New waste-free technology for recycling concrete rubble proposed

Concrete is a material that is used in a vast majority of buildings and engineering structures, with the current output of this material standing at around 20 billion tonnes per year. This figure is expected to double over the next two to three decades, leading the construction industry to seek new ways to recycle unwanted material. Without a doubt, sustainable solutions are needed in the industry. The EPA reports that in one year alone, the construction industry generated some 569 million tons of waste. One group of engineers from the Bialystok University of Technology in Poland has recently put forth a new method that enables concrete rubble to be recycled with zero resulting waste.

Thermal mechanics for waste-free concrete recycling

The new technology relies on thermal-mechanical treatment to recycle concrete rubble, producing a high quality coarse aggregate and cement mortar. This aggregate can replace natural aggregates in concrete, producing similar or better quality material than concretes made with natural aggregates. The ground mortar can be added to cement and sand-based composites. The engineers have patented the system, which will hopefully be used on a global scale to create sustainable concrete for buildings.

The benefits of recycled materials in construction

There are many environmental benefits from recycling construction waste. These include a decreased reliance on raw materials. Currently, around 600 billion tons of natural resources are used in the construction industry, including sand, rock, stone, clay and timber. Recycling materials can also reduce landfill waste and cut costs in many stages of building. Constructors and developers relying on sustainable concrete and other materials can also obtain green certifications, thus building an eco-friendly brand consumers can connect with. Consumer interest is high in everything from renewable energy to water conservation, and creating a reputation for sustainability is wise from a business point of view, as well as a purely ecological one.

How does thermal mechanics work in recycling?

The process used to recycle concrete has various stages. The first involves crushing rubble to less than 40mm in size. The second is to place the waste in a thermal furnace, heating it to a specific temperature. Afterwards, the rubble is subjected to a mechanical treatment to separate cement mortar from coarse aggregate grains. Finally, the cooled material is placed in a sieve to separate fine and coarse elements. Different devices have been designed to carry out the different processes involved in each stage. There are two resulting products that can be used in future construction: a high quality recycled aggregate and a finer material made up of recycled cement mortar. The latter can be used to make autoclaved products with up to 20% of sand and lime mass. It can also be used to substitute cement in some composites to boost strength.

Finding new ways to recycle construction materials is vital in a world in which landfills are already overcrowded and tonnes of raw materials are used in industry every year. A new system that relies on thermal-mechanical treatment is one way to recycle waste concrete. This system produces two main products that can be used to create both aggregate and finer material, which can then be used to boost the strength of composite materials.

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