MECHANICAL CHARACTERISTICS OF RECYCLED ASPHALT BY SUPERPAVE TECHNIQUE, NAJRAN AREA, KSA.

Abstract

The physical and mechanical properties of RAP depend on the properties of aggregate, asphalt binder, pavement type, amount of time of the original pavement in service, method of recover in Existing flexible pavements represent available supplies of aggregates that can be recycled. This can significantly contribute to environmental preservation by reducing the amount of new materials required for highway construction and avoiding the problems associated with disposal of the old pavement materials. Recycling also reduces the amount of energy needed to produce the new construction materials and transport those materials to the roadway construction site. Recycling has been defined as “the reuse, usually after some processing, of a material that has already served its first-intended purpose”. The recycling procedures in pavement construction have many economical advantages over the traditional procedures. This paper evaluated the performance Superpave mix designs containing recycled asphalt pavement (RAP). The RAP used in each mix design contained aggregate from the same source as the virgin aggregate. The 3-Tier concept was used to incorporate RAP into the mixtures in the first (less than 15%),15: 25 % and third (greater than 25%) tiers. Each mix was also made by modifying the respective binder with rubber. In general, the mixtures containing RAP improved the rutting resistance and either increased, or had no significant effect on the indirect tensile strength (ITS). The tensile strength ratio (ITS) was not affected by the addition of RAP.The recycled asphalt mixture samples were tested in the laboratory. The results indicated that asphalt in the old mixtures used for recycling have low penetration and high softening point. It has also been indicated that asphalts in the recycled mixtures made by the Rejuvenating method have not been rejuvenated completely. The results also showed that Fatigue life of the recycled mixtures is longer than that of the conventional mixture. Other characteristics have been identified such as water-resistance, which showed that the recycled asphalt has high water-resistance.