The cement industry is facing one of its greatest transformations: The pressure to drastically reduce the CO₂ footprint is forcing manufacturers to make fundamental changes in production. Holcim is pursuing a strategy at the Dotternhausen location that is increasingly regarded as central in the industry: massive expansion of alternative raw materials. What was previously considered a niche issue is becoming an industrial policy lever – with far-reaching consequences for material flows, waste management, and the regulatory framework for the entire industry.
Dotternhausen as a real-world laboratory for the cement industry
The Dotternhausen plant in Baden-Württemberg plays a special role in the German cement landscape. Here, Holcim produces around one million tons of cement annually – while simultaneously testing technologies that could be groundbreaking for decarbonizing the entire industry. The announcement to significantly expand the use of alternative raw materials is not a minor note, but part of a systematic strategy: The location is to become a pilot for a production method that gradually moves away from traditional clinker manufacturing.
Cement production is responsible for approximately eight percent of global CO₂ emissions. Most of these emissions do not arise from energy consumption, but from the chemical process itself: In the manufacture of clinker from limestone and clay at temperatures exceeding 1,400 degrees Celsius, CO₂ is released. This process-related emissions can only be reduced through a fundamental change in the raw material base – or through the use of materials that have already been industrially pre-treated and release less CO₂.
Which alternative raw materials are being used specifically?
Holcim plans to increasingly rely on three categories of alternative raw materials in Dotternhausen: blast furnace slag from the steel industry, fly ash from coal power plants, and processed recycled concrete. These materials either replace clinker itself or at least parts of the raw materials required for its production.
Blast furnace slag, a by-product of steel production, is the quantitatively most important substitute material. It is produced when iron ore is smelted and is granulated by rapid cooling. In ground form, it possesses latent-hydraulic properties, meaning it hardens in combination with water and lime – similar to cement. The use of blast furnace slag not only reduces the clinker content but also significantly improves the CO₂ balance, as no additional thermal treatment is required.
Fly ash, the second major pillar, is produced in coal power plants and has hitherto been frequently deposited or only partially utilized materially. It can partially replace cement as a pozzolanic material and also improves the workability and long-term strength of concrete. However, the gradual phaseout of coal raises long-term questions about fly ash availability – a problem that is increasingly concerning the cement industry.
Recycled concrete, finally, is the material of the future: Processed demolition concrete is converted into recycled aggregates that can serve as coarse aggregates or even as raw material for clinker production. However, the industry is still in its infancy here. Technically much is possible, but the availability of high-quality recycled aggregates and the logistics of their collection are not yet solved across the board.
Material flows: Where does the substitute material come from – and where does it go?
Expanding the use of alternative raw materials in Dotternhausen has direct implications for regional waste management and industrial circular material flows. Holcim depends on reliable supplies – and must simultaneously ensure that the materials meet the strict requirements of cement standards. This means: close cooperation with steel mills, power plant operators, recycling companies, and municipal waste management.
The use of recycled concrete in particular requires new logistics concepts. Unlike blast furnace slag or fly ash, which are produced in large quantities at few locations, demolition concrete is distributed decentrally. To use it economically, sorting technologies are needed that remove contaminants such as gypsum, plastics, or wood, as well as processing plants that standardize the recycled aggregates. A new market is currently emerging here – with significant investment requirements.
Holcim's strategy in Dotternhausen exemplifies how the value chains of the building materials industry are changing. The classical cement manufacturer becomes a purchaser of industrial by-products and a partner to the recycled building materials industry. This changes not only production processes but also business models.
Regulatory framework: Standards as driver and brake
The cement industry operates within tight regulatory constraints. DIN EN 197-1 defines which cement types are permitted and which proportions of clinker and additives they may contain. On one hand, this standard guarantees quality; on the other hand, it also acts as an innovation brake: New substitute materials must be extensively tested and approved before they can be used on a larger scale.
In parallel, EU taxonomy is increasing pressure on the industry. Only cement that meets certain CO₂ limits will be considered sustainable in the future – and only such projects can hope for favorable financing. For Holcim, this means: Expanding alternative raw materials is not just an ecological but also an economic necessity. Those who want to remain competitive in the future must demonstrably reduce their CO₂ footprint.
At the same time, there are funding programs at national and European level that support investments in climate-friendly production processes. Whether Holcim has applied for such funds for Dotternhausen is not publicly known – but the strategy fits seamlessly with the political objectives of the federal government, which wants to massively advance the circular economy and resource conservation.
Economic perspective: Costs, availability, competition
The use of alternative raw materials sounds like a win-win situation: fewer emissions, less raw material consumption, more circular economy. But reality is more complex. Substitute materials such as blast furnace slag and fly ash are in high demand – and their availability is limited. With declining steel production in Europe and the phase-out of coal-fired power generation, supply will decrease in the medium term. This drives prices up and intensifies competition between cement manufacturers.
At the same time, Holcim must invest in new plant technology in Dotternhausen: grinding mills, mixing aggregates, quality assurance systems. These investments only pay off if the use of alternative raw materials remains economically viable in the long term – and if regulatory conditions remain stable. The decarbonization challenge is thus also a matter of financing and political will.
Competitors such as Heidelberg Materials pursue similar strategies but place different emphases – such as on carbon capture or alternative binders. The competition for the best decarbonization strategy is in full swing. Dotternhausen could become a benchmark – or a warning that technical feasibility alone is not enough.
Signaling effect for the industry: What follows from Dotternhausen?
If Holcim successfully demonstrates in Dotternhausen that the use of alternative raw materials is technically sound, economically viable, and ecologically effective, it will find imitators. Other locations in Germany and Europe could follow suit – and demand for industrial by-products and recycled building materials would skyrocket. This would further drive up prices but also create new business opportunities for waste and recycling companies.
At the same time, pressure on standardization bodies would grow to accelerate the approval of new substitute materials and make standards more flexible. The construction industry, in turn, would have to adapt to changing cement qualities – not in terms of performance, but in composition. This requires communication, transparency, and trust.
Holcim's strategy in Dotternhausen is not a panacea for the cement industry's climate crisis. But it shows that the industry is ready to fundamentally change its production methods – and that this requires not only new technology but also rethinking material flows, standards, and value chains. How measurable the decarbonization strategy ultimately is will become clear in the coming years – Dotternhausen will play a central role.
Conclusion: From pilot to model?
The planned expansion of alternative raw materials in Dotternhausen is more than a local measure. It is a test run for the entire cement industry – and an indicator of whether the industry's decarbonization can succeed without compromising supply security. The challenges are enormous: limited availability of substitute materials, regulatory hurdles, high investment costs. But the alternative – clinging to previous production methods – is no longer an option.
Holcim is pursuing a strategy in Dotternhausen based on realism, pragmatism, and industrial logic. Whether this becomes a model for the entire industry depends not only on technical solutions but also on political decisions, economic incentives, and the willingness of all stakeholders to take circular economy seriously. The path to climate-neutral cement production leads through plants like Dotternhausen – or it leads nowhere.
