Comprehensive evaluation of the long-term performance of rubberized pavement, phase II : the influence of rubber and asphalt interaction on mixture durability.

PDFTech ReportFHWA-GA-12-1229Hot mix paving mixturesAsphalt mixturesCrumb rubberLaboratory testsDynamic modulus of elasticityFatigue (Mechanics)RuttingBituminous bindersWeatheringPavement performanceMix designEvaluationGeorgiaGeorgia. Department of Transportation. Office of ResearchShen, JunanXie, ZhaoxingLi, BoGeorgia Southern UniversityUnited States. Federal Highway AdministrationUS Transportation CollectionThis project investigated the long-term performance of hot asphalt mixes containing crumb rubbermodifiers (CRM) added in dry or wet processes. A total of eight asphalt mixtures\ue2\u20ac\u201dfour PorousEuropean Mixtures (PEMs) and four Stone Matrix Asphalts (SMAs)\ue2\u20ac\u201dwere designed with PG 76-22modified with CRM, which was added in either a dry or wet process. These mixtures were compared tocontrol mixtures using an SBS-modified PG 76-22. Mixtures incorporating a \ue2\u20ac\u153hybrid\ue2\u20ac?-modified PG76-22 were also evaluated. First, the samples were weathered in the Georgia Weathering Asphalt Device(GWAD) for 1,000 hrs and 3,000 hrs and tested to determine their dynamic modulus, fatigue life,rutting, and Cantabro. Binders extracted from the weathered samples were then evaluated using adynamic shear rheometer (DSR), gel-permeable chromatography (GPC), and Fourier transform infraredspectroscopy (FTIR). Second, the interactions of dry- and wet-processed CRM with asphalt binder werecompared during storage and paving. Results indicated: 1) adding TOR to the CRM binder improvedPG grade and separation resistance; 2) the dynamic modulus, |E*|, of both rubberized PEM and SMA indry process did not differ significantly from that of the control mixtures or mixtures using the \ue2\u20ac\u153hybrid\ue2\u20ac?-modified binders before and after weathering; 3) the fatigue life (Nf) of unaged rubberized PEM andSMA in the dry process was similar to that in wet process, although lower than that of control SBS; 4)after 3000-hrs aging, the fatigue life of the dry-processed rubberized SMA is similar to that of thewet-processed but lower than that of hybrid and SBS SMA, regardless of strain and stress levels or testtemperatures; 5) the rutting and Cantabro loss of the rubberized PEM and SMA in dry process werehigher than those of control SBS after weathering; 6) CRM and asphalt binder interact during theproduction and paving stages based on DSR, GPC, FTIR, and AFM results. The effect of weathering onthe properties of the asphalt binders in rubberized, dry-processed PEMs and SMAs was similar to that inthe wet-processed mixtures but greater than that in the control SBS