Optimized or Balanced Mix Design Crack Resistant Rut Resistant - - PowerPoint PPT Presentation

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Optimized or Balanced Mix Design Crack Resistant Rut Resistant - - PowerPoint PPT Presentation

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Optimized or Balanced Mix Design Crack Resistant Rut Resistant Resistant to Moisture Damage 1 Balanced Mix Design: ETG Definition Asphalt mix design using performance tests on appropriately conditioned specimens that address

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Optimized or Balanced Mix Design

  • Crack Resistant
  • Rut Resistant
  • Resistant to Moisture Damage

1

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Balanced Mix Design: ETG Definition

  • Asphalt mix design using performance tests on

appropriately conditioned specimens that address multiple modes of distress taking into consideration mix aging, traffic, climate and location within the pavement structure

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Performance Pendulum (Shane Buchanan, Oldcastle)

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Disk‐Shaped Compact Tension (DCT) Test

  • ASTM D7313‐13
  • Loading Rate:
  • Crack Mouth Opening Displacement
  • CMOD Rate = 1.0 mm/min
  • Measurements:
  • CMOD
  • Load

3

P P CMOD, u

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SLIDE 4

Semi‐Circular Bend (SCB) Test

  • Multiple variants exist
  • Early work in Europe
  • Simultaneous cold (Marasteanu et al. – MN)

and intermediate temperature (Mohamed et al. – LA) versions

  • Recent work from Al‐Qadi et al. (IL)  AASHTO TP 105
  • AASHTO TP 105 (I‐FIT)
  • Line load control, loading rate = 50 mm/min
  • Test temperature = 25 deg. C
  • Measurements:
  • Displacement
  • Load
  • Outcomes
  • Fracture Energy
  • Flexibility Index (FI)

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Fracture Parameters Sf

Displacement (CMOD or LL), u Load, P

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P P CMOD

Fracture work: Area under Load‐Displacement curve Fracture Energy, Gf: Energy required to create unit fracture surface Gf = Fracture Work, Sf Fracture Area Flexibility Index, FI: FI = Gf / m

m

P LL

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SLIDE 6

Choosing A Fatigue Test for Long Life Asphalt Pavement (LLAP)

Mansour Solaimanian, Ph.D., P.E.

Pennsylvania State University August 2nd, 2017

Scott Milander Pezhouhan Kheiry Xuan Chen Saman Barzegari Ilker Boz

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Today’s Talk

  • A Review of Asphalt Concrete Fatigue Tests
  • Semi‐Circular Beam (SCB) Test
  • PSU SCB Study and Preliminary Results
  • Next Steps
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Today’s Talk

  • A Review of Asphalt Concrete Fatigue Tests
  • Semi‐Circular Beam (SCB) Test
  • PSU SCB Study and Preliminary Results
  • Next Steps
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SLIDE 9

Monotonic Tests

  • Indirect Tensile Strength
  • Semi‐Circular Beam
  • Disk‐Shaped Compact Tensile

Cyclic Tests

  • Four Point Bending Beam
  • Indirect Tensile
  • Uniaxial Push‐Pull
  • Texas Overlay

Picture Curtesy: IPC Global, Umass, Penn State

Lab Scale Tests

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Lab Scale Tests (Cyclic Tests)

Fatigue/Cantilever Trapezoid Texas Overlay Tester Bending Beam

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Model Scale Accelerated Tests

  • Third Scale Model Mobil Load Simulator (MMLS3)
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Test Tracks and Full Scale Tests

Picture Curtesy: NCAT

Penn State Track NCAT Track …and ALF, HVS, MLS, ….

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Today’s Talk

  • A Review of Asphalt Concrete Fatigue Tests
  • Semi‐Circular Beam (SCB) Test
  • PSU SCB Study and Preliminary Results
  • Next Steps
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Background on SCB

  • Early Work on Rocks (Chong and Kuruppu, 1984)
  • Introducing SCB for Asphalt Testing (Molenaar, 2000 &

2002)

  • Further Research (Mohammad et al., 2004) ‐ LA
  • Further Research – IFIT (Alqadi et al., 2015) ‐ IL
  • Implementation in Specs (Mohammad et al., LTRC, 2016)
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SCB Test Setup

Applied Load Support Support

120 mm 150 mm

Notch Specimen Thickness: 50 mm Notch Depth: 15 mm Notch Width: 1.5 mm

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SLIDE 16

16 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 1 2 3 4 5 6 7 8

Load (N) Displacement (mm) Slope @ Inflation Point (m) Slope @ 50% Peak Load Critical Displacement

Parameters Used For Evaluation

Work of Fracture (W) Peak Load (P

)

FI A G absm G W B · L

Fracture Energy Flexibility Index

B: Specimen Thickness L: Ligament Length A: Constant

Stiffness Index

Slope @ 50% Peak Load in Pre‐Peak Curve

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Advantages of SCB Test

  • Specimen Easily Prepared Using SGC or Field Cores
  • Four Specimens from One Compacted Mix
  • Easy to Perform and Simple to Analyze
  • Possible To Perform Test Using Marshall‐Type Stability Tester
  • Good Correlation to Field Performance Has Been Reported.

(Limited Data so far)?

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Current Issues

  • In the SCB test, do we know the answer to these?
  • What test temperature?
  • How fast to test?
  • What is good versus poor performance?
  • What pass/fail criteria?
  • Test short‐term aged or long‐term aged mix?
  • Test variability and how to reduce variability?
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Today’s Talk

  • A Review of Asphalt Concrete Fatigue Tests
  • Semi‐Circular Beam (SCB) Test
  • PSU SCB Study and Preliminary Results
  • Next Steps
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Study Objectives

  • Effect of Test Temperature
  • Effect of Loading Rate Range
  • Effect of Aging (short term vs long term)
  • Effect of Binder Content and Binder Stiffness
  • Effect of Voids

Use data to establish Temperature – Loading Rate Master Curve and Propose the Final SCB Test Protocol

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Test Temperature

I‐FIT Protocol: Fixed Temperature for All Mixes, i.e. 25 Proposed Protocol: Using Effective Temperature Concept NCHRP 704: A Performance‐Related Specification for HMA

Freq: Loading Frequency, Hz; MAAT: Mean Annual Air Temperature, ; MAAT: Standard Deviation of the Mean Monthly Air Temperature; Rain: Annual Cumulative Rainfall Depth, inches; Sunshine: Mean Annual Percentage Sunshine, %; and Wind: Mean Annual Wind Speed, Mph.

Harrisburgh is around 18

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Test Loading Rate

Current Protocol:

  • 50 mm/min (too fast, not enough data points, higher COV)
  • 0.5 mm/min (too slow, affected by creep)

Proposed Protocol based on our results so far:

  • Using loading rate between 5 to 20 mm/min will minimize the

effect of creep, and provide a reasonable range for FI for long term aged mix.

  • A set of tests (3 replicates) can be conducted within 5 minutes
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20 mm 50 mm 50 mm 20 mm 150 mm 150 mm

Specimen Preparation

  • SGC Specimen or Field Cores
  • Cut to Ensure Minimum AV Gradient
  • Obtain Density
  • Condition Specimens at Test

Temperature

  • Conduct Test

It Takes 3 days from Mixing to Obtain Results

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Specimens After Cutting Ready for Testing Specimens Before (L) / After (R) Testing

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25 500 1000 1500 2000 2500 3000 3500 1 2 3 4 5 6 7 8

Load (N) Displacement (mm)

Typical Load vs Displacement Curves 3 Replicates, PG 58‐28, 25°C

25 mm/min 5 mm/min 1 mm/min 50 mm/min

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Temperature/Loading Rate Effects

500 1000 1500 2000 2500 3000 3500 4000 4500 5000 Virgin Agg+PG58+7AV Virgin Agg+PG58+4AV Virgin Agg+PG58+7AV+5.9BC Virgin Agg+PG76+7AV Virgin Agg+PG58+7AV @ 18C Virgin Agg+PG58+4AV @ 18C Virgin Agg+PG58+7AV+5.9BC @ 18 C Virgin Agg+PG76+7AV @ 18C

Fracture Energy (J/m^2)

Fracture Energy Comparison

1 mm/min 5 mm/min 20 mm/min 50 mm/min

Tested @ 25 Tested @ 18

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27 5 10 15 20 25 30 35 40 45 50 Virgin Agg+PG58+7AV Virgin Agg+PG58+4AV Virgin Agg+PG58+7AV+5.9BC Virgin Agg+PG76+7AV Virgin Agg+PG58+7AV @ 18C Virgin Agg+PG58+4AV @ 18C Virgin Agg+PG58+7AV+5.9BC @ 18 C Virgin Agg+PG76+7AV @ 18C

Flexibility Index

Flexibility Index Comparison

1 mm/min 5 mm/min 20 mm/min 50 mm/min

Tested @ 25 Tested @ 18

Temperature/Loading Rate Effects

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Aging Effect

5 10 15 20 25 30 35 40 45 50 Virgin Agg+PG58+7AV @ 18C Virgin Agg+PG58+4AV @ 18C Virgin Agg+PG58+7AV+5.9BC @ 18 C Virgin Agg+PG76+7AV @ 18C Virgin Agg+PG58+7AV @ 18C LTOA Virgin Agg+PG58+4AV @ 18C LTOA Virgin Agg+PG58+7AV+5.9BC @ 18 C LTOA Virgin Agg+PG76+7AV @ 18C LTOA

Flexibility Index

Flexibility Index Comparison, all at 18°C

1 mm/min 5 mm/min 20 mm/min 50 mm/min

Short Term Aged Long Term Aged

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Correlate Stiffness Indices of Aged Mixes

y = 1.3827x + 1846.5 R² = 0.8427

3000 6000 9000 12000 15000 3000 6000 9000 12000 15000

Long Term Aged Results Short Term Aged Results

Stiffness Index Comparison

Line of Equality

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Correlating Facture Energy of Aged Mixes

y = 0.6063x + 811.61 R² = 0.8137

1000 1500 2000 2500 3000 3500 4000 4500 1000 1500 2000 2500 3000 3500 4000 4500 Long Term Aged Fracture Energy (J/m^2) Short Term Aged Fracture Energy (J/m^2)

Fracture Energy Comparison

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Correlating FI of Aged Mixes

5 10 15 20 25 30 35 5 10 15 20 25 30 35

Long Term Aged Flexibility Index Short Tem Aged Flexibility Index

Flexibility Index Comparison 1 mm/min 5 mm/min 20 mm/min 50 mm/min

Line of Equality

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Temperature/Loading Rate Sweep in SCB

4 8 12 16 20 5 10 15 20 25 30 35 40

Flexibility Index Temperature ()

Flexibility Index Long Term Aged Material

1 mm/min 5 mm/min 20 mm/min 50 mm/min

Faster Loading

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500 1000 1500 2000 2500 3000 1 2 3 4 5 6 7 8

Load (N) Displacement (mm) Typical Load vs Displacement Curve STOA, PG64‐22, 7% AV

4.7% BC 5.2% BC 5.7% BC 6.2% BC

Post Peak Slope

Effect of Binder Content

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Effect of Binder Content

10 20 30 40 50 60 4 4.5 5 5.5 6 6.5 7

Flexibility Index Binder Content (%) 7% Air Void

PG58‐28 PG64‐22 PG76‐22

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Effect of Binder Content

5 10 15 20 25 30 35

4 4.5 5 5.5 6 6.5 7

Flexibility Index Binder Content (%) 4% Air Void

PG58‐28 PG64‐22 PG76‐22

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500 1000 1500 2000 2500 3000 1 2 3 4 5 6 7 8

Load (N) Displacement (mm) Typical Load vs. Displacement Curve STOA, 7% AV, 5.2% BC

PG58‐28 PG64‐22 PG76‐22

Effect of Binder Grade (Stiffness)

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Effect of Binder Grade (Stiffness)

10 20 30 40 50 60 52 58 64 70 76 82

Flexibility Index Binder High Temperature Grade

7% Air Void

4.7% BC 5.2% BC 5.7% BC 6.2% BC

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Effect of Binder Grade (Stiffness)

5 10 15 20 25 30 35 52 58 64 70 76 82

Flexibility Index Binder High Temperature Grade 4% Air Void

4.7% BC 5.2% BC 5.7% BC 6.2% BC

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Effect of Binder Grade (Stiffness)

10 20 30 40 50 60 70 52 58 64 70 76 82

Flexibility Index Binder High Temperature Grade 10% Air Void

4.7% BC 5.2% BC 5.7% BC 6.2% BC

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500 1000 1500 2000 2500 3000 3500 4000 4500 1 2 3 4 5 6 7 8

Load (N) Displacement (mm) Typical Load vs. Displacement Curve STOA, PG64‐22, 5.2% BC 2% AV 4% AV 7% AV

Effect of Air Void

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Effect of Air Void

5 10 15 20 25 30 35 40 45 50 1 2 3 4 5 6 7 8 9 10 11 12

Flexibility Index Air Void (%) 5.2% Binder Content

PG58‐28 PG64‐22 PG76‐22

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The Effect of Air Void Reported by UIUC

Source: Maxwell 2016

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The Effect of Air Void Reported by UIUC

Source: Maxwell 2016

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Where do we go from here?

  • Effect of Modifiers
  • Effect of RAP/RAS
  • Effect of Crumb Rubber
  • Plant vs Lab Mixes
  • Cataloging PA Mixes
  • Correlation with Field

Performance

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PAPA Proposed Crack Performance Testing

  • Virgin vs. 15% RAP mix
  • Design Binder vs. +0.5% AC
  • Lab mix vs. Production mix
  • Short‐term vs. long‐term aging
  • 16 cells in matrix
  • Baseline for existing mixes

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Thank you!