Atomic-structure, microstructure and mechanical properties of glass powder modified metakaolin-based geopolymer

This objective of this study is to utilize recycled glass powder as a partial replacement precursor of the metakaolin-based geopolymer to develop a sustainable geopolymer material. Four glass powder replacement ratios were selected for the metakaolin-based geopolymer preparation (0%, 5%, 10%, and 20% by the total precursor weight). The pair distribution function (PDF) analysis indicated that a higher amount of the four-membered ring structures in the formed gel with the added glass powder. Both PDF and EDX analysis showed that the Si/Al ratio of the binder phase increased with glass powder content in the mixtures. The added glass powder can improve the workability of the geopolymer binder and prolong the setting time of the synthesized geopolymer samples. The nanoindentation test results showed that the elastic modulus of the formed gel increased with replaced 10% and 20% glass powder. In addition, the samples with 5% of glass powder achieved the highest compressive strength among tested samples. The test results indicated that the appropriate glass powder replacement can affect the geopolymerization process and modify the formed gels in the metakaolin-based geopolymer to improve the mechanical properties of the mixture. The information obtained in this study can promote the utilization of waste glass powder as a partial replacement of the precursor for the production of sustainable alkali-activated materials