Activated clays in future binders for effective and sustainable concrete infrastructures (ClayBind)

Important results from the project

The project goal is to evaluate the potential of using Swedish clays with cement. Replacing a part of cement by clays will lead to a non-negligible decrease of CO2 emissions due to cement production. Clays need to be activated before use with cement. The activation method depends on the type of clay. Therefore, another goal of the project was to find the optimal method of activation for all the different type of Swedish clays. Finally, different mix recipes containing cement and activated clay was tested (strength development), as well as the environmental impact when using those mixes.

Expected long term effects

The south of Sweden has sedimentary clays while the east and west coasts have glacial clays. Calcination can positively activate all clay samples characterized in the project. This method is more effective on sedimentary clays. For glacial clays, a ball milling treatment is preferred. A satisfactory strength gain is achieved in mortar samples cast with calcined clays. This was achieved by replacing the cement with 30% of calcined clay and 15% of limestone. A binder containing 30% of calcined clay and 15% of limestone emits 35% less CO2 per kg of binder compare to a 100% cement sample.

Approach and implementation

The most reactive Swedish clays (sedimentary) are situated in the south of the country, unfortunately in protected area, which make their exploitation challenging. The most common and easy to exploit clay, (glacial), cannot be fully activated by calcination. A mechanical activation lead to much better results, giving us a promising way of using this type of clay. A project is now on-going to optimise a binder made with glacial Swedish clays.

External links

RISE project web page.