A Study of the Effects of RAP Modification and Aging Protocol on ΔTc Parameters for PG XX-34 and PG XX-28 Binders Used in Kansas

Application of ΔTc parameter to evaluate cracking susceptibility of asphalt pavements has gained significant attention by asphalt community and agencies. At least 10 agencies, including Kansas Department of Transportation (KDOT), have adopted or are expected to adopt the ΔTc as a specification parameter. In a recent document produced by the Asphalt Institute and KDOT engineer, Mr. Blair Heptig, the state-of-the-knowledge was well-documented. Specifically, KDOT has devoted a significant level of effort by conducting tests on 72 asphalt binders to determine ΔTc at two Pressure Aging Vessel (PAV) test protocols (20-hour PAV and 40-hour PAV). ΔTc is a parameter that targets cracking of asphalt pavements related to the binder aging, level of stiffness, and its incapability to relax stresses at low temperatures. This parameter is identified through conducting Bending Beam Rheometer test (BBR) at multiple temperatures. While promising results have been obtained on the validity of using ΔTc either as a specification parameter or a durability parameter, this proposal aims at answering two important questions to supplement the current efforts conducted by KDOT: (1) How different levels of RAP binders will affect ΔTc? (2) How different aging levels (20-hour PAV and 40-hour PAV) affect the value of ΔTc? It is crucial to address these questions since the state of Kansas allows high percentage RAP in asphalt mixtures, in many cases with RAP contents of 40%. It has been shown in the literature that blending virgin binders with RAP binders adversely affects ΔTc parameter. Furthermore, the aging duration has been shown to affect ΔTc values. This research aims to address these two questions by evaluating the effect of different RAP contents (e.g., 16%, 25%, and 40%) at two aging levels (i.e., 20-hour PAV and 40-hour PAV) on the ΔTc value. This research effort will be conducted through close coordination with KDOT engineers to develop an optimum testing matrix to specifically target binders used in the state of Kansas.


    • English


    • Status: Active
    • Funding: $87654
    • Contract Numbers:

      K-TRAN: KU-22-5



    • Sponsor Organizations:

      Kansas Department of Transportation

      Eisenhower State Office Building
      700 SW Harrison Street
      Topeka, KS  United States  66603-3754
    • Performing Organizations:

      University of Kansas Center for Research, Incorporated

      2291 Irving Hill Drive, Campus West
      Lawrence, KS  United States  66045
    • Principal Investigators:

      Darabi, Masoud

    • Start Date: 20210901
    • Expected Completion Date: 20240831
    • Actual Completion Date: 0

    Subject/Index Terms

    Filing Info

    • Accession Number: 01832315
    • Record Type: Research project
    • Source Agency: Kansas Department of Transportation
    • Contract Numbers: K-TRAN: KU-22-5, RE-0833-01, C2196
    • Files: RIP, STATEDOT
    • Created Date: Jan 7 2022 1:24PM