Why aren't large Lego bricks used to build full-size buildings? © Alamy

Why aren’t large Lego bricks used to build full-size buildings?

We've all dreamed of building a Lego castle, but it'll probably be cost rather than structural integrity that brings this grand design to a halt.

Asked by: Edward Seymour, Hove

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The plastic used in Lego – a type of polymer called ‘acrylonitrile butadiene styrene’ (ABS) – is surprisingly strong. In fact, it’s able to withstand compression better than concrete. Researchers at the Open University in 2012 found that an ordinary-sized Lego brick can support the weight of 375,000 other bricks before it fails. Theoretically, that would allow you to build a tower almost 3.5km high! But Lego is far too expensive to be used as a large-scale building material.

There are, however, Lego-style construction techniques that use other materials. ‘Insulated concrete formwork’ (ICF) uses hollow polystyrene blocks that are assembled into walls and then pumped full of concrete. The polystyrene acts as a mould and provides insulation. And in developing countries, interlocking blocks of compressed earth mixed with a small amount of cement are used as a cheap alternative to bricks and mortar.

How do recycled plastic building bricks work?

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