Presentation on theme: "Steve Jackson, PE Technical Manager NB West Contracting As seen on shinglerecycling.org 6 th Asphalt Shingle Recycling Forum Denver, CO With Solutions."— Presentation transcript:
Steve Jackson, PE Technical Manager NB West Contracting As seen on shinglerecycling.org 6 th Asphalt Shingle Recycling Forum Denver, CO With Solutions
Joe Schroer, PE Field Materials Engineer Missouri Department of Transportation Steve Jackson, PE Excellence Engineer NB West Contracting
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)
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
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
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*
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 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
SievePercent Passing by Weight (Mass) BaseBP-1BP-2 1 inch (25.0 mm) 100 ¾ inch (19.0 mm) 85-100100 ½ inch (12.5 mm) 60-9085-10095-100 No. 4 (4.75 mm) 35-6550-7060-90 No.8 (2.36 mm) 25-5030-5540-70 No. 30 (1.18 mm) 10-3510-3015-35 No. 200 (75 µm) 6-125-12
SievePercent Passing by Weight (Mass) BP-1BP-2 1 inch (25.0 mm) 100 ¾ inch (19.0 mm) 100 ½ inch (12.5 mm) 85-10095-100 No. 4 (4.75 mm) 50-7060-90 No.8 (2.36 mm) 30-5540-70 No. 30 (1.18 mm) 10-3015-35 No. 200 (75 µm) 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 Not the mix Ron Sines spoke about yesterday
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
Volumetric Properties of High RAP Mixtures Based on Calculated Bulk Specific Gravities of RAP and Constituent Aggregates Nassim Sabahfer Mustaque Hossain, Ph.D.,P.E. Department of Civil Engineering Kansas State University
VMA Obtained Using Gsb from Different Methods (Shilling RAP)
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.
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
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
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%
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.