X-ray micro-diffraction studies of heterogeneous interfaces between cementitious materials and geological formations

•1st MicroXRD study on cement-clay interfaces.•MicroXRD investigations were performed with beam sizes down to 1 μm.•MicroXRD pattern from a filled vein of a cement-clay interface from Maqarin (Jordan).•1st microXRD data from the Mont Terri Project “Cement-Opalinus Clay Interaction (CI).

In the present study the challenge of analyzing complex micro X-ray diffraction (microXRD) patterns from cement–clay interfaces has been addressed. In order to extract the maximum information concerning both the spatial distribution and the crystal structure type associated with each of the many diffracting grains in heterogeneous, polycrystalline samples, an approach has been developed in which microXRD was applied to thin sections which were rotated in the X-ray beam. The data analysis, performed on microXRD patterns collected from a filled vein of a cement–clay interface from the natural analogue in Maqarin (Jordan), and a sample from a two-year-old altered interface between cement and argillaceous rock, demonstrate the potential of this method.