Co-reactive secures €6.5 million for CO2-negative building material technology

German climate tech startup Co-reactive has completed a seed financing round totaling €6.5 million. The young company has set itself the goal of converting CO2 emissions into high-performance, CO2-negative cement replacement materials. To achieve this, the startup, founded in 2024, has developed a technology that continuously mineralizes CO2. With the fresh capital, Co-reactive aims to scale this technology from prototype to industrial application.

CO2-negative materials from minerals

In the financing round, High-Tech Gründerfonds (HTGF) acts as lead investor. Additional funders include NRW.Bank, HBG Ventures, AFI Ventures (the early-stage impact arm of Ventech), Evercurious VC, and Climate Tech Business Angels. Additionally, the young company receives funding from the German Federal Ministry for Economic Affairs and Energy (BMWE) in the seven-figure range. Co-reactive is now scaling to a continuous 1,000-ton demonstration plant and preparing industrial pilot plants on a ten-thousand-ton scale.

Co-reactive has developed a continuous process that converts CO2 together with natural minerals such as olivine or metallurgical slag into CO2-negative Supplementary Cementitious Materials (SCMs). The materials enable a significant reduction in the clinker content in cement and building materials. This in turn means a substantial reduction in the carbon footprint. At the same time, the materials contribute to the compressive strength and durability of building materials. The solution is designed as a drop-in technology and should integrate seamlessly into existing production processes.

Co-reactive reduces emissions and provides raw materials

In doing so, Co-reactive addresses two central challenges facing the industry: high emissions and raw material scarcity. Cement production causes around eight percent of global CO2 emissions. With rising carbon pricing, manufacturing costs threaten to double over the coming decade. Classic cement replacement materials such as fly ash and blast furnace slag are becoming increasingly scarce due to coal phase-out and the transformation of the steel industry.

With the seed financing, Co-reactive is initially scaling its current laboratory and pilot operations to a continuously operated demonstration plant with approximately 1,000 tons of capacity per year by Q2 2026. In parallel, the young company is preparing first-of-a-kind plants on a ten-thousand-ton scale together with industrial partners, which from 2027 onwards are to mineralize biogenic or process-related CO2 streams on-site in the cement and steel industries.

“Bringing CO2 mineralization into industrial continuous operation”

“Support and science are the foundation – real transformation only happens through entrepreneurial action. With the right co-founders and an interdisciplinary team, we’re bringing CO2 mineralization from the lab into industrial continuous operation. We’re building a solution that is urgently needed today so it can have an impact at industrial scale tomorrow,” says Andreas Bremen, co-founder and CEO of Co-reactive.

Anna Stetter, Investment Manager at HTGF, comments: “The construction industry is at a turning point: classic cement replacement materials like blast furnace slag and fly ash are becoming scarce and expensive due to decarbonization – fly ash prices have quadrupled in some cases over the last two years. Co-reactive offers a scalable alternative that is not only CO2-negative but also integrates as a drop-in solution into existing processes. With strong unit economics and an experienced team of mineralization and plant engineering experts, Co-reactive has the potential to sustainably transform the industry.”