Reactivity of Mineral Additions

Date This project started on 01 November 2005 and ended on 01 December 2009

Status This project is Finished

Authors
Ecole Polytechnique Fédérale de Lausanne, CH
University of Aarhus, DK
University of Leeds, UK
Technological University of Denmark, DK
Objectives

Traditional Portland cements based purely on interground clinker and calcium sulfate (e.g. gypsum) are being increasingly replaced by blended cements, where part of the clinker is replaced by secondary cementitious materials (SCMs) such as blast furnace slag, fine ground limestone of fly ash from coal fired power stations.

This trend is extremely important for increasing the sustainability of cement manufacture in reducing the consumption of raw materials and of CO2 emissions. Increasing the level of substitution is limited by the ability to well predict the performance of these blends in terms of strength development and durability, particularly when the reactivity of the SCM is variable.

This project will develop a methodology to follow the reaction of the clnker and the SCM component separately in blended cements and so provide the means for understanding the factors determining the reactivity of SCMs and their contribution to the performance of cementitious materials.

The presence of different phases requires the used of complementary techniques. X-ray diffraction (XRD) allows us to investigate the highly crystallized phases whereas Nuclear Magnetic Resonance (NMR) is well adapted to the study of amorphous as well as crystalline materials. Chemical shrinkage, provides a complimentary method to follow the overall reaction. Other methods such as Electronic Microscopy and Thermal Analysis will be used to support understanding of the hydration mechanisms. In parallel the evolution of basic properties such as strength/elastic modulus and absorption will be studied.

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