Imagine if we could build new buildings using renewable concrete bricks. Although it may not be immediately obvious, the construction industry is actually one of the major sources of greenhouse gas emissions, which are gradually causing global temperatures to rise. However, a new technology that will be publicly available for the first time in 2021 could soon revolutionise this sector.


The new technology, led by researchers at the University of Tokyo, is called the Calcium Carbonate Circulation System for Construction (C4S). The construction industry is a major contributor to climate change because limestone, a key ingredient in the production of Portland cement, requires high temperatures to produce calcium. Portland cement, the most common ingredient in concrete, was invented in England in the early 1800s.


However, if we make renewable concrete bricks, we can reduce greenhouse gas emissions because we no longer need to extract large quantities of calcium from limestone. We can simply recycle existing bricks and construction waste and turn them into new building materials.


This also helps to solve the problem of the limited limestone resources. Like many other precious resources on which we depend, limestone will eventually run out. But with C4S technology, researchers can combine construction waste with CO₂ from the air to create calcium carbonate concrete.


The bricks they produced in 2021 were initially smaller in size and not as strong as conventional bricks. But recently, researchers took concrete from a demolished school building, ground it into a fine powder, mixed it with CO₂ for three months, and made renewable concrete bricks.


These new bricks are compressed bricks made from a calcium bicarbonate solution, which are layered in a mould and then heated to shape. It is claimed that these bricks are not only large in volume, but also strong enough to be used to build habitable houses, and can even be used to pave pavements.