Green Fly Ash
Green’ fly ash could be a viable alternative in development
research from the University of Alberta has put a B.C.-based company one step closer to developing a green alternative to fly ash used in cement.
Progressive Planet, a mineral exploration company with its flagship Z1 zeolite Quarry in B.C., announced its project with the university to modify the rheology of its zeolite mixture has been successful. Rheology, or slump, refers to the flow of something, a key aspect of properly pouring cement.
Researchers found the mixture, which includes zeolite, recycled glass that has been pulverized and other proprietary ingredients, has been able to achieve a slump better than targeted. Now the team is working to get CSA testing conducted so the product can be ready for commercial use as a supplementary cementing material.
Steve Harpur, CEO of Progressive Planet, said he not only sees an opportunity to fill in a gap as the coal plants that supply fly ash are phased out, but also put a dent in one of the globe’s worst sources of pollution.
Large amounts of glass end up in landfills that could easily be used in a cement mix. And the cement making process is less polluting as well.
Harpur explained that traditional fly ash must be heated to over 1,000 degrees several times, requiring a large amount of energy and releasing almost half of the fly ash material as carbon dioxide.
“This is the main reason that the production of Portland cement is the second biggest man-made cause of CO2 pollution,” said Harpur. “It’s absolutely monstrous. It’s a tremendously destructive force in global warming.”
Harpur explained natural pozzolans like zeolite are volcanic in origin and have already been rapidly heated and cooled. This makes them amorphous in structure rather than crystalline. They only need to be ground into a fine powder to be used in a cement mixture rather than heated.
The material’s use in construction is ancient. Harpur explained pozzolanic ash was famously used in the roman concrete that makes up the Parthenon’s dome. The structure remains the world’s largest and oldest unreinforced concrete dome.
Harpur said he anticipates being able to soon sell a product that could be used to reduce the amount of Portland cement in a mix by 20 per cent.
But first the product must go through several CSA tests that measure compressive strength, alkali-silica reaction, sulphate resistance and freeze-thaw resistance. In addition, one American Society for Testing and Materials test will be completed to analyze air voids.
The company will be targeting the 2021 construction season to have a commercial product that it can offer as a competitive alternative to fly ash to the ready mix and pre-cast concrete industries in B.C. and Alberta.
Harpur explained traditional fly ash is already becoming scarce. Coal plants that produce electricity and fly ash are already starting to get phased out and by 2029 they won’t be allowed in some provinces.
Harpur hopes the technology can go even further than just a supplementary material. Progressive Planet is already in the early stages of researching a geopolymer mix without any Portland cement and even developing a way to reverse the cement making process to sequester carbon.
“Concrete is the most consumed building material in the world,” said Harpur. “We don’t have a perfect solution but it’s a better solution. Our corporate values are to continue to find better solutions. That’s why we were so excited to be taking a product, glass, that is basically single use and it can be involved in structures for decades.”