As you read this you are probably surrounded by the most important artificial material ever invented by the human race. Is there a floor below you?, walls around you?, a ceiling above? It is very likely that they are made, at least in an important part, of that amazing material: concrete.
For most people, concrete is just the ugly stuff used for paving and building parking lots. But concrete is an invention as transformative as fire or electricity.
Since its widespread use in the early 20th century, this man-made stone has changed where and how billions of the world’s people live, work and move. It is the skeleton of almost all apartment blocks and shopping malls, and of most of the roads that connect them. It gives us the power to dam massive rivers, erect Olympic-high buildings, and travel the world with an ease that would amaze our ancestors.
We tend to assume that concrete is as permanent as the stone it imitates. it is not. Concrete fails and fractures in dozens of ways. Heat, cold, chemicals, salt, and moisture attack that seemingly solid artificial rock, working to weaken and break it from within. You could say that our cities are like sandcastles, except they are almost literally sandcastles. Many of the world’s concrete structures are already slowly disintegrating.
Worldwide, up to 100 billion tons of poorly manufactured concrete structures – buildings, roads, bridges, dams, everything – may need to be replaced in the coming decades, at a cost of trillions of dollars.
Also, we’re running out of one of concrete’s essential ingredients: sand.
Our planet contains huge amounts of sand, of course, but the usable kind, found mostly in riverbeds, floodplains, and beaches, is a non-renewable resource. (Desert sand, eroded by wind rather than water, is generally too round to use for construction.) Humans consume almost 50 billion tons of sand and gravel each year, enough to cover the entire state of California. Most of that is used to make concrete.
Sand mining is its own colossal industry with its own litany of environmental devastation. From Vancouver Island to Newfoundland, Canada produces nearly 300 million tons of sand and gravel each year, worth approximately $3.6 billion. But here, as in other countries, more and more accessible sources are being exploited.
The Lower Mainland of British Columbia and rural areas of Saskatchewan and Alberta are already running out of resources. In California, officials warn the state has access to only about a third of the sand and gravel it will need over the next 50 years.
Around the world, sand mining is killing river fish and birds, damaging coral reefs, undermining bridges, and causing riverbanks to collapse. Sand and gravel mining in British Columbia’s rivers has wiped out the salmon nurseries and breeding grounds; in one case in 2006, a mining road built to access the Fraser River cut off a crucial spawning channel, killing an estimated two million pink salmon fry. Prince Edward Island had to ban sand mining on its beaches in 2009 because the province’s coastline was badly eroded.
Then there is the harm that sand mining causes directly to humans. That cycle cannot continue indefinitely, any more than we can continue to pump oil out of the ground indefinitely to fuel an ever-growing fleet of automobiles. We have started to think twice about how much oil we can burn, how many forests we can cut down, and how many fish we can catch from the sea.
Is it time to start thinking about how much concrete we can afford?
It is an interesting question and one that, as part of the construction industry, we must all ask ourselves to look for new alternatives.