摘要: |
From May 2010 to September 2010, researchers of the US Army Engineer Research and Development Center and Mississippi State University evaluated the performance of different warm-mix asphalt (WMA) mixtures for their use for airfield pavements. The performance of mixtures produced using different WMA technologies was compared to the performance of the same mixtures produced at hot-mix asphalt (HMA) temperatures. Studied were permanent deformation, durability, non-load associated cracking, moisture damage, and workability. Evaluated were Evotherm 3G, Sasobit , and foamed asphalt. Two aggregates, crushed chert gravel and crushed limestone, were used. The base binder was PG 67-22 from a single refinery. Three reclaimed-asphalt pavement (RAP) contents were used (0, 25, and 50%) to study the incorporation of higher percentages of RAP in WMA than allowed in HMA. Results indicated WMA is a viable product for airfield pavement surface mixtures. However, rutting from traffic and moisture- damage susceptibility must be addressed. Adding RAP to the mix could help, but also could reduce low-temperature performance and durability. Findings suggest WMA with RAP is less susceptible to low-temperature performance problems than HMA with RAP. However, it s not possible to translate the lab results for durability or workability to field performance. Two engineering technical letters (ETLs) and a guide specification were developed from this study. The first, ETL 11-3, was published in August 2011 and provides general information and guidance. The second ETL and the guide specification, both under review, provide more specific guidance on design and construction of airfield pavements using WMA. |