For the most part, concrete is the stuff that man-made structures are made of. Cement is an essential ingredient in the making of concrete, but most people have no idea that 8% of the carbon dioxide we produce globally is in the production of cement.
Cement manufacturing generates massive amounts of carbon dioxide. It is such a massive carbon dioxide producer that this one industry produces more carbon dioxide than all other countries except for the US and China.
Global cement production is expected to grow from the present four billion tons a year to five billion tons a year within the coming three decades, according to Watchdog Chatham House.
Cement factory emissions mostly come from fossil fuels burned to produce heat to facilitate cement formation. This includes the chemical processes that convert limestone to clinker within kilns, after which the kiln is ground and combined with other ingredients that form cement.
The construction industry resists change. Safety concerns, issues of reliability are not necessarily always compatible with reducing the carbon footprint of the industry.
The Global Cement and Concrete Association in 2018 launched a set of Sustainability Guidelines for the industry that sets standards for key measurements like emissions and water usage with a view to improve transparency and encourage improvement.
At the same time, experts are pursuing lower-carbon processes for manufacturing cement. A New Jersey startup for example is working on a chemical process that reduces the carbon dioxide produced in cement manufacturing by 30%.
Solidia which is based in Piscataway, N.J., uses a larger quantity of clay and less limestone than the typical cement making process. The company also uses less heat, which reduces its reliance on carbon fuel.
Another startup, CarbonCure based in Dartmouth, Nova Scotia, harnesses carbon dioxide from other chemical processes using a process of mineralization. It turns a potential by product from a hazard.
A Montreal company CarbiCrete has opted to create concrete without any cement at all. They use steel slag, a steel manufacturing by product to replace cement.
Norwegian cement producer Norcem wants to create the first zero-emissions cement manufacturing plant in the world. Norcem is currently using alternative fuels harnessed from industrial waste and now wants to invest in carbon capture as well as storage methods that completely eliminate emissions.
Researchers are also researching with bacteria that absorb atmospheric carbon dioxide in concrete formulations and thus create a better and more environmentally friendly concrete.
Multiple startups including N.C.s BioMason are experimenting with ‘live’ building materials. BioMason works with bacteria and aggregate particles to grow bricks a lot like cement.
Researchers based at the University of Colorado Boulder have published their research with cyanobacteria, micro-organisms which they use to build a concrete alternative.
By inoculating a scaffold of sand and hydrogel with bacteria, they created brocks that are capable of healing cracks.
Even though these replacement concrete bricks cannot replace the many uses of concrete, they can be used in place of concrete for things like facades, pavers, and other structures that don’t bear heavy loads.