University of Toronto Researchers Detail Biochar's Potential as Structural Material Rivaling Mild Steel

Researchers at the University of Toronto have advanced materials science by demonstrating that biochar, typically used for environmental remediation, exhibits mechanical properties comparable to mild steel. This significant finding, published in the journal Biochar X on October 21, 2025, suggests a major opportunity to reposition carbon-based materials as core components for demanding engineering applications.

The research team, led by Professor Charles Q. Jia at the Green Technology Laboratory, analyzed biochar produced from seven different wood species, including maple, pine, bamboo, and African ironwood. By processing these materials through pyrolysis at temperatures between 600 and 1,000 degrees Celsius, the scientists successfully revealed latent structural strength. A critical measurement showed that biochar derived from African ironwood achieved an axial hardness of 2.25 gigapascals, placing its performance directly alongside that of standard mild steel.

The investigation, which included contributions from Qinyi Wang, Yating Ji, Mohana M. Sridharan, Lizhong Lang, Yu Zou, and Donald W. Kirk, highlighted a pronounced characteristic: extreme anisotropy. For instance, hemlock-derived biochar displayed an axial hardness that was an astonishing 28.5 times greater than its transverse hardness. Advanced analysis determined this directional dependency stems not from the basic carbon structure, but from the preserved, hierarchical pore network inherited from the original wood structure.

This work represents a fundamental re-categorization of biochar's utility, moving beyond simple incremental gains. The ability to create a quantitative model for designing monolithic biochar with predictable mechanical responses offers engineers a new avenue for sustainable construction. Professor Jia noted the material's promise for developing high-strength electrodes, lightweight composite structures, and specialized flow-directional filters, affirming this paradigm shift.

The innovation leverages the pre-existing, nature-designed architecture of wood to dictate macroscopic mechanical performance. This approach avoids the energy-intensive synthesis processes common to high-performance materials, aligning with the global push for greener technologies. By establishing a tangible benchmark against mild steel, the University of Toronto's research empowers innovators to envision a future where waste biomass is converted into essential, high-performance engineering components.