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https://www.nationalacademies.org/trb/events

Evaluation of Thick Lift Surface Asphalt Pavement Mixtures

When paving asphalt mixtures in a deep patching and rehabilitation application the Virginia Department of Transportation (VDOT) currently limits lift thickness to approximately three to four times the nominal maximum aggregate size (NMAS) of the mixture (VDOT, 2018). For a typical asphalt surface mixture having an NMAS of 9.5 mm, the practice generally limits lift thickness to approximately 1.5 inches. Where deeper distresses must be repaired multiple lifts will be required which increases construction time, prolongs traffic disruption, and introduces additional interfaces between lifts that may affect construction efficiency and field performance. Therefore, there is a need to evaluate whether asphalt surface mixtures can be placed in a single thick lift without compromising construction quality or long term performance. The study addresses this need by investigating 1) the performance of a 9.5 mm NMAS asphalt mixture in a single 4 inch lift and (2) evaluating the performance of that layer using a combination of laboratory testing, controlled construction, and accelerated pavement testing to assess compaction behavior, material properties, and structural performance.