Innovative Concrete Mixes: Biochar and Desert Sand Pave the Way for Sustainable Construction

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Research into biochar and desert sand as sustainable concrete alternatives is gaining traction, with major industry players beginning to adopt these materials.

In recent years, the construction industry has seen an increasing interest in sustainable building materials, particularly biochar and desert sand. Two years ago, researchers from Heriot-Watt University in Scotland, under the leadership of Dr. Mehreen Gul, began exploring the potential of biochar as a low-carbon alternative in concrete production. Dr. Gul highlighted that integrating just one percent of biochar into cement mixtures could enhance compressive strength by approximately ten percent. This innovative material, created by pyrolyzing organic biomass—ranging from food waste to forestry byproducts—in low-oxygen environments, serves as a carbon sink, effectively sequestering carbon that would otherwise be released into the atmosphere. It is estimated that each kilogram of biochar can prevent the emission of up to three kilograms of CO2, thus contributing positively to the environment.
Dr. Gul expressed optimism that their research would accelerate the adoption of biochar within the industry. She emphasized the importance of consulting with industry stakeholders to assess the material's effectiveness, cost, and social acceptance. The shift towards acceptance has already begun, as evidenced by Swiss-based Holcim, one of the largest concrete producers globally. In 2025, Holcim initiated pilot projects incorporating biochar into concrete mixes across Europe. According to Edelio Bermejo, Holcim's head of Global R&D, the company showcased a scalable prototype utilizing biochar at the 2025 Architecture Biennale in Venice, in collaboration with renowned architect Alejandro Aravena from the design firm ELEMENTAL.
Following this, Holcim conducted test pours using biochar derived from forestry residues and coffee grounds in partnership with London’s Canary Wharf Group, marking the development of their first net-zero concrete. Jasen Gauld, the national Readymix product development director for Holcim UK, noted that the objective of these trials was to demonstrate that advanced concrete mixes could perform on par with, or exceed, traditional concrete standards, thereby instilling confidence in contractors and the broader supply chain to embrace these sustainable alternatives.
Furthermore, Bermejo indicated that the mainstream use of biochar is expanding, as clients no longer view it merely as an experimental additive but recognize it as a high-performance material capable of reducing emissions. In addition to biochar, Holcim plans to incorporate calcined clay into their cement formulations starting in 2026. This supplementary cementitious material (SCM) is anticipated to significantly reduce the CO2 footprint of cement production while maintaining performance levels, reducing reliance on increasingly scarce or costly traditional SCMs such as slag and fly ash.
Holcim's commitment to sustainability extends beyond material innovation. The company aims to achieve a 33 percent reduction in overall freshwater intake by 2030. This initiative includes pilot projects in Ecuador and Mexico, where Holcim is integrating its operations with the local water cycles of adjacent industries, highlighting a transformative approach to supply chain management.
In a parallel research effort, scientists from the Norwegian University of Science and Technology (NTNU) and the University of Tokyo have been investigating the feasibility of using desert sand to create a novel concrete mix termed Botanical Sand Concrete or Sandcrete. The environmental impact of sourcing conventional sand for concrete—often extracted from riverbeds, oceans, and crushed rock—is significant. The Sandcrete mixture combines desert sand with small wood particles, using lignin as a natural binder instead of relying solely on cement hydration.
While the concept of using desert sand is not entirely new, its application in traditional concrete mixes has been limited due to its fine-grained nature, which previously rendered it unsuitable for construction. Ren Wei, a researcher at NTNU, explained that laboratory tests conducted at the University of Tokyo have examined how various factors such as temperature, mixing ratios, pressure, and pressing times affect the strength and density of Sandcrete. Results have demonstrated that this innovative mix can produce concrete strong enough for paving stones and walkways, with hopes of expanding its applications to indoor use pending further testing.
However, challenges remain, particularly regarding cold weather durability and the logistics of transporting desert sand to concrete manufacturing sites, which could undermine its environmental advantages. Despite these hurdles, the potential for Sandcrete is significant, considering that deserts span an estimated 19 million square miles globally. With ongoing development, botanical sand concrete could emerge as a vital component of sustainable building materials in the future, addressing the paradox of excessive sand consumption while abundant supplies lie in arid regions.

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