Micro-level Exploration of KOH-Contaminated Kaolinitic Clays Under Different Experimental Conditions

Contamination of soils due to caustic alkali has significant effect on the volume change behavior of soils, which in turn can have direct bearing on their geotechnical properties and can affect the stability of structures built on them. The existing literature strongly highlights the fact that failure of structures along with alterations in mineralogy and morphology occurs due to NaOH contamination. Efforts were made to simulate long-term effects of NaOH on mineralogical and morphological alteration by varying the experimental conditions in laboratory, so that preventive measures can be taken at a much faster rate. On the other hand, KOH is another strong alkali which is extensively used for commercial purposes. However, no studies were reported in literature to highlight the adverse effects of KOH. Thus, to understand the long-term effect of KOH on mineralogical and morphological alterations, a preliminary investigation is carried out in the present study by considering different experimental conditions (field contamination, long-term interactions, and temperature effects at 4 N KOH). Two types of kaolinitic clays, namely red earth and kaolin with varying mineral content were selected for the study. Micro-level investigations (XRD and SEM) have been carried out to noticeably understand impact of varying experimental conditions at particle-level interaction. Test results indicated that neogenic formations varied with type of experimental conditions along with variation in the morphology of soils. Further, it is observed that, long-term effects of KOH can be simulated within short period of time by conducting the experiments at elevated temperature.