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Beneficial Use of Coal Combustion By-products in the Rehabilitation of Failed Asphalt Pavements

Authors: Tarunjit S. Butalia, William E. Wolfe


This study demonstrates the use of Class F fly ash in combination with lime or lime kiln dust in the full depth reclamation (FDR) of asphalt pavements. FDR, in the context of this paper, is a process of pulverizing a predetermined amount of flexible pavement that is structurally deficient, blending it with chemical additives and water, and compacting it in place to construct a new stabilized base course. Test sections of two structurally deficient asphalt pavements were reclaimed using Class F fly ash in combination with lime and lime kiln dust. In addition, control sections were constructed using cement, cement and emulsion, lime kiln dust and emulsion, and mill and fill. The service performance and structural behavior of the FDR pavement test sections were monitored to determine how the fly ash sections compared to other more traditional pavement rehabilitation techniques. Service performance and structural behavior were determined with the use of sensors embedded in the road and Falling Weight Deflectometer (FWD) tests. Monitoring results of the FWD tests conducted up to 2 years after reclamation show that the cement, fly ash+LKD, and fly ash+lime sections exhibited two year resilient modulus values comparable to open graded cement stabilized aggregates (more than 750 ksi). The cement treatment resulted in a significant increase in resilient modulus within 3 weeks of construction and beyond this curing time, the stiffness increase was slow. On the other hand, the fly ash+LKD and fly ash+lime test sections indicated slower shorter-term increase in stiffness. The fly ash+LKD and fly ash+lime section average resilient modulus values at two years after construction were in excess of 800 ksi. Additional longer-term testing data will be available from ongoing pavement performance and environmental condition data collection at the two pavement sites.

Keywords: FWD, coal fly ash, full depth reclamation, pavement rehabilitation

Digital Object Identifier (DOI):

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[1] FHWA (1997). "User Guidelines for Waste and Byproduct Materials in Pavement Construction", Turner-Fairbank Highway Research Center, FHWA-RD-97-148.
[2] Timms, A.G., and Grieb W.E. (1956). "Use of Fly Ash in Concrete", Proceedings, Vol. 56, American Society for Testing and Materials, Washington, DC, pp. 1139-1160, 1956.
[3] Agdun-Nur, E.A. (1961), "Fly Ash in Concrete - An Evaluation", Highway Research Board Bulletin 284, Highway Research Board, National Research Council, Washington, DC.
[4] Halstead, Woodrow J. (1986). "Use of Fly Ash in Concrete", National Cooperative Highway Research Program Synthesis of Highway Practice No. 127, Transportation Research Board, Washington, DC.
[5] ARRA (2001). "Basic Asphalt Recycling Manual", Asphalt Recycling and Reclaiming Association, 2001.
[6] Rosenmerkel, James (2007). "Waukesha County Airport / Crites Field Waukesha, Wisconsin - a Case Study", Case Study 15, Full Depth Reclamation, USEPA.
[7] U.S. Environmental Protection Agency (2005). "Using Coal Ash in Highway Construction: A Guide to Benefits and Impacts", EPA-530-K- 05-002.
[8] Irwin, Lynne (1994). "Instructional Guide for Back-Calculation and the Use of MODCOMP3 Version 3.6", Cornell University Local Roads Program, CLRP Publications No. 94-10.
[9] FHWA (2004). "Guide for Mechanistic-Empirical Design", US Federal Highway Administration.