CONCEPT AND PERFORMANCE O-F OPEN GRAD ASPHALT IN INDIA, GERMANY AND THE US

Abstract

Porous pavement is a technology that was developed to improve roadway safety. It is designed with an open graded aggregate to increase the amount of permeable air voids. This allows water to penetrate through the voids removing it from the surface of roadway much faster than traditional dense graded pavement. The prime objective of this was to contribute towards the research for the design and use of OGAs especially for conditions prevailing in India. Based on exhaustive review of research findings related to open graded mixes like OGAs and the latest specifications for OGAs adopted by various agencies around the world, major differences were observed in these specifications, particularly with regard to the gradation band, compaction method, binder grade and binder type. The high air void content and open structure of OGA mix promote the effective drainage of rain water, which also minimizes hydroplaning during wet weather, this reduces splash and spray behind vehicles and improves wet weather skid resistance. This mix also reduces pavement noise and roadway glare during wet weather conditions. This thesis work summarizes details of laboratory investigation on the effect of aggregate gradation on the performance of Open Graded mixes. Three different aggregate gradations were investigated with polymer modified bitumen as a binder. The performance was evaluated in terms of stone on stone contact condition, air voids, draindown, moisture susceptability, rutting, permeability and stiffness of OGA mixes. The findings provide a better understanding of the effect of aggregate gradation on the performance of OGA mixes.