How CO2 can make Robust concrete bricks - Japan achieved this.

Each concrete after it's life span, returns to landfills and its production accounts for roughly 8% of worldwide carbon emissions.

Researchers at the University of Tokyo have discovered an innovative way to transform old concrete into something new. Interestingly, these new concrete blocks are strong enough to build houses and pavements.

Such innovative applications  not only recycles waste but also helps combat climate change by capturing carbon dioxide. The same process can be repeated, making it a truly circular economy solution, this is the applaudable part. 

In Japan, the current demand for construction material is less than in the past, so it is a good time to develop a new type of construction business, while also improving our understanding of this vital material through our research said he researcher team. 

How the new block was made

The process is surprisingly simple. Old concrete is crushed into a fine powder, reacted with atmospheric carbon dioxide, shaped into layers under pressure, and heated to solidify into new concrete blocks. 

For this development, the heat-trapping carbon dioxide was captured from the atmosphere or industrial emissions. Moreover, the demolished concrete from the school building was used for recycling. 

As per the press release, the concrete underwent a three-month carbonation procedure. Carbonation is a gradual natural process where concrete components like portlandite and calcium silicate hydrate react with atmospheric carbon dioxide to produce calcium carbonate. The carbonated powder was then crushed using a calcium bicarbonate solution before drying.

Therefore, allowed them to build a robust new material called calcium carbonate concrete bricks. Moreover, the procedure increased the strength of the blocks for usage. 

“The blocks could theoretically be remade again and again, through the same process,”. 

“These blocks can theoretically be used semipermanently through repeated crushing and remaking, a process which requires relatively low energy consumption. Now, concrete in old buildings can be thought of as a kind of urban mine for creating new buildings,”. 

Scarcity of limestone

Limestone is a crucial ingredient in concrete. It provides concrete with strength and durability. 

Despite its importance, limestone is a finite resource, and countries like Japan have limited reserves. As a result, there’s a growing emphasis on recycling and reusing materials rather than creating new ones.

“Over the next few years, Japan also plan to move to a pilot plant, where we can improve production efficiency and industrial application, and work on creating much larger building elements, as they are moving towards making this material commercially available.