonds. In contrast, systems incorporating BWD demonstrated reduced performance due to their elevated SiO2/Al2O3 molar ratio and limited geopolymerization, resulting in the presence of unreacted particles within the final microstructure. Stoichiometric adjustments and mechanical activation were critical in improving the compositions performance and enhancing the reactivity of the BWD residue, enabling the production of geopolymers with compressive strengths reaching 31.34 MPa. These findings emphasize the importance of optimizing both the chemical composition and synthesis processes to advance the development of geopolymeric materials, facilitating novel precursor combinations and the sustainable reutilization of industrial waste.