A laboratory study on strength loss in kaolin surrounding lime–cement columns

This study evaluated property changes in laboratory-prepared kaolin surrounding lime–cement columns. The parameters investigated included geotechnical parameters such as undisturbed undrained shear strength, remoulded shear strength, water content, and Atterberg limits. In addition the exchangeable Ca2+, Na+ and K+ ion concentrations were assessed. Four types of small-scale lime–cement columns were manufactured using different production methods and binder blending ratios. Tests were performed 7, 14, 30 and 90 days after installation. The migration of Ca2+, Na+ and K+ ions from the lime–cement columns into the surrounding soil has been confirmed through the chemical analysis on a large number of samples taken. The results illustrate that the undrained shear strength properties in the surrounding kaolin were significantly affected by the migration of Ca2+, Na+ and K+ ions. An increase in the Na+ and K+ ion concentrations in the front of the migrated Ca2+ ions was observed. The tests illustrate that, under the experimental conditions chosen, the remoulded undrained shear strength decreased in a thin zone as a result of the migrated Na+ and K+ ions. The magnitude of the strength loss depended on the binder blending ratio in the lime–cement columns.