Stabilization of Dispersive Soil Using Industrial by-Products

Abstract

Dispersive soils are highly susceptible to erosion due to higher sodium content, and it deflocculates in the presence of flowing water. Under saturated conditions, the attractive forces are less than the repulsive forces, and this will help the particle to segregate and to move in suspension. In the earlier days, it was said clayey soils are non-erodible. But recently it was found some clayey soils with low-to-medium plasticity (CL and CL-CH) that contain montmorillonite have the tendency to erode. The erosion due to the dispersion of soil depends on mineralogy and clay chemistry and the dissolved salts in pore water. Dispersive soils contribute to the failure of many conservative practices. The stabilization of dispersive soils is very important for the success of many geotechnical projects all across the world. In this investigation, an attempt has been made to stabilize the dispersive soil with cement clinker, ground granulated blast furnace slag (GGBS) and flyash. Samples were prepared with the different predetermined proportions of dispersive soil, cement clinker, GGBS, and flyash to determine the strength and durability of the stabilized soils. Results of unconfined compressive strength (UCS) are found to be increased significantly by mixing additives in different proportions. From the results of the UCS tests, the optimum mix proportion was obtained with the mixing of 20% of flyash, 15% of GGBS and 30% of cement clinker in dispersive soil. Outcomes of this study suggest that the combined mixture of cement clinker, flyash, and GGBS are more effective to improve the strength than an alone mix. To evaluate the effect of freeze-thaw cycles and water immersion aging on the strength properties of different mix proportion, 0, 1, 3, 6, 9 and 12 cycles freeze-thaw tests and 32 days water immersion tests were done on cylindrical samples at 7, 14, 28, 60 and 90 days curing periods. A coefficient of strength loss/gain was also defined to determine the influence of freezing-thawing and water immersion aging on the durability of the mix proportion. The scanning electron microscope (SEM) and X-ray diffraction tests (XRD) divulge the changes in microstructure and the formation of hydrated particles play a vital role to enhance the strength because of the reaction between the soil and the additives. The UCS of dispersive soil stabilized with cement clinker, GGBS and flyash were modeled and predicted using Gaussian Process (GP), Artificial Neural Network (ANN), Random Forest (RF), M5P, Linear Regression (LR) and Adaptive Neuro-Fuzzy Inference System (ANFIS). Three statistical performance evaluation parameters such as coefficient of correlation (R), Mean Square Error (MSE) and Root Mean Squared Error (RMSE) were used to evaluate the performance of the above-developed models. Results obtained from this study suggest that the RF-based model is most suitable than other discussed models for the prediction of is most suitable for UCS, UCSFT, and UCSWIT. Sensitivity analysis is also carried out to find the most influencing parameter for the best-developed model.