Effect of Placement Moisture Content on Swelling–Shrinkage Behaviour of Expansive Soil

Abstract

Rapidly increasing infrastructural activities across the world demand suitable land for founding the substructure. The coming era shall face trouble both with the scarcity of suitable land as well as challenges to deal with the existence of problematic soils at the site. Volumetric changes in the form of swelling and shrinkage with moisture variation are most commonly observed in expansive soils. Large damage/distress to the infrastructure founded on this type soils has been observed. Understanding of swelling and shrinkage of expansive soils with moisture variation is of primary importance. This paper presents an experimental study on determination of swelling–shrinkage and its variation with time and placement moisture content. An experimental setup has been designed and developed to accommodate three soil samples of 100 mm diameter and 100 mm height and swelling pressure measurement through constant volume method. Soils were procured from Delhi–Mumbai Expressway site near Ankleshwar, Gujarat, which was later aired dried and pulverized. Soil samples were prepared at three different preparation moisture content (i) at optimum moisture content, (ii) 5% on the dry side of optimum and (iii) 5% on the wet side of optimum. Experimental findings revealed maximum swelling pressure generation within first 24 h after commencement of the experiment. Swelling pressures of 41.8 kPa, 59.44 kPa and 23.22 kPa were observed for specimen prepared at optimum moisture content, at 5% dry side of optimum and 5% wet side of optimum, respectively. While swelling pressure found to increase till seven days, though at a lower rate, observed swelling pressure values were 55.73 kPa, 83.6 kPa and 37.25 kPa for specimen prepared at optimum moisture content, at 5% dry side of optimum and 5% wet side of optimum, respectively. The % shrinkage area were found as 22%, 33.8% and 15.2% for the samples prepared at OMC, WSO (OMC + 5%) and DSO (OMC-5%), respectively.