Concrete usually gets a bad rap from environmentalists, and understandably so, but there are eco pros and cons

• The quarries from which the aggregate is taken can scar the landscape. Because quick delivery is crucial for ready-mix concrete, it goes by road, creating millions of lorry journeys per year. Making cement produces a lot of CO2 emissions, then the chemical process that occurs when concrete sets creates even more.

• These effects can be somewhat mitigated by using a concrete made with pulverised fuel ash or ground granulated blast furnace slag. These are both waste products from power stations, and can be used to replace up to 50 per cent of the cement in concrete. Most ready-mix contractors offer this kind of aggregate - to search for a company near you, go to www.aggregain.org.uk. To find out where pulverised fuel ash actually comes from, the United Kingdom Quality Ash Association has this information on its website, www.ukqaa.org.uk.

• To make your mix more environmentally friendly still, the aggregate could be old concrete, ground up and recycled.

• Concrete is incredibly tough and long-lasting, so using it can increase a building's lifespan.

• Your concrete can also be used in a way that helps the environment. A concrete block wall can store about twice the heat of a plaster stud wall. This is called high thermal mass, and means concrete can work as a heat sink, warming up slowly during the day and then emitting heat in the cool of the night - or vice versa, in summer.
  
  To find out more about the various applications of concrete and how it can be an eco choice, visit www.concrete.org.uk and www.sustainableconcrete.org.uk.

Words: Joanna Booth