I am a seismic engineer with Arup based in the...
Making better use of stone for building could be particularly useful for people in developing countries, enabling them to build affordable, durable homes that could even resist natural hazards – in particular, earthquakes.
For many people, building to an adequate standard in steel or reinforced concrete is too difficult and too expensive. Stone, on the other hand, is readily available in many countries and, used properly, it should be a safe, easy-to-use and affordable alternative to poor quality reinforced concrete construction.
So why aren’t universities around the world researching how to build safely with stone – as they do with steel and reinforced concrete? Shouldn’t we have codes that would enable engineers to design with stone in different locations, including areas of seismic risk?
We need this research because although many stone buildings around the world have stood the test of time (and earthquakes), there’s currently no reliable way to know for sure whether a vernacular stone-built structure will be safe. There are rules of thumb, but very little guidance for engineers to design with stone.
As an engineer, I need guidance that enables me to work out the loads and assess this against the structural strength of stone walls. This strength is influenced by the stone material, the shape of the stone, the bonding pattern and the type of mortar, and the quality of workmanship.
If I had this information, I could be certain the stone masonry home I designed would be safe – even in an earthquake and know if it required specific enhancements to make it earthquake resistant.
Currently, people in developing countries often believe that reinforced concrete gives them this certainty because it is perceived to be modern and therefore safe. But the truth is that a home built badly from concrete is no safer than one built poorly from stone. Poor quality reinforced concrete was one reason for the widespread devastation in the earthquakes in Turkey in 1999, Pakistan in 2005 and Haiti in 2010.
I argue that if you can’t afford high quality steel and concrete along with the engineering skills to put them to use safely, you should look instead at traditional methods of construction using readily available materials. After all, if you can build safe, resilient homes with what you’ve got, surely that’s the best option?
In many places stone construction should be an obvious consideration for building homes. Stone doesn’t rust, it needs no manufacturing other than cutting into shape, it doesn’t corrode, it doesn’t pollute, and it generally doesn’t readily disintegrate.
Stone has a large thermal mass and its attractive appearance means it doesn’t necessarily need finishing with paint or plaster. What’s more, quarrying and working stone is labour-intensive – meaning it would create jobs. And although you can’t build tall buildings from stone, that doesn’t matter, because in most places in the world the majority of people still live in low-rise homes.
However, to realise all these benefits we need more research into building with stone. My colleague Peter Johnson argued that better data will help fight fires; better data could also help us build safer homes from stone and make more use of a naturally available resource.
Although there are thousands of ways of building with stone masonry, I suspect there is a set of design features one could specify to improve performance. However, discovering what these are requires research that simply isn’t being carried out at the moment.
I believe the engineering community must do the research to prove that building with stone can be safe. Then we can tell people with confidence how to build cheaply and easily in stone to create safe buildings – buildings that resist earthquakes in the same way as buildings designed using modern reinforced concrete or steel construction codes.