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Technical University of Crete
Technical University of Crete
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| URI: | http://purl.tuc.gr/dl/dias/5EFB42E1-A993-48AC-93A9-BA3DE3658397 | ||
| Year | 2006 | ||
| Type of Item | Peer-Reviewed Journal Publication | ||
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| Bibliographic Citation | G. E. Christidis , A. E. Blum , D.D. Eberl , "Influence of layer charge and charge distribution of smectites on the flow behaviour and swelling of bentonites ",Ap. Clay Sc.,vol. 34,no.1,pp.125-138 ,2006.doi :10.1016/j.clay.2006.05.008 https://doi.org/10.1016/j.clay.2006.05.008 | ||
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The influence of layer charge and charge distribution of dioctahedral smectites on the rheological and swelling properties ofbentonites is examined. Layer charge and charge distribution were determined by XRD using the LayerCharge program [Christidis,G.E., Eberl, D.D., 2003. Determination of layer charge characteristics of smectites. Clays Clay Miner. 51, 644–655.]. Therheological properties were determined, after sodium exchange using the optimum amount of Na2CO3, from free swelling tests.Rheological properties were determined using 6.42% suspensions according to industrial practice. In smectites with layer chargesof −0.425 to −0.470 per half formula unit (phfu), layer charge is inversely correlated with free swelling, viscosity, gel strength,yield strength and thixotropic behaviour. In these smectites, the rheological properties are directly associated with the proportion oflow charge layers. By contrast, in low charge and high charge smectites there is no systematic relation between layer charge or theproportion of low charge layers and rheological properties. However, low charge smectites yield more viscous suspensions andswell more than high charge smectites. The rheological properties of bentonites also are affected by the proportion of tetrahedralcharge (i.e. beidellitic charge), by the existence of fine-grained minerals having clay size, such as opal-CT and to a lesser degree bythe ionic strength and the pH of the suspension. A new method for classification of smectites according to the layer charge based onthe XRD characteristics of smecites is proposed, that also is consistent with variations in rheological properties. In thisclassification scheme the term smectites with intermediate layer charge is proposed.
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