An Experimental Study on the Behaviour of a Sandy Soil by using Cutback Bitumen
Pages : 1134-1137Download PDF
The key point of a stable and well-constructed structure is the stability and strength of its foundation. Whether it is a building or a road pavement both require a good substructure. Fine grained soils are susceptible to expansion, contraction and high compressibility and course grained soils may have a high permeability and are also susceptible to erosion. Subgrade is the most important part of a road pavement structure as it provides support to the pavement as its foundation. The formation of waves, corrugations and rutting in black top pavements are generally attributed to poor Subgrade conditions. Gullies and cutting edges are also due to poor shear strength and high permeability of subgrade. Many types of binders are helpful in improving the shear strength of subgrade soils. Sand as a subgrade soil may have low shearing strength and high permeability. The improvement of sub-grade soil will increase its durability and the performance of road structure as a whole. In the present study, MC-30 bituminous cutback has been used as a stabilizer to improve the properties of a locally available cohessionless soil. The percentage of bituminous cutback added to the sandy soil has been varied from 4% to 18%. A uniform compaction was provided to all the samples prepared. Unconfined Compressive Strength and CBR value of the soil samples were studied. From the UCS test, it is observed that maximum unconfined compressive strength is obtained at 12% cutback content further increase of cutback in the soil leads to decrease in UCS value due to excessive fluidity causing decrease in density. A sharp increase in CBR value of sand was observed with a small increment in cutback bitumen content (about 8 %). Further increase in cutback content (8% to 10%) increased the C.B.R value moderately to reach a peak and then still further increase in cutback content (i.e more than 10%) reversed the trend.
Keywords: Subgrade, Cohessionless Soil, Unconfined Compressive Strength etc.