Perpetual Pavement Design An Introduction to the PerRoad Program

Transcription

1 Perpetual Pavement Design An Introduction to the PerRoad Program Dave Timm Auburn University / NCAT Dave Newcomb Texas A&M Transportation Institute Michigan Asphalt Conference 2016

2 Overview Pavement design background Layered elastic theory Perpetual pavement design philosophy Sensitivity Study Program basics Example problems Design simulations

3 WHY ARE PERPETUAL PAVEMENTS IMPORTANT?

4 Perpetual Pavement Award Started by the Asphalt Pavement Alliance in Road must be >35 years old. No thickness increase >4 inches. No overlay interval less than 13 years. Nominated by DOT.

5 Washington State Performance HMA (Lane Miles) PCCP (Lane Miles) Lane Miles or More Age (Years)

6 Washington State Performance HMA (Lane Miles) PCCP (Lane Miles) Description PSR Rating IRI NHS Ride Quality Lane Miles Very Good 4.0 <1.0 m/km (<60 in/mi) Good m/km (60-94 in/mi) Fair m/km ( in/mi) Mediocre m/km ( in/mi) Acceptable (0-2.7 m/km) 200 Poor 2.5 >2.7 m/km (>170 in/mi) Less than Acceptable (>2.7 m/km) or More IRI (m/km)

7 Material Usage Save 31% Save 28% Save 32% Save 28%

8 Perpetual Pavement versus Conventional Design

9 A City in Texas Asphalt Performance Problems Ban Asphalt? A City in Texas 9

10 Goal of Perpetual Pavement Design Design the structure such that there are no deep structural distresses Bottom up fatigue cracking Structural rutting All distresses can be quickly remedied from surface Result in a structure with Perpetual or Long Life

11 Avoid These! Structural Rutting Bottom-Up Fatigue April 21, 2014 Panel Briefing 11

12 Surface Distresses Only Top Down Cracking Non-Structural Rutting

13 Pavement Design: Where were we? Using 1960s performance equations 1950s type of load Thin pavement structures (Max. 6 HMA) Meaning of structural coefficients Limited reliability analysis Some movement to M-E

14 AASHO Road Test Trucks

15 M-E Design Framework Load Configurations WESLEA σ, ε Structural Parameters Transfer Function(s) n D = ni Nf i Νf D>1? D<<1? Final Design

16 1 2 3 Before Loading During Loading How an Elastic Material Behaves. After Loading - Same Size as Before Loading

17 Dynamic Modulus Test

18 HMA Modulus Versus Temperature Modulus, 1000 psi Temperature, F

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20 Soil Modulus Testing

21 Effect of Moisture Content 100 Modulus, ksi Moisture Content, %

22 M-E Design Framework Load Configurations WESLEA σ, ε Structural Parameters Transfer Function(s) n D = ni Nf i Νf D>1? D<<1? Final Design

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24 M-E Design Framework Load Configurations WESLEA σ, ε Structural Parameters Transfer Function(s) n D = ni Nf i Νf D>1? D<<1? Final Design

25 Three Layer Systems Tire has a total load P, spread over a circular area with a radius of a, resulting in a contact pressure of p. Pavement Reactions h 1 h 2 Deflection (δ) Tensile Strain (ε t ) Compressive Strain (ε v ) Layer 1 HMA E 1 Layer 2 Granular Base E 2 Layer 3 Subgrade Soil E 3 No horizontal boundary, assume layers extend infinitely. No bottom boundary, assume soil goes on infinitely.

26 M-E Design Framework Load Configurations WESLEA σ, ε Structural Parameters Transfer Function(s) n D = ni Nf i Νf D>1? D<<1? Final Design

27 10,000 Fatigue Transfer Function Horizontal Tensile Strain ( in./in.10-6 ) 1, E ε log N = log ( t f ) log ( 3 ) 10 E = 500,000 psi (3,450 MPa) 10-6 E = 200,000 psi (1,380 MPa) Load Applications (N ) f

28 -6 Vertical Compressive Strain ( in./in. 10 ) 100,00 10,00 1,000 Rutting Transfer Function N = x 10 ( ) f Load Applications (N ) f ε v

29 Strain, (10E-06) Normal Range for Fatigue Testing Endurance Limit E+08 Number of Loads to Failure

30 M-E Design Framework Load Configurations WESLEA σ, ε Structural Parameters Transfer Function(s) n D = ni Nf i Νf D>1? D<<1? Final Design

31 Structural/Performance Analysis Initial trial design Initial estimate of layer thickness Required repairs to the existing pavement Pavement materials characterization Analyzed by cumulative damage incrementally over time using Structural response Performance models

32 Perpetual Pavement Design Log ε Threshold Strain Log N No Damage Accumulation

33 Tandem Axles Axle Group Weight, kn Axles / 1000 Heavy Axles Rural Interstate Rural Principal Arterial Rural Minor Arterial Rural Major Collector Rural Minor Collector Rural Local Collector Urban Interstate Urban Other Freeways and Expressways Urban Principal Arterial Urban Minor Arterial Urban Collector Axle Group Weight, kip

34 PerRoad 3.3 Sponsored by APA Developed at Auburn University / NCAT M-E Perpetual Pavement Design and Analysis Tool

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39 Coming Refinement Currently a single fatigue endurance limit is used. Results in one-size fits all overly conservative Use FEL Ratio. Use distribution of strains. Ratio = FEL n /FEL lab April 21, 2014 Panel Briefing 39

40 PerRoadXPress

41 Vehicle Type Distributions

42 PerRoadXPress

43 Download PerRoad 3.3 And PerRoadXpress Free! Go To: OR Google David Timm at Auburn University

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45 At the 2016 AAPT Meeting: Leading Edge Workshop: Cracking Tests 5 Presentations on Cracking Tests Symposium: Balanced Mix Design 5 Presentations on High RAP/RAS Implementation of Specifications Aging Behavior Forum Topic: World Asphalt Market