From bauxite residue mineralogy to reactivity and properties of blended cements
Michael J. Wenzel, Fabien Georget, Thomas Matschei
Abstract
This paper reviews the efforts taken towards developing bauxite residue (BR) based blended cements (>30% substitution) contributing to the cement industry's net-zero targets, while utilizing the Bayer-processes by-product. We provide a comprehensive review of physical properties, element composition and mineralogy of Bayer and sintering BR. This defines the main challenges that BR based SCMs have to overcome to be utilized in sustainable blended cements. Several activation treatments and their impact on SCM characteristics and reactivity are introduced and compared to other reactive SCMs . Furthermore, the review summarizes the impact of BR addition on the engineering performance of blended cements and includes selected durability issues. Our main goal is linking macroscopic observations to microstructural features of the binders and outlining a way towards a complete understanding of these blended cements. We outline specific knowledge gaps, in particular the effect of bauxite residues on the phase assemblage and microstructure of blended cements.