Performance evaluation concept for crack healing in bacterial concrete structure using electro mechanical impedance technique with PZT patch

Abstract

Beginning and development of cracks reduce the structural performance and durability, thus a novel strategy is required to prevent such kind of occurrence. The incorporation of bacteria in the concrete system is likewise a technique to prevent the growth of the cracks by the microbial induced calcite precipitation. The Electro mechanical impedance (EMI) technique is the smart sensor-based technology that is an efficacious technique to examine the health of structures, whereas the prediction of frequency band and corresponding healing damage indicator for real-life application is the governing factor. The examination of crack healing performance in bacterial concrete by EMI technique with PZT sensors was not reported by previous studies to date. This research is motivated by the quality evaluation of crack healing in bacterial reinforced concrete beam specimens using the EMI technique with surface-bonded PZT patch and embedded concrete vibration sensor (CVS), respectively. For the fabrication of bacterial reinforced concrete beam specimen, the Gram-positive Bacillus subtilis bacteria have been used. To induce the structural damage, the three point loading was applied to the prepared reinforced concrete beam specimen. The optimal frequency band was determined which resulted in the structural condition for that the four statistical indices were investigated with various crack severities in several sub-frequency bands. The optimal frequency band was determined as 161–215 kHz. Further, the crack healing performance was investigated with a pre-evaluated optimal frequency band using the statistical damage indices. The damage indicators RMSD, MAPD, and CC were appropriate for the evaluation of damage severity; however Cov was appropriate for damage severity evaluation in lesser amounts in a sub-frequency band. The evaluated damage indicators RMSD, MAPD, Cov, and CC successfully signified the crack healing by the bacterial incorporation in concrete structures. The SEM and XRD tests were performed for the confirmation of calcite deposition at the cracks. The developed concept is resulted in significantly evaluating the healing quality of the cracks by bacterial incorporation over time.