The Future of Asphalt Pavement Structural & Mixture Design Complex Modulus, /E*/

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1 The Future of Asphalt Pavement Structural & Mixture Design Complex Modulus, /E*/ Thomas Harman Asphalt Pavement Team Leader, R&D Federal Highway Administration A A S H T O F H W A I N D U S T R Y SUPERPAVE 2005

2 Future Structural 2002 Guide Construction Materials A A S H T O F H W A PRS / Warranty I N D U S T R Y SUPERPAVE 2005 Superpave II

3 The Players A A S H T O F H W A 2002 Guide NCHRP 1-37A1 Recommend Test(s) SPR-0003(84) E* Pooled Fund Evaluate Test Procedures NCHRP Recommend Test(s) NCHRP Equipment Specs First Articles Eval Revise Specs I N D U S T R Y SUPERPAVE 2005 Superpave II

4 Simple Performance Test for Superpave Mix Design Advanced Asphalt Technologies, LLC Engineering Services for the Asphalt Industry

5 SPT What Is It? Test(s) that indicates how mix will perform Rutting Cracking

6 SPT Requirements Absolute Requirements of Test Compliment Superpave Volumetric Design Use Gyratory Specimens High Correlation to Rutting/Fracture Identify Inferior Mixes Preferred Requirements of Test Tied to Structural Design Adaptable to QC/QA

7 Project Candidate Tests Complex Modulus, /E*/ Rutting Cracking Creep Test, FT Rutting Repeated Load Test, FN Rutting

8 Project Correlation Study MnRoad WesTrack FHWA-ALF

9 ALF: Rut Depth vs. 130 F (54.4 C) Rut 10,000 Passes (mm) Unconfined -- Linear Range Se/Sy = 0.35 R 2 = AC Styrelf 8 - Novophalt 9 - AC AC Base AC Base AC E*max/sinf (10^6 psi)

10 Complex Modulus, /E*/ Stress Strain Time E * = σ ε 0 0 Rutting Min E* at High Temp Fatigue Cracking Max E* at Intermediate Temp

11 Creep Flow Time, FT STRESS TIME STRAIN Flow Time Rutting Min FT at High Temp

12 Repeated Load Permanent Deformation Test, Flow Number STRESS STRAIN TIME Flow Number Rutting Min FN at High Temp

13 Advantages Complex Modulus, /E*/ Used for Structural Design in 2002 PDG Addresses Rutting and Cracking Creep, FT Simple Test Equipment Minimal Training Repeated Load, FN Potentially Best Simulation of Actual Loading

14 Disadvantage Specimen Size 1:1.5 D/H Ratio required to ensure fundamental properties 100 mm Diameter by 150 mm High Smooth Parallel Ends (Sawed) Sawed and Cored From Over- Height Gyratory Specimens Not all SGC can produced Specimens

15 Project SPT Criteria Development Use Models proposed in 1-37A, 1 account for: Climate Traffic Level Structure Test at Effective Pavement Temperature Minimum or Maximum Values Traffic Level Pavement Structure Completed in Fall 2002

16 Project Validation Criteria Will Be Validated Not the tests In-Service Pavement Data 50+ LTPP and Other Test Sections Completed in 2002

17 Project Equipment Specifications Simple Performance Test System All 3 Tests Automated Specimen Fabrication Equipment Encourage Innovation by Manufacturers User Friendliness Reliability Cost

18 Project Specification Development Research Test Protocols Draft Equipment Specs Cost Estimate Manufacturer s Review User s Workshop Ideas First Article Equipment Specs Revised Estimate

19 First Article SPT Procurement EnduraTec Instron Interlaken Shedworks Specifications Advantages Cost Past Performance

20 First Article SPT Systems Tests Complex Modulus Flow Time Flow Number Temperature Range 20 to 60 C Confining Pressure Range 0 to 210 kpa

21 First Article Simple Performance Test Systems INTERLAKEN SHEDWORKS

22 Instrumentation LVDT s

23 Shedworks

24 Interlaken

25 Specimen Fabrication System Pine Shedworks Specifications Automated Cost

26 First Article Specimen Fabrication System

27 First Article Specimen Fabrication Equipment BLADES CHUCK CORE BARREL

28 Summary- Simple Performance Test Work Completed Three Candidate Tests Detailed Draft Protocols Detailed Equipment Specifications First Article Devices Simple Performance Test System ($25 k to $45 k) Automated Specimen Fabrication System ($12 k)

29 NCHRP Timeline Criteria Development Early Fall 2002 Criteria Validation End of 2002 First Article Evaluation Early 2003

30 Complex Modulus, /E*/ for Structural Design

31 2002 PDG Requires a Range of Frequencies & Temp. s Stress (kpa) Hz, kpa, 20 Cycles 1 Hz, kpa, 50 Cycles 0.1 Hz, kpa, 20 Cycles Hz, kpa, 100 Cycles 10 Hz, kpa, 200 Cycles 25 Hz, kpa, 200 Cycles 180 seconds rest period between frequencies Time (sec.)

32 Example 10 Hz and 62 kpa Stress (kpa) Time (sec.)

33 /E*/ Pooled Fund Study UConn (2002 PDG) Perliminary Result of Round Robin Study MD NC AAT E*, MPa C 38 C FHWA 54 C Frequency, Hz

34 Understanding Modified Binders NCHRP 90-07, 07, TPF 5(019)

35 FHWA-ALF ALF Mean and Standard Deviation of /E*/ (3 Replicates, 50 C, 10 Hz) E*, MPa Mean Std EVA CMCRA ESL SBS L Air Blown EVAG PG SBS RG SBS LG Elvaloy PG 64-28

36 FHWA-ALF ALF Coefficient of Variation of /E*/ (3 Replicates, 50 C, 10 Hz) %CV EVA CMCRA ESL SBS L Air Blown EVAG PG SBS RG SBS LG Elvaloy PG 64-28

37 TRB Superpave Binder Expert Task Group /E*/ Concern AASHTO/ TRB / NCHRP / FHWA

38 Lab Mix Similar PG Grade /E*/ at 10 Hz Dynamic Modulus, IE*I, GPa Elvaloy PG64 SBS L SBS LG PG70 AB SBS RG EVA G ESI CRA EVA

39 Permanent Strain 25 to 0.1 Hz 600 Change in Strain, ε, Micro Strain Elvaloy CRA SBS LG EVA PG64 PG70 SBS RG ESI SBS L AB EVA G

40 SST vs /E*/ Accumulative Strain (Simple Shear Test) /E*/, GPa (Simple Performance Test) Elvaloy SBSL SBSLG PG70 AB SBSRG ESI CRA

41 /E*/ x (??( max /??) Normalized SST Permanent Deformation Normalized Weighted Complex Modulus Elvaloy SBSL SBSLG PG70 AB SBSRG ESI CRA

42 Summary A A S H T O F H W A 2002 Guide I N D U S T R Y SUPERPAVE 2005 Superpave II NCHRP 1-37A1 Complex Modulus, /E*/ Issues of repeatability Concern with modifiers NCHRP 9-19/299 Links Mix Design to Structural Design

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44 Smooth Roads Ahead