Summary Reader Response Draft #4

In the article, “The Self-Healing Concrete That Can Fix Its Own Cracks,” Spinks (2015) states that Hendrik Jonkers created self-healing concrete innovation to “decrease the amount of new concrete produced, lower maintenance and repair costs for city officials, building owners and homeowners” by inlaying self-activating limestone-producing bacteria into the concrete. The self-healing concrete has a longevity of up to 200 years and helps to reduce carbon emitters. However, the concrete can only repair up to 0.8mm wide of cracks and cost €30 per metre cube more than normal concrete. According to Alker, who is director of policy at the UK Green Building Council, it will be hard to convince the industry to adopt the new innovation. It will take unconventional consumers and developers who are willing to test their building with the new concrete to demonstrate positive results before others will support it. Jonker has also been experimenting across the world where he claims that the people realized the profit because they can save from maintenance cost.

 

Spinks discussed the advantages and disadvantages of self-healing concrete but failed to mention how the researchers can improve on its short-comings, which are the hefty cost, limited healing ability and limited durability.

 

The first point is overcoming the hefty cost of self-healing concrete. Li (2012), states that the current cost cycle of normal concrete has a high cumulative cost over time due to additional costs and maintenance fees. However, in comparison, the self-healing concrete may have a high initial cost of 45 SGD, but its healing ability assures the quality of the infrastructure with minimum, or no additional cost added to the cost cycle. This suggests that the cost cycle of self-healing concrete and normal concrete are competitive. The total cost cycle of both concretes may be very similar in the long run. The best way of overcoming the hefty cost of self-healing concrete is to educate consumers and developers to look at the benefits instead of focusing on the initial cost.

 

The next point is improving the healing ability of self-healing concrete. According to Xu(2019), self-healing concrete should ideally have a “highly porous structure as it can provide oxygen, water and growth space to bacteria after concrete cracks”. In the article by Xu(2019), it was said that rubber particles obtained from scrap rubber tires are incorporated into the self-healing concrete to decrease its brittleness. It resulted in a smaller crack width as compared to normal concrete. By reducing the crack width when the concrete is damaged, the self-healing concrete would be able to repair the cracks within its ability.

 

Lastly, Spinks also failed to mention how to increase the durability of the self-healing concrete. Silica powder, bacteria (Bacillus Subtilis), and sodium chloride can be added into the self-healing concrete. Hussein (2019) mentioned that silica powder, bacteria (Bacillus Subtilis), and sodium chloride were added to improve the properties of self-healing concrete. Different concentrations of the bacteria (Bacillus Subtilis) were added to the concrete mixture before conducting experiments to test for water absorption and compressive strength. It was noted that there was an increase in compressive strength and density in the specimen with the bacteria. This shows that introducing different bacteria into the self-healing concrete is the approach done to improve its durability.

 

All in all, Spinks mentioned the advantages and disadvantages of self-healing concrete. However, she did not mention how it can be improved on. There are many ways in which self-healing concrete can be further improved, and I believe these are the deciding factors which can win over the risk-averse construction industry.

 

 References 

Anbarlouie, M., Mahdikhani, M., & Maleki, A. (2018, October 16). The contribution of encapsulated Polyurethane adhesive in improving the static TORSIONAL resistances of self-healing concrete beam Comparing BONDED Frp technique. Journal of Construction and Building Materials 904-911.

https://www.sciencedirect.com/science/article/pii/S0950061818323705

Hussein1, Z. M., Abedali1, A. H., & Ahmead2, A. S. (2019, August 1). Improvement Properties of Self Healing Concrete by Using Bacteria. IOP Conf. Ser.: Mater. Sci. Eng. 584 012034.

https://iopscience.iop.org/article/10.1088/1757-899X/584/1/012034/meta.

Li, V. C., & Herbert, E. (2012, June 28). Robust self-healing concrete for sustainable infrastructure. Journal of Advanced Concrete, 10(6), 207-218.

https://www.jstage.jst.go.jp/article/jact/10/6/10_207/_article/-char/ja/

Spinks, R. (2015, June 20). The self-healing concrete that can fix its own cracks. The Guardian. 

https://www.theguardian.com/sustainable-business/2015/jun/29/the-self-healing-concrete-that-can-fix-its-own-cracks

Xu, H., Lian, J., Gao, M., Fu, D., & Yan, Y. (2019, July 19). Self-Healing Concrete Using Rubber Particles to Immobilize Bacterial Spores. Materials, 12(14). 

https://www.mdpi.com/1996-1944/12/14/2313