Concrete is one of the most widely used materials in the world as it is readily available. It has an impressive compression strength, making it ideal for building durable structures. But like any other material, concrete has downsides. It is prone to cracks and when that happens, the structure either needs repair or replacement. Depending on the location and accessibility of the structure, sometimes the repair can be expensive. To avoid this problem, self-healing concrete, also known as bacterial one, was developed, and we’ll examine its advantages and disadvantages.
Naturally, the concrete repairs a crack with autogenous healing. Scientists have discovered bacteria and fungi produce calcium carbonate, a mineral that is part of this healing. During the blending process, the spores of these bacteria and fungus are included in the concrete mix. That way, when cracks appear and water passes through them, the spores create an environment for the growth of calcium carbonate, which repairs cracks.
Once these fissures heal, spores switch back to the dormant state, ready to come to the rescue when the cracks form again. In a nutshell, this is how bacterial or self-healing concrete works. Now that you are well-versed with the topic, let’s delve straight into its pros and cons.
Advantages of bacterial concrete
With bacterial concrete, you can even reach the smallest cracks, and some other benefits are as follows.
1. It is highly durable
There are several factors due to which crack appears in concrete. The most common reasons are exposure to water, overstress, salts, and temperature variation. All these factors negatively impact the durability of structures made of concrete. With bacterial concrete, the tiny cracks are automatically repaired as they appear. Therefore, it prevents potential bigger problems and makes structures highly durable. In other words, mixing the concrete with microbes induces self-healing. Eventually, it mends the crack and retains its durability. Furthermore, researchers have predicted that bacterial concrete can extend the life of the structure by 20 years.
2. Bacterial concrete reduces permeability
The permeability of concrete is one of the important factors that impact its durability. The lower the permeability, the lesser the possibility of external agents attacking the concrete and steel reinforcement. In bacterial concrete, this permeability is reduced by the higher amount of carbonation. Also, permeability impacts the aesthetic value of the structures. With bacterial concrete, this property can be reduced for preventing attacks on concrete and retaining its aesthetics.
3. It improves the compressive strength
The compressive strength of concrete is enhanced with microbial-induced calcium carbonate precipitation. Hence, it makes bacterial concrete stronger than conventional concrete. When bacteria interact with the concrete matrix it raises the compressive strength. This is to say that the production of calcium carbonate in bacterial concrete not only acts as a binding agent but also fills the pores. Ultimately, it also improves the adhesive property of the concrete.
4. Bacterial concrete requires low maintenance
There are risks associated with conventional concrete such as higher repair and maintenance costs. With the self-healing mechanism of bacterial concrete, as you all might have guessed, these risks are reduced. The bacteria added to the concrete can live up to 200 years in the dormant state provided they have particles as their food. It’s only when the crack appears that the water seeps in and activates the self-healing mechanism for repairing the cracks.
Bacterial concrete requires low maintenance and reduces the repair costs of structures made up of concrete. Additionally, it comes in the form of a spray that can be applied to existing cracked structures for overall repair and maintenance. To summarize, higher compressive strength, lower permeability, and the greater durability of bacterial concrete make it efficient and low upkeep.
5. It is eco-friendly
Bacterial concrete was conceived to reduce the amount of new concrete production. This is because concrete hurts the environment, causing 8% of the world’s carbon dioxide emissions. Green technology such as bacterial concrete reduces the production of new concrete along with lowering the use of concrete for repairs. This results in lower carbon dioxide emissions, making it an environmentally friendly technique. Additionally, it is a promising technology for avoiding complicated repairs and extending the service life of the concrete.
Disadvantages of bacterial concrete
The addition of bacteria in the concrete changes its matrix, causing the aforementioned impact on its strength. The following are several other downsides of bacterial concrete.
1. It is expensive
Along with easy availability, the cheap cost of concrete is one of the factors for its wide acceptance across the globe. However, when it comes to bacterial concrete, it is costlier than conventional concrete. In fact, you can expect the cost to be twice that of the conventional one. Despite the returns of investment being high with the use of bacterial concrete, its initial high cost discourages businesses from accepting this green technology. More people have yet to realize the long-term profits and environmental benefits of using self-healing concrete.
2. Bacterial concrete requires skilled labor
If the initial high cost of bacterial concrete was not off-putting, the requirement for higher-level expertise and technical knowledge becomes the other major drawback. To work with bacterial concrete, the laborers should possess the needed skill to mix it appropriately. But this incurs more costs and takes up more time, thereby complicating the construction process and even slowing it down.
3. It is unsuitable in some environments
Even though the bacteria added to the concrete increases the durability by repairing the cracks, the environment plays an important role in the process. Firstly, the bacteria are introduced to the harsh conditions of the concrete matrix, which is problematic for its life. Then other factors such as high temperature, high alkalinity, and reduced oxygen supply impact its survival. Therefore, several aspects such as the survival characteristics of microbes and optimal conditions are taken into account in bacterial concrete.
4. Bacterial concrete does not have IS code
Bacterial concrete is still a new technology. Not many people are aware of this form of concrete, hence there is no code available for standardizing it. Also, since only a few people know about it, the majority of people have yet to learn how to use it, causing problems in cons one and two above.