Holcim opens Czech calcined clay line to cut cement clinker
A new line at Cizkovice makes over 115,000 tonnes of calcined clay a year, letting Holcim supply about 580,000 tonnes of lower-carbon cement.
On 3 September 2026, the building materials company Holcim opened a calcined clay production line at its Čížkovice cement plant, the first of its kind in the Czech Republic, Holcim and Global Cement reported. Heated clay replaces part of the clinker in cement. Holcim says this cuts the cement's carbon footprint by about 30 percent without lowering its performance.
- 115,000 tof calcined clay the line can produce each year
- 580,000 tof lower-carbon cement it can supply each year
- 6calcined clay projects due to start worldwide in 2026
- 22 Mtyearly cement capacity of Nepal's plants, per CemNet
- 50%share of Nepal's cement output that is pozzolana cement
What happened
Holcim, a Swiss-based company, held a launch ceremony for the new line on 3 September 2026, according to Global Cement, a trade publication. The Czech Prime Minister, Andrej Babiš, attended. The line takes clay from Holcim's own nearby quarry, heats it and prepares it so that it can replace part of the clinker in cement. Holcim says it is the first production line of this kind in the Czech Republic.
The line can make more than 115,000 tonnes of calcined clay a year, Holcim says. That is enough to supply about 580,000 tonnes a year of the company's lower-carbon cement, sold under the name ECOPlanet. Holcim states that the cement has a carbon footprint about 30 percent lower than ordinary cement, with no loss of performance. These figures come from the company and have not been independently tested.
Holcim calls the line the largest investment in the history of its Czech business. It says 330 million Czech koruna, about 13 million Swiss francs, came from the Czech environment ministry's Modernisation Fund. Global Cement puts the total project cost at about 40 million euros, with about 13.5 million euros from that fund. Holcim opened Europe's first dedicated calcined clay line in France in 2023, and a large line in Ecuador in 2025.
The engineering behind it
Ordinary Portland cement is made mostly of clinker. In general terms, clinker is produced by heating limestone and clay in a kiln to about 1,450 degrees Celsius. This releases a large amount of carbon dioxide, partly from the fuel and partly because the limestone itself gives off carbon dioxide as it breaks down. The more clinker a cement contains, the larger its carbon footprint.
Calcined clay is a supplementary cementitious material, a powder that can take the place of some clinker. Clay is heated to a much lower temperature than clinker, typically in the range of 700 to 850 degrees Celsius. This drives water out of clay minerals such as kaolinite and turns them into a reactive form. In the cement, this reactive clay combines with calcium hydroxide released as the clinker hardens, forming extra binding compounds. This general chemistry is well known.
Because calcined clay is made at a lower temperature and does not come from limestone, it releases much less carbon dioxide per tonne than clinker. Many blends also add some limestone powder, a mix often called LC3. The cement must still meet the strength and durability standards that engineers rely on. Mix designs may need adjusting, because blended cements can gain strength at a different rate and need water in different amounts.
A wider trend
Global Cement reports that the LeadIT group, which tracks green cement technology, published a report around the same time. It found six calcined clay projects planned to start in 2026, including Čížkovice. The others are in South Africa, Ivory Coast, Burkina Faso and Portugal. LeadIT also counted five delayed projects and five with no announced start date. In total, 14 projects in the pipeline represent 405 million dollars of investment and 3.3 million tonnes a year of capacity.
Global Cement gives several examples. A German equipment maker launched an electrically heated calcination conveyor in late 2025, and a Danish company is marketing its own calcination tower. In the United Kingdom, a brick maker said in July 2026 that it wants to calcine its surplus clay on a much larger scale. In Australia, a clay supplier signed an agreement in July 2026 to supply calcined clay to Holcim's Australian business.
Global Cement notes that equipment makers and raw material suppliers are entering the market, including brick makers looking to use surplus clay. Some companies are also testing ways to activate clay without heating it. The magazine concludes that calcined clay is already working at scale, at lower cost than carbon capture, and is delivering carbon dioxide reductions.
What it means in Nepal
Nepal has a large cement industry of its own. CemNet reported in January 2025 that Nepal had 65 cement plants in 2023, 42 grinding units and 23 integrated plants, and that 21 factories can produce clinker. Domestic consumption was about 8 million tonnes in 2024. By December 2025, CemNet put the combined capacity of more than 50 plants at 22 million tonnes a year, far above demand.
Blended cement is already common in Nepal. According to CemNet, about half of the cement produced is pozzolana cement, 40 percent is ordinary Portland cement and 10 percent is slag cement. CemNet also reports that Nepali producers typically use 75 to 80 percent local raw materials. A pozzolana cement already uses a supplementary material in place of some clinker, so the idea behind calcined clay is not new to the local industry.
For a civil engineer, the practical skill is to understand what these materials do to concrete. That means knowing how blended cements gain strength, how they affect durability, how the relevant standards classify them, and how to adjust a mix design. Whether calcined clay would suit a particular plant depends on its local clay and costs, which are questions for testing and study rather than assumption.
What to study if this interests you
Engineering Chemistry, ENSH 103, in the first semester of BCE, covers the chemistry of cement, lime and clay minerals. Civil Engineering Materials, ENCE 103, also in the first semester, introduces types of cement and their properties. Concrete Technology, ENCE 205, in the third semester, deals with mix design, admixtures and blended cements, and how they change strength and durability.
Words in this story
- Clinker
- The hard lumps made by heating limestone and clay in a kiln, which are ground to make cement.
- Calcined clay
- Clay heated to drive out water and make it reactive, so it can replace part of the clinker in cement.
- Supplementary cementitious material
- A powder such as fly ash, slag or calcined clay that replaces some clinker and adds to concrete strength.
- Pozzolana
- A material that reacts with calcium hydroxide in cement paste to form extra binding compounds.
Where this comes from
- Holcim, 3 Sep 2026
- Global Cement, 9 Sep 2026
- CemNet (International Cement Review), 3 Jan 2025
- CemNet (International Cement Review), 31 Dec 2025
Written in our own words; no sentence is copied from these reports. Researched with AI assistance on 11 October 2026; no member of faculty has reviewed it yet. If you spot a mistake, call 01-5091616 and we will correct it and say so.
