Effect of microbes addition on the properties and surface morphology of fly ash-based geopolymer paste

This present study analyzed the effect of Rhizopus oligosporus and Sporosarcina pasteurii addition on the properties and surface morphology of fly ash-based geopolymer paste mixtures as a green sustainable material. The addition of bottom ash and a foaming agent were also conducted to improve the paste quality. Compressive strength, porosity, X-Ray Diffractometry (XRD) and Scanning Electron Microscopy (SEM) tests were performed sequentially. The addition of microbes can improve the compressive strength of specimens by up to 43.75%. All microbe-added specimens exhibited a higher amount of closed porosity compared to the non-microbe-added specimens which also responsible to the higher compressive strength. The addition of foaming agent and bottom ash to the mixtures showed a negative effect to the inoculated microbes. SEM analysis showed the initial result of the potential of R. oligosporus and S. pasteurii as a self-healing agent for fly ash-based geopolymer pastes.