A DRIFT spectroscopy study of clays. Ground Movements: Shrink/Swell Project.

This report describes a study of a new technique for analysing the mineralogical composition of clay soils. It was carried out as part of a Science Budget programme of research for the Ground Movements: Shrink/Swell Project (ESB8390006703) which is itself part of the Urban Geoscience and Geological Hazards (UGGH) Programme.
This study uses a diffuse reflectance infrared spectroscopy (DRIFT) technique that can be an alternative to x-ray diffraction (XRD) values. Infrared spectroscopy was carried out on samples obtained from in-situ sampling techniques from quarries, pits and cliff-faces in the UK. The samples formed a representative range of clay soils from the Gault, Mercia Mudstone and Lambeth Group Formations.
A critical evaluation of the characteristic absorption features of the clay minerals most likely to be encountered, when testing the samples, was undertaken. Following this analysis, seventeen clay soils were tested using the DRIFT technique. Of these initial samples, nine were analysed in greater detail to ascertain their likely mineralogical composition.
The kaolinite and/or smectite content of the Newbury 1 sample was higher than the Newbury 2 and 3 samples, in contrast absorption bands indicative of kaolinite were not observed in the clay sample from Hemmington. In the soils from Arlesey the spectra were dominated by bands at 1429 and 2512 cm-1, which originate from the carbonate mineral calcite. No absorption bands from organic matter were observed in any of the shrink swell soils, the most likely explanation being that the strong mineral bands overlap and mask peaks from organic matter.