6. Sustainable Design of Indian Rural Roads with Reclaimed Asphalt Materials

Designing low-volume roads (LVRs) or rural roads without having premature failures, in terms of heavy rutting and fatigue cracking, has always been a challenging task for the design engineers. This is especially due to the design procedures followed to obtain the pavement thickness which is completely based on the subgrade soil properties and the expected traffic volume. The current design procedure in India neglects the properties of the pavement material in base/subbase layers which will, in principle, provide structural support to the traffic loading. Hence, there is a need to revisit the design methodology by adopting the damage analysis of these pavement layers. Besides, the longevity of the pavement system can be improved by adopting sustainable pavement materials such as a combination of reclaimed asphalt pavement (RAP) material and virgin aggregates (VA). This study focuses on developing a design chart for selecting the thickness of base layer for low-volume roads when 80 % RAP material and 20 % VA mixture treated with different dosages of fly ash are used based on damage analysis. For the damage analysis, resilient modulus and unconfined compressive strength of the pavement layers are necessary to adopt in pavement analyses software such as KENLAYER and IITPAVE. The resilient modulus data was obtained from repeated loading triaxial tests in this study. Damage analysis has been performed in KENLAYER to obtain the desired pavement thickness calculated corresponding to a design life of 10 years. In addition, the fatigue and rutting strains developed in the pavement layers due to a standard wheel load obtained from KENLAYER are compared with the data obtained from IITPAVE software. It is noticed that based on the damage analysis, the base layer thickness has been reduced by about 50 % when 80R:20A mix stabilized with 40 % fly ash against conventional virgin aggregates.