Evaluation of Reclaimed Asphalt Pavement M aterials from Ultra-Thin Bonded Bituminous Surface

摘要

Ultra-thin bonded bituminous surface (UBBS), also known as Novachip, is a preventivemaintenance or thin surface treatment that consists of a thin, gap-graded hot-mix asphalt(HMA) layer applied over a thick polymer-modified emulsion membrane. The KansasDepartment of Transportation (KDOT) has been using UBBS since 2002. However, someof these projects are now being rehabilitated. The objective of this study is to evaluatewhether reclaimed asphalt pavement (RAP) materials from existing UBBS layers can beused in chip seal and Superpave mixtures. UBBS millings were studied with two differentpolymer-modified emulsions to assess their performance as precoated aggregates in chipseal. The ASTM D7000-04 sweep test was used to assess chip retention of UBBSmillings. Three different mix designs were developed for both 12.5-mm and 9.5-mmnominal maximum aggregate size (NMAS). Superpave mixtures using a PG 70-22asphalt binder and three different percentages (0%, 10%, and 20%) of reclaimed UBBSmaterials. The designed Superpave mixes were then tested for performance in terms ofrutting and stripping using the Hamburg wheel tracking device (HWTD) and moisturesensitivity by the modified Lottman tests. Sweep test results showed that UBBS millingsdid not improve chip retention. Superpave mix design data indicated volumetricproperties of Superpave mixes with UBBS millings met all requirements specified byKDOT. HWTD and modified Lottman test results indicated all designed mixes performedbetter with the addition of UBBS millings as RAP materials.