Effect of a Recycling Agent on the Performance of High-RAP and High-RAS Mixtures: Field and Lab Experiments

Abstract

Reclaimed asphalt pavement (RAP) and recycled asphalt shingles (RAS) have been increasingly used in asphalt mixtures. The use of RAP and RAS in asphalt mixtures not only reduces the consumption of virgin materials, conserves energy, and protects the environment but also improves the rutting resistance of asphalt pavements. However, as more recycled materials are used in asphalt mixtures, there is increasing concern over their potential negative effects on the mix cracking resistance. To improve the cracking resistance of asphalt mixtures with high RAP/RAS contents, one of the approaches considered is using recycling agents to potentially restore performance properties of the aged binder. This project was conducted to evaluate the effect of a recycling agent (RA), known as Hydrogreen, on the long-term field performance of high RAP and RAS mixes. The field study consisted of three test sections, each constructed by placing a dense-graded surface lift at a depth of 4.5 cm (1.75 in.) on SR 7 near Harrisonville, Missouri, in August 2013. The three mixes placed in the three test sections included: (1) a control mix containing 30% RAP using an SBS-modified PG 70-22 binder with no RA; (2) a 40% RAP mix using the same PG 70-22 binder with RA; and (3) a 25% RAP and 5% RAS mix using a neat PG 64-22 with RA. This paper presents data collected during the construction of the test sections, laboratory performance testing results, and early field performance. The research results showed that the recycling agent could be used in the 40% RAP and 25% RAP and 5% RAS mixes to achieve similar construction quality, laboratory performance, and early field performance to the 30% RAP control mix. As these sections are still in service, it is recommended that they continue to be monitored in order to evaluate their long-term performance.

Investigation of the Performance of Bio-Oils from Three Different Agricultural Wastes as Rejuvenators for Recycled Asphalt

“…They lead asphalt binders to increase in viscosity and to be harder than fresh asphalt binders [13,14]. In order to overcome these problems, many types of rejuvenating RAP binders have been used [9,[15][16][17][18][19].…”

Research on Rejuvenation of Styrene-Butadiene-Styrene Block Copolymer Modified Asphalt with Rejuvenating Agent Based on Pre-Mixing Method

“…Finally, a variety of methods are used to evaluate the performance recovery effect, such as component change analysis [13], fluorescence differential analysis [14,15], dynamic rheological properties [16][17][18] attached total reflection imaging in the mid-infrared [19], morphologies and chemical components analysis [20], and interfacial adhesion between aggregate and regenerated SBS-modified asphalt [21]. In addition, many scholars prepare asphalt mixture from regenerated SBS-modified asphalt and then evaluate the rejuvenation effect by testing the technical performance of the mixture [22][23][24][25]. ese performances include rutting resistance and fatigue cracking performance [26,27], stress creep recovery [28], compaction performance [29], durability [30], and viscoelasticity [31].…”

Impact of Rejuvenators Type on Physical Properties of Aged Asphalt Cement

“…Tran et al (2016) studied the effect of recycling agent (RA) on performance of asphalt pavement by preparing three mixture consisted of: (a) reference mixture containing 30% RAP with an SBS-modified PG 70-22 binder with no RA; (b) 40% RAP combine with the similar PG70-22 binder with RA; and (c) 25% RAP with 5% RAS mix using an efficient PG 64-22 with RA. The volumetric traits of the three mixes and their gradations were extremely comparable, the dosages of RA were determined for the 40% RAP and 25% RAP/5% RAS mixes to attain the same level of field performance as the reference mixture through their resistance to moisture damage [4].…”