Activated clays in future binders for a sustainable concrete infrastructure

The production of “green” infrastructures made of concrete goes generally through the use of supplementary cementitious materials (SCMs), which decreases the carbon dioxide footprint due to reducing the Portland cement content needed for production of the concrete. However, limitations on the availability of the major SCMs such as slag or fly ash are expected in the near future. Moreover, some common SCMs like silica fume or metakaolin are not only being expensive but can also not be used in large proportions because it would affect negatively the early properties of fresh concrete.

Those limitations brought a lot of attention to clays during the recent years. Clays have not been used in their full potential as cement constituents due to an ample supply of other SCM in the past. It is known that these materials exhibit pozzolanic properties when activated (by e.g. calcination) and can react with the calcium hydroxide of the cement. The energy consumption and CO2 emissions during calcination of clays are lower than in the cement production. Therefore, the substitution of a fraction of Portland cement by calcined clays will improve the sustainability of a blended binder.

To account for the potentials of the use of Swedish clay resources, a three-step project is suggested. Step I will focus on optimizing the activation process of the different clays. In step II, the reactivity and pozzolanic activity of the clays in cement systems will be studied. Finally, step III, the possibility of application of activated clay in existing Concretes used for infrastructures will be investigated.