An Improved Method for LowTemperature Asphalt Binder Grading

1
An Improved Method for Low-Temperature Asphalt
Binder Grading

• S.A.M. Hesp and S. Iliuta, Queens University
• M.O. Marasteanu, University of Minnesota
• K.K. Tam and T. Masliwec, Ministry of
  Transportation Ontario
• TRB Annual Meeting, Washington, D.C.
• January 12, 2004

2
Acknowledgments

• Charitable Foundation of Imperial Oil of Canada
• Natural Sciences and Engineering Research Council
  of Canada (NSERC)
• Ministry of Transportation Ontario
• National Cooperative Highway Research Program
  Innovations Deserving Exploratory Analysis
  (NCHRP-IDEA)
• University of Minnesota

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Main Research Product

• Test Method LS-296 Laboratory Standard for
  Fracture Performance Grading of Asphalt Binders

• A Much Improved Binder Grading Method
• Determines an Accurate Grade Temperature
• Assesses Fracture Energy in Brittle State
• Assesses Fracture Energies in Ductile State

4
Ontarios Pavement Trial Sections
Hwy 655 (2003)
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C-SHRP Trial on Highway 631

• Constructed near Hearst in 1991
• Twelve Years Performance Data
• PG 52-40 _at_ 98 Confidence PG 46-34 _at_
  50 Confidence
• 1990 AADT 300 (75 trucks) 2000 AADT 600 (175
  trucks)
• Four Test Sections
• B (PG 52-28, 50 mm)
• A (PG 52-28, 50 mm)
• AA (PG 46-34, 50 mm)
• BB (PG 52-28, 100 mm)

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C-SHRP Trial on Highway 631
750
1997
515
2003
500
Cracks/km
236
250
74
49
14
5
2
5
0
B
A
AA
BB
52-33.5
52-33
46-37
52-33
PG grades
150-200B 150-200A 150-200AA 150-200B
CGSB grades
Calculated Minimum Pavement Temperatures
(Kapuskasing) -32 C, -33 C (1994), -33 C
(1996), -30 C (1999), COLDEST -33 C
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Pavement Trial on Highway 118

• Constructed near Bracebridge in 1994
• PG 53-32 _at_ 98 Confidence or
  PG 46-26 _at_ 50 Confidence
• Traffic Split between Sections 2 and 2A
• 2000 AADT 3450 (200 trucks) for sections 1 and
  2
• 2000 AADT 1250 (50 trucks) for sections 2A to 6
  
• Seven Test Sections
• 118-1 (PG 70-24, 42 mm)
• 118-2 (PG xx-26, 45 mm)
• 118-2A (PG xx-33, 42 mm)
• 118-3 (PG 64-32, 45 mm)
• 118-4 (PG 70-38, 37 mm)
• 118-5 (PG 64-33, 42 mm)
• 118-6 (PG 70-25, 41 mm)

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Pavement Trial on Highway 118
Calculated Minimum Pavement Temperatures (Muskoka
Airport) -27 C (1996), -27 C (1997), -27 C
-27 C (2003)... COLDEST -27 C
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SPS-9A Trial on Highway 17

• Constructed near Petawawa in 1996 and 1997
• PG 54-33 _at_ 98 Confidence or
  PG 47-27 _at_ 50
  Confidence
• 1994 AADT 5670 (680 trucks)
  
• 2000 AADT 6000 (840 trucks)
• Six Test Sections (all 2 x 65 mm lifts)
• 17-01 (85/100, Marshall)
• 17-02 (PG 58-41, Superpave)
• 17-03 (PG 58-35P, Superpave)
• 17-60 (PG 58-31, Superpave)
• 17-61 (PG 58-35, Superpave)
• 17-62 (PG PG 58-41, Marshall)

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SPS-9A Trial on Highway 17
Calculated Minimum Pavement Temperatures (CFB
Petawawa) -24.7 (1999), -26.5 C -27.2 C
(2003) COLDEST -27 C
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Better Ways to Grade Binders

• Fracture Toughness KIc is a time-tested material
  property which provides a measure of strength in
  the presence of a sharp crack
• Fracture Energies Gf KIc2/E or we Wt/lt
  -bwpl are material properties which provide
  measures of resistance to cracking under brittle
  or ductile conditions in the presence of sharp
  cracks
• Crack Tip Opening Displacement CTOD GIc/sty is
  a measure of strain tolerance close to the
  ductile state in materials with sharp cracks

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Where To Go From Here?
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Measuring Fracture Properties
Three Point Bending
Compact Tension
25 x 12.5 x 12.5 mm
?
25 x 5000 mm slit notch
?
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Advantages of the Fracture Test

• Single Test Uses Only 4-5 g Binder
• No Release Agent or Silicone Mold Required
• No Cutting, Scraping or Sharpening Required
• Compatible With SHRP DTT and Superpave
• Aluminum Mold Is Easily Made and Assembled
• Test Results Can Be Highly Reproducible
• Based On Fundamentally Sound Principles that
  Combine Rheological Properties (i.e., E and sty)
  with Fracture Properties (i.e., KIc and GIc)
• Predicts Onset As Well As Severity of Thermal
  Cracking

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Reproducibility of the Fracture Grading Test
Method
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How Do Different Methods Compare?
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Ductile Fracture Energies
Ligaments (L) 5, 10, 15, 20 and 25 mm
Binder 118-4
Andriescu et al., TRB 2004
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Ductile Fracture Energies
30
5
23.3
4
20
16.7
3
2.7
15.2
-3
-2
we,
bw
, MJ.m
kJ.m
2.2
p
1.8
2
10
1
3.9
0.5
0
0
118-1
118-4
118-5
118-6
Binder
T 0 Celsius Strain Rate 30 mm/min
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Conclusions

• Physical Hardening Effects Are Large
• AASHTO M320 is Inaccurate
• AASHTO MP1-a is More Inaccurate
• Fracture Energy Appears to be Most Critical and
  Thus Desirable for Performance Grading
• Fracture Energies in Ductile State, we and wp,
  Vary Widely and Should Therefore Be Included in
  Future Specification

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New Hwy 655 Trial Sections

• Sections Are 500 m Long, Both Lanes, 50 and
• 40 mm Thick Lifts on 20-50 cm of New Subgrade
• Seven PG xx-34 Grades
• Elvaloy RET
• SBS
• SBS
• SBS
• Oxidized/SBS
• Oxidized
• Unmodified Control

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New Hwy 655 Trial Sections
Asphalt plant used three separate storage tanks
to avoid contamination between products.
2 x 5 Thermocouples at 1 cm and 4 cm depth
measure each 30 min. 2 Thermocouples for air
temperature.
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Questions