- Issue: Winter 2019
Concrete is an old material—8,000 years old. The Romans built with concrete from 300 BC to 476 AD.
By 2050, it’s estimated that Earth will hold 75% more infrastructure, i.e., highways, ports, and power plants, than it does today, and much of it will be manufactured out of concrete. This material—a composite of aggregate (sand and gravel), cement, and water— forms the very foundation of modern civilization. But its use is not without consequences.
For starters, you can’t use just any sand: desert sand, for instance, is too smooth to make concrete. There are still many effective sources of "good" sand, but over-extraction can cause problems. For instance, mining sand from river beds increases bank erosion, degrades habitat, and reduces the amount of sediment carried downstream, making deltas more prone to sea-level rise. And with much of the high-quality sand already extracted, a global shortage is sparking international disputes and fueling organized crime.
Another downside: Cement processing is a major greenhouse gas emitter, accounting for 5% to 10% of global emissions. If the cement industry were a country, it would be the third-largest emitter in the world.
And then there’s concrete’s heavy toll on freshwater: Almost 10% of industrial water use goes into making concrete.
WWF is working to address the concrete problem on all sides, by raising awareness of impacts to nature and people; helping cement producers find more climate-friendly practices; encouraging engineers to integrate new aggregates (e.g. those made from shredded car tires and post-disaster debris) and develop non-cement binders; encouraging sand-efficient construction technology and reduction in over-building and over-design; and pushing policy-makers to ban illegal sand mining and back that up with enforcement.
WWF is pursuing solutions ranging from completely "green" (only ecosystem elements) to "hybrid" (combining ecosystem elements with built infrastructure) because it makes sense. After all, nature-based infrastructure can be both cost-efficient and effective.