Calcined Clay as a Component of Cement and Concrete

In recent decades, technological developments in the cement industry have been limited. In this regard, manufacturers are increasingly striving to influence the main indicators of production efficiency and sustainable development of the industry (such as specific heat and electricity consumption, emissions of pollutants and CO2, as well as the depletion of critical resources), using auxiliary tools for fine tuning clinker and cement processes. These include, for example, the use of alternative fuels and raw materials and of natural or technogenic mineral additives (MA) in the composition of cement. The wider use of alternative fuels and materials and MA in the process flows of production of cement and cement-based building materials (such as concrete) requires joint action by industry experts, end users of these materials, as well as government agencies and design engineers to bring standards for cement and concrete and industry performance targets in line with international best practices and R&D. This paper discusses the general situation in the field of the development of calcined clay additives for use in concrete and mixed cements. The production of such additives is developing rapidly due to the limited availability and often insufficient quality of a number of man-made MAs, such as ground granulated blast furnace slag (a by-product of steelmaking) and fly ash, mainly generated at coal-fired power plants.

Author: S. Gross, H.W. Meyer, P.H. Heersche

Section: New materials

Keywords: calcined clay, clinker substitution, flash calciner, rotary kiln, cement, concrete