Biochar's Impact on Building Materials: A Comprehensive Study

Strategic Insights -

Researchers at Beijing Forestry University conducted a comprehensive study to investigate the effects of biochar on the mechanical properties and carbon emissions of biochar-cement composite concrete. The study, funded by the National Natural Science Foundation of China (NSFC), aimed to demonstrate the benefits of using biochar with high carbon content in reducing carbon emissions and improving the compressive strength of concrete.

Key Takeaways:

  • The study tested the pozzolanic ability of four biochars with carbon content ranging from 78 wt% to 90 wt% and evaluated their pozzolanic activity levels.
  • Biochar with high carbon content (up to 90 wt%) exhibited strong pozzolanic activity, which was determined by its amorphous SiO2 content and carbon content.
  • Biochar-cement composite pastes with high pozzolanic activity levels showed improved compressive strength and reduced carbon emissions, especially when the biochar dosage was as high as 20 wt%.
  • The researchers found that the compressive strength of the composite paste was positively linked to the sum amount of hydration products from both cement hydration reaction and biochar pozzolanic reaction.
  • The relative strength-to-emission ratio, a parameter used to evaluate the comprehensive performance of compressive strength and carbon emission, showed that the biochar-cement composite paste with a biochar dosage of 20 wt% had a value several times to tens of times higher than that of biochar-free cement paste.

Statistics:

  • 78 wt% to 90 wt%: the range of carbon content in the four biochars tested.
  • 20 wt%: the highest biochar dosage tested in the study.
  • Several times to tens of times: the increase in the relative strength-to-emission ratio of the biochar-cement composite paste with a biochar dosage of 20 wt% compared to a biochar-free cement paste.

Sources:

  • NewsRx (2025). New Building and Construction Data Have Been Reported by Investigators at Beijing Forestry University (Pozzolanic Activity of Biochar With High Carbon Content and Its Influence On Comprehensive Strength-emission Performance of Biochar-cement ...). Global Warming Focus. June 9, 2025; p 83.
  • Pozzolanic Activity of Biochar With High Carbon Content and Its Influence On Comprehensive Strength-emission Performance of Biochar-cement Composite Paste. Construction and Building Materials, 2025;478.
  • Elsevier Sci Ltd (no date). Construction and Building Materials. Retrieved from
  • Wen Liu, Beijing Forestry University, Dept. of Civil Engineering, Beijing 100083, People's Republic of China (no date). Contact information.