Concrete on the half-shell

It’s amazing how a concept as ancient as concrete can be made fresh and new through endless innovation.

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By Korky Koroluk

It’s amazing how a concept as ancient as concrete can be made fresh and new through endless innovation.

I’m thinking here of ultra-high-performance concrete (UHPC), and the dramatic things you can do with it.

When Lafarge Canada Inc. first introduced its UHPC, called Ductal, the company’s Andy Radler and I had a long conversation about it and the possibilities it offered. I was intrigued then; I still am.

Because of my interest in innovation of all sorts, I read a lot of newsletters. One of the best for keeping up to date with the world of concrete is called Concrete Technology Today, published by the Portland Cement Association.

The latest issue arrived just a few days ago, and as its lead item it has an article on the use of UHPC in the construction of 24 curved canopies supported on single columns, at a light rail transit station in Calgary.

UHPC (specifically Ductal) was chosen because of its unique combination of ductility, strength, and durability in an easily moulded product with a pleasing finish.

The precast canopies were produced by Lafarge as halfshells, individually cast by injection into closed steel forms. The columns were made the same way, while other components, like struts and tie beams, were conventionally cast. The half-shells and tie beams were pre-assembled at the casting plant.

The newsletter contains a lot more detail, of course, and a couple of photos, including one of the finished station. The shell-like canopies appear graceful, almost airy, and turn something as mundane as a transit station into a nice addition to the cityscape.

It’s a structure that would not have been possible with conventional concrete. The airy look I mention was achieved because the canopies are extremely thin—just 20 mm, or about three-quarters of an inch.

The article also includes a table summarizing test data from the production of the canopies. The newsletter is, after all, aimed at architects, engineers and concrete technologists. But it will also appeal to general contractors, pre-casters and just about anyone else who makes their living working, at least in part, with concrete.

It is published three times a year and arrives by e-mail. You can see the current issue and subscribe to future issues at www.concretetechnologytoday.org

There is, of course, a lot more information about concrete from the Portland Cement Association, at www.cement.org

The Cement Association of Canada is another goldmine of information. In fact, the publications offered for sale in the newsletter are available at either association. You can find them and a whole bunch of other good stuff at www.cement.ca

If you want more information about Ductal specifically, there are many photos and a lot of technical information at www.imagineductal.com

Click on Products, then on Ductal. You will also find a link to an article outlining the reaction by Alberta engineers to UHPC.

If you’re really, really keen, there is an international symposium in Germany next month on UHPC. You can find more on it at www.uni-kassel.de/uhpc2004

Finally, a note of thanks and a request.

David Lynch, a project manager with the Peel District School Board, sent a message saying he found the recent columns on spam (and other pests) useful. Thanks, David, for your kind words.

I’d like to ask two other readers to contact me again. I’ve been playing with a new e-mail client, and some messages have been lost. One was from a reader suggesting a discussion of online tenders and drawings in CAD format. The other reader needed some sources of information about biodiesel fuel.

I’d like to explore both subjects further, so would whoever sent those messages, please send them again? The disappearing e-mail problem has, I hope, been solved.

You’re always welcome to comment on anything you see in this column, or suggest topics for discussion. You can reach me at korkykoroluk@rogers.com