Analysis of Dispersivity Behavior of Clay Minerals by Fuzzy Computational System and Experimental Methods

Abstract

In general, dispersive soils may cause some geotechnical problems, although in a geo-environmental context they can be used as an excellent contaminant absorbent due to their large surface area and well exposed clay particles to soil pore fluid. Because of this environmental application, using dispersive clay is common in many landfill projects. On the other hand, the dispersivity behavior of soils is known to be a function of clay mineral and concentration of salt in pore fluid. Most previous studies have based their experimental research on pure clayey soils such as montmorillonite, illite or kaolinite. Considering the fact that from a realistic point of view, there are very few cases of single clay mineral application in geo-environmental projects, there is a need to pay more attention to the behavior of soils which are composed of different minerals. This research investigates the role of mineral type and concentration of pore fluid on dispersivity performance of smectite, illite, kaolinite and their mixtures by means of turbidity, XRD and atomic adsorption tests. In addition, in this article a fuzzy set method based on laboratory tests is developed, with an aim to predicting the geo-environmental behavior of clay minerals mixtures. The system introduced is verified by a database which is compiled from laboratory tests. The results indicate that this system provides extensive knowledge concerning the necessary salt concentration required to disperse pure clay minerals and their mixtures. Furthermore, the numerical results generate some applicable graphs to estimate the required concentration of salt to disperse clayey soils with a view to using it in geo-environmental projects.