Concrete is one of the most widely used building materials in the word. Globally, about ten billion tons of it are produced each year. Since the Romans pioneered its use more than a thousand years ago, architects and engineers have used it in everything from skyscrapers to suburban backyards.

Chances are, your home uses it somewhere – in a foundation, a driveway, or even a decorative wall. Its durability and versatility make it one of the most useful building materials available.

Environmental Costs

But all that utility comes at a large environmental cost. The production of cement (an ingredient in concrete) is responsible for an estimated five percent of human-generated carbon dioxide, a key greenhouse gas contributing to global climate change.

Concrete is also hazardous to the environment in other ways:

  • Mining limestone for cement can pollute groundwater and surface water.
  • Production is water-intensive.
  • Runoff from production can pollute water.
  • Some types are impervious to water, which causes runoff and pollution.
  • It’s not biodegradable.

Benefits

Given its environmental impact, why use concrete at all? Simply put, because it is one of the most durable and versatile building materials around. It’s also inexpensive, and the raw materials needed to produce it are abundant.

It also has some potential environmental benefits that, while they don’t completely offset the drawbacks, make the judicious use of concrete a reasonable option in a sustainable building project:

  • It’s durable and stable – concrete-made buildings can be retrofitted and reused rather than torn down.
  • It can be energy-efficient – its reflective qualities can mitigate the urban heat island effect.
  • It is scalable – builders can produce just as much as they need for a project.
  • It’s recyclable.

Responsible Concrete Use

Chemists and engineers are investigating new materials and methods for producing concrete that they hope will one day allow us to reap the benefits of concrete while reducing its environmental footprint.

In the meantime, here are some steps you can take to ensure your project uses it in the most environmentally responsible way:

  1. Use locally sourced concrete to reduce transportation emissions.
  2. If you’re in the San Francisco Bay Area, consider using products from Watershed Materials, which produces low-cement concrete blocks made with locally sourced minerals and recycled materials.
  3. Use concrete made with recycled aggregates, if possible.
  4. Recycle any concrete left over from demolition.
  5. Make sure contractors mix only what they will use – look for contractors that use volumetric mixers.
  6. Use reclaimed, non-potable water for mixing, if possible.
  7. Make sure contractors use concrete washout bags, which allow for capturing waste and wastewater for delivery to a recycling center or proper disposal location.
  8. Consider permeable paving, where possible.

Talk to your architect, engineer or contractor about the best ways to reduce the environmental footprint of your project.

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This post first ran in 2017.