Mineralogy and plasticity in clay sediments from north-east Tunisia

Journal of African Earth Sciences (Impact Factor: 1.38). 04/2010; 57(1/2):41-46. DOI: 10.1016/j.jafrearsci.2009.07.007

ABSTRACT Several cross-sections carried out in the Bir M'Cherga area (northern Tunisia) provided a complete Trias-sic–Miocene stratigraphic sequence, rather representative of the whole Tunisian Ridge Field located in the northern Atlas. Mineralogical analysis revealed a predominance of illite in the Early Cretaceous, while smectite is dominant in the Late Cretaceous and Tertiary. In terms of Atterberg limits, the Bir M'Cherga samples can be divided into two groups: one of moderately plastic clay samples until the Early Creta-ceous, and another represented by the Late Cretaceous and Tertiary clays, which are the most plastic. As expected, the Atterberg limits increase with the amount of phyllosilicates present in the sample, which is dependent on the amount of smectite. This analysis was complemented by the use of the equiv-alent basal spacing (EBS) parameter, which gives a good correlation between the mineralogical character-istics of the clays and their plasticity. Using EBS, we can predict the mechanical/plastic behaviour of any clay sample according to its mineralogical composition.

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Available from: F. Rocha, Sep 27, 2015
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    • "Furthermore, the Tunisian clay formations have been the subject of several studies and geological researches (e.g. Agafonoff and Jouravsky, 1934; Jamoussi, 2001; Grabowska- Olszewska, 2003; Jamoussi et al., 2003; Felhi et al., 2008; Jeridi, 2008; Jeridi et al., 2008; Mahmoudi et al., 2008; Hajjaji et al., 2010; Mahmoudi et al., 2010). "
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    ABSTRACT: The geological study of Miocene clays from Gram area, North West of Tunisia shows an important series of clay materials to use them in the faience ceramic. Selected samples were studied with the objective of analyzing their chemical and mineralogical composition, morphology, particle size, plasticity, thermal analysis and their ceramic aptitude to be used in the faience ceramic. Raw materials are mainly composed of illite and kaolinite are the dominant clay minerals with minor quartz and dolomite. The plasticity indexes are lower than 15.40%, suggesting that these clays are not plastic. Technical characterization was carried out on one representative mixture of Miocene clay samples. The firing characteristics (shrinkage and water absorption) were measured. The optimum firing temperature of clay mixture (M) has been established. These clays could be used in the manufacture of ceramic pieces.
    Applied Clay Science 08/2015; 112:1-9. DOI:10.1016/j.clay.2015.03.027 · 2.47 Impact Factor
    • "Determining the ceramic properties of a clay may involve a plethora of approaches, ranging from the characterisation of specific clayey outcrops (Dondi, 1999; Hajjaji et al., 2010; Marques et al., 2011; Montana et al., 2011; Nyakairu et al., 2002) to the evaluation of the effects of firing (e.g. Arsenović et al., 2012; Bauluz et al., 2003; Dondi, 1999; Mahmoudi et al., 2010; Manoharan et al., 2011; Monterio and Vieira, 2004; Ngun et al., 2011; Trindade et al., 2011). "
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    ABSTRACT: For the first time, the characterisation and the ceramic properties of thirty clays from southern Tuscany are discussed on the basis of their particle size distribution, Atterberg limits, geochemical (XRF) and mineralogical (XRD) composition and microfossils content. Very little information was available for the Albegna Basin, therefore, sampling included all outcroppings of Neogene–Quaternary clays. The results allowed the distinction of Miocene, Pleistocene and Holocene Ca-poor clays, suitable for the production of red stonewares and dense and frost resistant masonry materials, from Pliocene Ca-rich clays, used for the production not only of red earthenware but also of hard and porous masonry materials.
    Applied Clay Science 04/2014; 91-92. DOI:10.1016/j.clay.2014.01.012 · 2.47 Impact Factor
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    • "shows the plasticity chart of Holz and Kovatz (Holz & Kovacz, 1981; Hajjaji, 2010) of the four tested samples considered as moderately plastic. Due to the high phyllosilicate content the JH showed a superior liquid limit (42%) and plasticity index (22%). "
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    ABSTRACT: This study aims to find alternatives to some overexploited deposits in the north of Tunisia. The clays of the Sidi Khalif formation, of Uppermost Jurassic to Lower Cretaceous age, seem suitable to support this strategy, due to their abundance. In terms of mineralogy, they can be divided into two distinct groups, related to their palaeogeographic and eustatic contexts. The clays of the Sidi Khalif formation from Jebel Houareb (JH) and Jebel Meloussi (JM) are richer in clay minerals, while those of Jebel Rhouis (JR) and Jebel Boudinar (JB) zones are dolomite-rich. The compositional differences between the two groups influenced their technological behaviour in production of ceramic tiles. Upon firing, forsterite and gehlenite crystallized in the carbonate-rich JR and JB clays, whereas mullite formed in the JH and JM clays. Concerning their ceramic properties, the tiles made from JR or JB clays showed low bending strength and high water absorption. For JH and JM, the tiles had slightly greater mechanical resistance, but exhibited considerable linear shrinkage. These defects were partially corrected by introducing new formulations based on the same clays and by altering the firing cycles (HM1, HM2, RB1 and RB2). With these modifications, ‘‘Porcelanico’’ and ‘‘Monoporosa’’ technologically conforming tiles were obtained from HM2 and RB2 formulations, respectively.
    Clay Minerals 06/2012; 47(2):165-175. DOI:10.1180/claymin.2012.047.2.02 · 0.97 Impact Factor
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