Cement, the key ingredient in the concrete used for everything from sidewalks to skyscrapers, has a significant environmental cost, with its production accounting for up to 10% of global greenhouse gas emissions. To tackle this problem, a research team at the University of Saskatchewan’s (USask) College of Engineering is pioneering a greener alternative by incorporating a unique material derived from agricultural waste into the concrete mix. Their solution utilizes biochar, a fine, carbon-rich powder produced by heating biomass, such as flax or wheat straw, in a low-oxygen environment, a process known as pyrolysis. This innovative approach not only reduces the amount of cement needed but also traps carbon within the concrete, effectively turning a standard building material into a tool for carbon sequestration.

The researchers, led by Ph.D. student Ravi Patel, experimented by replacing 0% to 5% of the cement in a standard concrete mixture with biochar. They then subjected these new concrete samples to a series of rigorous tests to evaluate their mechanical properties, including compressive strength, tensile strength, and water absorption. To understand the changes at a microscopic level, the team utilized the powerful synchrotron technology at the Canadian Light Source, a national research facility at USask. This allowed them to create highly detailed 3D images of the concrete’s internal structure, revealing how the biochar particles integrated into the material and affected its overall density and porosity.

The results, published in the journal Scientific Reports, were remarkable. The team discovered an optimal mixture where replacing just 2% of the cement with biochar led to significant improvements. This “green concrete” was 18.95% stronger under compression and had 19.64% greater splitting tensile strength than conventional concrete. Furthermore, it absorbed less water, indicating a denser, less porous structure that is likely to be more durable over time. The advanced analysis confirmed that the biochar helped generate more calcium-silicate-hydrate, the primary binding compound that gives concrete its strength, effectively acting as a superior glue for the composite.

While these initial findings are promising, the team is now focused on the long-term performance of their biochar-enhanced concrete. “In our research, we have studied the new-formula concrete for up to 56 days,” said Patel in a university press release. “But we need to check this concrete strength after a year or two years, because all the structures are going to stay here for 50, 60, 70 years.” The next phase of research will be crucial for proving the material’s viability in the construction industry, potentially paving the way for more environmentally friendly building practices, longer-lasting infrastructure, and a novel way to repurpose agricultural waste.

References

• Funk, E. & University of Saskatchewan. (2025, August 21). Adding biochar to cement yields concrete that’s stronger, more environmentally friendly. Tech Xplore; University of Saskatchewan. https://techxplore.com/news/2025-08-adding-biochar-cement-yields-concrete.html

• Patel, R., Stobbs, J., & Acharya, B. (2025). Study of biochar in cementitious materials for developing green concrete composites. Scientific Reports, 15(1), 22192. https://doi.org/10.1038/s41598-025-07210-3