Effects of Chemical Stabilisation of Eggshells-Lime and Fly-Ash-Cement on the Structural Strength of Subgrade Soil in Rural Roads

Abstract

This study examines the chemical compositions of eggshell powder (ESP) and lime as the soil stabilisers and compared with the compositions of cement and fly-ash to understand the optimal distribution of chemical stabilisers maximising the bearing capacity and structural integrity of subgrade soil. The different proportions of eggshell powder (ESP) (2%, 4%, 6% and 8% of total soil mass) were mixed with a fixed proportion of lime (6% of total soil mass) to analyse the optimum proportion of eggshell maximising the soil structural integrity. Similar proportions of fly-ash (2%, 4%, 6% and 8% of total soil mass) were mixed with cement (4% of total soil mass) to analyse the comparative effects of ESP-lime and fly-ash-cement on the soil stability. The soil samples were collected from three different points of unpaved roads in Ganderbal district of Jammu & Kashmir State in India that experiences the seasonal variations resulting in uneven moisture distribution throughout the year. The CBR tests of both treated (chemical stabilisation) and untreated soils were performed followed the code of practices in Indian standards that is IS: 2720 1985. The combination of 4% ESP and 6% lime resulted in highest CBR value at 19.06%; and the combination of 4% fly-ash and 4% cement had the CBR value of 18.73%. The increase in bearing capacity of subgrade soil mixed with ESP and lime supports the pavement structure with less thickness resulting in the reduction of budgetary allocation for road construction, maintenance and rehabilitation operations.