Performance Studies on Pavements Using Chemically Stabilized Soils

Abstract

Pavements constructed on weak soils can cause significant distress due to moisture-induced volume changes and low strength, thereby reducing the pavement life. Soil stabilization is the alteration of one or more soil properties, by mechanical or chemical means, to obtain an improved soil material possessing the desired engineering properties. Subgrade soils may be stabilized to increase the strength and durability or to prevent erosion and dust generation. In the present study two types of soils, Lateritic Soils (LS1 and LS2) and Black cotton soil and were stabilized with five different stabilizers viz. Terrasil, Terrabind, Cement, Road Building International grade 81, and marginal materials like Fly ash, Arecanut coir and aggregates. These additives can be used with a variety of soils to improve their native engineering properties, but their effectiveness depends on the amount of additive and the nature of soil. The laboratory investigations were conducted for different curing days to determine the basic and engineering properties of soil such as Atterberg’s limits, grain-size distribution, Maximum Dry Density (MDD), Optimum Moisture Content (OMC), California Bearing Ratio (CBR), Unconfined Compressive Strength (UCS), Indirect Tensile (IDT) Strength, Durability, Fatigue and Resilient Modulus (E). The investigations are also carried out to study the effect of addition of 12.5 mm down aggregates to the soil with optimum content of Cement and RBI 81 to evaluate the extent of modification in the Compaction, CBR, IDT strength and resilient modulus tests. The experimental investigations indicate that there is a good improvement in the engineering properties of the soils treated with different stabilizers. KENPAVE software was used for stress strain and damage analyses of both natural and stabilized soils and also to prepare pavement design sections for low and high volume pavements. For low volume pavements, CBR 3% and traffic T4 to T7 conditions were considered as per IRC-SP-72:2007. For high volume pavements, analyses were carried out for CBR 8% and traffic 2 to 150 million standard axles, using the standard design thickness as per IRC-37:2012 guidelines. Trial and error method was adopted to determine the thickness for treated soil aggregate mixture, by keeping the strain value within permissible limits. For stabilized soil, rutting and fatigue lives and damage ratio were also observed to be significantly improved. From the results of theexperimental research and KENPAVE analysis, it has been observed that modified soil can be effectively used as a modified subgrade and base layers. Analysis was also performed in IITPAVE for high volume roads under dual wheel loading. Cost analysis was carried out as per the Schedule of Rates (SOR) 2014-2015 for stabilized and unstabilized materials.