Novel SCM produced by the co-calcination of aluminosilicates with dolomite

Abstract

In this work, a novel type of supplementary cementitious material (SCM), produced by the calcination of aluminosilicate such as clays and micas in the presence of dolomite, is investigated. The thermal activation was assessed at different calcination temperatures. The activity of the produced SCM was tested in combination with Portland cement in paste and mortar. The compressive strength results demonstrate that the novel SCM out-performs all tested state of the art references. The cause for the improved reactivity is associated with the formation of poorly crystalline, reactive calcium and magnesium-rich phases such as free lime, periclase, melilite, dicalcium silicate, calcium aluminates and ferrites during the calcination. The hydration study of the different composite cements demonstrates that the presence of the novel SCM results in a higher quantity of portlandite formed, the stabilisation of ettringite over monosulfate and the formation of strätlingite together with hemicarboaluminate.