Effect of calcined clay on the improvement of compaction, swell and microstructural characteristics of expansive soil

Abstract

Expansive soil is problematic soil because its alternate swell shrink behaviour depends on the presence of water. Soil stabilization technique was widely adopted to alter the characteristics of the expansive soil which is suitable for construction. Among the various soil stabilization techniques, chemical stabilization was found to be more suitable method of sustainable stabilizing the soil due to its effective and timely reaction with the chemical compound. Calcined form of clay material is used as an admixture to study the effects on the improvement of soil properties. Calcined Clay (CC) is added into the virgin soil with different percentages of 2%,4%,6%,8% and 10% under varying 1,3,7,14,28 and 60 days of curing by conducting experiments such as standard proctor test, Free Swell test to analyse the compaction characteristics and swelling behaviour of the soil. In addition to that the X-Ray Diffraction (XRD) and Scanning Electron Microscope (SEM) on virgin and treated soil were studied by varying 2% incremental of CC up to 10% at 28 days of curing. From the test results it shows the variation in the compaction characteristics by rising in Maximum Dry Density (MDD) and reduction in Optimum Moisture Content (OMC) that merges at 8% as an optimum to develop the soil behaviour and from the free swell test, it was found that the Free Swell Index (FSI) of the soil decrease from 210 to 80 at 10% calcined clay added soil and the Mineralogical studies also show the variation in the compounds. Thus, this naturally available calcined clay was used to improve the soil Compaction and swell characteristics that influences the reduction in deformation and increase in shear strength of soil which helped to minimize the environmental problem as well as one of the effective admixtures to improve the expansive soil characteristics.