Recycled pulp mill waste adds strength and resilience to cement
Pulp mills generate significant amounts of waste and we're seeing scientists get quite creative with how it might be put to use, with the possibilities including everything from foams, to batteries to stronger concrete. The latest example comes from researchers at the University of British Columbia (UBC), who have used a pulp mill waste product as a filler material for cement, which they report proved stronger and more resilient.
The waste product at the heart of the breakthrough is known as pulp mill fly ash (PFA), which the pulp and paper industry in North America generates more than a million tons of each year. Rather than consigning it all to landfill, the UBC team set out to investigate how it could be used as a sustainable binder material for road construction instead.
Through their experiments, they found that the structure of this recycled wood ash serves to form stronger bonds between the different materials making up cement. They were also able to produce this sustainable construction material in a more energy-efficient fashion than conventional cement.
“The porous nature of PFA acts like a gateway for the adhesiveness of the other materials in the cement that enables the overall structure to be stronger and more resilient than materials not made with PFA,” says study author Dr. Chinchu Cherian. “Through our material characterization and toxicology analysis, we found further environmental and societal benefits that producing this new material was more energy efficient and produced low-carbon emissions.”
One of the issues around using recycled pulp mill products like PFA is the possibility that toxins used as part of the initial processes at these facilities might leach out of the material and into the environment. The team confirms that the bonds within the cement are so strong that little to no chemicals are able to leak out, and therefore describe it as safe for use.
“Overall, our research affirms the use of recycled wood ash from pulp mills for construction activities such as making sustainable roads and cost-neutral buildings can derive enormous environmental and economic benefits,” Cherian says. “And not just benefits for the industry, but to society as a whole by reducing waste going to landfills and reducing our ecological footprints.”
The study was published in the Journal of Cleaner Production, while the video below offers an overview of the research.
Source: University of British Columbia