Effect of Biochar Dosage and Fineness on the Mechanical Properties and Durability of Concrete

Materials (Basel). 2023 Mar 31;16(7):2809. doi: 10.3390/ma16072809.


Biochar (BC), a byproduct of agricultural waste pyrolysis, shows potential as a sustainable substitute material for ordinary silicate cement (OPC) in concrete production, providing opportunities for environmental sustainability and resource conservation in the construction industry. However, the optimal biochar dosage and fineness for enhancing concrete performance are still unclear. This study investigated the impact of these two factors on the mechanical and durability properties of biochar concrete. Compressive and flexural strength, carbonation resistance, and chloride ion penetration resistance were evaluated by varying biochar dosages (0%, 1%, 3%, 5%, 10%) and fineness dimensions (44.70, 73.28, 750, 1020 μm), with the 0% dosage serving as the control group (CK). The results showed that the addition of 1-3 wt% of biochar could effectively reduce the rapid carbonation depth and chloride diffusion coefficient of concrete. The compressive and flexural strength of BC concrete initially increased and then decreased with the increase in biocarbon content, BC with a fineness of 73.28 μm having the most significant effect on the mechanical strength of concrete. At the dosage of 3 wt%, BC was found to promote the hydration degree of cement, improving the formation of cement hydration products. These findings provide valuable insights for the development of sustainable and high-performance cement-based materials with the appropriate use of biochar as an additive.

Keywords: anti-carbonation; biochar; cement-based materials; chloride ion resistance; fineness; mechanical strength.

Grants and funding

The author would like to thank the high-level innovation team and outstanding scholar program of Guangxi colleges (granted to Yinghong Qin), the National Natural Science Foundation of China (No. 41561015).