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Biochar affects compressive strength of Portland cement composites: a meta-analysis
Zhihao Zhao1, Ali El-Naggar1,2,3, Johnson Kau4
1Department of Renewable Resources, University of Alberta, 442 Earth Sciences Building, Edmonton, AB T6G 2E3 Canada.
Biochar
|March 11, 2024
Summary
Adding biochar, a sustainable material, to Portland cement composites can enhance compressive strength. Optimal biochar properties and dosage are key for improving cement performance while reducing CO2 emissions.
Area of Science:
- Materials Science
- Civil Engineering
- Environmental Science
Background:
- Portland cement production is a major source of CO2 emissions.
- Supplementary cementitious materials (SCMs) offer a strategy to reduce cement content.
- Biochar, a stable porous material, is a potential eco-friendly SCM.
Purpose of the Study:
- To investigate the impact of biochar addition on Portland cement composite performance.
- To analyze how various biochar characteristics influence compressive strength.
- To determine optimal conditions for biochar as an SCM.
Main Methods:
- A meta-analysis of 606 paired observations on biochar-amended Portland cement composites.
- Evaluation of 7- and 28-day compressive strength.
- Analysis of influencing factors: feedstock, pyrolysis conditions, pre-treatments, dosage, and curing.
Main Results:
- Plant-based biochars (excluding rice/hardwood) improved 28-day strength by 3-13%.
- Higher pyrolysis temperatures (>450°C) and specific heating rates enhanced strength.
- Small particle size biochar increased strength by 2-7%; dosage <2.5% was beneficial.
Conclusions:
- Appropriate biochar addition can maintain or enhance the mechanical performance of cement composites.
- Biochar's effectiveness is influenced by its properties and dosage.
- Further research is needed to understand the underlying mechanisms of biochar's effects.
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