摘要: |
Asphalt surface treatment (AST) pavements using high float emulsions and dense-graded aggregates have been used for more than 20 years in Alaska. However, the normally positive economics of these pavements have sometimes been offset by problems during or after construction. The general intent of this report is to provide information that improves the constructability and long-term performance of high float pavements. Alaska DOT&PF engineers and contractors argued that most problems could be solved if a mix design method were devised to ensure compatibility between emulsion and aggregate and optimum application rates of emulsion and aggregate. This is the first documented attempt to pursue this goal by developing a high float mix design method for use in Alaska. This report presents an outline of the mix design method, an example application of the method and discusses reasons supporting each element of the mix design method. The mix design method determines application rates of high float emulsion and dense -graded aggregate based on simple volumetric calculations. The method recommends development of new laboratory test methods for determining aggregate density and emulsion/aggregate bond. The method requires that 15 percent additional aggregate be added to the design amount determined through voids calculations. The additional aggregate is intended to aid compaction of an otherwise very thin layer of AST pavement (AST thickness usually less than 1 inch). Before brooming, the additional aggregate also protects the AST from direct traffic action while curing allows development of aggregate/asphalt bonding. |