CIAM-COR-R34
Research Team
Mehdi Shokouhian, Morgan State University
Funding Sources
Morgan State University Core Funds — $139,275
Morgan State University Match — $146,463
Total Project Cost — $285,738
Agency ID or Contract Number
69A3551847103
Start and End Dates
10/01/2021 — 09/30/2022
Project Description
Concrete is one of the major construction materials in transportation and infrastructure systems including pavements, bridges, and tunnels, however evidence of concrete decay can be observed anywhere the material is found. Concrete is highly susceptible to cracking due to its porous nature, and developments in its composition have increased its strength but done little to fix the tendency to form cracks. These unavoidable fissures allow water to rust the steel in the concrete, forming stains on the surface. The visible rusty orange stains are so called ‘concrete cancer’ and there is no cure. Once water seeps into the structure, exposed steel begins oxidizing at a faster rate. The concrete must be manually repaired quickly, because if it is left untreated, the chemical oxidation can deteriorate the reinforcements to the point of failure. The appearance of small cracks (<300 μm in width) in concrete is almost unavoidable, not necessarily causing a risk of collapse for the structure, but surely impairing its functionality, accelerating its degradation, and diminishing its service life and sustainability. These factors and the inevitability of cracks described by De Belie suggest a need to reduce repairs by solving the problem of cracks. This reduction of damage would lead to less demolition and less concrete production, and therefore a more sustainable solution for one of the world’s most common building materials. Robust self-healing concrete, which requires less maintenance and repair throughout its service life than ordinary concrete, can be used for the development of sustainable infrastructure. A true robust self-healing concrete should, have a long shelf life, include pervasive quality healing properties throughout the material, be versatile in various environmental conditions, and be repeatable over the service life of the structure.
Although many approaches can be used to promote self-healing in cement-based materials, use of biomineralization (the process by which organisms stimulate the formation of minerals) for this purpose has generated considerable interest. Previous research on biomineralization, specifically microbial-induced calcium carbonate precipitation, suggested that this process can improve durability and remediate cracks in concrete, however the protection schemes for microorganisms can’t still guarantee the healing performance of bacteria-based concrete when concrete is exposed to the harsh environment. Therefore, this research aimed at investigating the self-healing properties of a bacteria-based concrete through experimental methods at microscopic and macroscopic levels. A new method will be employed to protect the microorganisms using air entraining agents to increase the survival rate of bacteria during the concrete mixing and after casting. Successful completion of proposed tasks in this proposal will yield a new method to create bioengineered self-healing concrete to enhance reliability of the concrete performance. It is expected that employing this material can significantly reduce maintenance costs and increase the durability of concrete in transportation infrastructure system.