Performance assessment of warm mix asphalt (WMA) pavements.

757338708Technical report.PDFTech ReportFHWA/OH-2009/08State Job No. 134312Warm mix paving mixturesPaving materialsOhioOhio Research Institute for Transportation and the EnvironmentSargand, ShadFigueroa, J. LudgwigEdwards, WilliamAl-Rawashdeh, Abdalla S.Ohio Research Institute for Transportation and the EnvironmentOhio. Dept. of Transportation. Office of Research and DevelopmentUnited States. Federal Highway AdministrationNTL-HIGHWAY/ROAD TRANSPORTATION-MaterialsNTL-HIGHWAY/ROAD TRANSPORTATION-Pavement Management and PerformanceUS Transportation CollectionWarm Mix Asphalt (WMA) is a new technology that was introduced in Europe in 1995. WMA offers several advantages overconventional asphalt concrete mixtures, including: reduced energy consumption, reduced emissions, improved or more uniformbinder coating of aggregate which should reduce mix surface aging, and extended construction season in temperate climates.Three WMA techniques, Aspha-min, Sasobit, and Evotherm, were used to reduce the viscosity of the asphalt binder at certaintemperatures and to dry and fully coat the aggregates at a lower production temperature than conventional hot mix asphalt. Thereduction in mixing and compaction temperatures of asphalt mixtures leads to a reduction in both fuel consumption and emissions.This research project had two major components, the outdoor field study on SR541 in Guernsey County and the indoor study inthe Accelerated Pavement Load Facility (APLF). Each study included the application of four types of asphalt surface layer,including standard hot mix asphalt as a control and three warm mixes: Evotherm, Aspha-min, and Sasobit. The outdoor studybegan with testing of the preexisting pavement and subgrade, the results of which indicated that while the pavement and subgradewere not uniform, there were no significant problems or variations that would be expected to lead to differences in performance ofthe planned test sections. During construction, the outdoor study included collection of emissions samples at the plant and on theconstruction site as well as thermal readings from the site. Afterwards, the outdoor study included the periodic collection andlaboratory analysis of core samples and visual inspections of the road. Roughness (IRI) measurements were made shortly afterconstruction and after a year of service.The indoor study involved the construction of four lanes of perpetual pavement, each topped with one of the test mixes. Thelanes were further divided into northern and southern halves, with the northern halves having a full 16 in (40 cm) perpetualpavement, and with the southern halves with thicknesses decreasing in one in (2.5 cm) increments by reducing the intermediatelayer. The dense graded aggregate base was increased to compensate for the change in pavement thickness. The southern half ofeach lane was instrumented to measure temperature, subgrade pressure, deflection relative to top of subgrade and to a point 5 ft (1.5m) down, and longitudinal and transverse strains at the base of the fatigue resistance layer (FRL). The APLF had the temperatureset to 40\uc2\ub0F (4.4\uc2\ub0C), 70\uc2\ub0F (21.1\uc2\ub0C), and 104\uc2\ub0F (40\uc2\ub0C), in that order. At each temperature, rolling wheel loads of 6000 lb (26.7 kN),9000 lb (40 kN), and 12,000 lb (53.4 kN) were applied at lateral shifts of 3 in (76 mm), 1 in (25 mm), -4 in (-102 mm), and -9 in (-229 mm) and the response measured. Then each plane was subjected to 10,000 passes of the rolling wheel load of 9000 lb (40 kN)at about 5 mph (8 km/h). Profiles were measured after 100, 300, 1000, 3000, and 10,000 passes with a profilometer to assessconsolidation of each surface. After the 10,000 passes of the rolling wheel load were completed, a second set of measurements wasmade under rolling wheel loads of 6000 lb (26.7 kN), 9000 lb (40 kN), and 12,000 lb (53.4 kN) at the same lateral shifts as before.Additionally, the response of the pavement instrumentation was recorded during drops of a Falling Weight Deflectometer (FWD)