Bio-Concrete:Self Healing

Week 2 Journal

150514134529-spc-make-create-innovate-self-healing-concrete-00031527-super-169Figure 1.

Since the use of concrete, human society has been profited from it a lot, speeding up the city construction, reinforce the structure of bearing more loads, and so on. However, it is also a pain for people to keep spending money and labor to maintain the concrete structure since concrete can easily crack in years. Cracks in concrete also increase the danger of people using the structure.

Screenshot (1).jpgFigure 2.

Recently, Dutch microbiologist Hendrik Marius Jonkers has invented a new type of concrete which can heal itself when the concrete cracked. The self-healing concrete is a mixture of concrete, bacteria called Basillus Pseudofirmus, and the nutrition for the bacteria calcium lactate.  The bacteria are dormant in the concrete and can “sleep” up to 200 years. When the concrete cracks, rainwater can flow into the cracks and “wake up” the bacteria. Bacteria then starts consuming calcium lactate to produce limestone to fill up the crack (shows in Figure 2). The self-healing process takes only 3 weeks.

growth_spurt_11Figure 3.  Self Healing

It sounds like a perfect innovation for concrete to expand the life to hundred years without human maintenance. However, is the “bacteria” reliable? Limestone produced by bacteria is a common stone abundantly found in nature. The hardness of limestone is only 3 level, which is a little harder than fingernails and can be easily scratched by copper coins. It may not provide enough hardness to support the concrete.  The danger caused by crack is not 100% solved. Another potential problem is that it can aggravate the unemployment rate since there are millions of people in the world who’s jobs are maintaining road and road construction. Overall it is still a brilliant innovation to expand life of concrete. Let’s count on future technology to produce never-cracked concrete.

 

Source:

http://www.architectmagazine.com/technology/five-cutting-edge-architectural-materials-to-watch-in-2016_o

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One comment

  1. heit0098umnedu

    Journal 2
    Response to Bio-concrete:Self Healing
    A Cautionary Response Towards Innovation
    Concrete that can repair itself with bacteria may at first appear like a step in the right direction for sustainable and economical building for the future yet we may be getting into something a lot more complex than more durable concrete. Views on Bio-concrete seem to show an overconfidence in the current capability of the innovation, little thought put into the concrete as an ecological component to a greater system and human health concerns related to living organisms used in the built environment.

    As explained previously, limestone’s ability to really act as a long term durable fix to cracking concrete in anything larger than a lifeguard stand is yet to stand the test of time. Also the softness of limestone seems especially inappropriate for the concretes toughest applications such as in pavement where this type of innovation is needed the most. Where tires, moving water and salt act to rip away the limestone repairs before any benefit is seen to hold up the concrete. Another concern is related to a living creature being designed to operate within indoor air quality standards. Are there any possible health side effects if it were to enter someone’s system? Or more specifically is it safe to use this type on concrete in hospitals where these standards are most strict? Also introducing a living organism at such a large scale is likely to have a great effects on the ecosystems they operate in. In any conversation about living concrete so far there has been no mention of its role and effects on living things nearby it. Before using this substance in any larger scale project there should be further study taken to insure its safety and what role it plays to operate within a greater system.

    Source:
    http://bgr.com/2015/05/17/self-healing-concrete-limestone-producing-bacteria/
    http://www.cnn.com/2015/05/14/tech/bioconcrete-delft-jonkers/

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