Effect of Alternative Materials on Engineering Properties of Alluvial Soil for Construction of Road Subgrade

With the increasing constructional activities in road sector, situation has arisen where conventional good quality soils for subgrade are in short supply in many locations due to variety of reasons. Particularly in densely populated areas this problem is very accute. On the other hand, due to rapid industrialization throughout the world, the production of huge quantity of waste materials creates not only the environmental problem but also the depositional hazards. Safe disposal of the same is very vital issue and such situation can be addressed by the bulk utilization of these materials mainly in the field of civil engineering applications. A systematic detailed investigation was undertaken by the authors for using rice husk ash (RHA) and pond ash with soils to enhance the quality of the soil as subgrade material. CBR value in soaked and unsoaked condition increases in a small amount for addition of RHA, but with addition of lime in RHA mixed soils, better increment has been observed in the CBR values both in the soaked and unsoaked conditions. Further mixing pond ash with the soil showed increment in CBR both in unsoaked and soaked condition and mixing of pond ash upto 150% has shown that the gain in CBR value is more than double for soaked and unsoaked conditions.