COMPARATIVE STUDY OF OVERLAYING AND RECYCLING OF BITUMINOUS PAVEMENT

Abstract

Rehabilitation and maintenance of the pavement structure is costly, time consuming and material intensive. Various types of rehabilitation methods like reconstruction, replacing, overlaying and recycling etc. are in use all over the world. In India, overlaying is the most commonly adopted technique of pavement rehabilitation despite its several limitations: Recycling or reuse of the existing pavement materials for rehabilitation and maintenance purposes offers several advan-tages over ti4 use of conventional material and techniques. The major benefits are conservation of aggregates, binder, energy and preservation of the environment and existing high way geometrics. Recycling technique, though, appeared to be an attractive alternative for pavement rehabilitatiOn and maintenance, yet, has not been adopted in India. In the present work, an attem-pt has been made to carry out a comparative study of over-laying and recycling of bituminous pavement. A section of about six kilometers Doiwala - Dehradun road (SH - 49) has been selected, for this study. The existing pavement is eva-luated by Benkelman Beam deflection method and overlay is designed as per I RC specifications. Three stretches in kilo-meters 207, 208, and 211 which required maximum overlay thick-ness have been selected for final study. Distressed pavement material is procurred from these above sections for experimental analysis. From the reclaimed material, bitumen content of mix, amount and gradation of salvage aggregates have been calculated and recycled mixes have been designed as per Marshall design criteria. The blend of new and recl-aimed mix in the ratio of 65 : 35 is selected and fresh bitumen of grade 80/100 is used. To compare the properties like strength, durability and elasticity of new and recycled mixes, tile parameters such as elastic modulus, resilient modulus and Marshall stability are studied. From the laboratory tests and analysis it has been observed that recycled mixes with 80/100 grade bitumen satisfy Marshall design criteria. Recycled mixes having higher stability and resilient modulus values are stronger and more rigid than new mix. Finally, economic analysis of two methods recycling and over-laying show that there is an overall saving of about 40 percent if former technique is adopted.