B. R. Phanikumar

Bio: B. R. Phanikumar is an academic researcher from VIT University. The author has contributed to research in topics: Expansive clay & Fly ash. The author has an hindex of 9, co-authored 15 publications receiving 233 citations.

Effect of lime and fly ash on swell, consolidation and shear strength characteristics of expansive clays: a comparative study

Abstract: Expansive soils swell on absorbing water and shrink on evaporation thereof. Because of this alternate swelling and shrinkage, civil engineering structures founded in them are severely damaged. For counteracting the problems of expansive soils, different innovative techniques were suggested. Stabilization of expansive clays with various additives has also met with considerable success. This paper presents, by comparison, the effect of lime and fly ash on free swell index (FSI), swell potential, swelling pressure, coefficient of consolidation, compression index, secondary consolidation characteristics and shear strength. Lime content (weight of lime/weight of dry soil) was varied as 0%, 2%, 4% and 6% and fly ash content (weight of fly ash/weight of dry soil) as 0%, 10% and 20%. A fly ash content of 20% showed significant reduction in swell potential, swelling pressure, compression index and secondary consolidation characteristics and resulted in increase in maximum dry density and shear strength. Swell pote...

Swell-compressibility characteristics of lime-blended and cement-blended expansive clays – A comparative study

Abstract: Chemical stabilisation of expansive soils has been quite efficacious in reducing swelling characteristics, namely, swell potential (S%) and swelling pressure (ps). When chemicals such as lime and cement are added to an expansive clay, flocculation and cementation take place. Flocculation, which is an immediate reaction, is instrumental in reducing plasticity and swell potential significantly. It also reduces the time required for equilibrium heave. This paper presents experimental data on lime-blended and cement-blended expansive clay specimens. Free swell index (FSI), heave, rate of heave and swelling pressure were studied. FSI, heave and rate of heave decreased with increasing lime content and cement content in the blends. But, during a 3-day inundation (a period, generally allowed for the sample to attain to equilibrium heave), cementitious products developed and resisted the applied compressive loads stiffly, resulting in high swelling pressures in the case of lime-blended specimens. Swelling pressure...

Fly ash columns (FAC) as an innovative foundation technique for expansive clay beds

Abstract: Various innovative foundation techniques have been in practice to counteract the swell–shrink problems posed by expansive soils. Apart from techniques such as belled piers and under-reamed piles, chemical stabilisation of expansive soils has also met with considerable success. Lime, cement and fly ash are the various additives used in chemical stabilisation. This paper presents an innovative foundation technique in the form of fly ash columns (FAC) for expansive clay beds. Results from a laboratory experimental study on expansive clay beds reinforced with fly ash columns (FAC) are presented. Heave tests and compressive load tests were performed on expansive clay beds into which fly ash was introduced as compacted columns. Heave decreased significantly on reinforcing the clay beds with FACs. Stress-settlement characteristics of expansive clay beds also improved when reinforced by FACs. Curing of FAC-reinforced expansive clay beds improved stress-settlement characteristics.

Studies on Hydraulic Conductivity of Fly Ash-Stabilised Expansive Clay Liners

Abstract: Earthen barriers or clay liners are a major concern in geo-environmental engineering. They are designed to preclude or reduce leachate migration. Hence, a low hydraulic conductivity (k) is an important parameter in the design of clay liners. Materials such as bentonite and lateritic clays, which have a low hydraulic conductivity at high dry densities, are used in the construction of clay liners. Compacted expansive clays which are high in montmorillonite content also have a very low hydraulic conductivity. When expansive clays are blended with fly ash, an industrial waste, the hydraulic conductivity further reduces as the ash-clay blends result in increased dry densities at increased fly ash contents. Hence, fly ash-stabilised expansive clay can also be proposed as an innovative clay liner material. It is, therefore, required to study various physical and engineering properties of this new clay liner material. Liquid limit (LL) and free swell index (FSI) are important index properties to be studied in the case of this clay liner material. The hydraulic conductivity of this new clay liner material depends on the fly ash content in the blend. Further, parameters such as solute concentration and kinematic viscosity also influence hydraulic conductivity of clay liners. This paper presents experimental results obtained on hydraulic conductivity (k) of fly ash-stabilised expansive clay liner at varying fly ash content and solute concentration. The tests were performed with deionised water (DIW), CaCl2, NaCl and KCl as permeating fluids. Fly ash content in the blend was varied as 0, 10, 20 and 30 % by weight of the expansive clay, and the solute concentration was varied as 5 mM (milli molar), 10, 20, 50, 100 and 500. It was found that hydraulic conductivity (k) decreased with increasing fly ash content, solute concentration and kinematic viscosity. Further, hydraulic conductivity (k) was correlated with LL and FSI of the clay liner material for different fly ash contents and solute concentrations. Useful correlations were obtained.

Correlation studies on index properties of fly ash-stabilised expansive clay liners

Abstract: The study of earthen barriers or clay liners has become very important in the field of geo-environmental engineering. The design of clay liners is based on the fact that leachate migration through clay liners depends on their hydraulic conductivity. The engineering behaviour of clay liners can be predicted through a proper estimation of some of the basic index properties like liquid limit which play a significant role in this study. An attempt at understanding the variation of index properties with the concentration of permeating fluids reveals useful facts about the clay liners. This paper proposes an innovative clay liner material in the form of fly ash-stabilised (or, fly ash-blended) expansive clay and presents a study on variation of index properties of the blend with varying fly ash content in the blend and concentration of salt solutions. The various permeating liquids used were deionised water and salt solutions such as CaCl2, NaCl and KCl. When expansive soils are stabilized with fly ash, index p...