Use of Fly Ash and Lime for Attainment of CN Properties in a Swelling Soil

• Published in: Circular Economy in the Construction Industry Vol. 1; pp. 145 - 151
• Main Authors: Naik, K.V.N. Laxma, Thanusree, A., Rani, C. H. Sudha
• Format: Book Chapter
• Language: English
• Published: CRC Press 2022
• Edition: 1
• Subjects: LL; Unconfined Compression Test Results; Optimum Moisture Content; Original Soil; Swelling Pressure; HDPE Fibre; Fa Content; MDD; Wick Drains; Swelling Pressure Tests; CBR; Unconfined Compressive Strength Test; Compression Index; Free Swell Index; Swelling Soil; Fly Ash Content; BIM; Fly Ash Percentages; Expansive Soil; Alkaliphilic Bacteria; Tonnes; Fly Ash; Ground Granulated Blast Furnace Slag; Geopolymer Mix; Moisture Content
• ISBN: 9781032108971; 9781032108964; 1032108967; 1032108975
• DOI: 10.1201/9781003217619-20

In India, with increase in population and industrialization, there is a much need for the soil to be used for various activities and improve the properties of soil, if the soil at any particular locality is unsuited for construction either fully or partially. Most of the problematic soils are swelling soils or filled up soils/landfills. Volumetric changes in terms of swelling in the presence of water are undesirable for stability reasons. Swell potential and swelling pressure of a swelling soil primarily depend on the initial dry unit weight, void ratio and moisture content. The naturally occurring soil may not suit to the design requirements of ongoing project (canal works, foundation/basements, pavements). Therefore, soil is to be prepared as CNS (Cohesive Non-Swelling) to meet the requirements. By mixing of admixtures to a soil to improve strength and reduce compression index, (many researchers have made attempts with admixtures). It has gained prominence due to its easy applicability and adaptability. Fly ash is a freely available waste product from thermal power plants which has little cementing property and can be used for altering the characteristics of swelling soil. This paper presents investigations on the plasticity characteristics, deformation characteristics (i.e., swelling and compression properties) and strength of a swelling soil admixed with fly ash and lime both in combination in varying percentages in order to arrive the optimum percentages for expressing as CNS material. The test results indicate that the measured plasticity characteristics, free swell index and swelling pressure are reduced substantially with the optimum dosage of fly ash in combination with lime, representing CNS materials properties (Katti et al. 2010). Volumetric changes in terms of swelling in the presence of water are undesirable for stability reasons. Swell potential and swelling pressure of a swelling soil primarily depend on the initial dry unit weight, void ratio and moisture content. The naturally occurring soil may not suit to the design requirements of ongoing project. The test results indicate that the measured plasticity characteristics, free swell index and swelling pressure are reduced substantially with the optimum dosage of fly ash in combination with lime, representing Cohesive Non-Swelling (CNS) materials properties. As soil samples possess liquid limit (LL) more than 50% and have a very high degree of swelling, suitable proportions of fly ash are added for reducing the LL to the desired value. The combination can be used for selected expansive soil for representing CNS material properties reducing environmental pollution and exploiting natural resources.