Economical Analysis of Lime and Fly Ash Stabilized Flexible Pavements

Abstract

Abstract

India is experiencing tremendous growth in infrastructure including road network and highways. Roads are to be designed with good reliability to fulfill the long-term performance during the design period. Most of the time flexible pavements in India need to be constructed on problematic subgrade soil. Such subgrades have low California bearing ratio which leads to more pavement thickness. Decrease in availability of suitable sub-base and base course materials for highway construction leads to a search for an economic method of converting locally available troublesome soil to a suitable one for highway construction. Present research study provides insight on economical analysis for the construction of flexible pavements by way of stabilization technique. Laboratory investigation was carried out on two selected soils employing hydrated lime and class F fly ash as stabilizers. Atterberg limit, Proctor, California bearing ratio, unconfined compression strength and triaxial shear tests were conducted to evaluate the benefits of stabilization on characteristic strength of subgrade soils for different percentages of stabilizers mixed with dry weight of soil. It was observed that 4.5% of lime and 10% of fly ash were optimum in terms of reduction in layer thickness, material saving and cost optimization. Pavement section was designed as per Indian practice code IRC 37: 2012 for different traffic intensities and construction cost was estimated for 1 km pavement section resting on unstabilized and stabilized subgrade with different percentages of lime and fly ash. It is revealed that due to stabilization process, there is considerable decrease in layer thicknesses leading to reduction in cost of construction and it is the function of percentage of lime, fly ash and traffic intensity for which pavement is designed.

Keywords: Subgrade soil, stabilization, California bearing ration, layer thickness reduction