Experimentation of Black Cotton Soil Using Flyash And Crumb Rubber for Subgrade Application In Pavement Construction

Abstract

Black cotton soil is known to possess the properties of high plasticity and significant swelling-shrinkage action. It consequently results in low bearing capacity and poor roadway performance of pavements. This research involves the stabilization of black cotton soil utilizing fly ash and crumb rubber so as to enhance its engineering properties for road construction. Different percentages of crumb rubber were incorporated in the soil, namely 7.5% 10% 12.5% and 15%, while the percentage of fly ash was kept constant at 20% based on the dry weight of soil. Experimentation was conducted following relevant Indian Standards in testing the materials to check the effect of these stabilizers on the geotechnical properties of soil. The various tests which were conducted as part of this study include Atterberg limits, California bearing ratio (CBR), standard Proctor compaction and unconfined compressive strength (UCS). The conclusions illustrated that the flexibility characteristics and swelling capacity of the untreated soil were significantly affected by fly ash. The ideal quantity of crumb rubber confirmed enhancement in the load-bearing capacity of stabilized soil, consequently enhancing its flexibility and deformation properties. But the compressive strength decreased when crumb rubber exceeded the optimum amount, which was due to the decrease in interparticle forces. To summarize, the combined use of fly ash and crumb rubber was an efficient and sustainable soil stabilization method for improving the geotechnical characteristics of expansive black cotton soil, thus opening perspectives for its application in construction of pavements and embankments while promoting waste and industrial resources utilization.