Mike Voth 2018 AASHTO COMP Meeting TS 2a August 6, 2018

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1 Mike Voth 2018 AASHTO COMP Meeting TS 2a August 6, 2018

2 Introduction / Background Motivation for performance grading Research completed ETF Efforts Testing & analysis Provisional Development Characteristics of a Provisional Specification Schedule

3 Why the need for performance graded emulsions Asphalt binder performance grading standards (Superpave) developed about 25 years ago. Emulsion technology still languishes with the antiquated technology of penetration grading 1888: Bowen of Barber Asphalt Co. invented penetration test in Committee D-4 adopted penetration test 1918 Bureau of Public Roads developed recommended penetration grades based on climate 1931 AASHTO published specifications

4 Why the need for performance graded emulsions FHWA s 1999 Pavement Preservation: A Road Map for the Future Use of emulsions is expanding Develop specifications based on performance Need to characterize and capture benefits of polymers and other additives Create more confidence with the selection, testing, and specifying of asphalt emulsions

5 Climatic differences 65 F 80 F 60 F 90 F 85 F 115 F 110 F

6 Climate Differences Death Valley N.P. Bryce Canyon N.P.

7 Traffic & roadway geometric differences

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9 Address climatic, traffic, and geometric differences Capture the benefits of polymers and create a level playing field for producers / suppliers Improved performance Cost efficiency (i.e. appropriate use of polymers, dosage rates, etc.) Improve confidence for specifiers in agencies

10 Key Research TXDOT funded research through Texas A&M (Amy Epps) Developed surface performance grade (SPG) system Robust field validation completed NCHRP 9-50 (NC State, Richard Kim) Developed emulsion performance grade (EPG) system Lab validation completed Some similarities and some difference in approaches challenge to combine into one consensus standard

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12 ETF s Development Group (EPG-SPG Development Group) Codrin Daranga, Paragon Testing Services, Inc. Amy Epps-Martin (Edith Arambula), Texas Transportation Institute Richard Kim (Cassie Hintz), NC State University Gayle King, GHK, Inc. Andrew Hanz, Mathy Technology & Engineering Services, Inc (MTE) Guy Sisler, Husky Energy Mike Voth, CFLHD, FHWA Testing Program Managed by the Asphalt Institute (Mike Anderson). Big thanks to the 3 labs that completed testing (gratis) : Husky, MTE, and Paragon

13 The principal goals of the testing program were to: Determine appropriate procedures to be used for high and low temperature rheological properties Determine the need for long-term aging Evaluate procedures intended to ensure the quality of polymer modification without excluding good performers Testing Program Complete 2017/18 18 emulsified asphalt samples from across the country. Samples included: polymer modified (both systems), unmodified, and high floats

14 Sample Locations Summer Testing Program

15 Asphalt Institute preliminary analysis complete. EPG-SPG Working Group 4 teleconferences in 2018 Direction on some issues Still some data gaps

16 Tests on Recovered Residue Property Standard System Parameter Limit(s) Test Temp. ( C) Cont. Grade SPG Grade High Temperature Grade AASHTO T315 SPG G*/sind 0.65 kpa Polymer Presence AASHTO T315 SPG Phase Angle PASS Test Temp. ( C) Added Test EPG Result MSCR Test AASHTO T350 Jnr 0.1kPa Report <8.0 (Low) EPG Jnr 3.2kPa <5.5 (Med) <3.5 (High) (Med) 67 MSCR Test AASHTO T350 Added Test 0.1 kpa Report 23.9% 15.5% Added Test 3.2 kpa Report 4.50% 1.20% No Polymer Detected Low Temp. EPG NCSU Draft EPG Critical Phase Angle (δc) - 8mm EPG Result <30 MPa (Low) G* at critical Phase <20 MPa (Med) Traffic Grade Angle <10 MP (Hight) Medium -25 High Medium Test Temp. ( C) Low Temp - Surface Stiffness MTE Procedure Added Test G(8) MPa Report Report G(60) MPa Report Low Temp PG MTE Procedure Added Test m(60) Report N/A ΔTc Report -0.1 Tests on Recovered Residue AASHTO R78 + PAV, 100 C, 20 hours Property Standard System Parameter Limit(s) Test Temp. ( C) Report Polymer Presence AASHTO T315 Added Test Phase Angle Report Polymer Detected MSCR Test AASHTO T350 Added Test 0.1 kpa Report kpa Report Added Test 0.1 kpa Report 54.2% kpa Report 37.90% 27.70% Critical Phase Angle (δc) - 8mm Low Temp. EPG NCSU Draft Added Test G* at critical Phase Angle Report Critical Frequency NCSU Draft Added Analysis G* Report Phase Angle Report Test Temp. ( C) SPG S(8) 500 Mpa Cont. Grade SPG Grade BBR AASHTO T S(60) S(60) <300 Mpa Added Test m(60) m(60)> N/A ΔTc Report -1.1 Test Temp. ( C) Low Temp - Surface Stiffness MTE Procedure Added Test Cont. Grade SPG Grade G(8) kpa Report G(60), kpa) Report Low Temp PG MTE Procedure Added Test m(60) Report N/A ΔTc Report -3.4 Report N/A Report

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18 Consensus items For recovery of residue: AASHTO R 78, method B (6-hr low temperature recovery method) 6-degree temperature increments with 3 degree offset from LTPPBind (PG PG 67-19) Two traffic level standards (NCHRP 9-50 proposed three)

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21 General Outline of Standard High temperature test (resistance to bleeding) Low temperature test (resistance to loss of aggregate / cold temperature shelling) Presence of modifier (polymer identifier)

22 High Temperature Test Primary: G*/sin δ, Min 0.65 kpa (adopt SPG approach) Max 3.2 kpa (AASHTO T 350) -Concern the material is too soft for meaningful results from DSR -Consider testing at lower stress levels or lower temperatures -Reference / Note: Test may be viable in the future after further evaluation of stress levels and test temperatures.

23 Low Temperature Test Primary: G* at critical phase angle, δc ( C). Derived from frequency sweep testing at 5 C and 15 C. (EPG approach) -Uses less material -Completing calculations requires good excel template Creep stiffness, T 313: S, Max 500 MPa, at low test 8 sec., C. On PAV aged material. -Questionable differentiation -Takes a lot of material, relatively -May not be practical for northern climates

24 Presence of Polymer Phase angle (δ), 84 temperature. where G*/sin δ = 0.65 kpa (unaged sample) -Not necessarily performance related (similar to plus tests on binders). -Evaluate if PAV aging is helpful with normalizing/conditioning of latex in effort to address difference of behavior (not related to performance) -Other approaches under consideration include: MSCR % recovery or rely on NC State s 5 and 15 degree frequency sweep.

25 Represents best available knowledge. A tool to stimulate additional research. A tool to stimulate pilot efforts & data collection. Not perfect. Changes are often expected. Limited life (5 to 7 years) Not widely used

26 June 2018: ETF Indianapolis Meeting evaluation August 2018: Present at COMP Meeting, TS 2a Fall 2018: Second round of testing with much narrower scope Fall 2018: Report from Asphalt Institute Complete Late Fall 2018: Submit provisional to TS 2a Jan / Feb 2019: mid-year TS 2a meeting address comments August 2019: COMP Meeting move to full ballot

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