Chemical Clay Soil Improvement: from laboratory to field test

Soil deterioration can be an important cause of earthflow activity. Current studies try to provide a deeper understanding of the processes that influence soil deterioration and of the processes that, on the contrary, can improve soil mechanical properties. This paper points out the role of the composition of pore fluid. In the Costa della Gaveta slope, this is an aqueous ion solution, with concentration increasing with depth to values typical of seawater. Na+ is the prevailing cation, a reduction of its concentration causes dramatic decrease in strength. On the other side, the laboratory results show that exposure of the soil to KCl solutions, inducing an increase in pore K+ concentration, makes shear strength increase greatly and permanently. First results of chemical treatment by KCl columns at Costa della Gaveta show that ion transport is faster than hypothesized on the basis of in situ falling head permeability tests, probably because of preferential flow patterns along the slip surface and other discontinuities.