COMPOSITE MIXTURE OF STONE DUST AND FLY ASH AS A SUBGRADE IN RURAL ROADS

Abstract

Fly ash is an industrial waste produced by the burning of coal in thermal power plants. From past years, fly ash is disposed in the form of landfills. Fly ash is an engineering material with unique properties. When compared with typical soils used for embankment construction, fly ash has large uniformity coefficient consisting of silt-sized particles mostly. Addition of Stone dust modifies the gradation of fly ash and also there will be an increase in unit weight of the composite material. This study has been carried out to know the possibility of using fly ash in combination with stone dust and lime or cement. The engineering properties of composite material (fly ash-stone dust-lime\cement) have been studied to bring out the possibility of using fly ash in the construction of embankments. Addition of stone dust to fly ash results in an increase in Maximum Dry Density (MDD), and at the same time observed a decrease in Optimum Moisture Content (OMC). Due to addition of stone dust, a significant increase in California Bearing Ratio (CBR) value is observed. The composite material consists of 60% fly ash +40% of stone dust and 40% of fly ash + 60% of stone dust were further tested by adding lime. With addition of lime, there is a decrease in MDD and increase in the CBR value. The composite consisting of 40% fly ash + 60% stone dust with 2% lime resulted in a soaked CBR value of 9.0 at Maximum Dry Density (MDD) of 1.55 g/cm3. This composite material may be used for the construction of subgrade for rural roads.