Clay mineralogy, chemical and geotechnical characterization of bentonite from Beni Bou Ifrour Massif (The Eastern Rif -Morocco)

Bentonite clay mineral is widely present in the Gourougou Volcanic Massif and its satellites located in NE Morocco. It originated from the alteration of pyroclastic flows in shallow marine water in a lagoon lake environment (Ibourhardayn deposit). All studied samples were collected from that area and analysed accordingly in order to characterize and identify their components. Experimental techniques used included X-ray diffraction, Fourier transform infrared spectroscopy, X-ray fluorescence and the geotechnical characterization of the clay fraction and Atterberg limits. Granulometric analysis exhibited the presence of a clay fraction (<2 µm) ranging from 9.2 to 32.4%. The geotechnical study showed that the bentonites studied were generally very plastic, with plasticity index values ranging from 19.4 to 46.6%, and are also characterized by very high liquidity limits of 37.3–67%. A high water retention capacity with water contents ranging from 8.2 to 40.7% indicated that Ibourhardayn bentonites have important swelling properties. Mineralogical results showed that all specimens were mostly composed of montmorillonite alongside other clay minerals. Some crystalline impurities were also detected by X-ray diffraction and Fourier transform infrared spectra.