Geotechnical Characteristics of Natural and Reconstituted Lacustrine Mexico City Clays

The behaviour of natural and reconstituted clay samples from the Basin of Mexico under uniaxial stress and strain conditions is compared. Samples from two sites in the former lake zone were reconstituted following a procedure facilitating a comparison of the obtained experimental results with those of other researchers from tests on northern European sedimentary clays and on clays from the city of Bogotá and the Campeche Sound in the Gulf of Mexico. The differences in the behaviour of natural and reconstituted materials with a wide range of plasticities is analysed, while referring to sedimentation compression lines (SCLs), oedometric compressibility curves, and intrinsic compression lines (ICLs). ICLs for the Mexico Basin clays plot above SCLs in the void ratio versus effective stress space, which reflects the influence of sedimentation conditions on the formation of more compact, less open structures in natural clays. New analytical expressions that relate intrinsic void ratios and intrinsic compressibility with index properties are presented and is demonstrated that the normalised ICL is unique for all of the clays considered herein. It is concluded that reconstituted materials are less sensitive and less fragile (more ductile) than natural soils.