An XPS and EDS Investigation of Portland Cement Doped with Pb2+ and Cr3+ Cations

Abstract

A series of cation doped Portland cement samples containing Pb²⁺ and Cr³⁺ ions have been examined by x-ray photoelectron spectroscopy (XPS) and low energy ion scattering spectroscopy (ISS). Evidence is presented for the location of the ions relative to the surface. The oxidation states after incorporaton and their possible chemical environments are discussed. A significant observation of the preferential surface location of Pb²⁺ supports a model for the Pb²⁺ induced retardation of cement setting by a surface blockage of the hydration process. Scanning electron microscopy and energy dispersive x-ray analysis have been used to examine sample morphology and cation distribution.