EVALUATION OF ASPHALT MIXES CONTAINING RAP COMPARED WITH CONVENTIONAL MIXES

Using Reclaimed Asphalt Pavement (RAP) in asphalt mixes has become a common practice in many countries. Experience indicated that the recycling of asphalt pavements is very advantageous from different perspectives. Some of the advantages of utilizing RAP include conservation of asphalt and aggregate resources, conservation of energy and reduction in life-cycle cost [5,6,7]. In this study, the suitability of asphalt mixes using RAP was investigated. Three hot asphalt mixes were prepared following gradations recommended by the Egyptian code of specifications. Marshall Mix design procedure was used to determine the optimum asphalt content. The first mix was composed of 100% fresh aggregate and virgin asphalt, the second mix was composed of 25% RAP and 75% fresh aggregates and virgin asphalt, and the third mix was composed of 40% RAP and 60% fresh aggregates and virgin asphalt. The results indicated that the bulk density increase with the increasing of the percentage of RAP in mix B, while increasing in RAP results decreases in Air Voids and flow values. Furthermore, the stability is changed from 2325 lb for the control mix to 2175 lb and 1829 lb for mixes with 25% and 40% RAP respectively. Comparing the results of the conducted tests indicated that the use of RAP in Hot Mix Asphalt (HMA) was advantageous in all properties measured, but the results are acceptable by Egyptian code specifications. The results of Marshall Properties indicate that the amount of new binder that needs to be added to the RAP mixture can be reduced without significant effects on the quality of the produced mix. Therefore, it is preferred to use mixes containing RAP in highways with studied proportions