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posted by cmn32480 on Saturday May 16 2015, @05:57PM   Printer-friendly
from the it's-alive! dept.

A team of microbiologists from the Delft University of Technology claims to have invented "bioconcrete" — concrete that heals cracks and breaks using bacteria. The goal was to find a type of bacteria that could live inside concrete and also produce small amount of limestone that could re-seal cracks. This is a difficult prospect because concrete is quite dry and strongly alkaline. The bacteria needed to be able to stay alive for years in those conditions before being activated by water. The bacteria also need a food source — simply adding sugar to concrete will make it weak. The scientists used calcium lactate instead, adding biodegradable capsules of it to the concrete mix. "When cracks eventually begin to form in the concrete, water enters and open the capsules. The bacteria then germinate, multiply and feed on the lactate, and in doing so they combine the calcium with carbonate ions to form calcite, or limestone, which closes up the cracks."

One thing that is left out of the articles mentioned above is the amount of time needed for a given crack to "heal" closed.

Related Stories

Micron-Sized Calcium Silicate Spheres Can be Used to Make Stronger Concrete 15 comments

Spheres can make concrete leaner, greener: Rice's microscopic particles promise stronger building materials and more

Rice University scientists have developed micron-sized calcium silicate spheres that could lead to stronger and greener concrete, the world's most-used synthetic material.

To Rice materials scientist Rouzbeh Shahsavari and graduate student Sung Hoon Hwang, the spheres represent building blocks that can be made at low cost and promise to mitigate the energy-intensive techniques now used to make cement, the most common binder in concrete.

The researchers formed the spheres in a solution around nanoscale seeds of a common detergent-like surfactant. The spheres can be prompted to self-assemble into solids that are stronger, harder, more elastic and more durable than ubiquitous Portland cement.

[...] The work builds on a 2017 project [DOI: 10.1021/acsami.7b12532] [DX] by Shahsavari and Hwang to develop self-healing materials with porous, microscopic calcium silicate spheres. The new material is not porous, as a solid calcium silicate shell surrounds the surfactant seed.

Size- and Shape-Controlled Synthesis of Calcium Silicate Particles Enables Self-Assembly and Enhanced Mechanical and Durability Properties (DOI: 10.1021/acs.langmuir.8b00917) (DX)

Related: Biologists Create Self-Healing Concrete
Probing Ways to Turn Cement's Weakness to Strength
Roman Concrete Explained
The Rock Solid History of Concrete
Fungi Can Help Concrete Heal Its Own Cracks


Original Submission

Self-Healing Concrete Uses CO2 to Repair Itself 23 comments

Self-healing concrete eats CO2 to fill its own cracks in 24 hours:

Concrete has a massive carbon footprint, so technologies that boost its performance and enable it to last longer could have profound benefits for the environment. This has led to the development of self-healing concrete that can repair its own cracks, and scientists have now demonstrated an exciting new form of this that makes use of an enzyme found in human blood.

Tiny cracks that form in concrete mightn't pose an immediate problem to the structural integrity of a construction, but as water gets in and the rupture spreads it can greatly compromise its strength. The idea with self-healing concrete is to intervene in this process while the cracks are still tiny, sealing up the material to prevent not just a catastrophic collapse, but expensive maintenance or a complete replacement of the structure.

[...] Through their testing, the scientists demonstrated their doped concrete can repair its own millimeter-scale cracks within 24 hours. The team says this is a marked improvement on some previous technologies that have used bacteria to self-heal, which are more expensive and can take up to a month to heal even far smaller cracks.

While the amount of CO2 the concrete gobbles up is likely to be negligible in the grand scheme of things, the real environmental potential of the material lies in its potential longevity. Rahbar predicts that this type of self-healing technology could extend the life of a structure from 20 years to 80 years, which reduces the need to produce replacement concrete in what is a notoriously carbon-intensive process.

There is a related 44-second video on YouTube.

Previously:
Biologists Create Self-Healing Concrete
Fungi Can Help Concrete Heal Its Own Cracks


Original Submission

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  • (Score: 2) by t-3 on Saturday May 16 2015, @06:30PM

    by t-3 (4907) on Saturday May 16 2015, @06:30PM (#183796)

    Maybe Michigan roads won't be so shitty once this gets rolled out. I really hope it works.

    • (Score: 4, Funny) by Jeremiah Cornelius on Saturday May 16 2015, @07:18PM

      by Jeremiah Cornelius (2785) on Saturday May 16 2015, @07:18PM (#183808) Journal

      I believe that this is how Greyscale was introduced to Westeros.

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    • (Score: 0) by Anonymous Coward on Saturday May 16 2015, @08:06PM

      by Anonymous Coward on Saturday May 16 2015, @08:06PM (#183813)

      Nah. There are just way too many freeze-thaw cycles. What would happen is a crack would form with contraction, the crack would be filled in, then expansion would cause the whole are to buckle. Instead of potholes you would get ridges. We already see that when they decide it is a good idea to run road maintenance into the colder months. Come spring, right now, these ridges form where cracks were the year before.

  • (Score: 1, Interesting) by Anonymous Coward on Saturday May 16 2015, @07:26PM

    by Anonymous Coward on Saturday May 16 2015, @07:26PM (#183809)

    Anyone into science fiction might have read some Allistar Reynolds http://www.alastairreynolds.com/ [alastairreynolds.com]

    In his novels, the plague, a rouge disease twists and contorts his concrete jungles.

    Here we go.

    • (Score: 0) by Anonymous Coward on Saturday May 16 2015, @10:37PM

      by Anonymous Coward on Saturday May 16 2015, @10:37PM (#183857)

      It would be interesting to see how biological roads could be turned into biological weapons.

      The sandpeople in Dirkadirkastan already turned roads into weapons... to the point where American soldiers are scared shitless of stepping on or driving over an IED.

    • (Score: 2) by tibman on Sunday May 17 2015, @06:01AM

      by tibman (134) Subscriber Badge on Sunday May 17 2015, @06:01AM (#183971)

      I really like that universe : ) You are talking about http://en.wikipedia.org/wiki/Chasm_City [wikipedia.org]

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  • (Score: 2) by darkfeline on Sunday May 17 2015, @11:04PM

    by darkfeline (1030) on Sunday May 17 2015, @11:04PM (#184209) Homepage

    The first test is whether the bacteria can repair cracks faster than the earth moves. Most cracks are created by geological activity/plate tectonics. If the bacteria works faster than that, then it will be very useful in keeping concrete structures crack-free.

    Actually, while writing this I realized that there's a big flaw in this. The concrete will crack under stress at its weakest point, which is likely the same point where it cracked before. Even if the rest of the concrete is still "active" and self-repairable, the part that keeps cracking will likely lose its self-repair ability very quickly, rendering the whole thing moot.

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