International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 02 Issue: 04 | -2015 www.irjet.net p-ISSN: 2395-0072 © 2015, IRJET.NET- All Rights Reserved Page 339 COMPARATIVE STUDY OF DESIGN CHARTS FOR FLEXIBLE PAVEMENT Sanjeev Gill* , Dr.D.K.Maharaj Ph.D scholar Shri Venkateswara University, Gajraula (UP) Director-Principal, GNIT, Mullana, Ambala ------------------------------------------------------------------------------------------------------------------------------------------------------------------ ABSTRACT: Various methods for development of design charts have been discussed. In Group Index Method the total thickness of pavement (surfacing, base and sub base) is determined. Also the thickness of sub-base is determined. The CBR method is probably the most widely used method for the design of flexible pavement. The CBR method is based on strength parameter of the material and is, therefore, more rational than the Group Index Method. North Dakota Method is similar to the CBR method. Pavement thickness is found from the design curve which is between pavement thickness and cone bearing ratio. The Burmister’s Design Method is based on the concept of two-layer system, consisting of road surfacing, base course and the sub-base as top layer of thickness h, and the sub-grade as bottom layer of infinite extent. In this method, the thickness corresponding to deflection of 5 mm has been recommended by Burmister as the required thickness of pavement. U.S. Navy Plate Bearing Test Method is also based on Burmister’s two-layer theory. This method uses modulus of elasticity of base course and sub-grade. California Resistance Value Method uses California Resistance value, called R-value. In McLeod Method curves are plotted between depth of construction and CBR for traffic conditions. Maharaj and Gill have performed axisymmetric finite element analysis by varying different parameters to develop design charts. The parameters varied are thickness of pavement, pressure and elastic modulus of subgrade. Based on finite element analysis varying above parameters four types of design charts have been developed. Each of the design charts has three parameters. For two known parameters, the third parameters can be obtained. Keywords: Design Chart, Finite Element Analysis, CBR, Group Index Method, Thickness. INTRODUCTION The flexible pavements consist of wearing surface built over a base course and they rest on compacted subgrade. The design of a flexible pavement is based on the principle that a surface load is dissipated by carrying it deep into the ground through successive layer of granular materials. Flexible pavements with asphalt concrete surface courses are used all around the world. LITERATURE REVIEW Khan (1998) describes the Group Index Method and California Bearing Ratio Method for design of flexible pavements. In Group Index Method the thickness is obtained by first determining the Group Index of soil. The curves are plotted between Group Index of subgrade and thickness for various traffic conditions. In