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Federal Highway Administration Research and Technology
Coordinating, Developing, and Delivering Highway Transportation Innovations

This report is an archived publication and may contain dated technical, contact, and link information
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Publication Number:  FHWA-HRT-14-086    Date:  November 2014
Publication Number: FHWA-HRT-14-086
Date: November 2014


The Use of Phosphoric Acid to Stiffen Hot Mix Asphalt Binders


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Baumgardner. G.L. et al., "Polyphosphoric Acid Modified Asphalt: Proposed Mechanisms," Association of Asphalt Paving Technologists, 74, pp. 283–305, 2005.

Orange, G. et al., "Chemical Modification of Bitumen Through Polyphosphoric Acid: Properties-Microstructure Relationship," in Proceedings of the Third Eurasphalt and Eurobitume Congress, Vienna, 1, pp.733–745,May 2004.

Bishara, S.W. et al., "Modification of Binder with Acid-Advantages and Disadvantages," Kansas Department of Transportation Report FHWA-KS-02-2, February 2003.

De Filippis, P. et al., "Sulphur Extended Asphalt: Reaction Kinetics of H2S Evolution," Fuel, 77, No 5, pp. 459–463, 1998.

Bonemazzi, F. and Giavarini, C., "Shifting the Bitumen Structure from Sol to Gel," Journal of Petroleum Science and Engineering, 22, Issues 1–3, pp. 17–24, 1999.

Giavarini, C. et al., U.S. Patent 5,565,510 ,"Mixtures of Bitumen and Polymer Composition," October 15, 1996.

De Filippis, P. et al., "Stabilization and Partial Deasphalting of Thermal Residues by Chemical Treatment," Energy and Fuels, 8, pp. 141–146, 1994.

Alexander, S. U.S. Patent 3,751,278, "Method of Treating Asphalt," August 1973.

Hoiberg, A.J., U.S. Patent 3,028,249, "Asphaltic Compositions," April 3, 1962.

Hoiberg, A.J. et al., U.S. Patent 2,890,967, "Asphalt Coating," June 16, 1959.

Hoiberg, A.J., U.S. Patent 2,450,756, "Air Blown Asphalt and Catalytic Preparation Thereof," October 5, 1948.

Hoiberg, A.J., U.S. Patent 2,421,421, "Process of Treating High Molecular Weight Hydrocarbons," June 3, 1947.


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