Success Story: CORNET project Opti-WCR

Optimisation of the water-to-cement-ratio to improve the setting, drying and high temperature behaviour of refractory castables

Induction furnace for treatment of refractory castables

Refractory materials are broadly used in process industries wherever high temperatures prevail and high corrosion resistance is needed, e.g. in iron and steelmaking, non-ferrous metallurgy and in the production of glass, cement or energy. Furthermore, any form of thermal treatment is usually carried out in furnaces that are lined with refractories, e.g. in the production of metals and all types of ceramics.

Refractories are key materials in all major process industries

Refractory linings are laid with shaped products (e.g. bricks) or are made from refractory castables, which are cast in templates on-site, directly into the units they are intended for. Refractory users increasingly prefer to employ refractory castables because they are so easy to install and therefore cost-effective. Furthermore, relining is quick and only interrupts production for a short period of time. Refractory castables already form 40 % of the overall market for refractories.

The processing of refractory castables is a decisive step

The processing of refractory castables may seem easy, but in fact requires comprehensive knowledge about the material. Most refractory castables rely on cement phases to develop mechanical strength even at low temperatures. As with concrete in building applications, the amount of water that is added during processing directly affects processing behaviour (pumping, casting, gunning etc). However, in the case of refractory castables, the amount of water also strongly affects their setting (development of mechanical strength at low temperatures) and heating-up performance. Accordingly, the ratio of water and cement phases in refractory castables (the “water-to-cement-ratio”) is fundamentally important for their processing behaviour.

Optimising the processing of refractory castables by recognizing the water-to-cement-ratio

The project partners all focused on different aspects.

The CORNET Opti-WCR project focused on the water-to-cement-ratio in refractory castables. The Opti-WCR project identifies the gap in know-how about refractory castables and focused on the influence of the water-to-cement-ratio on processing steps like setting, drying and heating-up performance.

In the CORNET project, each partner focused on one aspect of the processing of refractory castables and how it is being influenced by the water-to-cement-ratio. Koblenz University of Applied Sciences investigates the influence of the water-to-cement-ratio on the formation of hydrates from the cement phases and their influence on the setting and hardening behaviour of linings made from castables. The Institute of Ceramics and Building Materials (ICiMB) focuses on the microwave drying of refractory castables with various water-to-cement-ratios and the influence of this drying process on the resulting properties of the material. Forschungsgemeinschaft Feuerfest (FGF) focuses on the influence of dehydration and sintering of refractory castables, with various water-to-cement-ratios, on their thermal properties up to application temperatures. For the first time, FGF determined thermal properties like thermal diffusivity in-situ during the heat treatment of refractory castables with a novel laser-flash device especially developed for refractories. With this three-fold approach, all aspects of the processing of refractory castables and the role of the water-to-cement-ratio on processing performance are investigated.

Potential for the refractory industry

The outcome of this project has the potential to improve understanding of the importance of the water-to-cement-ratio of refractory castables during their processing. Manufacturers of refractory castables will be able to create improved products with even shorter and more manageable processing. The integration of the Opti-WCR Project into the CORNET programme offers a significant advantage in that a technical problem can be monitored from several points of view within one project. Furthermore, the bilateral nature of the project facilitates broad distribution of the results to SMEs throughout the European refractory industry.

Dipl.-Ing. (FH) Johannes Kasper, email:, tel: +49 2624 9433 173, Forschungsgemeinschaft Feuerfest e.V. (FGF)


Participants from Germany

FGF – Forschungsgemeinschaft Feuerfest e.V., Höhr-Grenzhausen – Coordinating association and Research organisation

Koblenz University of Applied Science – Materials Engineering Glass & Ceramics, Höhr-Grenzhausen – Research organisation


Participants from Poland

ICiMB – Institute of Ceramics and Building Materials, Refractory Materials Division, Gliwice – Research Organisation

SPMO – Stowarzyszenie Producentów Materiałów Ogniotrwałych, Gliwice – Participating association


Pictures: © Forschungsgemeinschaft Feuerfest e.V. (FGF)