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posted by martyb on Tuesday January 23 2018, @08:19AM   Printer-friendly
from the wise-cracks dept.

[researchers] have found an unusual candidate to help concrete heal itself: a fungus called Trichoderma reesei.

We initially screened about 20 different species of fungi in order to find one that could withstand the harsh conditions in concrete. Some we isolated from the roots of plants that grew in nutrient-poor soils, including from the New Jersey Pine Barrens and the Canadian Rocky Mountains in Alberta.

We found that as calcium hydroxide from concrete dissolved in water, the pH of our fungal growth medium increased from a close-to-neutral original value of 6.5 all the way to a very alkaline 13.0. Of all the fungi we tested, only T. reesei could survive this environment. Despite the drastic pH increase, its spores germinated into threadlike hyphal mycelium and grew equally well with or without concrete.

We propose including fungal spores, together with nutrients, during the initial mixing process when building a new concrete structure. When the inevitable cracking occurs and water finds its way in, the dormant fungal spores will germinate.

As they grow, they'll work as a catalyst within the calcium-rich conditions of the concrete to promote precipitation of calcium carbonate crystals. These mineral deposits can fill in the cracks. When the cracks are completely caulked and no more water can enter, the fungi will again form spores. If cracks form again and environmental conditions become favorable, the spores could wake up and repeat the process.

The spores wake up when cracks form in concrete and admit moisture.


Original Submission

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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: 0) by Anonymous Coward on Tuesday January 23 2018, @08:35AM (1 child)

    by Anonymous Coward on Tuesday January 23 2018, @08:35AM (#626461)

    why don't we make a chunk of cement with these spores in it, and throw it on Europa? (the satellite, not the continent or the goddess).
    that would be one way of ensuring that the basic building blocks of live survive the death of the Sun (and probably humanity).

    • (Score: 5, Insightful) by bootsy on Tuesday January 23 2018, @11:50AM

      by bootsy (3440) on Tuesday January 23 2018, @11:50AM (#626518)

      I for one welcome our new Mycotal Jovian overlords

  • (Score: 0, Offtopic) by Anonymous Coward on Tuesday January 23 2018, @10:22AM

    by Anonymous Coward on Tuesday January 23 2018, @10:22AM (#626484)

    I suppose it is too early for an Ethanol_fueled butt-crack application? Asking for a friend.

  • (Score: 2) by GreatAuntAnesthesia on Tuesday January 23 2018, @10:58AM (4 children)

    by GreatAuntAnesthesia (3275) on Tuesday January 23 2018, @10:58AM (#626503) Journal

    So these spores fill the gaps in the concrete, but where do they get the materials to do so? There's only one place they can get it, and that's from the concrete itself.
    Does this mean that whenever the spores fill a gap, they weaken the concrete around the gap? Could this be mitigated by somehow providing the spores with an alternate food source? Periodically spraying structures with calcium-rich liquid?

    • (Score: 4, Interesting) by looorg on Tuesday January 23 2018, @12:49PM (1 child)

      by looorg (578) on Tuesday January 23 2018, @12:49PM (#626529)

      Indeed. What happens to the structural integrity of the concrete if it becomes all fungi filled? If it is the same then why just not replace concrete with it. My guess is that it doesn't have the same (or better) properties then concrete. So the fungi would just be a temporary fix so there doesn't come more water etc down into the crack until you have time to actually repair the construct. Somehow out of sight soon becomes out of mind and then people get all shocked and surprised when something collapses.

      researchers will need to conduct a thorough assessment to investigate any possible immediate and long-term effects on the environment and human health prior to its use as a healing agent in concrete infrastructure.

      We still don't fully understand this very young but promising biological repair technique.

      • (Score: 2) by bob_super on Tuesday January 23 2018, @08:21PM

        by bob_super (1357) on Tuesday January 23 2018, @08:21PM (#626730)

        > the structural integrity of the concrete if it becomes all fungi filled?

        Peace on Earth: Looking forward to exploding heads of the conspiracy theorists who scream about jet fuel melting steel beams, when you tell them about concrete that may burn.

    • (Score: 0) by Anonymous Coward on Tuesday January 23 2018, @01:52PM

      by Anonymous Coward on Tuesday January 23 2018, @01:52PM (#626544)

      There should be more than enough concrete, so weakening the concrete around does not matter (plus, the material it "steals" would probably have been washed away by the water anyway).
      The point is likely to prevent water from washing out tiny cracks and have them become deeper and deeper, and particularly badly if the water freezes in them.

    • (Score: 2, Informative) by khallow on Tuesday January 23 2018, @04:01PM

      by khallow (3766) Subscriber Badge on Tuesday January 23 2018, @04:01PM (#626592) Journal

      Does this mean that whenever the spores fill a gap, they weaken the concrete around the gap?

      That sounds reasonable. But an unplugged gap will weaken the concrete around the gap more since it isn't a process that halts.

  • (Score: 0) by Anonymous Coward on Tuesday January 23 2018, @12:36PM (1 child)

    by Anonymous Coward on Tuesday January 23 2018, @12:36PM (#626526)

    If this really works, it sounds like it could extend the life of concrete highways, preventing/postponing frost cracking. In which case the highway builders (and the politicians in their pockets) will never have it.

    • (Score: 2, Insightful) by khallow on Tuesday January 23 2018, @04:03PM

      by khallow (3766) Subscriber Badge on Tuesday January 23 2018, @04:03PM (#626593) Journal
      Except of course, if the licensers of the technology pay the appropriate kickbacks. That works even in rocket science.
  • (Score: 1, Insightful) by Anonymous Coward on Tuesday January 23 2018, @04:38PM (2 children)

    by Anonymous Coward on Tuesday January 23 2018, @04:38PM (#626616)

    Impregnating all concrete with live fungal spores that are constantly growing in some piece of concrete around you at any given moment sounds like a major health hazard. Has anyone ever lived in a house with a moldy basement? It can make you really sick.

    • (Score: 0) by Anonymous Coward on Tuesday January 23 2018, @05:04PM (1 child)

      by Anonymous Coward on Tuesday January 23 2018, @05:04PM (#626630)

      You could, you know, plaster over the concrete on interior surfaces? Or don't use it in your house.

      This sounds like a great idea. Whatever the fungus does is MUCH PREFERABLE to what water + freezing cycles will do.

      • (Score: 1, Insightful) by Anonymous Coward on Tuesday January 23 2018, @05:18PM

        by Anonymous Coward on Tuesday January 23 2018, @05:18PM (#626637)

        "Plaster over the concrete inside your house."

        Sounds like someone has zero experience with how that works on concrete that has moisture problems. Hint: it doesn't last even 6 months.

        And the concern is not ONLY basements, but the entire built environment. Another hint: seasonal outdoor mold issues affect A LOT of people. An enclosed space is not necessary, although that certainly makes it worse.

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