Imagine if we could use renewable concrete bricks to construct new buildings. While it may not be immediately obvious, the construction industry is actually a major source of greenhouse gas emissions, which gradually contribute to global temperature rise. However, a new technology that was first introduced in 2021 may soon bring about a transformative change in this field.
Led by researchers from the University of Tokyo, this new technology is known as the Calcium Carbonate Circulation System for Construction (C4S). The construction industry plays a significant role in climate change as the production of Portland cement, a key ingredient in concrete, requires the high-temperature heating of limestone. Portland cement was invented in early 19th century England.
By manufacturing renewable concrete bricks, we can reduce greenhouse gas emissions by eliminating the need to extract large amounts of calcium from limestone. Instead, we can recycle existing bricks and building waste, transforming them into new building materials.
This also helps address the issue of limited limestone resources. Just like many other precious resources essential for our survival, limestone is finite. However, with the C4S technology, researchers can combine building waste with CO₂ from the air to produce calcium carbonate concrete.
The bricks they produced in 2021 initially had smaller volumes and lower strength than traditional bricks. However, recently, researchers obtained concrete from a demolished school building, ground it into fine powder, mixed it with CO₂ for three months, and created renewable concrete bricks.
These new bricks are compressed bricks made from calcium bicarbonate solution, layered in molds and heated for shaping. It is claimed that these bricks are not only large in volume but also sturdy enough to be used in the construction of habitable homes and even for paving sidewalks.
This marks an important step towards producing genuinely renewable concrete bricks, with the company aiming to construct a two-story residential building using these new bricks by 2030. Other companies are also exploring ways to reform the concrete industry, with one even developing concrete completely free of cement. The research on C4S was published on July 24 in the “Advanced Concrete Technology” journal.