Concrete -- the main downstream product for cement -- is the world's second most consumed material behind water, but its recycling rate varies wildly by region.
The Netherlands, for example, banned concrete waste from entering landfills so nearly all concrete is recycled. On the other end of the spectrum, data suggest Spain and Portugal recover just a fraction of the construction and debris waste generated in the two countries.
Concrete is comprised of cement, water, coarse aggregate, such as stone or gravel, and fine aggregate, such as sand. Since it is a downstream product of cement, cement producers note they can only have an indirect role in supporting the zero waste goal. It has also tried to reduce environmental impacts in other ways, such as slowing the rate of greenhouse gas emissions growth; the cement industry is responsible for about 5 percent of global greenhouse gas emissions.
One way to do improve the concrete recycling rate is to increase awareness of the recycling opportunities. When crushed, for instance, it can take the place of the aggregate materials in concrete. Up to 30 percent of recycled concrete aggregate can be used in structural concrete in Australia without sacrificing strength or workability, according to the government. Crushed concrete is also used in roadwork.
Both reuse scenarios cut the need for new virgin aggregate materials and prevent tons of recyclable material from entering landfills.
To get concrete's landfill rate to zero, the Cement Sustainability Initiative recommends better data collection and statistics that is publicly reported, the creation of targets for recycled concrete use on road construction and building sectors, research to identify recycling best practices, economic and regulatory incentives for concrete recycling and increased education to raise awareness of the benefits of recycling concrete.
The Cement Sustainability Initiative, formed under the auspices of the World Business Council for Sustainable Development, is made up of 18 cement companies responsible for about a third of the world's cement production, such as Lafarge, Cemex, Holcim and Ash Grove Cement.
Image CC licensed by Flickr user Sister72.