Bacteria-based crack healing of 3D printed PVA fiber reinforced geopolymer mortars

Abstract

Geopolymers have been regarded as a promising environmentally friendly alternative to cementitious materials in 3D printing. In this study, 3D-printed fly ash based geopolymer mortars containing silica fume were produced with PVA fiber at 0%, 0.5%, 1%, and 1.5% ratios. Cracks were created in the specimens using flexural strength test after 28 days. Then, bacterial self-healing process was applied to the half of cracked samples and the remaining cracked samples were used as control samples. Sporosarcina pasteurii was used for healing. Lastly, the visual inspection, flexural strength, compressive strength, and water absorption analyzes were conducted mechanical properties to evaluate the healing performance of 3D-geopolymer samples containing PVA. In addition, the samples were subjected to microstructural examination using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and Fourier transform infrared spectroscopy (FTIR) to determine the changes in the microstructural of bacterial based healing. As a result, CaCO3 precipitates, which are the bacterial healing output, filled the cracks and boosted the mechanical characteristics of 3D-geopolymer. The application in 3D-printed PVA fiber reinforced geopolymer mortars of bacterial healing resulted in a significant 36.23% improvement in flexural strength and an 11.57% reduction in the capillary water absorption coefficient compared to the non-healed samples.