Effect of Elevated Temperature on Compressive Strength of MICCP and EICCP Biocemented Mortar

Recently biocementation has got attention of many researchers worldwide as one of the most potent techniques for sustainable construction. Several studies have been carried out worldwide on biocementation by urea hydrolysis. Biocementation by bacterially induced calcium carbonate precipitation by different bacterial species has been among the most widely researched areas in this field. Biocementation has proved efficient in enhancing the strength and durability of cement-based materials. However, no significant work has been carried out to determine the performance of biocemented specimens at elevated temperatures. This study primarily focuses on the effects of high temperatures (300, 450, and 600 degrees C) on the compressive strength of two types of biocemented specimens prepared by using ureolytic bacteria and rich in urease watermelon seeds. The motive behind testing these two types is to know how the enzyme induced or microbially induced react to temperature elevation. Also, the effect of different cooling techniques (viz., natural cooling, water spray cooling and fire extinguishing foam spray cooling) were studied. These cooling techniques were selected so as to check which cooling technique should be preferred in case of fire situation in a cement-based structure. Results show that biocemented specimens can perform very good up to the temperature 300 degrees C as compared to control specimens in terms of compressive strength. At 450 degrees C temperature, there is no significant difference in compressive strengths of control and biocemented specimens. When the specimens were subjected to 600 degrees C, biocemented specimens showed lower strength than control specimens at the same temperature due to denser microstructures. Thus, biocemented cement mortar should not be used in reactors, muffles and ovens where temperature would go above 450 degrees C.