27 Al and 29 Si NMR and XRD characterisation of clinkers: Standard phases and new waste based formulations

Abstract

²⁷Al and ²⁹Si magic angle spinning (MAS) nuclear magnetic resonance (NMR) and powder X-ray diffraction (XRD) studies of Portland type cement clinkers are reported. Common phases in such cements (C₂S, C₃S, C₃A and C₄AF) were prepared with high purity grade chemical reagents to be used as reference, and characterised. Subsequently, clinkers with selected compositions were prepared by combining several industrial wastes and byproducts: Al rich anodising sludge, sludge from the filtration/clarification of potable water, sludge generated in marble sawing processes and foundry sand. The clinkers were found to contain the reference cementitious phases, the two characterisation techniques used (NMR and XRD) being complementary in the information provided. The general similarity of the major phases formed in waste based and reagent based formulations clearly demonstrates the potential of the use of wastes in cement formulations of industrial interest.