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OPTERRA launches Portland pozzolan cement

Published by , Deputy Editor
World Cement,

After a development and test phase of almost three years, OPTERRA has launched OPTASTONE® from the Wössingen plant, a special cement for concrete products that relies on natural trass. This recipe optimisation has not only compensated for the use of blast furnace slag, but also improved the ecological footprint of cement at the same time.

Cement-based products are indispensable in many areas of construction. At the same time, there are strong efforts to improve the ecological footprint of buildings and thus also of building materials. In the production of cements, the use of burnt Portland cement clinker should be kept as low as possible. This is made possible by the use of valuable alternative raw materials, among other things. This includes trass, which is formed as rock after volcanic eruptions from lava, and is extracted in quarries. Its special property is that trass is latently hydraulic and forms permanently stable connections with calcareous stimulants and water. This leads to very good consolidation and tightness of cement stone in concrete. The Rheinische trass used is a rock that was created during a volcanic eruption in the Eastern Eifel.

In the production of Portland pozzolan cement, cement clinker is ground with trass and other additives, thus offsetting the use of blast furnace slag.

In the late summer of 2018, the application consulting team started their first attempts to use this raw material for cement production in close cooperation with the quality department. The numerous tests of mortar and concrete in 2019 were followed by extensive factory tests at producers of concrete products in 2020. Due to the high quality of the concrete products manufactured, the producers attested that the new trass cement from Wössingen had good workability in addition to the expected properties.

The new cement type with the normative designation CEM II / AP 42.5 R will in future be delivered to customers as OPTASTONE® from the Wössingen plant. Since autumn 2020, the cement has been supported by the Verein Deutscher Zementwerke e. V. (VDZ) certified. Like all types of cement, it is therefore subject to both its own and constant external, institutional monitoring.

The OPTERRA plant in Wössingen is one of the few cement plants in Germany that offers pozzolan cement. In addition to the successful development of a new cement for the OPTERRA product family, OPTASTONE® is also a fully-fledged alternative to the long-term, limited quantities of blast furnace slag.

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