Prepared by Xiomara Sanchez, Doubra Ambaiowei, Susan Tighe (CPATT) & Vince Aurilio (DBA)

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.