Of all the building materials we use today, concrete is by far the most favoured. It is also, perhaps, the most ignored – or even despised.
For many years the word ‘concrete’ was used as a term of abuse; when Basil Spence won the competition to build the new Coventry Cathedral he was accused of foisting a ‘concrete monstrosity’ on the city – even though his design was for a largely-traditional sandstone building. This prejudice against concrete has been with us for some time.
In his pioneering work ‘The Pattern of English Building’, published in 1972, Alec Clifton Taylor waxes eloquent on stone of all types (sandstone, limestone, granite, slate, marble, flint) and on the fired earths (brick and tiles).
He praises mud, cob and pulverised chalk construction, pronounces himself much in favour of wood as a building material and of thatch – straw, reed or heather – to cover roofs.
But concrete barely gets a look in; when he mentions it, it is only to say that it can be decently hidden behind a surface of one of his preferred materials, as if, like Victorian piano legs, it needs to be modestly cloaked from the eyes of the easily-upset public.
This is a pity, as concrete has a long and honourable history as a building material. Next year we shall celebrate the 1900th anniversary of the start of work on the Pantheon in Rome, for many centuries the largest dome in world, and one made entirely of concrete.
Roman concrete had a special ingredient, a volcanic sand called pozzuolana.
There had been earlier forms of concrete (some as long ago as 6,500 BC) that used powdered limestone or seashells as a binding agent, but pozzuolana gave Roman concrete its special hardness and durability.
As with so many discoveries, the technique for making Roman concrete vanished after the fall of Rome (though we may detect some remaining ability to make it in the rock-hard wall and ceiling linings of early Christian crypts, including Ripon’s).
It wasn’t until manuscripts that described how to make it were rediscovered in 1414 that there was any renewed interest in concrete building.
Even so, it was only after 1793, when John Smeaton discovered that by burning limestone containing clay to make clinker that could then be ground into powder resembling pozzuolana, that there was any great leap forward in concrete technology.
He used this new material at the Eddystone Lighthouse. Then in 1824 Portland cement was invented, eventually enabling modern concretes to be made.
At first the ‘new’ material was used sparingly, mostly in limited amounts in industrial buildings. There were some experiments in making houses of concrete – there is a pair of semis in the Isle of Wight dating from 1854, and a gothic-style house in London, known as The Concrete House, of 1873. But it wasn’t until reinforced concrete was invented that very-much-larger structures could be built.
The first to build an iron structure covered with concrete was a Frenchman, François Coignet, in 1853, but the first patent for reinforced concrete, using a metal mesh as a strengthener, was taken out by another Frenchman, Joseph Monier.
He was a gardener, and the patent allowed him to make reinforced flower pots. He soon saw wider applications, for columns and girders, thus laying the foundations (sometimes literally) for the modern building industry.
Reinforced concrete has never been without its problems. In the early days the concrete was porous, and water would penetrate to the ironwork and cause it to rust. Even with the advent of steel there were problems.
Many of these difficulties have been solved with modern technology, but some problems remain.
The chief of these is the environmental cost of making concrete – and more particularly of the cement that is needed for it.
Cement production produces large quantities of carbon dioxide, and consumes a great deal of energy.
There are now types of ‘green’ concrete on the market, which somewhat reduce the amount of energy need to make it and which use recycled materials (sometimes crushed concrete) in the mix.
Another problem with concrete is that, while it is wonderfully versatile when wet (it can be poured easily into moulds – the Tempest Anderson Hall in York’s Museum Gardens is an early example of a poured-concrete building) once set it cannot be recycled, as can brick, stone or wood.
It can only be crushed for aggregate or rubble.
Nonetheless, concrete is a useful material, and can be used to fine effect: we may have come to dislike the ‘brutalist’ structures of the 1960s (‘brutalist’ comes not from their visual violence but from the type of concrete finish, known as ‘Béton Brut’, which was popular then) but today polished or smooth concrete is popular; think of the recent Hepworth Gallery in Wakefield, for example.
Other interesting concrete structures include a series of World War I ‘acoustic mirrors’ placed along the east coast to amplify the sound of approaching enemy aircraft in the days before radar.
After World War 2, anti-nuclear bunkers, like that at RAF Holmpton near Withernsea in East Yorkshire, relied concrete walls several metres thick to preserve vital services and communications in the event of a nuclear attack.
At the other end of the scale, concrete structures can be elegant; Frank Lloyd Wright’s Guggenheim Museum in New York, designed in 1943 and opened in 1959, is an important example.
So is the Kingsgate Bridge, constructed over the River Wear in Durham in 1963, and now a Grade-I-listed structure. In 1965 it won a Civic Trust Award and in 1993 it received a Certificate of Outstanding Performance from the Concrete Society, set up in 1966.
Kingsgate Bridge was designed by the Newcastle-born engineer Sir Ove Arup. Arup also worked closely with Basil Spence on the construction of Coventry Cathedral.
There is some concrete in the cathedral – the tapering columns that rest on bronze pins and hold up the vault, for example. So concrete can have its place, and doesn’t need to be hidden.
Whatever our attitude to it, it’s certainly here to stay.