California bearing ratio behavior of soil/fly ash mixtures

Fly ash is a byproduct of the combustion of pulverized coal in thermal power plants. Energy and environmental considerations over the coming years point to greater use of coal and hence a further increase in the quantity of fly ash. Geotechnical and chemical characterization of fly ash and its interaction behavior with soil is likely to provide viable solutions for its large-scale disposal and utilization. Concerted efforts have been initiated in the laboratory to understand the effect of fly ash addition on the California Bearing Ratio (CBR) values of black cotton soil both for unsoaked and soaked conditions. The study indicates that CBR values of black cotton soil/fly ash mixtures increase up to an optimum fly ash content wherein fly ash acts as a coarser material. The CBR values decrease beyond this optimum fly ash content and again increase to an optimum value wherein black cotton soil acts as a binder.