Low-Carbon Binders for Sustainable Hempcrete Emissions

Strategic Insights -

Researchers at the University of Technology Sydney have found that industrial hemp can be used to create a sustainable building material with the potential to alleviate carbon emissions and energy usage in the construction industry. The study investigated three low-carbon binder alternatives for hempcrete, a mixture of industrial hemp and a binder, which can reduce greenhouse gas emissions and energy consumption. The research revealed that a geopolymer binder made from calcined clay and ground blast furnace slag achieved the best performance in terms of compressive strength, surface bonding capacity, and thermal conductivity.

Key Takeaways:

  • The building sector is responsible for approximately 40% of total anthropogenic greenhouse gas emissions and 37% of global energy consumption.
  • Hempcrete, made from industrial hemp and a low-carbon binder, can offer a tremendous potential to alleviate the carbon emissions and energy usage from buildings and construction.
  • Conventional lime-based binders for hempcrete are carbon intensive, making it essential to explore alternative low-carbon binders.
  • The study investigated three low-carbon binder alternatives: HL-Ref (100% hydrated lime), HL-CC (50% hydrated lime, 50% calcined clay), and HL-CC-LS (50% hydrated lime, 50% calcined clay and limestone).
  • The geopolymer binder made from calcined clay and ground blast furnace slag achieved the best performance in terms of compressive strength, surface bonding capacity, and thermal conductivity.
  • The HL-CC-LS hempcrete achieved the best acoustic performance with the highest sound absorption coefficient.
  • The study concluded that low-carbon calcined clay-based binders for sustainable hempcrete could be a viable solution for reducing greenhouse gas emissions and energy consumption in the construction industry.
  • The research was supported by the Australian Research Council and the Australian Hemp Masonry Company Pty. Ltd.
  • Additional authors include Siddharth Girish Nair, Arnaud Castel, Peter J. Irga, Cecilia Gravina da Rocha, Qiaoxi Zhu, Mahmoud Karimi, Yixiang Gan, Haiyi Zhong, Fraser R. Torpy, Sara Wilkinson, Danielle Moreau, and Fabien Delhomme.

Statistics:

  • 40%: The building sector is responsible for this percentage of total anthropogenic greenhouse gas emissions.
  • 37%: The building sector is responsible for this percentage of global energy consumption.
  • 100%: Hydrated lime was used in the HL-Ref binder.
  • 50%: The proportion of hydrated lime used in the HL-CC binder.
  • 50%: The proportion of calcined clay used in the HL-CC binder.
  • 70%: The proportion of calcined clay used in the Geo-CC geopolymer binder.
  • 30%: The proportion of granulated ground blast furnace slag used in the Geo-CC geopolymer binder.
  • 50%: The proportion of hydrated lime used in the HL-CC-LS binder.
  • 50%: The proportion of calcined clay and limestone used in the HL-CC-LS binder.

Sources:

  • Low-carbon Calcined Clay-based Binders for Sustainable Hempcrete. Materials and Structures, 2025;58(6).