The joint project "Celitement" is developing an environmentally friendly cement which can increase resource efficiency in the cement-making process. The project combines the capabilities of the Celitement GmbH, the Karlsruhe Institute of Technology (KIT) and the SCHWENK Zement KG of Ulm.
Concrete is indispensible as a "glue" in cement production. Every year over three billion tons of this binding agent are produced and almost as many tons of carbon dioxide are emitted – that are five to seven percent of carbon dioxide emissions world-wide.
Celitement is produced like traditional cement from limestone and silicates. Although they are both based on the same raw materials, there is an important difference: The water-free Portland cement which has been used so far consumes enormous resources of limestone and gypsum when produced and processed. Celitement on the other hand contains water chemically bound in calcium hydrosilicates as a reaction medium and requires only one third of the amount of limestone which is usually needed, there is no need for gypsum at all. This is made possible by a novel manufacturing process at temperatures of between 200 and 300 °C – compared to 1,450 °C for conventional Portland cement.
Low process temperatures and the reduced limestone content can halve the energy consumption for the production of Celitement compared to Portland cement. In addition, as the CO2 emissions from the manufacture of cement mainly come from limestone up to 50 percent of CO2 emissions can be avoided by reducing this raw material.
Celitement is a dry, storable powder which is processed like traditional cement. Due to its similar material properties and its compatibility Celitement can be mixed with known cements. As the new binding agent is free from components which are corrodible Celitement is even more durable than Portland cement.
Currently the pilot plant produces 100 kilograms of Celitement every day and makes it possible to develop the manufacturing process into an industrial production process. By 2015 a marketable product from a first industrial reference plant with an annual production of 50,000 tons is to be available.