Exploring the Potential Use of Biochar in Construction

Exploring the Potential Use of Biochar in Construction

The rise in global CO₂ emissions and their detrimental effects on the environment have become undeniable. Between 1990 and 2022, CO₂ emissions increased from 22.75 billion tons to approximately 37.15 billion tons. The buildings and construction sector is the largest emitter of greenhouse gases, accounting for a staggering 37% of global emissions. Cement, the most consumed construction material worldwide, contributes approximately 8% to total anthropogenic CO₂ emissions (Habert et al., 2020). This highlights the urgent need for innovative solutions and alternative materials to achieve global carbon neutrality. One such material making significant strides in revolutionizing the construction industry is biochar.

Biochar, a carbon-enriched material produced from the thermochemical conversion of biomass waste, has garnered significant attention for its ability to sequester carbon and improve the performance of construction materials. This article explores the production of biochar, its application in construction, and its potential to drive the industry toward carbon neutrality.

Table of Contents

1. What is Biochar?
2. Biochar Production Methods
3. Environmental Impact of Biochar Production
4. Biochar in Construction: A Game-Changer for Sustainability
5. Environmental and Technical Advantages of Biochar in Construction
6. Challenges and Future Research Directions
7. Conclusion
8. References

What is Biochar?

Biochar is a porous, carbon-rich material produced by heating organic biomass (such as wood, agricultural residues, or manure) in an oxygen-limited environment—a process known as pyrolysis (Lehmann & Joseph, 2015). The resulting material is highly stable, capable of sequestering carbon for hundreds to thousands of years. Biochar is not only a potential solution for long-term carbon storage but also offers several benefits when integrated into construction materials.

Biochar Production Methods

Biochar can be produced through various thermochemical processes, each yielding biochar with distinct properties:

1. Pyrolysis:
   This is the most common method, where biomass is heated at temperatures between 300°C and 800°C in the absence of oxygen. The biochar produced has a high carbon content and is characterized by its porous structure, which is beneficial for applications in construction (Tripathi et al., 2016).
2. Gasification:
   In this process, biomass is partially oxidized at temperatures above 700°C. Gasification produces a biochar with higher porosity and surface area, making it suitable for applications where these properties are advantageous, such as in concrete as a lightweight aggregate (You et al., 2018).
3. Hydrothermal Carbonization (HTC):
   HTC involves the conversion of wet biomass into biochar at relatively low temperatures (180°C to 250°C) under high pressure. This method is particularly useful for treating biomass with high moisture content, such as food waste or sewage sludge. The biochar produced by HTC, known as hydrochar, has unique properties that make it useful in specific construction applications, such as asphalt modification (Cao et al., 2021).

Environmental Impact of Biochar Production

The environmental benefits of biochar production are significant. By converting waste biomass into biochar, we can reduce greenhouse gas emissions from both the biomass itself and the construction materials in which the biochar is used (Lehmann et al., 2021). Studies have shown that biochar production can reduce CO₂ emissions by as much as 3.7 gigatonnes per year, contributing significantly to global carbon sequestration efforts (Fawzy et al., 2021).

Moreover, the energy produced as a byproduct during biochar production (in the form of bio-oil and syngas) can be utilized for electricity and heat generation, further enhancing the environmental benefits of this technology (Tomczyk et al., 2020).

Biochar in Construction: A Game-Changer for Sustainability

Biochar's unique properties make it an excellent additive in various construction materials, including cement, asphalt, and polymers. Here’s how biochar can be utilized to create more sustainable, carbon-neutral construction materials:

Biochar-Cement Composites

Cement production is a major contributor to global CO₂ emissions, but incorporating biochar into cement composites can mitigate these impacts. Biochar can serve as a filler or aggregate in cement, offering several benefits:

• Carbon Sequestration: Biochar can absorb CO₂ during the curing process of cement, helping to offset the emissions from cement production (Wang et al., 2021a).
• Improved Durability: The porous structure of biochar enhances the internal curing of cement, reducing shrinkage and increasing the durability of the final product (Praneeth et al., 2020).
• Enhanced Mechanical Properties: Fine biochar particles can fill the voids in cement, improving its compressive strength and making it a viable option for high-performance applications like ultra-high-performance concrete (UHPC) (Dixit et al., 2021).

Research has shown that incorporating 4% biochar into cement can store an additional 0.12 kg of CO₂ per kilogram of cement, contributing to carbon-negative concrete (Praneeth et al., 2021).

Biochar-Asphalt Composites

Asphalt, widely used in road construction, also benefits from biochar integration. Biochar enhances the properties of asphalt in several ways:

• Improved Rutting Resistance: The addition of biochar improves the high-temperature performance of asphalt, making roads more resistant to deformation under heavy traffic (Zhang et al., 2018).
• Ageing Resistance: Biochar's carbon content helps protect asphalt from oxidative ageing, extending the lifespan of pavements (Zhao et al., 2014a).
• Enhanced Sustainability: Biochar, when used in asphalt, not only improves performance but also reduces the overall environmental footprint of road construction (Hu et al., 2021).

For example, incorporating hydrochar (a type of biochar produced through HTC) into asphalt improves its high-temperature performance and rutting resistance, making it a more durable and sustainable option for road construction (Hu et al., 2021).

Biochar-Polymer Composites

Biochar can also be incorporated into polymers, offering a sustainable alternative to traditional fillers like carbon black. The benefits of biochar in polymer composites include:

• Mechanical Enhancement: Biochar improves the tensile strength, flexural strength, and elongation properties of polymers, making them suitable for various structural applications (Jiang et al., 2020).
• Thermal Stability: The stable, porous structure of biochar enhances the thermal resistance of polymers, making them more suitable for applications requiring flame retardancy (Das et al., 2017b).
• Electrical Conductivity: In certain applications, biochar can improve the electrical conductivity of polymers, making them useful in electronics and electromagnetic shielding (Poulose et al., 2018).

Biochar's ability to improve the properties of polymers while reducing the carbon footprint of these materials makes it an attractive option for various industrial applications.

Environmental and Technical Advantages of Biochar in Construction

Beyond its role in enhancing the properties of construction materials, biochar offers several environmental and technical benefits:

• Humidity Regulation: Biochar's porous structure allows it to absorb and release moisture, making it an excellent material for regulating humidity in buildings. This property can contribute to improved indoor air quality and reduced energy consumption for heating and cooling (Chen et al., 2022b).
• Thermal Insulation and Noise Reduction: Biochar's thermal properties make it an effective insulator, helping to reduce energy consumption in buildings. Additionally, its porous structure can absorb sound, contributing to noise reduction in urban environments (Gupta & Kua, 2020).
• Contaminant Immobilization: Biochar's ability to adsorb contaminants makes it useful for improving indoor air quality by trapping pollutants and preventing them from entering living spaces (Muthukrishnan et al., 2019).
• Electromagnetic Shielding: In modern buildings, where electromagnetic interference can be a concern, biochar's conductive properties make it an effective material for shielding electronic equipment from interference (Tam et al., 2019).
• Self-Sensing and Self-Healing Properties: Biochar-enhanced materials can be designed to self-sense and self-heal, improving the longevity and safety of structures. For example, biochar can be used in cement composites that can detect cracks and initiate self-healing processes, extending the lifespan of buildings and infrastructure (Wang et al., 2019b).

Challenges and Future Research Directions

While the potential of biochar in construction is vast, several challenges remain. The production of biochar at a commercial scale must be optimized to ensure consistency in quality and cost-effectiveness. Moreover, the long-term performance of biochar-enhanced materials needs to be thoroughly studied to ensure they meet industry standards for durability and safety.

Future research should focus on the following areas:

• Customization of Biochar: Tailoring the properties of biochar to meet specific construction requirements is essential. This includes optimizing the particle size, surface area, and chemical composition of biochar to maximize its benefits in different applications (Karnati et al., 2020).
• Life Cycle Analysis: Comprehensive life cycle assessments are needed to quantify the environmental benefits of biochar-enhanced materials and compare them with traditional construction materials (Matuštík et al., 2020).
• Economic Viability: While biochar offers significant environmental benefits, its economic feasibility needs to be demonstrated to encourage widespread adoption in the construction industry (Reis et al., 2020).

Conclusion

Biochar represents a promising pathway to achieving carbon neutrality in the construction industry. Its ability to sequester carbon, enhance the performance of construction materials, and provide environmental and technical benefits makes it a valuable tool in the fight against climate change. However, realizing the full potential of biochar in construction will require continued research, innovation, and collaboration across the industry.

As the world continues to grapple with the challenges of climate change, the integration of biochar into construction materials offers a sustainable solution that not only reduces the carbon footprint of the construction industry but also contributes to a healthier, more resilient built environment. By embracing biochar, the construction industry can take a significant step toward a more sustainable future.

Interested in Biochar? Explore Jord’s biochar made from sustainable C4 grass and learn how it can benefit your projects!

References

Chebil, S., Chaala, A., & Roy, C. (2000). Use of softwood bark charcoal as a modifier for road bitumen. Fuel, 79(6), 671–683. https://doi.org/10.1016/s0016-2361(99)00196-9

Choi, W. C., Yun, H. D., & Lee, J. Y. (2012). Mechanical properties of mortar containing bio-char from pyrolysis. Journal of the Korea Institute for Structural Maintenance and Inspection, 16(3), 67–74. https://doi.org/10.11112/jksmi.2012.16.3.067

Gupta, S., Kua, H. W., & Low, C. Y. (2018). Use of biochar as carbon sequestering additive in cement mortar. Cement and Concrete Composites, 87, 110–129. https://doi.org/10.1016/j.cemconcomp.2017.12.009

Gupta, S., Kua, H. W., & Tan Cynthia, S. Y. (2017). Use of biochar-coated polypropylene fibers for carbon sequestration and physical improvement of mortar. Cement and Concrete Composites, 83, 171–187. https://doi.org/10.1016/j.cemconcomp.2017.07.012

Gupta, S., Pang, S. D., & Kua, H. W. (2017). Autonomous healing in concrete by bio-based healing agents – A Review. Construction and Building Materials, 146, 419–428. https://doi.org/10.1016/j.conbuildmat.2017.04.111

Habert, G., Miller, S. A., John, V. M., Provis, J. L., Favier, A., Horvath, A., & Scrivener, K. L. (2020). Environmental impacts and decarbonization strategies in the cement and concrete industries. Nature Reviews Earth & Environment, 1(11), 559–573. https://doi.org/10.1038/s43017-020-0093-3

Khushnood, R. A., Ahmad, S., Restuccia, L., Spoto, C., Jagdale, P., Tulliani, J.-M., & Ferro, G. A. (2016). Carbonized Nano/microparticles for enhanced mechanical properties and electromagnetic interference shielding of cementitious materials. Frontiers of Structural and Civil Engineering, 10(2), 209–213. https://doi.org/10.1007/s11709-016-0330-5

Restuccia, L., & Ferro, G. A. (2016). Nanoparticles from food waste: A “green” future for traditional building materials. Proceedings of the 9th International Conference on Fracture Mechanics of Concrete and Concrete Structures. https://doi.org/10.21012/fc9.276  

Sajjad Ahmad, Jean Marc Tulliani, Giuseppe Andrea Ferro, Rao Arsalan Khushnood, Luciana Restuccia, & Pravin Jagdale. (2015). Crack path and fracture surface modifications in cement composites. Frattura Ed Integrità Strutturale, (34). https://doi.org/10.3221/igf-esis.34.58

Schmidt, H.P. (2012). 55 Uses of biochar. Ithaka Journal, 1, 286-289. https://www.delinat-institut.org, www.ithaka-journal.net. ISSN 1663-0521

Suarez-Riera, D., Restuccia, L., & Ferro, G. A. (2020). The use of biochar to reduce the carbon footprint of cement-based materials. Procedia Structural Integrity, 26, 199–210. https://doi.org/10.1016/j.prostr.2020.06.023

Tagliaferro, P. A. (2021). Biochar: Emerging applications. Institute OF PHYSICS PUBL.

Zhao, S., Huang, B., Shu, X., & Ye, P. (2014). Laboratory investigation of biochar-modified asphalt mixture. Transportation Research Record: Journal of the Transportation Research Board, 2445(1), 56–63. https://doi.org/10.3141/2445-07

Zhang, Y., He, M., Wang, L., Yan, J., Ma, B., Zhu, X., Ok, Y. S., Mechtcherine, V., & Tsang, D. C. (2022). Biochar as construction materials for achieving carbon neutrality. Biochar, 4(1). https://doi.org/10.1007/s42773-022-00182-x