Effect of natural graphite additions on the microstructural and mechanical behavior of metakaolin based geopolymer materials

This investigation aims to develop a metakaolin (MK) based geopolymer composite reinforced with natural graphite (NG). The microstructural, mechanical, and physical properties of geopolymer composites were evaluated in relation to the NG addition (0–70 wt%). Several methods including XRD, FTIR, TGA, SEM/EDS, compressive strength and setting time were applied to investigate the influence of NG inclusion on the MK-based geopolymer matrix. According to the results, the microstructural characterization revealed that the graphite sheets are integrated in the geopolymer network and that the amount of carbon rises with the progressive NG additions while having a substantial influence on the densification of the geopolymer composites. The mechanical parameters of the elaborated geopolymer composite indicated that the optimal amount of NG is 30 wt%, which boosts the compressive strength by 49% above the reference composite based on the high mechanical properties of graphite. The use of NG for optimal mix proportion extended the setting time of the geopolymer composite paste by 663 min as compared to the reference geopolymer paste. These findings demonstrated that the developed geopolymer composite offers an economic and environmental potential in several potential fields. •Natural graphite (NG) reinforcement improves geopolymer compressive strength by 49%.•XRD analysis shows increased graphite content densifies the geopolymer matrix.•NG acts as a microcrack bridge, enhancing compressive strength in geopolymer composites.•Developed geopolymer offers economic and environmental potential for various applications.