Can we recycle concrete?
Researchers from the University of Tokyo have developed an innovative method to manufacture concrete bricks using demolished building materials and carbon dioxide from the air.
This breakthrough, known as the Calcium Carbonate Circulation System for Construction (C4S), was first introduced in 2021 and has the potential to significantly reduce greenhouse gas emissions from the construction industry, a major contributor to climate change reports BGR.
Traditionally, producing Portland cement requires heating limestone to high temperatures to extract calcium, which results in substantial carbon emissions. However, the C4S process bypasses this by reusing existing building waste and combining it with CO2 to form calcium carbonate — the key component in these new concrete bricks.
Recently, the researchers enhanced the process by grinding concrete from a demolished school into a fine powder and mixing it with CO2 over several months. This produced strong, large bricks suitable for constructing homes and paving surfaces.
Initially, the bricks produced through this method were small and lacked the strength of conventional bricks.
But the ability to create durable bricks from recycled materials not only reduces the need for new limestone but also offers a sustainable solution as natural limestone resources diminish.
The researchers aim to construct a two-story home with these bricks by 2030, marking a significant step towards sustainable construction.