Self Healing Concrete

Let’s start off with a beautiful quote!

“A pile of rock ceases to be a rock pile when somebody contemplates it with the idea of a cathedral in mind” - Antoine Saint Exupery.

Innovations in science and technology are being made every day that are changing our lives .In civil engineering, new innovations incorporate nonstandard materials, address concerns about sustainability and environmental impact, and make full use of new and existing technologies..Imagine, the crack on pillars of your house or cracks on the driveways getting healed automatically. This literally means we are getting more durable concrete. The question then arises, why do need self- healing concrete? Because cement which is the core element of concrete is always available and we will not certainly run out of it in near future. Therefore whenever there is a crack in any reinforcement we can just get it treated by patching it with another layer of concrete or start from scratch. So why are we even concerned about it? Time to get hands on some serious stuff!!!!

Firstly ,Concrete is the single most widely used construction material in the world .In fact ,it is the second-most consumed substance on Earth, after water. Concrete is a major component in the construction industry as it is cheap, easily available and convenient to cast. But drawback of these materials is it is weak in tension so, it cracks under sustained loading and due to aggressive environmental agents which ultimately reduce the life of the structure which are built using these materials. . Therefore, it seems obvious that inspection, maintenance and repair of concrete cracks are all indispensable. However, crack repair becomes difficult when cracks are not visible or accessible. Moreover, costs related to repair works is also high. Secondly, Concrete is actually the final product made from cement. The primary component of cement is limestone. To produce cement, limestone and other clay-like materials are heated in a kiln at 1400°C and then ground to form a lumpy, solid substance called clinker; clinker is then combined with gypsum to form cement. Cement manufacturing is highly energy – and – emissions intensive because of the extreme heat required to produce it. Producing a ton of cement requires 4.7 million BTU of energy, equivalent to about 400 pounds of coal, and generates nearly a ton of CO2.Concrete is used so widely that world cement production now contributes 5 per cent of annual anthropogenic global CO2 production. This is where comes the question of having self -healing concrete which would ensure durability of establishments, low cost repair and also contribute in reducing The good news is that researches are going on to manufacture self -healing concrete. In 2010, a graduate student and chemical engineering professor at the University of Rhode Island created a new type of "smart" concrete that "heals" its own cracks. The concrete mix is embedded with tiny capsules of sodium silicate. When a crack forms the capsules rupture and release a gel-like healing agent that hardens to fill the void. While this group of researchers opt for making” smart concrete” which they believe is cost effective, we see another group of researchers developing an environment friendly alternative method for crack remediation called the Microbiologically Induced Calcite Precipitation (MICP). The concept was first introduced by Ramakrishna, Journal publication on self-healing concrete over the last decade .According to this method, the self-healing is achieved through the inclusion, in the mix, of materials that include a bacteria that remains latent and is only activated when a crack appears, generating calcite (calcium carbonate). This fills the holes created by the fissure, and the concrete not only recovers its appearance but also its resistant capacity. This technology is environmentally friendly not only because it gives strength to sand body, but also it allows water to penetrate to sand body, which is unlike silicate cement that will destroy the ecosystem of the earth. Calcium carbonate precipitated by bacteria acts as a binding material to sand particles, so incompact sand will be consolidated. MICP is highly desirable because the Calcite precipitation induced as a result of microbial activities is pollution free and natural. The technique can be used to improve the compressive strength and stiffness of cracked concrete specimens. Research leading to microbial Calcium Carbonate precipitation and its ability to heal cracks of construction materials has led to many applications like crack remediation of concrete, sand consolidation, restoration of historical monuments. Humans have been using concrete in their pioneering architectural feats for millennia. Over the centuries, engineers and architects have devised ever-new ways to build taller, stronger and more beautiful creations using game-changing materials like steel girders, earthquake-proof foundations and glass curtain walls. It’s only a matter of time till we see more amazing futuristic construction technology that would change the way we build!!!

References-

• Crow, J.M. 2008.The concrete conundrum. The Chemistry World.18:62-66

• Patil Gaurao S., Patil Nikhil M., Dhange Ankush B. ,Jadhav Swati B., Jaybhaye Archana L.2016. Smart Concrete – A New Technology. International Journal of Engineering Research and General Science. 4:488-490

• Roos.D.2014. 10 Futuristic Construction Technologies. [https://science.howstuffworks.com/engineering/structural/10-futuristic-construction-technologies.htm].Accessed June 14,2018

.• Breugel KV. SELF-HEALING MATERIAL CONCEPTS AS SOLUTION FOR AGING INFRASTRUCTURE. Delft University of Technology; 2012. Available from: http://www.cipremier.com/e107_files/downloads/Papers/100/37/100037009.pdf