Missouri's Experience w-RAS in HMA - Purdue Engineeringncaupg/Activities/2014... · accordance with...

Steve Jackson, PE Technical Manager NB West Contracting

As seen on shinglerecycling.org

NCAUPG Kansas City, MO

With Solutions

B.S. of Civil Engineering B.S. of Economics

University of Missouri- Rolla

Professional Engineer 23 years in construction 15 years in asphalt

First shingle research in 2003 2.5%, 5%, 7.5%, 10%, 15%

First shingle project 2004

First MoDOT shingle project 2005

First MoDOT shingle – WMA project 2009

Most contractors were using RAP & RAS concurrently (2006-2010) 18% RAP and 2% RAS 17% RAP and 3% RAS

Due to the Smooth Road Initiative most work was being done on interstates Superpave mixes Percent Within Limits (Pay Factors)

20 610

8,400

24,000

53,000 54,800

80,700

58,800

0%

5%

10%

15%

20%

25%

30%

0

10000

20000

30000

40000

50000

60000

70000

80000

90000

2005 2006 2007 2008 2009 2010 2011 YTD 2012

Perc

ent R

ecyc

le

Tons

RAS in Asphalt Mixtures in Missouri (MoDOT)

RAS Percent Recycle

COARSE

FINE

Shingle size is key to success

Overheating shingle mixes to “melt” the shingles (370° - 390° F)

Variability in RAS asphalt content Real and perceived

Inflated specific gravities impact mixes*

Sporadic Mixing Problems Confined to Plants not Mixture

Harder to Place in Cool Weather Low Voids on Long Haul Tenderness Asphalt Foamers Run at HMA Temps. Shingle Pancakes – Clumps, Wads, Clinkers

Emphasis shifted from Primary Routes to Secondary Routes Bituminous Pavements (MoDOT Section 401) in

lieu of Superpave (MoDOT Section 403) Less advanced quality control testing ▪ Gradation, deleterious, asphalt content and density ▪ No Percent Within Limits

Contractor Perspective - 2008 Asphalt Cement prices are high Supply of shingles is high Less “Mill & Fill” projects ▪ Less RAP from projects ▪ Large amounts of RAP stockpiled

Fiercely competitive market Longer haul distances

401.4.4.1 Base, BP-1 and BP-2 mixtures shall have the following properties, when tested in accordance with AASHTO T 245. The number of blows with the compaction hammer shall be 35 or the number of gyrations shall be 50 with the gyratory compactor.

Air Voids Stability lb (N) VMA 3.5-4.5 750 (3350) 13.0

Sieve Percent Passing by Weight (Mass)

Base BP-1 BP-2

1 inch (25.0 mm) 100 100 100 ¾ inch (19.0 mm) 85-100 100 100 ½ inch (12.5 mm) 60-90 85-100 95-100 No. 4 (4.75 mm) 35-65 50-70 60-90 No.8 (2.36 mm) 25-50 30-55 40-70 No. 30 (1.18 mm) 10-35 10-30 15-35 No. 200 (75 µm) 6-12 5-12 5-12

Sieve Percent Passing by Weight (Mass)

BP-1 BP-2

1 inch (25.0 mm) 100 100 ¾ inch (19.0 mm) 100 100 ½ inch (12.5 mm) 85-100 95-100 No. 4 (4.75 mm) 50-70 60-90 No.8 (2.36 mm) 30-55 40-70 No. 30 (1.18 mm) 10-30 15-35 No. 200 (75 µm) 5-12 5-12

403.2.6.2 Reclaimed Asphalt Shingles. Reclaimed Asphalt Shingles (RAS) may be used in any mixture specified to use PG 64-22 in accordance with AASHTO PP 53 except as follows: When the ratio of virgin effective binder to total binder in the mixture is between 60 and 70 percent, the grade of the virgin binder shall be PG 52-28 or PG 58-28.

Shingles shall be ground to 3/8-inch minus.

Higher percentages of recycled materials Less virgin binder in the mixes Dryer looking mixes Rut resistant roadways Fatigue cracks earlier?

Is there a limit on recycled materials? Contractors attempted to run up to 12% RAS

Changed design air voids to 3.5% Increased VMA requirements: Bit Base 13.0% BP-1 13.5% BP-2 14.0% (Surface Leveling)

50 gyration mix design was eliminated and

replaced with a 35 gyration mix design Requires a higher asphalt content

Corelok specific gravities were used in lieu of traditional AASHTO T 84/T 85

Gse values were variable 2.450 to 2.800 Could be impacted by reported asphalt content

No significant change in virgin binder content

in some areas, but some higher quality aggregates were used

𝐺𝐺𝐺𝐺𝐺𝐺 = 100−𝑃𝑃𝑃𝑃100𝐺𝐺𝐺𝐺𝐺𝐺−

𝑃𝑃𝑏𝑏𝐺𝐺𝑏𝑏

Pb = Percent binder in the shingles Gmm = Rice value of the shingles Gb = Specific gravity of the shingle binder

Gse is used as the Gsb during mix design



Higher RAS asphalt content the higher the specific gravity

Higher specific gravity makes it easier to meet the VMA requirements however it allows for lower asphalt content

14.1 14 14.2 14.1 14.3 12.6

11.8 11.3 11.9 11.4 12.5 11.5

11 11.7 11.1 12.4

11.4 10.8 11.5 10.9

0

2

4

6

8

10

12

14

16

20% RAP 30% RAP 40% RAP 30%FRAP

40%FRAP

VMA (%) Gse

Gsb (Ignition)

Gsb (Extract)

RAP Gmm

KDOT Requirement

Research on RAS and VMA increase High quality aggregates Fibers

Contractors were meeting the VMA requirements.

Virgin asphalt cement was decreased

Total asphalt contents was also decreased

20% effective binder replacement from RAS used in the surface leveling mixtures for the May and June contracts.

Not very many contracts - 2

Did not impact Superpave or other low volume route mix designs

Contractors got together in a morning session, worked together to provide recommended specification changes.

Met with MoDOT representatives after lunch and discussed the recommendations.

Adopted as a job special provision for the next bid letting.

Set Gsb of RAS at 2.600

Changed the gradation of the Surface Leveling mix design: 90-100% passing the 3/8” sieve.

Set Gsb of RAP at the Gsb of the virgin aggregates*

VMA minimum: 14.5%

MoDOT EPG 403.1.11

“The RAS fraction may be adjusted by a maximum of 3% from the original JMF.”

“The RAP fraction may be adjusted by a maximum of 15% from the original JMF.”

Variations in materials Mix design was based on materials sampled many

months in advance Asphalt content of reclaimed materials is different

than what was used during mix design

Mix was not performing as expected Allow for the removal of RAS in Fall

* Any time that adjustments are made to the plant percentages, including the hot bin percentages, the inspector and RE must be notified immediately. The resulting combined aggregate gradation of the adjusted mix must be within the master range for that particular type of mix (see Standard Specification Section 403.3.1). During production of the adjusted mix, the combined aggregate gradation must be within the limits of Standard Specification Section 403.5.1.1 or 403.5.1.2, whichever is applicable. If the cold feed settings have been adjusted, the composition of the mix has been changed. Therefore, the new bulk specific gravity of the combined aggregate (Gsb) must be calculated using the adjusted cold feed percentages so that the VMA can be accurately calculated during production. If an adjustment from the job mix is made, the contractor should be required to recalculate the porphyry/Non-carbonate percentage to assure that is still meets the contract requirements. A spreadsheet has been developed to assist in checking the contractor’s calculation. The spreadsheet can be found in the same folder on the V drive as the SuperPave spreadsheet. If the percentage of RAS or RAP is increased from the original JMF the percent virgin effective binder replacement (Pbv) should be recalculated to assure compliance with section 403.2.5 of the Standard Specifications. The Pbv should also be recalculated when the percent of binder in the RAP changes as determined by Section 403.19.3.

Must meet the master range gradation

Bulk Specific Gravity (Gsb) must be re-calculated

VMA will be impacted by Gsb change

Porphyry requirements must be maintained

The virgin effective binder replacement must be re-calculated when the RAP or RAS percentage changes

or when the percent of binder in the RAP changes

403.2.6.2 Reclaimed Asphalt Shingles. Reclaimed Asphalt Shingles (RAS) may be used in any mixture specified to use PG 64-22 in accordance with AASHTO PP 53 except as follows: When the ratio of virgin effective binder to total binder in the mixture is between 60 and 70 percent, the grade of the virgin binder shall be PG 52-28 or PG 58-28.



Lower RAS asphalt content the lower the effective binder replacement

Allows more shingles to be used in the mix

www.modot.org/business/contractor_resources/forms.htm

http://www.modot.org/business/contractor_resources/forms.htm

http://www.modot.org/business/contractor_resources/forms.htm

Contribution of Binder from Recycled Materials

Effective Binder ComputationPb 5.70 Gmm 2.434 Gse 2.653 Type of StockpilePbmv 4.50 Gb 1.030 Pba 1.52 virgin - Quarried aggregate

Gsb 2.547 Pbe 4.18 reclaim - Reclaimed aggregate such as concrete, steel slag, wet bottom slag, chatRAP - Reclaimed asphalt pavement

Stockpile Type Ps Pbr Psr x Pbr Psmv Psmr Pbmr RAS - Reclaimed asphalt shingles1 virgin 80 76.412 RAS 2 25 0.50 1.43 0.473 RAP 18 4.3 0.77 16.45 0.7345678

100 94.29Pbe 4.18Pbev 2.98Psmv 76.41Psr x Pbr 1.27Psmr 17.88Pbmr 1.20R 71

Pb - Percent total binder in mixturePsv(1,2,..) - Pecent stone by fraction for virgin or reclaimed aggregatePsr(1,2,..) - Pecent stone by fraction for RAP or RAS aggregatePbr(1,2,..) - Percent binder by fraction in RAP or RASPsmv(1,2,..) - Pecent stone by fraction for virgin or reclaimed aggregate by weight of total mixturePsmr(1,2,..) - Pecent stone by fraction for RAP or RAS aggregate by weight of total mixturePsmr - Pecent stone of RAP or RAS aggregate by weight of total mixturePbmr(1,2,..) - Percent binder by fraction in RAP or RAS by weight of total mixturePbmr - Percent binder of RAP or RAS by weight of total mixturePbmv - Pecent new binder by weight of total mixtureR - Percentage of new binder (Pbev) to total binder (Pbe)

Pbr1

Pbr2

RAS

RAP

Steel Slag

Limestone

Pbmv

Pbmr2

Pbmr1

Psmr1

Psmr2

Psr1

Psr2

Psv1

Psv2

Psmv1

Psmv2

Pb Pbr2

Pbr1

Psm

( )( )( )100/...100

100

332211

11 +×+×+×−

−×=

brsrbrsrbrsr

bsvsm v PPPPPP

PPP

( ))100/...)((100

100)100/(

332211

1111 +×+×+×−

−××−=

brsrbrsrbrsr

bbrsrsrsmr PPPPPP

PPPPP

...321 +++= smrsmrsmrsmr PPPP( )2

111 100

100 bbrsrbmr

PPPP −××=

...321 +++= bmrbmrbmrbmr PPPP

be

bev

PPR 100×

=

...321 +++= smvsmvsmvsmv PPPP

bmrbbmv PPP −=

17% RAP at 5% asphalt content

2% RAS at 25% asphalt content

Gmm = 2.434 Gsb = 2.547 Total Binder 5.77% Virgin Binder 4.5%


Effective Binder Computation

Pb 5.77 Gmm 2.434 Gse 2.656 Pbmv 4.50 Gb 1.030 Pba 1.56

Gsb 2.547 Pbe 4.21

Stockpile Type Ps Pbr Psr x Pbr Psmv Psmr Pbmr 1 virgin 81 77.37 2 RAS 2 25 0.50 1.43 0.47 3 RAP 17 5 0.85 15.43 0.80 4 5 6 7 8

100 94.2

Pbe 4.21

Pbev 2.94

Psmv 77.4

Psr x Pbr 1.35

Psmr 16.9

Pbmr 1.27 R 70

27% RAP at 5% asphalt content

0% RAS

Gmm = 2.434 Gsb = 2.547




Gsb 2.547 Pbe 4.21

Stockpile Type Ps Pbr Psr x Pbr Psmv Psmr Pbmr 1 virgin 73 69.73 2 RAS 0 25 0.00 0.00 0.00 3 RAP 27 5 1.35 24.50 1.27 4 5 6 7 8

100 94.2 Pbe 4.21 Pbev 2.94 Psmv 69.7 Psr x Pbr 1.35 Psmr 24.5 Pbmr 1.27 R 70

We would still need to re-calculate Gsb We did remove virgin aggregate

Porphyry requirements would have to be checked if applicable

Gmm may change

27% RAP Mix Designed at 5% RAP asphalt content

Mix total asphalt content is 0.4% high Gmm dropped Low air voids




Gsb 2.547 Pbe 4.53

Stockpile Type Ps Pbr Psr x Pbr Psmv Psmr Pbmr

1 virgin 73 69.74 2 RAS 0 25 0.00 0.00 0.00 3 RAP 27 6.6 1.78 24.09 1.67 4 5 6 7

8

100 93.8

Pbe 4.53

Pbev 2.86

Psmv 69.7

Psr x Pbr 1.78

Psmr 24.1

Pbmr 1.67

R 63

Reduce virgin asphalt content by 0.4%

This is not a change to the mix design because you have not changed the total asphalt content




Gsb 2.547 Pbe 4.21

Stockpile Type Ps Pbr Psr x Pbr Psmv Psmr Pbmr

1 virgin 73 70.03 2 RAS 0 25 0.00 0.00 0.00 3 RAP 27 6.6 1.78 24.19 1.68 4 5 6 7

8

100 94.2

Pbe 4.21

Pbev 2.53

Psmv 70

Psr x Pbr 1.78

Psmr 24.2

Pbmr 1.68

R 60

Could have a dry looking mix

Could have a dry performing mix

By specification this mix would require an AASHTO M323 blending chart analysis

Mixtures containing a combination of RAS and RAP may have a 30 to 40 percent effective virgin replacement under the following conditions: (1) with a virgin binder grade change from a PG64-22 to a PG 58-28 or (2) with a combination of a PG64-22 binder and a rejuvenator provided testing demonstrates that a PG58-28 , meeting the requirements of AASHTO M320, is achieved.

Compaction Aid

Surfactant

Anti-Strip

Shingles are only part of the problem Grind size Meet current specification

Late season paving Moisture Temperatures WMA chemical admixtures can help

VMA requirements were a big part of the problems Increase VMA for low volume routes Gse calculations can inflate VMA RAS increases VMA

Watch your requirements when making field

adjustments

The asphalt cement that we are using today is not the same asphalt we were using 10 years ago MSCR Shale oil versus oil from Venezuelan coast Crude slates are changing rapidly

MoDOT and MAPA have a GREAT working relationship MoDOT and MAPA have a small Technical

Working Group that meets to “Talk Geek” Afternoon session has MoDOT and MAPA

contractors

[email protected]

www.nbwest.com

@sjackson_nbwest

Steve Jackson

Missouri's Experience w-RAS in HMA - Purdue Engineeringncaupg/Activities/2014... · accordance with...

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