Many of the pavement structures fail well before their design life owing to the poor quality of construction materials, inadequate compaction, inadequate preparation of the subgrade, overloading etc. Two options are considered during the design of a pavement structure in order to improve the longevity of the pavement. The first option is by increasing the thickness of different pavement layers and the other option is by increasing the rigidity of the layers within the system so as to reduce the stresses transferred to lower layers. Of these two methods it has been widely observed that increasing the strength and rigidity of the pavement layers is a more efficient method to lower stresses on the pavement layers thereby increasing the life of the pavement. In the present research work, the improvement in the strength and stiffness of the sub-base layer in a flexible pavement system through the use of geocell confinement was investigated by conducting field plate load tests and series of laboratory plate load tests. The improvement in the strength of the pavement is reflected by the increase in modulus of the section confined with geocells to the section without geocell confinement. This paper will describe the field and laboratory tests, interpretation of the data from these tests and the application of this data for design of flexible pavements.