Using Fly Ash and Rice Husk Ash as Soil Improving Materials along with its Cost Effectiveness in flexible Pavement Construction

Unstable soil has always been a hurdle in swift construction projects, which can only be eradicated by soil stabilization. Soil stabilization is used for a plethora of projects; however, it is more common in pavement construction, where the purpose is to enhance the strength of soil and to minimize the expenses by providing indigenous available materials. Thus the use of alternative materials like coal combustion product (fly ash) and agriculture waste (Rice husk ash) will certainly lower the cost of construction and therefore reducing the environmental hazards. Hydrometer analysis, Atterberg limits, modified proctor test and California Bearing Ratio (CBR) tests were carried out on the natural soil. Next three different percentages of fly ash (5%, 10% and 15%) were mixed with soil for the CBR test. In this study, the Rice Husk Ash (RHA) was also used for soil stabilization same as the percentages (5%, 10% and 15%) we selected in stabilization for fly ash. After finding CBR, the pavement was designed for natural soil and stabilized soil. The detail cost estimation was performed for 1km long and 7.62m wide road construction with specific thicknesses of designing road on natural soil and stabilized soil. In conclusion, the fly ash and RHA resulted in less thickness of road layers as compared to road design on natural soil. Furthermore, it was also concluded that the road construction cost using the fly ash and RHA is significantly less than the natural soil.