Studying the behavior of Sodium Lignosulfonate treated expansive soil

Abstract

The volume change behaviour of expansive soil causes failures in structuressuch as embankments, retaining walls, foundations, road subgrades. The chemical stabilization methods are commonly used to mitigate the swelling behaviour of expansive soils. The traditional chemical stabilizers such as lime and cement are used widely which are imposing negative impacts on environment either through the direct use or indirectly during production. Many of the researchers suggested the need of non-traditional, environment friendly stabilizers to be used in soil stabilization works.The wood and pulp (biomass) processing industry waste product; lignosulfonate can be effectively used to improve problematic behaviourof expansive soil. In present study theexpansive soil is treated with different percentages of sodium lignosulfonate powderfrom 1% to 12%; and it is concluded that the plasticity, compaction, strength, microstructural characteristics of expansive soil are improved. The MDD and OMC values are slightly changed for treated soils which are attributed to the poly-anionic nature of lignosulfonate. The reduced liquid limit and plasticity index is due to the adsorption of lignosulfonate particles which produced waterproofing effect due to the hydrophobic carbon chain. The maximum increase in unconfined compressive strength is observed for LS9which is 1.4 times the control mix at 28 days curing; the swelling index is alsoreduced from 1930% to 144%. The direct shear test in UU conditions found the shear parameters with increased cohesion suggested the increased stiffness of soil which is supported by results of UCS test.the CBR test conducted showed the maximum bearing value for LS9 in soaked condition.It is found from SEM, FTIR and XRD analysis that the bonds are created between the clay particles surfaces and the Na-Lignosulfonate through ion exchange process.