Comparison of bacteria-based self-healing methods in metakaolin geopolymer mortars

Abstract

This study aims to compare the bacteria-based self-healing methods in metakaolin-based geo-polymer mortars. In addition, the effects of Microbially-Induced Calcium Carbonate Precipitation (MICP) on the mechanical properties of metakaolin-based geopolymer mortars were determined in this study. For this purpose, the submersion, spray, and injection methods were utilized for bacteria-based self-healing. The bacterial and bacteria-free medium solutions were used in these methods. In addition, the samples without Sporosarcina pasteurii (S.pasteurii) cells (H), the samples with S.pasteurii cells (M), and the samples with both S.pasteurii cells and the nutrient medium (Z) were prepared according to the microbiological content. Metakaolin-based geopolymer cubes and prisms samples using these contents were produced and cured at room temperature (20 +/- 2 degrees C) for 28 days. Then, cracks were formed in the samples. These cracks on samples were healed using different self-healing methods. Lastly, the mechanical properties of samples were determined. This study showed that the injection method was the most effective method for completely closing cracks. Also, this study found that the M series healed with the injection method had the highest recovery percentage for flexural strength, and it was about 29.69%.