Permeability of lime- and cement-treated clayey soils

The permeability (k) of lime- and cement-treated clayey soils was investigated in the laboratory by flexible-wall permeability tests and oedometer tests. Test results indicate that for the cement-treated soils (with up to 8% cement content by dry weight), the value of k is almost equal to that of untreated soils under identical void ratio (e) conditions, and the k value decreases significantly when the cement content is higher than 8%. For lime-treated soils, the threshold lime content is about 4%. Investigation of the soil microstructure using the mercury intrusion porosimetry (MIP) test and scanning electron microscope (SEM) imaging indicates that when the cementation products formed by the pozzolanic reaction fill mainly the intra-aggregate pores, the value of k is comparable for the treated and untreated samples. When the cementation products begin to fill the interaggregate pores, the value of k of the treated sample becomes smaller than that of the untreated soil sample under the identical e value condition. An indication that the cementation products have filled the interaggregate pores is the rapid increase in strength of the treated soil.