Week 2 Journal
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.
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.
Figure 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.