Magazine article The Spectator

The Wonders of Modern Concrete

Magazine article The Spectator

The Wonders of Modern Concrete

Article excerpt

'Look! Concrete!' Bruno Lafont crashes his fist on the table. 'You could put 30 tonnes on top of this table and it wouldn't break. Tougher than steel!' The table doesn't look like concrete at all.

The top is only a centimetre thick. The surface is painted a Tuscan tone, giving it the feel and look of polished stone. Lafont turns to his desk and bookshelves: 'They're also concrete. Aren't they wonderful?' These are a more utilitarian beige, but equally handsome. Scattered around the room are more clues to his passions: lumps of gypsum, vital for making cement; more rocks; and an enormous elephant painting, a present from the Prime Minister of Zambia.

Lafont is chief executive of Lafarge, the world's biggest cement maker. On the corner of a Paris side-street, his suitably concrete 1970s-style headquarters sits oddly in the 16th district, with its chi-chi cafés and markets. It's early in the day but Lafont is in high spirits: he's just flown back overnight from opening a new cement works in Morocco; before that he spent a week in India for the opening of the world's longest conveyor belt, taking limestone into Bangladesh to make cement.

No wonder he's happy: construction is booming everywhere and concrete is suddenly sexy. Scientists are turning this drab, grey material into bendy, light, hi-tech structures. Even investors get the message:

Lafarge's share price soared 49 per cent over the last year, even before last week's announcement of record profits for 2006.

Back to Lafont's table, the clue to concrete's future. It's made of Lafarge's revolutionary new hi-tech material called Ductal.

Not only is Ductal lighter and tougher than conventional concrete but it moves too -- making it perfect for earthquake zones. Five times tougher than normal concrete, it's also many times stronger than steel. Mixing fibres made from steel or polymers into the concrete makes it stronger, eliminates the need for reinforcing steel bars, and allows it to bend without breaking as ordinary concrete does -- a property called ductility.

Architects and engineers are crazy about this material. They can design structures such as roof canopies and bridges to be more delicate yet longer-lasting. A pedestrian bridge has just been built in Korea in concrete that is only a few centimetres thick. A light rail transit station in Calgary, Alberta, has been made entirely of Ductal to cope with huge weights of snow and fierce winds.

There are environmental advantages, too.

Less cement, and therefore less energy, is needed for any given structure. 'After water, concrete is the product most consumed by humans on earth, ' Lafont expounds. The US alone uses 500 million tonnes of the stuff every year -- and the cement industry is responsible for some 7 per cent of the world's carbon dioxide emissions. Enormous amounts of fossil fuels are needed to heat limestone and clay to the high temperatures needed to create cement -- the paste which binds concrete.

Making concrete itself is simple -- the recipe is about 70 per cent sand, gravel or crushed stone, 15 to 20 per cent water, plus the cement. But to make a tonne of Portland cement, the most common sort, about a tonne of carbon dioxide is released into the atmosphere.

Lafarge is not alone in pushing concrete to new frontiers. Rivals in Germany are working on translucent cements in which tiny transparent optical fibres the thickness of hair create a material which literally allows sunlight to pass through a structure. …

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