The glue that holds it all together |

The glue that holds it all together

Alan Braunholtz

Lionshead now proudly sports a huge hole. It’s big enough to transcend being just another ugly building site. The size and complexity of filling a hole this big, in the correct order, intrigues the mind. I’m guessing the average guest will find our “big dig” at least as fascinating as the 1970s architectural subtleties of the old gondola building.Even now, finding your way around Lionshead is easier than before. There’s no concrete plaza with endless Salvador Dali steps to get lost in. The commonsense tactic of avoiding walking into a mud pit and following the informative wall with view windows is all you need to find the ski lifts.At the moment the hole is its own best promoter. You know that something serious is being built and you’ll want to come back and see what. Luckily, Colorado is a rocky place. The sand and mud of New Orleans requires 100-meter deep foundations to avoid tower blocks tipping like gravestones.Concrete is the material of choice for foundations and it’s all over the place. The world lays about 1 ton of concrete per person per year. That’s quite a legacy of architectural artifacts for some alien race or smart rodent ancestor to dig up after we’ve gone the way of the dinosaurs.Concrete is so common we take it for granted. We shouldn’t. It’s fascinating stuff and perhaps more responsible for modern society than anything else. Concrete drains and sewers have probably saved more lives through preventing disease than any medical campaign.Concrete is literally dirt cheap. It’s basically dirt held together with cement – the cheapest glue ever. Cement is a mix of powdered clay, limestone and chalk burnt to ash in a kiln. These ashes are then ground to dust and that’s it. Add water and it reacts to form interlocking calcium silicate hydrate crystals that hold the mix together. There are some other reactions going on too. Some help and some weaken the bond. It’s quite complex, really.The Romans used a cement made from volcanic ash and lime, but this knowledge vanished with their empire. In 1824, a tinkering Yorkshire stone mason invented the process to make modern cement. He called it Portland cement due to its resemblance to the most popular quarried rock at the time, which came from Portland in Dorset, England.It’s so essential to building that there’s a worldwide shortage as the planet’s construction boom continues. China produces over a third of the world’s cement but consumes about half with huge dams, pre-Olympic construction and general economic growth. The tsunami created a demand for reconstruction and India is growing rapidly, too. Cargo ships find a Europe/-China loop more profitable, so there’s also a shortage of ships willing to bring it here and we import a quarter of the cement we use. It’s surprising that something as common as cement can be in such short supply.The speed of China’s growth caught everyone by surprise. Cement plants are time-consuming to build and expensive, so investors are wary of creating a glut. Economically, suppliers prefer a shortage to oversupply. Regulations add to the time and as with any shortage, there are always cries to abandon every regulation to facilitate industry’s needs when industry gets it wrong. It’s an easy (and profitable) out that’s also short-sighted. Montana’s taxpayers paid more in cleanup costs than they ever got from their mining operations.Industry’s historical untrustworthiness is mainly to blame anyway. They’re paying the price for some pretty huge past abuses of people and places. Most opposition to big industrial plants comes from residential neighbors who are more NIMBYs than anything. They are quite happy to panel their den with illegal hardwoods from the Amazon but vocal critics of anything that impinges on their view. Ironic that the real estate industry depends on cement and gravel pits, but few homeowners want one near them.Portland cement produces 1 ton of carbon dioxide for every ton made. It requires a lot of fossil fuels to heat a kiln to 1,450 C and the chemical conversion also releases carbond dioxide. Concrete production accounts for 7 percent of the world’s CO2 emissions. There is an eco-cement that uses magnesium carbonate rocks (dolomite, magnesite) instead of calcium carbonate (limestone). This cement requires about half the kiln temperature and it actually soaks up CO2 from the atmosphere after it’s set. Cement manufacturers usually add in inert waste called fly ash to boost cement volume and reduce the heat released when it sets. Magnesium cement is less alkaline and reactive, so it can absorb more waste and go further – a double plus. It’s not quite as strong as Portland cement in some applications, and it doesn’t have the pedigree that Portland’s years of use and working experience provide. The building industry is justifiably very conservative, sticking with what it knows works.Ideally, eco-cement can establish itself as an alternative. It would be cool if our concrete cities sat there absorbing CO2 like the fields they replaced. Eventually we’ll have tree-lined streets with buildings that are also green from their roots to their roofs.Amazing what can come from holes in the ground.Alan Braunholtz of Vail writes a weekly column for the Daily. Vail, Colorado

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