NCHRP 9-59-Binder Fatigue Test: Update

Transcription

1 NCHRP 9-59-Binder Fatigue Test: Update September 15, 2016 FHWA Binder ETG Fall River, MA Advanced Asphalt Technologies, LLC Engineering Services for the Asphalt Industry

2 NCHRP 9-59 Objective The primary objective of NCHRP 9-59 is to develop a test or tests that will help to effectively and efficiently control the properties of asphalt binders that contribute to the fatigue resistance of asphalt mixtures

3 Presentation Objective Describe general approach to developing an improved binder fatigue test Provide summary of results to date Describe future efforts

4 Problem Bill Ahearn, Pamela Marks, Simon Hesp

5 Questions Can G* sin() be improved? Added to? Replaced? How does modulus affect fatigue performance? Relationship between fracture and fatigue performance of binder and mixture?

6 Strain-Based Cracking Model N f FSC binder FSC = fatigue strain capacity N f mix FSC VBE

7 Generalized Failure Theory N f FSC binder FSC = fatigue strain capacity FSC = { ( Nf *ebinder 1.38(90/d ) )} d/ ( ) n å i=1 é( ) i D = N i ë e binder FSC D ù û 1.38( 90 d) Phase angle is for the binder, not the mix

8 Generalized Failure Theory N N D f f n FSC FSC i mix FSC VBE mix N i i 1 VBE 100 D binder FSC = fatigue strain capacity Phase angle is for the binder, not the mix

9 Failure Strain or FSC, % Typical Failure Envelope 1.E+03 1.E+02 1.E+01 1.E+00 1.E-01 FSC = f(stiffness or G*) 1.E-02 1.E+04 1.E+05 1.E+06 1.E+07 1.E+08 1.E+09 1.E+10 Secant Modulus/3 or G*, Pa ARC Fatigue AAT Misc. DT/NM AAT ARC/9-25 DENT/NM DT PMod Failure Envelope 9-25 Fatigue ALF2 DT/NM ALF DENT/NM DENT PMod Heukelom

10 Fatigue/Fracture Performance Ratio, FFPR Typical FSC or * S 9, T, t ST t FFPR is defined as the ratio of observed to expected failure strain. Values significantly above 1 are good, below 1 are bad. The equation above is preliminary. FFPR Measured FSC or * Typical FSC or *

11 Preliminary Results: Testing of ALF Binders

12 ALF Fatigue Experiments Most of the binders for the first and second ALF fatigue experiments were tested These included PG 70-22, air blown binder, Terpolymer, SBS-LG, crumb rubber binder, AC 5 and AC 20 RTFOT aging

13 Binder Test Methods DSR frequency sweep (R value) Modified double edge notched tension (DENT) Linear amplitude sweep (LAS) Single edge notched bending (SENB) Various others from existing data

14 LAS FFPR ALF Binders: Correlation among LAS FFPR Direct Tension FFPR FFPR Values R² = 82% DENT FFPR R² = 65% DENT FFPR R² = 79% Direct Tension FFPR

15 Cycles to 25 m Cracking Cycles to 25 m Cracking 250,000 ALF Binders: Correlation Between Cracking and FFPR: ALF 1 & 2, 100 mm Test Sections 200, , ,000 50, , , , ,000 50,000 0 R² = 90% DENT FFPR R² = 94% LAS FFPR

16 Cycles to 25 m Cracking Cycles to 25 m Cracking 250,000 ALF Binders: Correlation Between Cracking and FFPR: ALF 1 & 2, 100 mm Test Sections 200, , ,000 R² = 90% 50, Direct Tension FFPR 250, ,000 R² = 57% 150, ,000 50, Binder R-Value

17 NCHRP 9-59 Test Plans

18 NCHRP 9-59 Tests Many binder tests correlated to ALF fatigue performance Will this approach work for 9-59 materials and test methods? Will binder and mixture test data correlate? Will test data match expected performance

19 NCHRP 9-59 Binders No. Additive PG Comments 1 SBS Grade is approximate; base, 6 %+ SBS 2 SBS SBS/PPA SBS Base binder = 58-28; SBS % = % 5 SBR Base binder = 64-22; SBR % = % (terminal) 6 EVA source source 2; significantly different chemistry/rheology 10 GTR terminal blend 11 oxidized oxidized REOB source 1 14 REOB source 2; significantly different chemistry/rheology 15 Terpolymer PPA 70-22

20 NCHRP 9-59 Mixture Testing Uniaxial fatigue (SVECD) Two temperatures Three replicates Overlay test (OT) 20C Three replicates Bending beam fatigue

21 NCHRP 9-59: Laboratory Aging Binders: RTFOT + 40 hour PAV Mixture: Standard short term aging followed by loose mix aging at 95C for 5 days. Based on data available at the start of the project, which was very limited

22 Comparison of Mix and Binder Laboratory Aging

23 Preliminary NCHRP 9-59 Results

24 Modified DENT Test Results Binder Temp Stiff/3, Pa Fail. Strain, % Expected FS, % FFPR PG SBS E E PG E E PG REOB E E LAS Test Results Binder Temp G*, Pa Avg. FSC, % Exp. FSC, % FFPR PG SBS E PG E PG REOB E

25 Uniaxial Fatigue Results Binder Temp G* Avg. FSC, % Exp. FSC, % Avg. FFPR PG SBS E E PG E E PG REOB E E Texas Overlay Test Results Binder Temp G* Cycles Avg. FSC, % Exp. FSC, % Avg. FFPR PG SBS E PG E PG REOB E

26 FSC or Failure Strain, % NCHRP 9-59 Data Compared to Typical Failure Envelope 1.E+03 1.E+02 1.E+01 1.E+00 1.E+05 1.E+06 1.E+07 1.E+08 G* or Stiffness/3, Pa Fit DENT PG FATIGUE PG TOT PG DENT PG FATIGUE PG TOT PG DENT PG REOB FATIGUE PG REOB TOT PG REOB LAS PG LAS PG LAS PG REOB

27 FFPR, Mix Uniaxial Fatigue Mix Uniaxial Fatigue vs Binder MDENT Data Equality R² = 85% FFPR, Binder MDENT

28 Avg. FFPR, Mix Uniaxial Fatigue Using Average Mix FFPR and Energy-Based DENT FFPR Data Equality PG PG PG REOB R² = 93% FFPR (Energy based), Binder MDENT

29 Total Energy to Failure, N-m Energy-Based DENT FFPR Typical ALF Blown ALF SBS LG ALF Terpolymer PG REOB PG Fit/Typical Specimen Stiffness at 3 Seconds, KN/m

30 FFPR, Mix Uniaxial Fatigue Mix Uniaxial Fatigue vs LAS Equality 1.0 R² = 61% FFPR, LAS

31 FFPR, Mix Uniaxial Fatigue Mixture Uniaxial Fatigue vs R R² = 38% Binder R Value

32 FFPR, Mix Texas Overlay Test Texas Overlay vs MDENT Equality Mix Tx OT Linear (Mix Tx OT) 1.0 R² = 92% FFPR, Binder MDENT

33 FFPR, Mix Tx Overlay Test Texas Overlay vs LAS Equality 1.0 R² = 46% FFPR, LAS

34 Interim Findings The proposed general failure theory and failure envelope appear to provide a powerful tool for evaluating the fatigue and fracture resistance of asphalt binders and mixes

35 Interim Findings The RTFOT + 40 hour PAV binder aging appears to produce a similar degree of aging as the 5 day loose mix aging at 95C, but much more research is needed to verify and fine tune these aging protocols

36 Interim Findings The modified DENT test correlates very well to both field fatigue performance in the FHWA ALF studies and in laboratory tests conducted in the first stage of NCHRP 9-59 testing. The LAS test is also promising we may need to make adjustments

37 Future work Additional binder testing: 13 more binders and including SENB test Healing study Parametric study on relationship between modulus and fatigue performance Validation testing

38 Acknowledgements Those I have borrowed data from Support of NCHRP The NCHRP Panel Industry suppliers Nam Tran and his associates at NCAT My associates at AAT, including Ray, Don, and Bob