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Student creates cost-effective self-healing concrete?

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May 27, 2010

Michelle Pelletier with her self-healing concrete

Michelle Pelletier with her self-healing concrete

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Self-healing “smart building materials” have the potential to reduce structure repair costs, lower cement-production carbon emissions and even save lives. One barrier that has kept these materials from being commercialized, however, is their potentially labor-intensive and thus expensive production process. Recently, an engineering student from the University of Rhode Island (URI) announced that she has developed a self-healing concrete that would be inexpensive to produce.

Michelle Pelletier, collaborating with URI Chemical Engineering Professor Arijit Bose, created a concrete matrix that was embedded with a micro-encapsulated sodium silicate healing agent. When cracks formed in the concrete, the capsules ruptured and released the agent into the adjacent area. The sodium silicate reacted with the calcium hydroxide already present in the concrete, and formed a calcium-silica-hydrate gel that healed the cracks and blocked the concrete’s pores. The gel hardened in about one week.

When Pelletier’s concrete was stress-tested to the point of almost breaking, it proceeded to recover 26% of its original strength. By contrast, conventional concrete only recovers 10%. Pelletier believes that she could boost the strength of her mix even higher, by increasing the quantity of the healing agent.

Michelle Pelletier's self-healing concrete

Other researchers have tried using bacteria spores that secrete calcium carbonate, or glass capillaries filled with a healing agent. According to Pelletier, her mix would be more cost-effective because it would be simpler to produce, and function more efficiently. “Smart materials usually have an environmental trigger that causes the healing to occur,” she said. “What’s special about our material is that it can have a localized and targeted release of the healing agent only in the areas that really need it.”

Pelletier is now researching how well the healing agent would work for minimizing the corrosion of steel rebar within concrete structures.

About the Author
Ben Coxworth An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away.   All articles by Ben Coxworth
5 Comments

Good ole liquid glass (sodium metasilicate Na2SiO3) great for cracked heads and blown head gaskets too! Great idea smart thinking.

greytoma
28th May, 2010 @ 03:02 am PDT

I live in a house built with self-healing mortar, which is a good thing as it is built on sand with little foundation. The house has been here a long time, it was extended in 1760 and again in 1790. Concrete is a mixture of Portland Cement and aggregate. Before Portland Cement was invented, houses in the UK were built using lime mortar, which heals after cracking. Under cracking conditions, Portland Cement breaks, whereas lime often produces numerous microcracks if the amount of movement is small. These microcracks then recrystallise on exposure to air, effectively self-healing. Lime mortar degrades to non polluting constituents and has a much smaller carbon footprint than Portland Cement. It's been around since the 4th century AD, so Ms Pelletier might have a wee problem patenting her product.

Doug MacLeod
30th May, 2010 @ 05:54 am PDT

@ Doug:

Copying from Wikipedia? Without citation? Dude.

Your comment is pointless and useless. Lime mortar is not concrete, and it's more difficult to work with, which you'd know from reading the Wikipedia article you so tastefully copied from. Plus, this is clearly an improvement of sorts on concrete itself, so ... eat a sock? Honestly, I don't know what to say. Not patentable? Seriously?

Congratulations, Pelletier. An improvement of healing strength by 150% over its previous value is incredible.

Andrew Reinders
8th September, 2010 @ 06:58 am PDT

Hello! I graduate from Belgorod State Technological University. Similarly, the question we zaniaemsya for several years. In our case, sodium silicate obtained already in the granular filler, added to the concrete after heat treatment. Our areas have a diameter of about 5 millimeters. Sodium Silicates react with concrete, reinforcing microcracks thereby increase its strength.

And how do you get the pellets? We could cooperate in this matter.

My e-mail amaksa@bk.ru

Facebook User
12th December, 2010 @ 11:48 pm PST

Add this with a house size 3d printer and you would self healing houses thats stronger then concrete ;-)

Nathan Jeffree
12th March, 2012 @ 09:08 am PDT
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