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Placement of Warm Mix Asphalt on the East Entrance Road of Yellowstone National Park
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12. Summary of Findings
- Visible smoke and fumes were substantially reduced in both of the warm asphalt mixes. Workers noted no handling difficulties of the warm asphalt mixtures at the reduced temperatures.
- Temperatures at the hot plant were difficult to regulate at the lower warm mix asphalt temperatures. Hot plant operators may need to make specific burner adjustments when producing mixtures at reduced temperatures.
- From a review of infrared thermal images, both of the warm mixes exhibited a more uniform windrow and mat temperature when compared to the control mix.
- Both warm mix additives examined in this technology deployment aided in the compaction process of the mix. This was exhibited both in mix design specimens that exhibited lower air void content than the control, as well as the as constructed pavement with average core densities higher than the control. All mixtures met the density requirement established in the contract with the warm asphalt mixtures providing the highest density values.
- Tests of the virgin binder that was modified with 1.5% Sasobit indicated a stiffening of the binder both on the upper and lower temperature values. This was not consistent with the results from the testing of the recovered binder from produced mix which did not indicate significant stiffening.
- The TSR testing provided consistent results with all three of the mixtures. Based on these results, none of the mixtures exhibited stripping characteristics. The results also indicate that the addition of 1% hydrated lime as an anti-strip agent in all of the mixes proved to be effective.
- The Hamburg rutting results indicate generally good performance by all of the mixtures; however, it was noted that the Sasobit mixture had the lowest rutting depths.
- Similar to the Hamburg results, the APA rutting results indicated good rut resistance for all of the mixtures with the Sasobit mixture having the lowest rut depth.
- There is defi nite fuel savings realized when using Advera and Sasobit as warm mix additives due to a reduction in the fuel used to heat the aggregates. Additional factors such as construction processes, hot plant operations, plant modifications, and location of project will certainly have an impact on the cost benefit analysis of using these additives. A complete cost benefit analysis was not performed on this project.
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