New concrete mixes leave the lab and join the material market
Holcim conducted biochar concrete pilot projects across Europe in 2025, including test pours with Canary Wharf Group using biochar from forestry residues and coffee grounds, producing their first net-zero concrete mix. The trials signal a shift for the biochar sector from experimental additive to commercial-scale construction material, with Holcim describing it as a high-performance emissions-reduction input rather than a niche product.
Biochar, an advanced carbon material, is making strides in the construction industry as a sustainable additive for concrete mixes. Researchers at Heriot-Watt University in Scotland, led by Dr. Mehreen Gul, have demonstrated that incorporating biochar into concrete can enhance compressive strength by approximately 10% when replacing just 1% of fine aggregate. Biochar is created by pyrolyzing organic biomass, which sequesters carbon and prevents its release as CO2, effectively turning buildings into carbon sinks. Each kilogram of biochar can prevent up to three kilograms of CO2 emissions.
Swiss-based Holcim Ltd., a major player in concrete production, has begun integrating biochar into pilot projects across Europe. Collaborating with architect Alejandro Aravena and design firm ELEMENTAL, Holcim showcased a scalable biochar technology prototype at the 2025 Architecture Biennale in Venice. Further trials in partnership with London's Canary Wharf Group utilized biochar from forestry residues and coffee grounds, leading to the development of Holcim's first net-zero concrete.
Holcim's trials aim to demonstrate that next-generation concrete mixes can match or exceed the performance of traditional concretes, encouraging wider adoption and promoting circular economy principles. According to Edelio Bermejo, Holcim's head of Global R&D, biochar is increasingly seen as a high-performance material that reduces emissions, moving beyond its experimental status.
In addition to biochar, Holcim plans to incorporate calcined clay into its cement formulations by 2026. This supplementary cementitious material can significantly reduce the CO2 footprint of cement without compromising performance, addressing the scarcity and cost of traditional low-emission SCMs like slag and fly ash.
Holcim is also pursuing sustainability through a 33% reduction in freshwater use by 2030, piloting initiatives in Ecuador and Mexico that integrate operations with local water cycles, turning industrial wastewater into a resource.
In parallel, researchers from the Norwegian University of Science and Technology and the University of Tokyo are developing Botanical Sand Concrete, or Sandcrete, using desert sand and wood lignin as a natural binder. This approach could mitigate the environmental impact of sourcing sand from traditional locations. While promising for paving stones, further research is needed to expand Sandcrete's applications and assess its performance in cold climates. Transportation of desert sand remains a challenge, potentially offsetting environmental benefits.
The potential of these innovations suggests a future where sustainable building materials, including biochar and Sandcrete, play a crucial role in reducing the environmental impact of construction.
Source: Biochar Feed