Laboratory Study on Use of RAP Material in WMA Pavement Using

Abstract

With the advent of new technologies, the use  of Recycled Asphalt Pavement material (RAP) has gained  increasing importance. Using RAP not only economises  Asphalt production, but also decreases the demand for virgin  material. The limit in the use of RAP proportion is restricted 

due to stiffness and workability issues related to RAP. This  problem is addressed with the help of Warm Mix Asphalt  (WMA) which increases the proportion of RAP used by  producing mixes having same/better properties viz., better  workability, reduced viscosity than Hot Mix Asphalt (HMA)  at lower temperatures. The use of Rejuvenator has also  improved workability of RAP- HMA mixes by rejuvenating  the stiff binder of RAP. This study deals with the effect of  Rejuvenator on WMA mixes produced with different  proportions of RAP. In this study effect of varying  proportions (Viz. 10%,15% & 20%) of Used-Mobile Engine  Oil (Rejuvenator), used in conjunction with 0.5% Evotherm  (WMA additive) was studied with different proportions of  RAP. The Evotherm additive dosage of 0.5% by weight of  bitumen and Rejuvenator dosage of 10%, 15% and 20% by  weight of bitumen was taken on the basis of research by  Hurley & Prowell 2006, and Zaumanis et al 2014  respectively. Laboratory study was conducted involving  material characterization of Virgin and RAP material,  followed by Mix design of Dense Bituminous Macadam  (DBM) using Virgin and RAP Material. Various tests viz.,  Marshal Stability, Retained Stability, Indirect Tensile  Strength, Unconfined Compressive Strength, Compactibility  and Aggregate Coating were conducted on HMA and WMA  Mixes prepared from virgin materials, and WMA mixes  prepared with 20%, 40% and 60% RAP material. These tests  helped in analysis and determination of Density, Voids, Flow  value, Strength, Moisture Susceptibility, Aggregate Coating,  etc. Based on the above analysis it was found that the  optimum dosage of Rejuvenator for Warm Mixes prepared  with 20%, 40% and 60% RAP material is 10%, 15% and 20%  respectively. All the three RAP proportions with these  Optimum dosages of Rejuvenator satisfied all the  requirement of DBM mix (MORTH specification) prepared  using Warm Mix technology. It was also found that upto 20%  RAP material can be used to prepare WMA mixes even  without addition of Rejuvenator and that the optimum  bitumen content is reduced as RAP proportion is increased.  This results in saving in the overall cost by lesser use of  Virgin materials.