Materials

Next-gen concrete bends instead of cracking

Next-gen concrete bends instea...
Prof. Yang En-Hua with a sample of the ConFlexPave
Prof. Yang En-Hua with a sample of the ConFlexPave
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Prof. Yang En-Hua with a sample of the ConFlexPave
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Prof. Yang En-Hua with a sample of the ConFlexPave
Where traditional concrete breaks, ConFlexPave bends
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Where traditional concrete breaks, ConFlexPave bends

Concrete may generally be a good choice for sidewalks, but it is a brittle material – this means that it needs to be poured thick, in order to keep those sidewalks from cracking under pressure. Scientists from Singapore's Nanyang Technological University, however, are developing an alternative. They've created bendable concrete that they say could be easily applied in the form of relatively thin, light paving slabs.

Ordinarily, concrete is made from a mix of cement, gravel, sand and water. The new material, known as ConFlexPave, additionally contains polymer microfibers. These are thinner than the width of a human hair, and serve to distribute loads evenly across the entire slab, instead of keeping them focused in one location.

As a result, the ConFlexPave is reportedly "tough as metal and at least twice as strong as conventional concrete under bending." As an added benefit, the microfibers are also claimed to enhance the material's skid resistance.

Where traditional concrete breaks, ConFlexPave bends
Where traditional concrete breaks, ConFlexPave bends

The researchers envision the slabs being manufactured ahead of time in a factory, and then simply being brought to construction sites and laid down as needed. This would not only be less labor-intensive than pouring traditional concrete, they say, but it would also take only about half the amount of time. When damage did eventually occur, individual slabs could just be pulled out and replaced – as is already the case with brittler regular concrete paving slabs.

ConFlexPave has so far been tested in the lab, using tablet-sized pieces. There are now plans to install full-size slabs in locations around the university campus, to see how they stand up to pedestrian and vehicular traffic over the next three years.

Source: Nanyang Technological University

6 comments
BartyLobethal
Less concrete requires less energy to manufacture which means lower costs. The article only mentions development for paving, but I would think this could also be used in the footings of domestic and smaller commercial buildings. In areas with reactive clay soils this should be more resistant to cracking than conventional mixes.
hibni
Fiber Reinforced Concrete has been around for years, if not decades. What is the innovation here? Micro-fibers instead of fibers? More strength? More ductility? It is not clear.
Bob Stuart
"As tough as metal and at least twice as strong as conventional concrete under bending" is about as informative as "as big as a boat." There are brittle metals, and a very wide range of concrete grades. Please, is the stuff ductile, or merely flexible? Can the advantage rival pre-stressed concrete? Is it any better than the similar tests from decades ago? How does the fiber affect mixing? Even a few percent can make a huge difference there. Pre-fab slabs are old news - you just get the same reduced transport weight as for wet mix.
Future3000
hibini you're right! Glass-, Ploymerfiber reinforced concrete is well known since decades, natural fiber reinforced concrete since Mr. Monier (modern reinventor of concrete). The problem in this shown case are the microcracks in the concrete. So water comes in. Probably in Nanyang it's warm, but in Europe we have winter, so the water inside the reinforced concrete freeze and crack the rest of the concrete... Company Züblin in Germany made a LOT of these tests in early 1990's
D_trigger2113
Who got there first? U of M has a tiny stretch of road with "super" concrete here in MI. though we could really start using it on all the other roads here for sure. http://www.engin.umich.edu/college/about/news/stories/2012/may/super-concrete
Douglas Bennett Rogers
This is interesting because it is a big area of confusion. The unusual property of the concrete is that it is ductile, like soft metal. There is already "ductile concrete" but I am not sure if it is truly ductile. The ductility may reside in the reinforcement. The ductility here seems to be due to fiber pullout, as in incompatibly bonded fiberglass.