This paper investigates the performance of crumb-rubber-modified (CRM) asphalt mixture. Two different asphalt mixtures containing two types of asphalt binder (#90 original asphalt and CRM asphalt) were used to prepare Marshall specimens and determine optimum asphalt content. Mechanical performances of asphalt mixes were evaluated by the wheel rutting test (WRT) (dynamic stability (DS)), midpoint beam bend test (MBBT), at low temperature, and indirect tensile test (IDT), at the freezing and thawing cycle. Superpave gyratory compactor (SGC) specimens were also prepared for the modulus test. Using the simple performance test (SPT) and universal testing system (UTS), viscoelastic mechanical characteristics were evaluated by static and dynamic modulus tests. Static modulus (E) data were measured by the un-confinement uniaxial compression test according to the specification of China. Moreover, dynamic modulus (E0) data were obtained by SPT. The crumb-rubber content varies from 0, 10 %, 20 %, to 30 % at the static modulus test. Two test temperatures were selected for the dynamic modulus test. The results indicated that the CRM asphalt mixture performs better than the standard asphalt mixture on dynamic behavior, rutting resistance, cracking resistance, and moisture stability.

This study investigated the laboratory performance of crumb rubber modified mixtures compared to a standard bituminous mixture using performance based test procedures. This study was part of an asphalt resurfacing program for the Seattle Washington area. Laboratory analyses were used to estimate the long term pavement performance of these mixtures in the field. Six mixtures were tested: The standard Class 'A' surface mixture for the Seattle area, Plus Ride II® base course gradation (dry process) using AC 5 and AR 4000W binder types, Plus Ride II® surface course gradation (dry process) using AC 5 and AR 4000W binder types, and ARHM-GG surface course gradation using crumb rubber modified (CRM) AR 2000 (wet process). The performance based tests used on each mixture evaluated the different failure modes a pavement may encounter in the field: fatigue cracking, permanent deformation (rutting), thermal cracking, age hardening, and water sensitivity. Many of the tests used were developed by the Strategic Highway Research Program (SHRP) to test for a mixtures susceptibility in these failure modes. Test results indicate the CRM mixtures performed better than the Class 'A' surface mixture, with respect to fatigue cracking. All of the Plus Ride II® mixtures performed inadequately when tested for permanent deformation. On the other hand, the ARHM-GG surface mixture performed well, even better than the Class 'A' surface mixture with respect to permanent deformation. The ARHM-GG surface mixture showed better low temperature characteristics when compared to the Class 'A' surface and Plus Ride II® mixtures. The CRM mixtures were less susceptible to aging than the Class 'A' surface mixture. Finally, all of the mixtures demonstrated low moisture sensitivity. The final conclusions were made relative to the Class 'A' surface mixture. The ARHM-GG surface mixture performed as well as, and in some cases better than, the Class 'A' surface mixture. The ARHM-GG surface mixture may be used where the Class 'A' surface mixture was specified. The Plus Ride II® base and surface (AC 5 and AR 4000W) mixtures did perform better than the Class 'A' surface mixture in some tests, however it performed worse in others. Therefore, it was recommended that the Plus Ride II® mixture designs be re-evaluated to provide adequate performance in the failed tests.

Presents rheological data on a number of polymers, making use of the master curve approach to determine unified curves for each generic type of polymer. The text offers a step-by-step procedure for developing a speadsheet computer program to obtain accurate thermoplastic rheograms at any tempertature without using sophisticated rheometres. It inclu