Prevention of Low Temperature Cracking of Asphalt Pavements Using the Bending Beam Rheometer

University Transportation Centers Program2019PDFTech ReportRomero, PedroUniversity of Utah. Department of Civil and Environmental EngineeringMountain-Plains ConsortiumUnited States. Department of Transportation. University Transportation Centers (UTC) ProgramUtah Department of TransportationMountain-Plains ConsortiumUnited StatesAging (Materials)Air voidsAsphalt pavementsBinder contentCreepLow temperatureMix designPavement crackingPavement performanceRecycled materialsRheometersMPC-19-405MPC-496An evaluation of the ability of the BBR as a test to determine changes in the low temperature properties of asphalt mixture parameters was conducted, along with the possible implications of adopting this test for low temperature pavement performance. It was found that the creep modulus and the m-value from the BBR are able to detect changes in binder content and air voids. The test indicates that RAP is detrimental to the overall expected performance of the mixtures when compared with a mixture with no RAP. The BBR appears to be a sensitive test capable of capturing the effect of aging and RAP on the material. It was found that aging of the loose mixture at 135\ub0C prior to compaction shows a more consistent trend than aging the compacted specimen at 80\ub0C. One hour of loose mix aging at 135\ub0C results in the same mechanical changes as 47 to 55 hours of compacted mix aging at 80\ub0C. Based on the results, it is concluded that adoption of the BBR as a required test might not affect the overall binder content of the mixtures but might affect the overall amount of RAP. The BBR appears to be capable of capturing the effect of aging and RAP on the material. Thus, adoption of the BBR as a specification test would likely result in changing the mixture design process to favor mixes with lower RAP content and less sensitivity to aging.133