GreenMixes, a fast-rising climate tech venture developing carbon-negative concrete solutions, has completed a three-month bench residency in our shared co-lab space at Co-labs by journey, after securing first place in the Post Doc Venture Creation Challenge 2026. The Challenge is run by Cambridge Zero, in partnership with Carbon13, Cambridge Enterprise, the Maxwell Centre, Energy IRC, King’s Entrepreneurship Lab and CISL Canopy.

The start-up was founded by two researchers from the University of Cambridge—Dr Dushanth Seevaratnam, PhD a research associate in the Fluids in Advanced Manufacturing Research Group at the Institute for Manufacturing with a background in nanotechnology engineering, and Callon Peate, a PhD student in the Fluid in Advanced Manufacturing (FIAM) Group who joined the Institute for Manufacturing in 2023.

GreenMixes is developing a biochar-based admixture that transforms concrete into a carbon sink—locking away more CO₂ than it emits while maintaining performance and requiring no changes to existing production processes. With concrete responsible for over 8% of global carbon emissions, the company’s technology aims to transform one of the world’s most carbon-intensive materials into part of the climate solution. GreenMixes continues to grow and progress with commercialisation alongside accelerating pilot projects to bring the technology to market.

Their time at Co-Labs reflects both the strength of the local innovation ecosystem and the increasing demand for flexible, city-centre lab solutions for spin-outs from the university. The workspace is designed to support high-growth ventures while offering a collaborative environment alongside other innovation companies. The journey team had the wonderful opportunity to see GreenMixes round up their time at Co-Labs with another competition win at the Cambridge Climate Challenge 2026 (Track 2), where journey were sponsors.

It was a pleasure to have GreenMixes in our community and support this phase of growth.

Get in touch with our team.