Strength Behaviours of the Clayey-Silt Soil Mixed with Fly Ash and Sand

Abstract

Fly ash and sand, both the materials have been added in the percentages of 10, 20, 30, 40, 50 and 60% with the clayey-silt soil by dry weight. Modified Proctor compaction was chosen for the California bearing ratio (CBR) tests and applied to soil-fly ash and soil–sand mixes. Un-soaked and soaked CBR of the soil are found as 54.50 and 3.90% respectively under modified Proctor compaction. Both fly ash and sand improved the CBR of the clayey-silt soil but addition of sand show the better result under both un-soaked and soaked conditions. However, the addition of 40% sand to the soil shows the maximum un-soaked CBR value as 70.07%. An addition of fly ash decreases the unconfined compressive strength (UCS) of the clayey-silt soil and increases in UCS observed at 40 and 20% addition of sand to the soil at standard and modified Proctor compaction respectively. The addition of both fly ash and sand to the soil increase the shear strength of the clayey-silt soil at standard Proctor compaction. Depending on availability of the material either fly ash or sand, it can be said that strength of the weaker clayey-silt soil can be improved using any of the additives.