Effect of zeolitization on the volume-change behaviour of kaolinitic soils

An attempt has been made to study the effect of zeolite formation on the volume-change behaviour of kaolinitic soil. This is studied in terms of two criteria, namely concentration and period of interaction. Conventional consolidation tests have been carried out to determine the extent of change in swell and compressibility of kaolinitic soils remoulded with water and inundated with an alkali solution. It was observed that abnormal swell occurs during unloading when specimens were inundated with a 4N alkali solution. While allowing a longer interaction period at 6.25 kPa, it was found that swelling in kaolinitic soils is induced after time lags of 30 and 15 days on inundation with 1N and 4N alkali solutions, respectively. Equilibrium is reached after 50-70 days in kaolinitic soils, however, and loading was undertaken later. A 16% swelling was observed in kaolinitic soils when inundated with a 4N alkali solution, indicating that zeolitization of kaolinite results in swelling at the seating load provided the period of interaction is sufficient. X-ray diffraction studies confirm the formation of zeolite.Key words: alkali, consolidation, kaolinite, swelling, X-ray diffraction, zeolite.