Applicability of the SER method for quality control of clays from the German 'Westerwald'

The specific electrical resistivity of the 'Westerwald' clays is mainly determined by the CEC and the water content at a given temperature. For these clays a similar correlation function as for Bavarian bentonites was obtained. Therefore, the specific electrical resistivity of 'Westerwald' clays is strongly influenced by the presence of smectitic layers (smectite and smectitic layers in illite/smectite mixed layer minerals) since smectitic layers significantly determine the CEC even in the presence of other clay minerals like kaolinite or illite. In conclusion, smectitic layer and the water content determine the electrical properties of the investigated clays containing only 10-20% w/w smectitic layers. The SER method is applicable for the in situ estimation of the CEC of Westerwald clays being relevant for their industrial application.