Laboratory Evaluation of Selected Syncrude Products and Upgraded by-Products as Pavement-Recycling Agents

摘要

The following conclusions appear warranted based on the information derived from this study: (1) Selected syncrude products and upgraded by-products may be successfully used as recycling agents for field aged asphalt pavements. Those tested in this study performed equally as well as the commercially produced recycling agents. (2) Several of the blends containing the syncrude recycling agents exhibited excessive hardening and weight loss upon exposure to the thin film oven test. (3) Properties of recycled mixtures are highly dependent upon the type and amount of recycling agent. (4) The Rostler-Sternberg separation analysis on both the syncrudes and syncrude blends does not seem to produce results that correlate with other recycling agents. (5) Rostler-Sternberg analysis indicated a relatively high fraction of nitrogen bases in the syncrude additives, particularly those from shale oil. Although basic nitrogen in asphalts has been associated with improved resistance to moisture, recycled mixtures containing these materials did not exhibit any significant improvement in resistance to damage by water. Recycled mixtures containing recycling agent 4 (a soft tar sand asphalt) imparted excellent flexibility and yet adequate strength to paving mixtures at low service temperatures. (7) All of the blends containing the syncrude-based recycling agents, except California Coastal with recycling agent 3 (Tar Sand Asphalt and Stabilized Shale Oil), met criteria set forth by Halstead and Krchma for acceptable field performance. (8) The syncrude-based recycling agents produced blends with Rostler parameters and N/P values nearer those of the original asphalts than the commercial recycling agents. (9) According to Rostler-Sternberg analyses, none of the recycling agents were able to restore a base asphalt to its original composition, but this was not and should be not expected. 33 figures, 21 tables. (ERA citation 07:062700)