The technology of road construction is subjected to changes to cope up with changing vehicular pattern, construction materials and sub-grade conditions. Majority of pavement failures could be attributed to presence of pure sub-grade conditions and expansive sub-grade is one such problematic situation. Expansive soils, because of the specific physic - chemical makeup are subjected to volume changes with changes in their ambient environment. The losses due to extensive damage to highways running over expansive sub-grade are estimated to be in billions of dollars all over the world. In many countries including India, these soils are so extensive that alteration of highway routes to avoid the material is virtually impossible. Various remedial measures like soil replacement, pre wetting, moisture control, lime stabilization, etc., have been practiced with varied degree of success. These techniques suffer from certain limitation in their adaptability like long time periods for pre wetting the required depth of highly plastic clays and high cost for soil replacement. Sustained efforts are being made all over the world on highway research to evolve more promising treatment methods for proper design and construction of pavements passing over expansive sub-grades. Recent investigations on chemical stabilization revealed that strong electrolytes like potassium chloride, ferric chloride can be used in place of conventionally used lime due to their ready dissolvability in water and supply adequate cations for ready cation exchange. Moreover, they can be applied to the ground in the form of electrolyte solution without pulverization and mixing problems, either by ponding for shallow depths or ponding cum bore holes for reasonable depths. In the present work, the efficacy of potassium chloride is studied in improving the properties of expansive soil. In order to improve the strength properties of expansive soils treated with potassium chloride, rice husk ash, a waste pozzolona, is also tried along with potassium chloride.
展开▼
