Strength, physicochemical and morphological characteristics of fly ash stabilized black cotton soil

Abstract

Black Cotton (BC) soil is one of the problematic soil deposits in India. These soils are problematic due to their poor engineering properties and high shrinkage and swelling properties due to high affinity to water. This paper, explore stabilization of Black cotton soil having poor strength characteristic and high shrinkage and swelling characteristic, with Class F Fly Ash (FA) to verify its scope for use as soil sub-base construction material. Fly ash is a good soil stabilizing additive in alone or along with other additives. It improves the index and engineering properties of Black cotton soil as verified from previous research work. In this research work, a Laboratory experimental program was planned with Fly ash, variation from 0% to 50% and humid curing period varies from 0 to 28 days. In the first stage of the experiment, Atterberg’s limits and compaction test have performed on Black cotton soil with all mixture and found their respective Optimum Moisture Content (OMC) and Maximum Dry Densities (MDD). In the second stage of the experiment, UCS and CBR tests were carried out for immediate, 7, 14, 28 and 45 days curing periods. The Atterberg’s limits, OMC, MDD, UCS, and CBR of Fly ash stabilized Black cotton found much satisfactory at 20% FA and 28 days curing period. CBR and UCS value get increments of 77.91% and 83.45% respectively. From the physicochemical analysis through X-Ray Diffraction (XRD) and Scanning of Electron Microscope (SEM), it was noticed That enhancement of strength is due to the pozzolanic reaction which causes the formation of new crystalline mineral of Alumino-Silicate-Hydrates (ASH) and Calcium-Alumino-Silicate-Hydrates(CASH) in void space of the matrix.