Self-Healing Concrete: The Future of Construction

Innovation created by: Hendrik Jonkers

Presentation written by: Jirah Taojo, taojojirah@gmail.com

Presentation supervised by: Assoc. Prof. Dr. Elena M. BARBU, elena.barbu@univ-grenoble-alpes.fr

 

1. General Information

             Concrete, the material we use for constructing buildings, roads and bridges is the most produced and used material after water. This consumption will increase over the years as indicated in developing countries’ growth on a global scale. Concrete is a mixture of aggregates, water and cement. Because of its properties and durability, there is no suitable alternative in the planet as of now. However, cracks in concrete appear over time due to usage and wear and tear. Because of this, structures need to be rehabilitated.

Hendrik Jonkers, a microbiologist at Delft University, came up with an idea to repair the cracks in concrete, targeting it during its first stages to prevent from reaching concrete reinforcement. He married two concepts: civil engineering and marine biology. This concept was born out of the thought of applying limestone-producing bacteria to monuments in order to preserve them. This innovation was a finalist at the 10th Annual European Inventor Awards in 2015.

 

2. Innovation

             As cracks occur in concrete, water seeps in, thus corroding the material that will lead to its degradation. Hendrik Jonkers’s innovation is designed to repair micro-cracks which embeds limestone-producing bacteria into building material. Bacteria is mixed and distributed evenly with the concrete which can lie dormant for a hundred years. Water and atmospheric moisture serve as catalyst to this process. The healing agent is the limestone produced by a bacteria that reacts as it comes in contact with water and heat. The agent will flow into the crack in a capillary action, the faces are bonded together and the crack is healed. This method is known as bio-mineralization technique, which gives promising results to self-healing concrete.

The application comes in different forms. There is a spray which can be applied to existing construction for repair of small cracks (0.5-0.8mm wide) or a mixture poured while mixing the concrete before construction.

While this is not presently available in the market, field tests are done to examine further the usage of this method. A project in Ecuador was done by Jonkers where they made a concrete canal and irrigation system with self-healing concrete.

Studies on another procedure that focuses on the durability of self-healing concrete with respect to carbonation and chloride ingress has also been initiated and supported by the Korean Government.

Source: www.slideshare.net

 

Source: www.rinnovabili.it

  

    Source: www.industrytap.com

 

3.   Environmental Impact

             According to a WWF report, by 2030, urban growth in China and India will place global cement output at 5bn metric tons per year. With current output already responsible for 8% of the global emissions total, we could see potential in self-healing concrete by reducing the future production of cement. As maintenance of structures are standard safety procedures, one cannot discount the multiple aspects of indirect pollution it contributes: the dust during construction, the smoke emissions of trucks used for bridge repairs and etc.

Although the environmental impact of other sources of pollution is more visible, it is best to address this implicit problem early on. Also, this will help lower maintenance for building owners, home owners and for the government as well.

 

4. Viability

             This technology currently heals no larger than 1mm wide thus it cannot heal wide cracks or potholes on the road. The application of this technology is still under research and development, there is no existing company nor brand that produces the material. Also, the cost for this type of concrete can be prohibitive. The standard price of a cubic meter of concrete is 70 Euros, while the self-healing concrete would cost 100 Euros, according to Jonkers which is roughly 40% higher.

 

Conclusion

            Concrete is the most used material for construction, it is used primarily because of its properties and durability. Concrete is composed of aggregates, water and cement. Due to wear and tear, cracks slowly appear in the concrete. Durability of concrete is impaired by these cracks therefore it is important to heal the cracks as soon as possible before leading to a collapse. Hendrik Jonkers has developed a new type of concrete that has self-healing abilities. His innovation is designed to repair micro-cracks by embedding limestone-producing bacteria into the building material. The bacteria reacts as air and moisture seep into the cracks thus producing the limestone and eventually healing the cracks.

The potential is seen in self-healing concrete to reduce future production of cement. Global cement production accounts for 8% global carbon emissions. This responsible innovation is aimed at targeting the source of with which concrete is made by lowering the amount of global cement production. Self-healing concrete would also contribute to a longer service life of concrete structures thus reducing costs involved in maintenance and repair of these structures. Current development provides only a limited measurement of concrete to be healed as it heals no larger than 1mm wide. Further research is initiated to continuously develop the technology for market availability.

 

References

Spinks, Rosie. “The Self-Healing Concrete that could Fix Itself.” Guardian Sustainable Business.

The Guardian, 29 June 2015. Web. 12 November 2017.

Snoeck, Didier (and team). “Self Healing Concrete” Ugent Department of Structural Engineering.

Ghent University. Web. 12 November 2017

Li, Victor, Yang, En-Hua. (2007) Self Healing in Concrete Materials. Springer Series in Materials Science, vol 100. Springer, Dordrecht