Mihai Marasteanu & Adam Zofka Summary of Shingles Work at the University of Minnesota

Mihai Marasteanu & Adam Zofka

Summary of Shingles Work at Summary of Shingles Work at the University of Minnesota the University of Minnesota

IntroductionIntroduction

Two smaller projectsMissouri samples

–Mixture testingMinnesota samples

–Mixture and binder testing

Missouri Missouri SpecimenSpecimenss

Table 1. Test details

Mixture Temperature

Replicate

designation

Average Thickness

[mm]

Diameter [mm]

17 43 150 -10°C 18 42 150 11 43 150 12 44 150 -20°C 13 43 150 14 44 150 15 44 150

20% RAP PG 64-22

-30°C 16 42 150 27 44 150 -10°C 28 43 150 21 40 150 22 41 150 -20°C 23 44 150 24 41 150 25 42 150

20% RAP PG 58-28

-30°C 26 41 150 37 46 150 -10°C 38 42 150 31 41 150 32 41 150 -20°C 33 43 150 34 40 150 35 43 150

15% RAP + 5% shingles

PG 58-28

-30°C 36 42 150 47 46 150 -10°C 48 42 150 41 47 150 42 41 150 -20°C 43 43 150 44 45 150 45 46 150

15% RAP + 5% shingles

PG 64-22

-30°C 46 42 150

Creep Stiffness Results, PG 58-28Creep Stiffness Results, PG 58-28

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

4.0

7.8

15.3

5.7

12.9

15.9

0

10

20

30

-10C -20C -30C

Stif

fnes

s @

500

sec

20% RAPPG 58-28

15% RAP5% shing.PG 58-28

Creep Stiffness Results, PG 64-22Creep Stiffness Results, PG 64-22

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

7.48.9

16.4

5.9

27.530.3

0

10

20

30

40

-10C -20C -30C

Stif

fnes

s @

500

sec

20% RAPPG 64-22

15% RAP5% shing.PG 64-22

Strength Results, PG 58-28Strength Results, PG 58-28

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

Strength Results, PG 64-22Strength Results, PG 64-22

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

Conclusions Missouri SpecimensConclusions Missouri Specimens

For PG-22 mixture, at temperatures below -10°C, the addition of shingles increases the mixture stiffness considerablyMost likely results in increased thermal cracking and fatigue cracking occurrence

Also in PG-28 mixtures but to a much lesser extent

Strength properties were not significantly affected by the addition of shingles for both the PG-22 and PG-28 mixtures.

Conclusions Missouri SpecimensConclusions Missouri Specimens

Worth mentioning that during the cutting process, the saw shutoff automatically due to the intense heat generated when cutting the specimens prepared with shingles. This did not occur for the specimens prepared only with RAP.

Minnesota SpecimensMinnesota Specimens

Three types of materials20% reclaimed asphalt pavement (RAP),15% RAP + 5% Tear-off recycled asphalt shingles (RAS),

15% RAP + 5% Manufactured RAS. All three mixtures contain the same virgin

asphalt binder PG 58-28

Binders were chemically extracted (MnDOT) and tested (MnDOT + UMN)

Asphalt Mixture Creep StiffnessAsphalt Mixture Creep Stiffness

0.2

2.7

10.0

0.5

5.0

13.5

0.2

5.5

8.2

0

4

8

12

16

0 -10 -20

Temperature [oC]

Stif

fnes

s [G

Pa]

20% RAP

15% RAP + 5% Tear-off

15% RAP + 5% Manufactured

0.1

1.1

5.6

0.2

2.3

8.7

0.1

2.7

5.3

0

4

8

12

16

0 -10 -20

Temperature [oC]

Stif

fnes

s [G

Pa]

20% RAP

15% RAP + 5% Tear-off

15% RAP + 5% Manufactured

Asphalt Mixture StrengthAsphalt Mixture Strength

3.2

4.64.8

3.2

4.5

5.1

2.9

4.5

5.3

0.0

2.0

4.0

6.0

0 -10 -20

Temperature [oC]

Ten

sile

Str

engt

h [M

Pa]

20% RAP

15% RAP + 5% Tear-off

15% RAP + 5% Manufactured

Missouri vs. MinnesotaMissouri vs. Minnesota

6.1

11.5

10.0

8.1

16.6

5.0

13.5

2.7

0

4

8

12

16

20

-10C -20C

Temperature [oC]

Sti

ffn

ess

[GP

a]

20% RAP - MO

20% RAP - MN

15% RAP + 5% Tear-off - MO

15% RAP + 5% Tear-off - MN

4.0

7.8

5.65.7

12.9

2.3

8.7

1.1

0

4

8

12

16

20

-10C -20C

Temperature [oC]

Sti

ffn

ess

[GP

a]

20% RAP - MO

20% RAP - MN

15% RAP + 5% Tear-off - MO

15% RAP + 5% Tear-off - MN

Conclusions Minnesota Mix Conclusions Minnesota Mix SpecimensSpecimensAddition of tear-off RAS material increases

significantly the stiffness of the mixtures at all test temperaturesLargest increase at -20°C

Addition of manufactured RAS material increased stiffness only at 0°C and -10°CStiffness at -20°C reached the lowest observed value from all tested materials

Strength properties were not significantly affected by the addition of shingles

Conclusions Minnesota Mix Conclusions Minnesota Mix SpecimensSpecimensResults indicate lower stiffness values for the

Minnesota RAP mixtures compared to Missouri mixtures

Similar observation for the combinations of RAP + RASSuggests differences in the tear-off RAS materials used in the two studies

Minnesota Specimens – Extracted Minnesota Specimens – Extracted BindersBinders

Bending Beam Rheometer (BBR) tests were performed on the binders extracted

Direct Tension Tests (DTT) were performed at temperatures around the temperature at which S(60s) = 300MPa

Minnesota Specimens – Extracted Minnesota Specimens – Extracted BindersBinders

File name Temp Binder S @60 sec Average m-value @60sec AverageBC061CP.csv 107 0.303BC061CPB.csv 123 0.311BC061CPC.csv 206 0.264BC061CPD.csv 206 0.264BC062CPAA.csv 99 0.329BC062CPBB.csv 106 0.322BC062CPC.csv -18 182 182 0.289 0.289BC063APA.csv 173 0.325BC063APB.csv 166 0.322BC063APC.csv 313 0.237BC063APCC.csv 384 0.236BC063APD.csv 331 0.263BC063APDD.csv 288 0.264

0.250

0.307

0.264

0.326

0.324170

329

206

115

103

5% Tearoff 15%RAP

15% RAP 5% Manuf.

20% RAP

-12

-18

-12

-18

-24

0

50

100

150

200

250

300

350

5% Tearoff 15%RAP 15% RAP 5% Manuf. 20% RAP

S @

60se

c [M

Pa]

Higher temp.

Lower temp.

BBR ResultsBBR Results

Addition of shingles changes the propertiesLowers the stiffness!!!Lowers the m-values

–Changes the relaxation propertiesNeed to look at master curveNeed to look at thermal stresses

BBR Master CurvesBBR Master Curves

1

10

100

1,000

0 0 1 10 100 1,000 10,000

Time [sec]

Cre

ep S

tiffn

ess

[MP

a]

5% Tearoff 15%RAP

15% RAP 5% Manuf.

20% RAP Tref=-18C

BBR Master Curves – All MaterialsBBR Master Curves – All Materials

1

10

100

1,000

10,000

1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07

Time [sec]

Cre

ep S

tiffn

ess

[MP

a]

5% Tearoff 15%RAP15% RAP 5% Manuf.20% RAPShingles (287)Shingles (292)Demcon tearoff (301)Demcon tearoff (303)PG58-28 PAV

Tref = -18C

Thermal StressesThermal Stresses

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

-50 -40 -30 -20 -10 0 10 20 30

Temp [C]

Str

ess

[MP

a]

5% Tearoff 15%RAP

15% RAP 5% Manuf.

20% RAP

PG58-28 PAV

Direct Direct Tension Tension ResultsResults 0

1

2

3

4

0 1 2 3 4 5Strain, %

Str

ess

, MP

a

Rep 1, -24°CRep 2, -24°CRep 3, -24°CRep 1, -18°CRep 2, -18°CRep 3, -18°CRep 1, -12°CRep 2, -12°CRep 3, -12°C

20% RAP

0

1

2

3

4

0 1 2 3 4 5Strain, %

Str

ess

, MP

a

Rep 1, -24°CRep 2, -24°CRep 3, -24°CRep 1, -18°CRep 2, -18°CRep 3, -18°CRep 1, -12°CRep 2, -12°CRep 3, -12°C

15% RAP + 5% Manufactured

0

1

2

3

4

0 1 2 3 4 5Strain, %

Str

ess

, MP

a

Rep 1, -24°C

Rep 2, -24°C

Rep 3, -24°C

Rep 1, -18°C

Rep 2, -18°C

Rep 3, -18°C

Rep 1, -12°C

Rep 2, -12°C

15% RAP + 5% Tearoff

Critical TemperatureCritical Temperature

y = -0.0817x + 1.6667

R2 = 0.9142

0

2

4

6

8

10

12

14

-50 -40 -30 -20 -10 0 10 20 30

Temp [C]

Str

ess

[MP

a]

20% RAP

Strength

Linear (Strength)

Critical TemperatureCritical Temperature

y = -0.065x + 1.73

R2 = 0.998

0

2

4

6

8

10

12

-50 -40 -30 -20 -10 0 10 20 30

Temp [C]

Str

ess

[MP

a]

15% RAP 5% Manuf.

Strength

Linear (Strength)

Critical TemperatureCritical Temperature

y = -0.1167x + 0.1333

R2 = 0.9735

0

2

4

6

8

10

12

14

-50 -40 -30 -20 -10 0 10 20 30

Temp [C]

Str

ess

[MP

a]

5% Tearoff 15%RAP

Strength

Linear (Strength)

Conclusions - Binder ResultsConclusions - Binder Results

The two types of shingles perform differentlyThe manufactured material seems to be beneficial

–Decreases stiffness–Does not affect strength–Reduces critical temperature very little

The tear off affects properties in a negative way (although it also decreases stiffness)

–Lowers strength significantly–Increases critical temperature

Conclusions - Binder ResultsConclusions - Binder Results

The role of m-value not fully understoodSpec requires higher m-values (> 0.300)However, authors showed that lower m-values result in less thermal stress accumulation

Needs to be further investigated

The limited data also shows that binder and mixture results do not always agreeMost likely due to other parameters from mixture preparation (gradation, air voids, etc)

Thank you!Thank you!