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 fungi 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 in the topic, let’s delve into its pros and cons in the upcoming sections.
What is Bacterial Concrete?
There is no construction possible in today’s world without concrete. Concrete is used pretty much everywhere, and that is why it becomes very important to choose good quality concrete so that the structure remains tall in the future. And while we all talk about good quality concrete, one name that always comes to our mind is Bacterial Concrete.
What is it and why is it so popular? Bacterial concrete is a type of self-healing concrete that uses a certain type of bacteria to improve its durability and lifespan.
Now, we can understand you scratching your head by reading its “self-healing” quality. But here is how it works. The bacteria inside the concrete is able to produce limestone when it comes in contact with water and oxygen. This process comes into play whenever there are cracks formed in the concrete.
When there are cracks, water gets inside it. Then the bacteria start producing limestone to fill those cracks before they spread and cause more serious damage.
This whole process gives an invincible feeling to the concrete. It significantly enhances the strength and sustainability of the structures and ends up saving a lot of money on repairs and maintenance.
Advantages of bacterial concrete
With bacterial concrete, you can even reach the smallest cracks, and some other advantages are as follows:
1. Bacterial concrete 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. It 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 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. Bacterial concrete 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. It 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 skills 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.
Benefits of Bacterial Concrete
Bacterial concrete has plenty of uses. Here are some of the most common benefits of bacterial concrete:
- Crack Repair: We all are aware of the special self-healing quality of bacterial concrete, and that is why it is used to automatically repair cracks in concrete structures.
- Infrastructure Longevity: It helps structures stay still for longer periods of time by healing cracks as they form. It does not allow the cracks to spread and damage the building further. It also helps in reducing maintenance costs and increasing safety.
- Waterproofing: The self-healing property of bacterial concrete also allows structures to get more watertight, as the bacteria seal the cracks that allow water ingress.