The benefits of recycled concrete are very often overlooked or dismissed, without recognising its invaluable contribution to a sustainable environment.
The numerous benefits of recycled concrete as a construction material are often discounted and according to Bryan Perrie, MD of The Concrete Institute, recycled concrete is used not nearly as efficiently as it should be in South Africa.
Bryan emphasises that the use of recycled concrete could reduce the carbon dioxide emissions associated with concrete manufacture, minimise dumping of concrete at landfill sites, as well as retard the depletion of natural resources.
“The demolition of in situ, precast and tilt-up reinforced concrete can be achieved relatively easily by modern, cutting, breaking and lifting equipment,” he continues. “Once demolition of reinforced concrete has been completed, the concrete and reinforcing steel can be separated for recycling. Recycled concrete can be used as aggregate for building products, such as bricks and blocks, and in layer works in road construction or land reclamation, thereby reducing the amount of material sent to landfills. This recycling also reduces the need for virgin materials which saves resources and the energy required to process them. Crushed concrete also absorbs carbon dioxide.”
At ready-mix concrete plants, wash water can be collected and re-used in fresh concrete, and aggregate from returned concrete can be screened out and re-used. This would reduce the amount of waste generated at the plants.
Bryan adds that precast components from structures can also be re-used in new buildings as opposed to demolishing and recycling the concrete. Structures using precast elements can be designed for such re-use.
Recycled concrete aggregate made from crushed concrete has proved viable and makes economic and ecological sense. As a coarse aggregate, it is particularly appropriate as bedding material, in concrete roads and pavements, floors, reinforced concrete, precast and masonry elements, and foundations.