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Susan Tighe, Xiomara Sanchez & Doubra Ambaiowei – Centre for Pavement and Transportation Technology University of Waterloo (CPATT).
Vince Aurilio - DBA Engineering Ltd. Sandy Brown – Ontario Hot Mix Asphalt Producers
(OHMPA). Fernando Magisano – KJ Beamish Construction Co. Seyed Tabib & Pamela Marks - Ministry of
Transportation Ontario (MTO).
Introduction Project Objectives Methodology Tests Description Preliminary Results Conclusions to Date Next Steps
Asphalt is North America’s most recycled material.
There is an increasing interest throughout industry to recycle RAP into pavements.
The use of Reclaimed Asphalt Pavement (RAP) in Hot Mix Asphalt (HMA) is a common practice in Ontario.
There is always the question how much of the AC from the RAP blends with the new AC
Some municipalities still do not accept RAP in their pavements
This study was intended to reassure municipalities
http://www.moasphalt.org/facts/environmental/facts.htm
RAP usage is encouraged because of its environmental and economic advantages: Save on dwindling aggregate
resources. Recovers non-renewable
petrochemical resources. Diverts large volumes of materials
from overloaded landfills. Contributes significantly to
provincial and municipal recycling obligations.
Reduces road building cost.
Use of RAP in HMA is a common practice in Ontario MTO began their recycling program in 1978. Early projects had RAP contents that were as high
as 70 percent. In the early days, performance of HMA containing
RAP was found to be directly related to the penetration of the recovered binder.
Higher RAP contents, lower virgin asphalt content of the mix was a problem.
Consider sustainability in pavement design and management.
15% RAP max in surface course and 30% in binder course permitted (2005).
Today MTO allows 20% in surface mixes and 40% in binder mixes.
Average contractor RAP usage 20% approx.
0
5
10
15
20
25
30
35
40
45
50
Pe
rce
nt
RA
P R
ep
lace
me
nt
(%)
State Code
Maximum Allowable Contractor Average Usage
American Association of Strategic Highway and Transportation Officials
(AASHTO) Subcommittee on Materials, Recycling Materials Survey,
Washington, D.C., 2010.
Evaluate impact of RAP on Ontario SuperPave SP12.5 mix.
Understand how the addition of RAP to HMA alters the performance and if it is possible to test the mix for RAP content.
Determine if performance tests can be used to back-calculate Performance Grade (PG) for RHM.
Analyze the differences of recycled hot mix for both Southern and Northern Ontario roads.
Study relationship between basic properties of the mix and performance.
Carry out comprehensive literature review on the state-of-the-art of RAP usage.
Evaluate consensus properties of aggregates. Recover and characterize asphalt cement in RAP. Extensive laboratory-based study designed to
evaluate performance:
o Thermal Stress Restrained Specimen Test (TSRST).
o Dynamic modulus testing.
o Fatigue beam.
o Disk-shaped Compact Tension Specimen.
RAP Content
SP12.5 (Surface Course)
Southern Northern
PG 58 -28 PG 58-34 PG 52-34 PG 52-40
0% X X
15% X X
20% X X
30% X X
40% X X
0
10
20
30
40
50
60
70
80
90
100
16 12.5 9.5 4.75 2.36 1.18 0.6 0.3 0.15 0.08
%P
ass
ing
Sieve opening (mm)
0%RAP
20%RAP
40%RAP
Minimum
Maximum
Mix Type
SP12.5mm %Crushed 1
face %Crushed 2
face Flat and
Elongated Uncompated
void Sand
Equivalent
0-52-34 98.9 98.5 0.4 44.4 77
No
rth
ern
20-52-40 99.1 98.8 0.1 45.7 74
40-52-40 99.8 98.6 0 44.9 93
0-58-28 99.8 99.7 0 44.6 57
So
uth
ern
20-58-34 98.4 98.2 0.1 45.9 73
40-58-28 97.2 96.9 0.7 44.5 88
Minimum 85 80 43 45
Maximum 10
Mix Type
SP12.5mm % Air Voids
%VMA %VFA DP %Gmm
@ ini %Gmm @ des
%Gmm @ max
TSR
0-52-34 4 15 73.4 0.7 88.5 96 96.8 96
No
rth
ern
20-52-40 4 14.3 72.1 1.2 88.2 96 97 96.2
40-52-40 4 14.2 71.5 1.1 88 96 96.7 91.5
0-58-28 4 14.8 73.1 0.7 88.7 96 96.7 96.2
So
uth
ern
20-58-34 4 14.7 73.1 1.2 87.6 96 97.3 98.7
40-58-28 4 14.3 72.1 1.1 88.1 96 97.1 92.1
Minimum 4 14 65 0.6 80
Maximum 75 1.2 89 96 98
Thermal Stress Restrained Specimen Test.
Resistance to thermal cracking. Beam 250 x 50 x 50 mm. Cools specimen at -10ºC/hour. Restrain from contraction. Fractures as internally
generated stress exceeds tensile strength.
Measure fracture stress at the fracture temperature .
Mix Type SP12.5mm
Mean Fracture
Stress (MPa)
Mean Failure Temp (°C)
Mean Max. Load (KN)
0-58-28 2.0 -30 5.1
0-52-34 1.7 -34 4.3
20-58-34 2.6 -34 6.4
40-58-28 2.2 -29 5.5
0.0
0.5
1.0
1.5
2.0
2.5
3.0
0-52-34 0-58-28 20-58-34 40-58-28
Fra
ctu
re s
tre
ss (
MP
a)
Mix type
ANOVA and t-test did not show significant difference.
Three replicates per mix type.
Vary temperature and loading frequency.
Sinusoidal axial compressive stress applied to a specimen.
Measure recoverable axial strain response.
Calculate modulus and phase angle.
Temperature 20.0 +/- 0.5ºC.
Lab compacted beam 380 x 50 x 63 mm.
Fatigue resistance / Flexural bending.
Graph number of cycles vs. strain.
Determine fatigue life.
Measure fracture resistance. Disk 150 x 50mm. Testing temperature
PG Low Temp + 10ºC. Fracture energy: area under
the curve Load (kN) vs Crack Mouth Opening
Displacement CMOD (mm), normalized by the area of the fractured surface.
It is possible to design efficient mixes containing RAP.
All the specified properties for the Superpave design are met, as well as the consensus properties.
Dust proportion is affected with the addition of RAP and the increase may reduce the effective asphalt.
RAP content does not affect the cold temperature fracture resistance.
Up to 40% RAP can be added without affecting the low temperature PG of the mix.
Finish performance testing and analysis first six cell. Evaluate methodology for RAP content and blended
binder PG determination. Design and evaluation on consensus properties and
PG recovery last 4 cells. Sample preparation, testing and analysis remaining
mixtures. Analysis and guidelines for the usage of RAP in
HMA.
Centre for Pavement and Transportation Technology University of Waterloo (CPATT).
DBA Engineering Ltd. Ministry of Transportation Ontario (MTO). Ontario Hot Mix Producers Association Natural Sciences and Engineering Research Council of
Canada (NSERC). Capital Paving Inc. McAsphalt Industries Ltd. Canadian Asphalt Industries Inc. Bitumar Inc. Coco Paving Inc.