Post on 29-Dec-2015
transcript
Asphalt Shingles in HMAMissouri DOT Experience
North Central HMA Conference
Joe Schroer, PE
January 10, 2007
In The Beginning
• Approached by Pace Construction and Peerless Landfill
–MoDOT Not Using RAP in Mixtures
–Deleterious Material
–Stiffness of Asphalt in Shingles
First LookThe “Ex” Factor
• Exhaustive Literature Search
• Exclusion of Tear Offs in States Allowing Manufacturing Waste
• Extra Clean Material – Contained Little Deleterious Matter
• Exceptionally Stiff Asphalt Extracted from Shingles
Shingle Components
• Asphalt 20%-40%
–Stiffen Roadway Asphalt
• Aggregate 30%
–Good Stuff
• Fiberglass or Paper Mat 30%
–No Harm if Well Dispersed
MoDOT Goals
• Engineering Properties First–Harmful Effects of Deleterious
Material–Asphalt Binder Properties
• Traffic Safety – Nails, etc.• If Everything Else Works Out,
Landfilling is Reduced
Why Should We Pursue Shingles?
• High Asphalt Content
• Granules Are Hard and Durable
• Recycling CO$T
Concerns
• How Will Deleterious Material Affect the Mixture
• Can the Low Temperature Grading be Maintained at Various Blending Ratios
Asphalt After Blending with Shingle Asphalt
• Resist Rutting
• Resist Fatigue Cracking
• Resist Cold-Weather Cracking
Asphalt Grades
• High Temperature for Rut Resistance
• Low Temperature for Fatigue and Cold Weather Performance
Performance Graded = PG
PG 64-22 (PG Sixty-four Minus Twenty-two)
High Temp 64°C (147°F)
Low Temp –22°C (-8°F)
High TemperatureCritical High Temp.
50
60
70
80
90
100
110
120
130
140
150
100 80 60 40 20 0
Percent Virgin Binder
° C
0 4 8 12 16 20
Percent Shingles @ 5% Total Binder in Mix
58-22
52-28
58-28
58-28 Flux
64
70
76
Low TemperatureCritical Low Temp.
-40
-30
-20
-10
0
10
20
30
40
50
100 80 60 40 20 0
Percent Virgin Binder
° C
0 4 8 12 16 20
Percent Shingles @ 5% Total Binder in Mix
58-22
52-28
58-28
58-28 Flux
-16
-22
-28
Assume Incomplete BlendingCritical Low Temp.
-40
-30
-20
-10
0
10
20
30
40
50
100 80 60 40 20 0
Percent Virgin Binder
° C
0 4 8 12 16 20
Percent Shingles @ 5% Total Binder in Mix
58-22
52-28
58-28
58-28 Flux
-16
-22
-28
50%
75%
100%
Asphalt Modifications Require PG 64-22
• Stiffer at High Temperature – OK
• Stiffer at Low Temperature
–Use Lower Percentage of Shingles
–Use Softer Roadway Asphalt
Deleterious Evaluation
• Specification for Aggregate
–0.5% “Other Foreign Material”
• Sticks, mud balls, deer fur, etc.
• Shingle “OFM”
–Approximately 3% Total
Deleterious Material
• Nails
• Wood
• Plastic
• Cellophane
• Paper
• Fiber Board
Trial by Fire
No Difference
• Visually
• Standard Mixture Tests
• Placement
Big Difference
• Rut Resistance
• Cold Temperature Tests
• OFM in Mixture
Trial ProjectUS 61/67, St. Louis Co.
• Part of Study with Minnesota
• 4 Mixtures 19.0 mm Superpave– PG 58-28
• 20% RAP• 15% RAP, 5% Shingles
– PG 64-22• 20% RAP• 15% RAP, 5% Shingles
Study Results
• IDT Testing by U of Mn
–Tensile Strength Little Difference
–Creep Stiffness Greatly Affected at Lower Temperatures
• Evaluation of Reflective Cracking in Sections to Be Made
10.8 12.0
19.5
9.5
34.4 34.7
0
10
20
30
40
-10C -20C -30C
Stif
fnes
s @
100
sec
20% RAPPG 64-22
15% RAP5% shing.PG 64-22
6.1
11.5
17.3
8.1
16.6
21.4
0
10
20
30
-10C -20C -30C
Stif
fnes
s @
100
sec
20% RAPPG 58-28
15% RAP5% shing.PG 58-28
4.54.9
3.94.3 4.2
4.7
0
3
6
-10C -20C -30C
Ten
sile
Str
engt
h [M
Pa]
20% RAPPG 64-22
15% RAP5% shing.PG 64-22
4.1
4.5 4.44.4 4.54.5
0
3
6
-10C -20C -30C
Ten
sile
Str
engt
h [M
Pa]
20% RAPPG 58-28
15% RAP5% shing.PG 58-28
PG 64-22 PG 58-28
Can Tear-Off Shingles be Used?
• Allowance in OFM Due to Small Percentage of Shingles and Trial Mixture
• Start with Softer Roadway Asphalt
Where Are We?The “Ex” Factor 2
• Extrinsic Material Allowance Raised–3.0% Total–1.5% Wood
• Expect PG 64-22 met w/ PG 58-28–Extra grades optional w/ testing–Examining various proportions and
asphalts• Exuberant Contractors
Newspaper
Plastic Bottles
Milk Jugs, Aluminum
Cardboard
Cans
Newspaper