Innovative SCM for low clinker cement: natural, artificial and CO2 mineralized pozzolanic additions blended with limestone

Abstract

SCMs has proven to be an effective mineral addition to cement and concrete. In fact, cement containing high amount of SCM can contribute at reducing the heat of hydration and increasing the resistance against sulfate attacks or improve chloride migration in concrete. During the latest years, besides more traditional materials such as GGBS and natural pozzolans, several innovative SCMs have been proposed as future materials for the cement sector. Calcined and mechanically activated clays are proposed as the most promising and attractive ones, as clays are widely spread on earth. Furthermore, the hydration mechanism of such SCMs can benefit from the presence of limestone enabling a further clinker reduction. Other promising SCMs obtained, for example, from the carbonation process of silicate rocks, or other innovative treatments are recently proposed, and they based on the pozzolanic reactivity of the amorphous SiO ₂ formed after the carbonation. These alternative materials, beside interesting properties deriving from their reactivity, may use part of the CO ₂ in the carbonation process forming calcium carbonate that will be incorporated in the SCM itself. The long‐term experience of the use of natural pozzolan in cement and their blend with other traditional cement constituents, such as slag and limestone, can give a good basis for understanding the possible impact of such innovative SCMs in terms of mechanical and durability performances.

This paper will provide an overview of the innovations ongoing with SCMs and put in relationship with the most recent industrial experiences of producing low clinker cements with calcined clay and natural pozzolan blended with limestone.