Performance Issues of RAS Mixtures in Missouri
Steve Jackson, PETechnical ManagerNB West Contracting
As seen on shinglerecycling.org
6th Asphalt Shingle Recycling ForumDenver, CO
With Solutions
Missouri’s Use of Reclaimed Materials in Asphalt Pavements2012 - MO AGC/MoDOT Conference
Joe Schroer, PEField Materials EngineerMissouri Department of Transportation
Steve Jackson, PEExcellence EngineerNB West Contracting
Steve Jackson
B.S. of Civil Engineering B.S. of Economics
University of Missouri- Rolla Professional Engineer 23 years in construction 15 years in asphalt
History
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
MoDOT RAS Mix Designs
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)
Tonnage
2005 2006 2007 2008 2009 2010 2011 YTD 2012
0
10000
20000
30000
40000
50000
60000
70000
80000
90000
0%
5%
10%
15%
20%
25%
30%
20 610
8,400
24,000
53,000 54,800
80,700
58,800
RAS in Asphalt Mixtures in Missouri (MoDOT)
RAS Percent Recycle
Tons
Perc
ent R
ecyc
le
Industry Questions
Can we eliminate the fibers in SMA (Stone Matrix Asphalt) and replace them with shingles?
Can we use shingles and PG 64-22 asphalt cement in lieu of polymer modified asphalt?
Dynamic Modulus (E*)SMA
1E-06 1E-05 1E-04 1E-03 1E-02 1E-01 1E+00 1E+01 1E+02 1E+03 1E+04 1E+05 1E+0610
100
1000
10000
4
20
45
PG76-22
PG 64-22 RAS
Reduced Frequency, Hz
E*, k
si
SMA with RAS
PG 64-22
PG 76-22
RAS Pooled Fund Study Iowa State, Dr. Chris Williams, P.I. Missouri Lead State
FHWA, MN, IA, IN, CA, CO, IL, WI (IL Tollway)
Binder & Mixture Properties QC/QA Grind Size RAP & FRAP Preconsumer vs. Postconsumer
Demonstration Projects
Ground Shingles
COARSE FINE
Thank You
Ground Shingles - RoadwayCOARSE FINE
1E+02 1E+03 1E+04 1E+05 1E+06 1E+07300
0% RAS 15% RAPPower (0% RAS 15% RAP)5% Fine RAS 10% RAP
Cycles to Failure (Nf)
Stra
in (
10-6
in./i
n.)
1000
800
450525
600
375
Fatigue Life(139)
(145)
(159)
0% RAS 15% RAP
5% Fine RAS 10%
RAP
5% Coarse RAS
10% RAP
-2
4
10
16
22
28
0100200300400500600700800
Criti
cal L
ow T
empe
ratu
re
(C)
Frac
ture
Ene
rgy
(J/m
2)
_
_
_
_
_
Low Temperature Testing
0% RAS15% RAP
5% Fine RAS10% RAP
5% Course RAS10% RAP
0 5 10 15 20 25 30 35 40 45 50
Transverse Cracking, ft/500ft
Pavement Evaluation
Pavement Cracking
At the same time we introduced shingles we also made other changes: Warm Mix Asphalt to eliminate joint
bumps Added an elastic recovery specification
for asphalt binder AASHTO Mechanistic – Empirical Design
▪ AMPT/SPT – Mixture evaluation led to thinner pavements
9.5 mm Superpave mixture laid 1 ¼” thick
Lessons Learned 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*
SRI – Phase Two
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
Work Availability and Recycle Contractor Perspective
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
Longer Hauls – low volume roads
2011 MoDOT Specifications 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
MoDOT Bituminous Pavements
Sieve Percent Passing by Weight (Mass)
Base BP-1 BP-21 inch (25.0 mm)
100 100 100¾ inch (19.0 mm)
85-100 100 100½ inch (12.5 mm)
60-90 85-100 95-100No. 4 (4.75 mm)
35-65 50-70 60-90No.8 (2.36 mm)
25-50 30-55 40-70No. 30 (1.18 mm)
10-35 10-30 15-35No. 200 (75 µm)
6-12 5-12 5-12
MoDOT Bituminous Pavements
Sieve Percent Passing by Weight (Mass)
BP-1 BP-21 inch (25.0 mm) 100 100¾ inch (19.0 mm) 100 100½ inch (12.5 mm) 85-100 95-100No. 4 (4.75 mm) 50-70 60-90No.8 (2.36 mm) 30-55 40-70No. 30 (1.18 mm) 10-30 15-35No. 200 (75 µm) 5-12 5-12
MoDOT RAS Specification 2011 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.
Mix Designs and the Market 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 Not the mix Ron Sines spoke about yesterday
2012 MoDOT 401 Specifications 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
What happened?
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
Gse Calculation
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
Gse Calculation
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
Volumetric Properties of High RAP Mixtures Based on Calculated Bulk Specific Gravities of RAP and Constituent Aggregates
Nassim SabahferMustaque Hossain, Ph.D.,P.E.
Department of Civil EngineeringKansas State University
VMA Obtained Using Gsb from Different Methods (Shilling RAP)
20% RAP 30% RAP 40% RAP 30% FRAP 40% FRAP0
2
4
6
8
10
12
14
1614.1 14 14.2 14.1 14.3
12.611.8
11.311.9 11.412.5
11.511
11.711.112.4
11.4 10.811.5 10.9
GseGsb (Ignition)Gsb (Extract)RAP Gmm
VMA (%)
KDOT Require-ment
Effective Binder
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.
Gse Calculation
Lower RAS asphalt content the lower the effective binder replacement Allows more shingles to be used in the mix
Effective Binder calculation
Contribution of Binder from Recycled Materials
Effective Binder ComputationPb 5.70 Gmm 2.434 Gse 2.653Pbmv 4.50 Gb 1.030 Pba 1.52
Gsb 2.547 Pbe 4.18
Stockpile Type Ps Pbr Psr x Pbr Psmv Psmr Pbmr
1 virgin 80 76.412 RAS 2 25 0.50 1.43 0.473 RAP 18 4.3 0.77 16.45 0.7345678
100 94.29
Pbe 4.18
Pbev 2.98
Psmv 76.41
Psr x Pbr 1.27
Psmr 17.88
Pbmr 1.20R 71
71%
Effective Binder calculation
Contribution of Binder from Recycled Materials
Effective Binder ComputationPb 6.37 Gmm 2.434 Gse 2.683Pbmv 4.50 Gb 1.030 Pba 1.92
Gsb 2.547 Pbe 4.45
Stockpile Type Ps Pbr Psr x Pbr Psmv Psmr Pbmr
1 virgin 92 87.902 RAS 8 25 2.00 5.73 1.873 RAP 0 4.3 0.00 0.00 0.0045678
100 93.63
Pbe 4.45
Pbev 2.58
Psmv 87.9
Psr x Pbr 2.00
Psmr 5.73
Pbmr 1.87R 58
58%
Problems with RAS Mixtures 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
Not Acceptable
Not Acceptable
MoDOT Response
No shingles were permitted to be 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
Industry Action
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.
2013 Job Special Provision - SL 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%
Effective Binder 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.
How NB West is Successful
Coffee Grounds not Corn Flakes
Education
Warm Mix Asphalt
Compaction Aid
Surfactant
Anti-Strip
Metallica
56th ANNUAL ASPHALT CONFERENCE
December 3-4, 2013
Havener Center, Campus of Missouri S&TRolla, MO
asphalt.mst.edu
