In an already emissions-heavy building sector, concrete and cement were linked to an estimated eight per cent of annual global emissions, according to a 2018 report from London think tank Chatham House.
Still, there is some hope for the building sector with demand for low-carbon concrete on the rise. Here are some of the latest global developments in decarbonising concrete, from massive national rollouts to wildly experimental possibilities.
Carbon capture and storage
One popular, but according to many observers highly dubious technique to lowering dangerous CO2 emissions is carbon capture and storage (CCS). This method aims at capturing emissions before they can escape into the atmosphere, transporting, and injecting CO2 back into geological formations for long-term storage.
In Canada, researchers announced new progress in testing large-scale CSS at Leigh’s Cement in Edmonton, Alberta. This study marks the first of its kind for Leigh Cement, the International CCS Knowledge Centre (Knowledge Centre), and Mitsubishi Heavy Industries (MHI) Group.
The feasibility study will test the viability of capturing 90-95 per cent of the factory flue’s emissions, an estimated 600,000 tonnes per year.
“This CCS feasibility study is essential for understanding how our industry can continue to meet growing production demands, while also meeting equally important climate targets,” president of Lehigh Hanson Canada Region Joerg Nixdorf said. “We are proud to be in a position to lead a global change with a crucial clean technology in our industry.”
The announcement came right on the heels of the Canada Climate Plan, which included an intention to develop a “comprehensive” CCS strategy to keep up with the growing industry.
Don’t get too excited for an international deployment of CCS anytime soon, though. Some industry giants are still dragging their feet on deploying the technology.
Once set to be an international example of CCS, ExxonMobil’s largest CCS project at LaBarge field, Wyoming, was delayed indefinitely, citing financial struggles from COVID-19. The US$260 million project was worth nearly 20 per cent of the oil giant’s emissions reduction targets.
It should be noted that Exxon is still proceeding with significantly more expensive (and polluting) oil projects, including a $9 billion crude oil expansion in Guyana.
Low carbon concrete manufacturing
Rather than simply trying to capture emissions, some manufacturers are taking the preventative approach by changing the actual manufacturing process to be low-carbon, or even use it to their advantage.
Out of the United States, Solidia has been making a big start with its own low carbon concrete manufacturing and CO2 curing process.
First developed out of Rutgers University, the start-up uses a low-temperature solidification process to create cement with low energy. Rather than use water to cure the mixture like traditional cement, Solidia injects CO2 into the product to cure it. The total process can cut emissions by up to 70 per cent while lowering energy consumption and water use.
The cleantech start-up has now teamed up with construction chemical company CHRYSO to create a new low carbon concrete that combines Solidia’s patented concrete with CHRYSO’s water-reducing admixtures. The final result will reduce the amount of water needed for curing and create stronger, smoother concrete.
In Australia, Wagner’s has made a name for itself with its Earth Friendly Concrete (EFC), a traditional concrete that uses an eco-friendly binder made from industrial waste byproducts, slag and fly ash. The end result is a concrete that can slash 80-90 per cent of CO2 emissions compared to Portland cement.
The Queensland construction materials company struck a deal with UK firms Capital Concrete and Keltbray Group in October to place 11000 cubic metres of EFC in the UK by the end of June 2021.
See our upcoming ebook on our event late last year, Building Circularity, for more on Wagner’s.
A future beyond old school concrete?
While some researchers are trying to make concrete manufacturing more emissions efficient, some are doing away with traditional cement altogether.
Researchers at RMIT announced a new technology that can manufacture concrete using rubber tyres and demolition waste to create a recycled alternative that is up to 35 per cent stronger than traditional concrete.
The new concrete casting method, Rubberised Concrete Casting Technology, combines aggregates with rubber tyre waste, cement and water that is pressed into a customised mould. Efficient and inexpensive, it offers a circular approach to sustainable building materials that can reduce landfill and CO2 emissions.
“By enhancing the properties of the recycled waste without the use of any additional materials, we have developed a feasible and practical solution that addresses the performance issues affiliated with waste recycling in concrete,” project leader Professor Yufei Wu said.
Another particularly wild possibility comes from researchers at the University of Colorado, Boulder: living, self-healing concrete.
This living concrete combines sand and gelatin with cyanobacteria to create a green-hued material that can regenerate itself three times over to heal potential cracks. Even better, the particular type of cyanobacteria used, Synechococcus, absorbs CO2 to produce calcium carbonate, the main ingredient in cement.
“It really does look like a Frankenstein material,” structural engineer and the head of the research project Wil Srubar told the New York Times.
CO2-absorbing Frankenstein concrete. What’s next?