Experimental Investigation on the Strength, Durability and Crack Behaviour of Bacterial Self-Healing Concrete with Different Doses

Abstract

The employment of carbonate-producing bacteria as a new approach to enhance the qualities of concrete has attracted a lot of interest since it is thought to be innocuous to the environment, natural, and maybe advantageous. This is a result of the favorable implications attached to these traits. The use of microbially induced carbonate precipitation as a remedy for several problems affecting concrete, such as fracture healing, reduction and change of porosity and permeability, and more, has been the subject of much investigation. Concrete crack healing is one of the topics that have been researched. Additionally, it has been shown that the procedure of bacterial carbonate precipitation, also known as bio deposition, contributes to the development of concrete\'s compressive strength. There has not yet been a thorough investigation of the research relating to the appropriate bacterial solution dose and its effect on concrete durability. This might occur as a result of the project not receiving enough time to complete it. As a result, it has been decided that an investigation will be conducted in order to determine the proper quantities of bacterial solution required for concrete. To do this, several concrete cube samples will be made using varying amounts of bacterial solution, such as 15 ml, 30 ml, 45 ml, 60 ml, and 75 ml, respectively. These quantities will be added to the appropriate moulds. This will allow you to determine the proper dosage of the bacterial solution to employ. In order to determine the optimal dosage that should be used, these various samples are also put through a battery of tests using a variety of laboratory techniques, such as the properties of materials, slump cone test, a compressive strength testing machine, an ultrasonic pulse velocity test, plate count cells, and scanning electron microscopes, Rapid Chloride Penetration Test (RCPT), Acid attack test.

Introduction

Recent research highlights the potential of carbonate-producing bacteria, such as Bacillus subtilis, in improving concrete properties. This eco-friendly and sustainable method, called Microbially Induced Calcium Carbonate Precipitation (MICP), enhances various concrete characteristics including:

• Crack healing

• Reduction in porosity and permeability

• Improved compressive strength

• Decreased water absorption

• Resistance to carbonation and chloride penetration

The bacteria catalyze urea hydrolysis, creating carbonate ions that react with calcium ions to form calcium carbonate (CaCO?), which strengthens the concrete. The overall process raises the pH, providing a favorable environment for CaCO? precipitation on bacterial cell walls.

Materials Used

• Cement: 53-grade OPC, specific gravity 3.15

• Fine Aggregate: Zone III sand (Godavari), specific gravity 2.386

• Coarse Aggregate: 12.5–20mm size, specific gravity 2.994

• Bacteria: Bacillus subtilis, capable of CaCO? precipitation

Mix Design & Methodology

• Concrete Grade: M30 (mix ratio 1:1.97:2.96)

• Bacterial Solutions Added: 15ml, 30ml, 45ml, 60ml, 75ml per mix

• Curing Durations: 7, 14, and 28 days

Tests Conducted:

• Slump Test: Showed reduced workability with bacteria (slump reduced from 110mm to 50mm)

• Compressive Strength Test: Performed at 7, 14, 28 days

• Plate Count Test: Verified bacterial viability

• SEM Analysis: Visualized CaCO? crystal formation

• Rapid Chloride Penetration Test (RCPT): Assessed durability and permeability

• Ultrasonic Pulse Velocity (UPV): Evaluated internal defects

Key Findings

Compressive Strength Results:

• Trend: Strength increases with bacterial concentration up to 60ml, then decreases slightly at 75ml due to potential oversaturation or bacterial interference.

• Improvement Over Control (M1, no bacteria): ~58% increase in 28-day strength.

Durability Results:

• SEM confirmed CaCO? deposition within concrete pores.

• RCPT indicated improved resistance to chloride penetration in bacterial concrete

Conclusion

The highlight the production processes that have been investigated and the performance that have been measure on bacterial self-healing concrete. In conclusion, any type of bacteria with ability to metabolically convert calcium source into calcium carbonate can be used in producing autogenous healing concrete. It is important to provide protection to bacteria in concrete to sustain the self-healing ability throughout the life span of concrete. Bacterial concrete has lower strength compared to conventional concrete about the same composition. However, bacterial concrete able to fully repair visible crack autogenously compared to conventional concrete. 1) Incorporating \"Bacillus Subtilis\" at the correct concentration results in concrete more strength. 2) The increasing of bacterial solution, the strength increases up to 60 ml and then strength decreases. 3) As compared with conventional concrete, the concrete specimen containing 45ml solution of bacteria increases 25% strength considering the average of three samples after 28 days of curing. 4) The concrete containing the 45ml bacterial solution is good to use for crack repairing purposes. 5) Ultrasonic pulse velocity probing in direct method maximum in 30 ml of bacteria used velocity is increased. 6) The maximum bacterial plate count in 45 ml 7) Maximum Rapid Chloride Penetration values are 60 ml dosage of bacterial concrete. 8) The resistance of concrete against the assault of acid is noticeably higher than that of regular, typical concrete. It has been shown that bacterial concrete with 60 ml as a substitute offers significantly improved resistance to acid assault. 9) A crack in concrete that is between one and forty-five micrometres wide may be healed in a period of thirty days, demonstrating that there is a viable cure for microcracks. 10) Oxygen is the agent that may cause corrosion. However, since bacteria consume oxygen, the rate of corrosion can be lowered while the bacteria continue to thrive. 11) The formation of cracks will be healed at an earlier stage than was originally envisaged, which will result in an increase in the service life of the structure beyond its projected life.

References

[1] Pipat Termkhajornkit, Toyoharu Nawa, Yoichi Yamashiro, Toshiki Saito Self- healing ability of fly ash cement systems. (2009). [2] S. Sunil Pratap Reddy, M.V. Seshagiri Rao, P. Aparna and Ch. Shashikala Performance of standard grade bacterial concrete, Asian Journal of Civil Engineering Vol.11, No.1 (2010). [3] Kaustubh Dasgupta, A. S. Sajith Proceedings of SECON\'19: Structural Engineering and Construction Management: 46 (Lecture Notes in Civil Engineering) [4] C.C. Gavimath, B.M. Mali, J.D. Mallpur, A.B.Patil Potential application of bacteria to improve the strength of cement concrete. BioIT Journal Vol 3, Issue 1, 2012. [5] Navneet Chahal, Rafat Siddique, Anita Rajor Influence of bacteria on the compressive strength, water absorption and rapid chloride permeability of fly ash concrete. [6] Mayur Shantilal Vekariya, Prof. Jayesh Kumar Pitroda Bacterial Concrete: New Era for Construction Industry. IJETT- Vol 4 Issue 9- Sep 2013 [7] Prof. M. Manjunath, Prof. Santosh A. Kadapure, Ashwin Kumar A. Kalaje An experimental investigation on the strength and durability aspects of bacterialconcrete with fly ash. ISSN 2224-5790 ISSN 2225-0514 Vol. 6, No.6, 2014. [8] Snajukta Sahoo, B.B. Das, A.K. Rath and B.B. Kar Acid, Alkali and Chloride resistance high volume fly ash concrete. Vol 8 (19) August 2015. [9] Harshali J., Mitali S., Neha A., Pragati B. Bio concrete and bacteria based self- healing concrete. IJRET eISSN: 2319-1163 pISSN: 2321-7308 Vol.05 Issue: 05 May 2016. [10] Dilja Rose Joseph, Life John Strength assement of fly ash modified microbial concrete. Vol.7 Issue No.4 April 2017. [11] Etaveni Madhavi, S.B. Sankar Rao, Gaddam Swarna Malika Strength properties ofa bacterial cement mortar when cement partially replaced with GGBS. Vol. 3, Issue-2, 2017. [12] IS 10262: 2009, Concrete mixing Proportioning. [13] IS: 383-2016 “Coarse and Fine aggregates of concrete specifications”, Bureau of Indian Standards, New Delhi. [14] IS: 12269-1987 “Specifications for Ordinary Portland Cement for 53 Grade”, Bureau of Indian Standards, New Delhi. [15] IS: 516-1959 “Method of tests for strength of concrete”, Bureau of Indian Standards, New Delhi.

Copyright

Copyright © 2025 Udayasri Mekala , Dr. Abhishek Kamishetty . This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.