Scientists create a way to recycle demolished buildings by combining concrete with water and wood dust for new construction material to combat 1.3 BILLION TONS of construction waste produced each year
- Researchers at University of Tokyo have devices a new way to recycle concrete
- The process involves mixing old concrete with wood powder and water
- The technique could help the country deal with debris from demolitions and construction, which generate more than 33 million tons of waste a year
A team of scientists from the University of Tokyo’s Institute of Industrial Science have devised a new and environmentally friendly way to recycle concrete.
The new technique is meant to help manage the growing amounts of debris from construction sites and building demolitions, which have created stress for the country’s waste management systems.
Typically concrete debris is converted back into cement in an energy intensive process that involves burning limestone at temperatures of 1,500 degrees Celsius.
Scientists from the University of Tokyo have developed a new method for recycling concrete reclaimed from demolition sites, by mixing it with water and wood dust
The new process devised by the University of Tokyo team involves mixing pulverized concrete debris with water and wood powder.
The mixture is then heated to 160 degrees Celsius in a chamber with the equivalent of five atmospheres of pressure.
The resulting compound has more flexural strength than conventional concrete, thanks to the addition of lignin, a plant-based polymer that strengthens the cell walls in wood, algae, and other plants.
‘It will help reduce carbon dioxide and reuse wood building materials and plants that would otherwise be scrapped,’ lead researcher Yuya Sakai told the Asahi Shimbun.
While the new mixture has more flexural strength than conventional concrete, the team believes its long term durability might be lower.
There are more than 1.3 billion tons of construction debris produced every year, much of which can be dangerous to dispose of because of its size and weight.
HOW IS CONCRETE MADE?
In its simplest form, concrete is a mixture of paste and aggregates, or rocks.
The paste, composed of cement and water, coats the surface of the fine and coarse aggregates.
Through a chemical reaction called hydration, the paste hardens and gains strength to form the rock-like mass known as concrete.
Within this process lies the key to a remarkable trait of concrete: it’s plastic and malleable when newly mixed, strong and durable when hardened.
These qualities explain why one material, concrete, can build skyscrapers, bridges, sidewalks and superhighways, houses and dams.
Polymer concrete is a type of concrete that uses polymers, typically resins, to replace lime-type cement as a binder.
To compensate, they suggest it be used for temporary facilities or used in settings that don’t entail heavy direct wear, such as parking blocks.
The team hopes their discovery could help Japan process the 33 million tons of new concrete waste produced in the country every year.
Globally, more than 1.3 billion tons of construction waste are generated every year, and according to a report from Transparency Market Research, that will rise to 2.2 billion tons by 2025.
Because of the large size and substantial weight of construction debris, safely disposing of it has proven challenging.
In 2015, 70 people were killed and 900 displaced after a construction debris caused a landslide in Shenzhen.
Many waste management officials worry that construction debris contains industrial chemicals not present in ordinary consumer waste, and might have negative long-term effects as those chemicals are absorbed into the soil and ground water.