Mineralogy and plasticity in clay sediments from north-east Tunisia
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.
SourceAvailable from: Hicham El Boudour El Idrissi[Show abstract] [Hide abstract]
ABSTRACT: Five clayey materials from two quarries located in the Amezmiz region (Morocco) were sampled and investigated for their physical, chemical, mineralogical and thermal characteristics to evaluate their potential suitability as raw materials in various ceramic applications. Physical properties were identified by particle size distribution, consistency limits and total organic content. Chemical, mineralogical, and thermal properties were investigated by XRF, XRD, and TG/DTA techniques, respectively. A common raw material in pottery manufacturing of Morocco was used as reference sample (REF). Results show that the main oxides in the samples were SiO2, Al2O3, and Fe2O3, whereas the other oxides were present only in small quantities. Quartz, illite and vermiculite were present as dominant mineral phases with minor kaolinite, calcite and smectite. The results showed that three of the studied clayey materials have adequate characteristics for the production of structural ceramics. However, for the two other clays it is necessary to add more plastic clays to enhance the workability.Applied Clay Science 11/2014; 102. DOI:10.1016/j.clay.2014.09.029 · 2.70 Impact Factor
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ABSTRACT: Casagrande and fall cone tests are standard methods widely used for liquid limit determination. This is a parameter that, in addition to the information provided by plastic limit assessment, allows the evaluation of the plasticity of soils. This study carried out the determination of liquid limit of 18 clayey samples by Casagrande and fall cone methods in order to compare them. A high correlation was found between the results of both methods. Moreover, the most recent equation proposed on literature for the comparison between methods was applied, and it seems suitable for the prediction of liquid limit assessed by fall cone test and the experimental value achieved by Casagrande device. As expected, good correlations between liquid limit, phyllosilicate amount and type of clay minerals was noticed. As complement, equivalent basal spacing (EBS) parameter was calculated and tested. Good correlations between this parameter and liquid limit measured were observed only for samples with <70% of phyllosilicate content; when the analysis is applied to the samples with higher amount of phyllosilicates, there is not a good match, suggesting that EBS calculation is not reliable in those cases.Materials Technology 08/2014; 29(B2):B82-B87. DOI:10.1179/1753555714Y.0000000153 · 0.75 Impact Factor
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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 · 2.70 Impact Factor