Monitoring of biochemical based sustainable bacterial concrete system using electromechanical impedance technique with PZT sensor

Structural health monitoring (SHM) is an efficacious novel strategy to monitor the important civil, mechanical, and aerospace engineering systems. The electro-mechanical impedance (EMI) technique is based on the SHM strategy, used for the investigation of strength properties and damages present in the structures. The damage present in structures can be mitigated by incorporating bacteria into the concrete matrix. In the presence of carbon-di-oxide and moisture, the bacteria produce calcite through the metabolism process and the produced calcites are environment-friendly biodegradable material. Therefore, the application of bacteria in concrete can be a solution to enhance the performance of concrete structural systems due to microbial-induced calcite precipitation. This research is motivated by the monitoring of bacterial concrete cube (BCC) and control concrete cube (CCC) specimens sized 150 mm using a smart material-based EMI technique. Overall, thirty-six numbers of cubes were prepared for experimental investigations; out of these, eighteen were BCC, and the remaining eighteen were CCC. To prepare bacterial concrete, the Bacillus subtilis bacteria have been used with a concentration of the 10(5) cells/ml. The compressive strength was determined for the concrete specimens after 3, 7, 14, and 28 days of curing using a compression testing machine. The enhancement in the bacterial concrete with respect to control concrete after 3, 7, 14, and 28 days of curing was 12.42%, 15.5%, 17.3%, and 18.5%, respectively. Furthermore, the strength was investigated through piezo-ceramic lead zirconate titanate (PZT) sensors bonded on the specimens in terms of admittance signatures during the loading. Moreover, the equivalent structural parameters, viz., stiffness and damping, were extracted for the concrete cubes in the MATLAB environment. The variations in the equivalent structural parameters in the frequency band 140-200 kHz have been presented. The extracted signatures have the same pattern and the shifting of peaks towards the right side indicates strength development. This study resulted that the strength of bacterial concrete was enhanced than the standard concrete due to microbial-induced calcite precipitation in the molecular space available in the concrete. For the quantification of developed strength, the statistical index, viz., root mean standard deviation, has been used. Furthermore, the sustainability of the bacterial concrete systems has been quantified in terms of RMSD percentage over time for the environmental reason. The study results in the development of novel research directions and sustainable construction improvement of real-life structures.

Automated summary

Structural health monitoring (SHM) is an effective strategy for monitoring important civil, mechanical, and aerospace engineering systems. The electro-mechanical impedance (EMI) technique, based on SHM, is used to study the strength properties and damages in structures. Introducing bacteria into concrete can enhance its performance and mitigate damage through microbial-induced calcite precipitation.