Carbon Cast Concrete

Alli Dryer — Fri, 25 Jun 2010 19:51:57 +0000

Carbon fiber is one of those futuristic-sounding, expensive materials that I associate with supersonic airplanes, fancy road race bicycles, and $400,000 dining tables. So imagine my surprise when I found out that, back in 2003, a group of precast concrete companies banded together with carbon fiber grid provider Chomarat to form AltusGroup, who manufacture a product called Carbon Cast Concrete. “AltusGroup members use Chomarat’s C-GRID®, as the carbon fiber epoxy based reinforcing in several precast building system products to enhance the strength and reduce the weight of precast concrete” (Drabestott). Reinforcing humble precast concrete with glamorous carbon fiber seems a lot like parading Susan Boyle around in haute couture, but whatever it’s CARBON FIBER.

Image credit www.bornrich.org

Carbon Cast concrete “uses conventional steel for primary reinforcing and C-GRID epoxy-coated carbon fiber composite grid for secondary reinforcing and shear transfer. This allows the material to be very lightweight compared to normal reinforced concrete” (Wright). The C-GRID is made with continuous PAN (polyacrylonitrile) carbon fibers and epoxy resin — the same materials as carbon/epoxy golf clubs and aerospace parts. The carbon strands are chemically bonded together at the intersections with epoxy resin (AltusGroup).

Images courtesy AltusGroup

So here are a few reasons Carbon Cast Concrete is great:

Non Corrosive: unlike typical steel reinforcing, the carbon fiber grid will not oxidize, nor will it cause rusting, staining or spalling. This allows precast manufacturers to reduce the amount of concrete over the grid by up to three inches. They use less concrete per panel, which reduces weight and raw material usage. This also increases the durability of the concrete.

Light Weight: less concrete means lighter pieces – up to 50% lighter in wall panels and up to 8% in double tees. Lighter weight components mean lighter structure, reducing costs for everything from transportation to construction cranes. Lighter pieces also speed erection time because it’s easier and faster to maneuver them into position.

Thermal efficiency: carbon fiber grids improve thermal performance. Because carbon fiber has low thermally conductivity, it reduces the transfer of heat or cold from outside to inside. “The insulation embedded in the walls can deliver 100 percent of its rated performance without hot spots or cold spots. As a result, building owners can benefit from long-term energy savings and a smaller investment in HVAC equipment” (AltusGroup).

Here’s why you won’t be using it:

Cost: Carbon fiber grids costs about twice as much as the conventional steel reinforcing it replaces.

WU XING:

I’m filing Carbon Cast Concrete under EARTH because of the carbon.

Cited:

Drabenstott, Michael. “Carbon Fiber Growing as Reinforcing Material in Precast Concrete.” Carbon Fiber Gear Blog. Accessed 06/25/10. URL.

Wright, Fiona. “Carbon Cast Concrete.” EzineArticles.com. Accessed 06/25/10. URL.

Is Graphene Elvis or the Russell Brand of Materials?

Alli Dryer — Wed, 23 Jun 2010 19:53:26 +0000

Say what you will about Elvis Presley and his rhinestone-studed white jumpsuits, the man definitely made waves in movies and the music world. Even half a century after his heyday I still catch Blue Hawaii airing on TV and even incurious millenials know Heartbreak Hotel. In contrast to Elvis, I offer you Russell Brand: a man who appears to live life like a young Bret Michaels, and whose notoriety stems from a certain abrasive yet undeniable charisma. Will Russell Brand’s … er … brand … stand the test of time? Is he another Elvis? I think not.

Image credit http://www.entertainmentwise.com

If there were a Rolling Stone magazine equivalent for the materials science set, graphene would be on the cover. Graphene consists of “single-atom–thick sheets of carbon prized for its off-the-charts ability to conduct electrons and for being all but transparent” (Service). Graphene, like Russell Brand, has some intriguing qualities: it’s extremely strong and highly conductive, which along with its transparency, make it an attractive alternative for use as a transparent conductor. Everything from computer displays and flat panel TVs to ATM touch screens and solar cells use transparent conductors these days, and finding a material that is strong, thin, and flaw-free has been a challenge.

Image credit http://www.lbl.gov

According to Moore’s Law, the density of transistors on an integrated circuit doubles every two years. Silicon and “other existing transistor materials are thought to be close to the minimum size where they can remain effective. Graphene transistors can potentially run at faster speeds and cope with higher temperatures. Graphene could be the solution to ensuring computing technology to continue to grow in power whilst shrinking in size, extending the life of Moore’s law by many years” (Science Daily). In other words, graphene might be about to drop Jailhouse Rock.

Since scientists first isolated graphene in 2004, they’ve struggled to produce the carbon sheets in sizes large enough to be useful. Last year, a group led by University of Texas, Austin chemist Rodney Ruoff grew graphene squares one centimeter square atop flexible copper foils. A few days ago, a group of researchers led by Jong-Hyun Ahn and Byung Hee Hong of Sungkyunkwan University in South Korea submitted a report in Nature Nanotechnologydescribing their efforts to scale up the approach taken by the Texas team to make graphene sheets large enough for full-screen displays (Service).

The graphene microchip. (Credit: Photo / Donna Coveney)

Ahn and Hong et al used chemical vapor depositionto grow graphene on large sheets of copper foil. A thin adhesive polymer was layered on top of the graphene, and then the copper backing was dissolved away. “Peeling off the adhesive polymer gave them a single graphene sheet. To make their film stronger, they repeated the initial steps, layering four sheets of graphene atop one another. The researchers then chemically treated their graphene sandwich with nitric acid to improve its electrical conductivity. The film allowed 90% of light to pass through and had an electrical resistance lower than that of the standard transparent conductor made from indium tin oxide (ITO)” (Service).

Credit: Jong-Hyun Ahn et al., Nature Nanotechnology, Advance Online Publication (2010).

Graphene could be used to make more efficient/cheaper solar cells, better large screen displays for electronics, and so on. If the larger sheet sizes pan out, we might just be looking at the Elvis of materials. Time will tell.

WU XING:

I’m filing graphene under EARTH because it’s carbon-based.

Cited:

Science Daily. “Breakthrough in Developing Super-Material Graphene.” 01/19/10. Accessed 06/23/10. URL.

Service, Robert F. “Graphene Finally Goes Big.” Science Now. 06/20/10. Accessed 06/23/10. URL.

carbon – ARCHITERIALS

Carbon Cast Concrete

Is Graphene Elvis or the Russell Brand of Materials?