Comparative Study on Design of Bituminous Mixes Containing Recycled Asphalt Pavement Materials

Abstract

RAP is a deteriorated bituminous mix that contains aged bitumen and aggregate. Hence its performance is comparatively poorer than virgin mix. Performance of RAP can be enhanced by adding virgin bitumen, virgin aggregates & rejuvenators (such as waste plastic) in suitable proportions. Recycling of Reclaimed Material from a deteriorated pavement to reuse partially or fully to produce new pavement materials results in considerable savings of material, money & energy. Recycling is one such alternative that reduces use of new materials, conserves natural resources & most importantly reduces carbon foot prints there by earning carbon credits for India. Present work focuses on evaluation and comparison of physical and engineering properties of bituminous mixes containing RAP material in various percentages through extensive laboratory tests for the construction of surface course in flexible pavements. Keywords: RAP, Bituminous Mixes. I INTRODUCTION: Effective, timely and speedy maintenance is the only way to protect the huge capital investments which are linked to the road system. The proper strengthening and maintenance of the road network is required. Where deteriorating of roads increase with the steady increase in traffic. Overlaying the distressed pavements with virgin courses had been adopted and continues to be the preferred method for restoration of aged pavements. The continuous application of overlays increases the pavement thickness and approaches the curb line. The conventional methods are responsible for 22 percent of the global energy consumption and 25 percent of fossil fuel burning across the world and 30 percent of global air pollution and greenhouse gasses. The availability and efficient recycling technology favored the adoption of Reclaimed Asphalt Pavements (RAP) Technology in many countries. Recycling, in place of conventional method of overlaying of asphalt pavements has made a rapid advancement in the developed countries. This method of strengthening and repairing of roads was based on their durability rather than their initial cost. The concept of RAP lies in restoring the physio-chemical properties of the aged bitumen to its original and at the same time it enhances the mechanical properties and strength of the aged binder. With the development of RAP technology, asphalt pavement rehabilitation costs would significantly decrease. The various ecological and economic advantages which contributed to enhancement of recycling processes throughout the world are conservation of aggregates and binders, decrease in pavement thickness, reduced cost of transportation, conservation energy and labour, preservation of existing pavement geometrics, preservation of environment. The ability to mill and remove old, distressed pavements allows for more effective rehabilitation techniques which create RAP may have substantial engineering benefits. Severely cracked or rutted layers can be removed so that their damage is not reflected through a new surface layer. The effective use of RAP solves a large societal problem because it does not occupy landfill space. II OBJECTIVE OF THE STUDY The objectives of the present study are as follows, 1. To study about the Reclaimed Asphalt Pavement (RAP) technology as a renewable resource. 2. To study Mix design approach for hot recycled RAP. 3. Extraction of bitumen from RAP materials is done using centrifuge method and the bitumen content to be determined. 4. To determine the physical properties of virgin aggregate which includes aggregate specific gravity, Impact value, Abrasion value, Water absorption, Flakiness and elongation index. 5. To determine optimum virgin bitumen content for different percentage of RAP material by Marshall Method of mix design. 6. To workout the economics of recycling of bituminous pavement material. III METHODOLOGY The present investigation aimed at the laboratory evaluation of bituminous mix containing RAP material which replaces virgin aggregates by various percentages. For the present study virgin aggregates are obtained from