Behavioral changes of non-expansive soil exposed to alkali contamination

Unplanned disposal of Industrial effluents in open lands is becoming a common practice in most developing regions, significantly impacting soil contamination. Alkali-contaminated soils witness behavioral changes based on the chemical concentration reaching the soil. Kaolinitic soils are more pronounced for their low swelling nature. Kaolinitic soils induce an unexpected swelling, which may not be observed with the changes in moisture content but due to chemical interactions. Alkali spills, leakages, and disposal of end solutions like caustic soda from industries into kaolinitic soil give rise to alkali-induced swelling. In the present work, a kaolinitic soil, i.e., red earth, is chosen for studying its behavioral changes by contaminating with the different concentrations of NaOH (0.1 N, 1 N, 4 N, and 8 N), which is alkaline in nature. The red earth mixed with NaOH solutions and different properties of soil are evaluated. The liquid limit and plasticity index values increased by a maximum percentage of 30.1 % and 33.19 % for red earth with 1 N NaOH compared to red earth with distilled water. In comparison with OMC and MDD values of red earth with distilled water, the OMC values of red earth with 1 N NaOH increased by 25%, and the MDD value decreased by 5.64 %. The UCS value increased by a maximum of 28 % with 4N NaOH. The red earth showed a maximum free swell of 19.15 % when inundated with 1 N NaOH, and the value dropped to 9.28 % with 8 N NaOH.