session w62 using reclaimed asphalt shingles (ras) in ...€¦ · using reclaimed asphalt shingles...

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Using Reclaimed Asphalt Shingles (RAS) in Asphalt Pavement Mixtures

Operations and Specifications

Victor (Lee) Gallivan FHWA- Office of Asset Management,

Pavement and Construction March 5, 2014

Session W62

Outline

• Operational Considerations • Processing, Plant, Laydown,

Compaction, and Design • AASHTO Reclaimed Asphalt

Shingles Material Revisions • NAPA Statistics- 2012

• Small size – Finer is better

• Process in winter – Better than summer – Especially for Manufacturer Waste

Processing Considerations

Previous Grind Specification

New Finer Grind

• Limit water use during processing – Higher the water content allows

faster processing – Limiting water constrains processing

Processing Moisture Content

• Moisture Limits Maximum Plant Production Rate

• Extra fuel to evaporate water

• 8% Moisture Maximum

Set Maximum Moisture Desired

• Once shingles get wet – They stay wet

• Stockpiles don’t “drain” • Maximum Moisture Content

– 15% to 25% – Depending on environment

Maintain Moisture Content

• Keep under cover (tent structure)

• Don’t fill to ceiling – Allow airflow – Stockpiles will

dry slowly

Maintain Moisture Content

• Use shingle shredding equipment – No wood

mulchers

Processing Size

• Use trommel screen – 3/8 inch – ¼ inch?

Processing Size

• Can blend with sand or RAP • Yes

• BUT NO BUCKET BLENDING

Sand or RAP Addition

• Must use feeder bins when building stockpile – Obtain homogenous blend

Blending is Separate Operation

• Very fine black dust – Asphalt and fiberglass

• Irritant – Makes you itch

• Safety – Breathing protection

Processing Dust

• Can use aggregate feeder – Difficulty feeding 3%

• Feed must be UNIFORM

Feeding Shingles

• If gate height setting too low – Won’t feed through opening – Tends to plug

• If gate height setting too high – Belt speed too low – Difficult to control

Feeding Shingles

• Use front end loader • “Fluff” shingles into feeder

– Don’t just dump in • Keep amount in feeder low

– Filling allows compaction – Won’t feed properly

• Empty feeder when not in use – RAS tends to “set up” in feeder

Loading Cold Feed

• Shingles need separate weigh bridge – Otherwise feed rate is “assumed”

based on bin feeder calibration • Need lower range load cell

– Aggregate 300 to 500 tons per hour – Shingles 5 to 25 tons per hour

Weigh Bridge

• Depending on plant location

• During windy conditions – Thin

“cellophane-like” plastic blows off

– Fine (black dust) blows off

Cover Feed Belts

• No difference from regular mix

• Can store for longer than a day

Silo Storage

• No difference • Fibers don’t

“cure” segregation – Still need

three dumps and other good practices

Trucking

• No change – Direct feeding to hopper – Shuttle buggy – Windrow pickup machines

Feeding into Paver

• Hot Mix Handwork – Mix is stiffer to handle – Still workable

• Foamed Warm Mix – High (5% ) shingles make mix too

stiff to handwork easily

Workability

• Mix is more stable – Tenderness is less of problem

• Keep rolling patterns tight – Breakdown rollers tight to paver

Compaction

Courtesy of Bruce Christianson - Alaska

• Handling in Laboratory • Batching specimens • Making specimens

Design Considerations

• Need accurate value for shingles • Use AASHTO T209 • How to handle “Floaters”

– Add hot (180°F) water when adding water to picnometer

– Need to cool to 77°F for vacuum saturation

Maximum Theoretical Gravity (Gmm)

77° F Water

180° F Water

• Calculate from Gmm test • Use for VMA calculations

– Error of using Gse instead of Gsb is acceptable

• Allow for asphalt content – 5% shingles is NOT 5% aggregate – Use aggregate contribution in VMA

calculation

Use Aggregate Effective Specific Gravity

• Two methods – “Dipping” – Splitting

• “The shingles are fine enough we don’t need to split them down in the lab”

• WRONG

Batching Specimens

• Dry shake to get apparent RAS gradation • Split shingles into

– +3/8 – +#4 – +#8 – +#16 – +#30 – -#30

Handling Shingles in Lab

• Batch according to apparent gradation

• WHY? – High asphalt content of shingles

makes errors greater – Lot of material on +#30 sieve

Handling Shingles in Lab

• Three samples of each

• Dipping – Scoop out of pan of dried shingles

• Batching – Break down and batch according to

apparent gradation

Dipping vs Batching

Dipping Batching Asphalt Content Average 26.32% 26.66% Std Deviation 1.13% 0.53%

Minus #200 Average 27.2% 29.0% Std Deviation 2.3% 0.7%

Dipping vs Batching

• Bulk Specific Gravity – Range of 0.010

Gyratory Pills

Reclaimed Asphalt Shingles (RAS) Industry Guidance

CDRA NAPA

Construction & Demolition Recycling Association (CDRA)

STANDARDS

• M323 Modifications; Binder replacement revisions for RAP and/or RAS (part 1 completed)

• MP15/PP53 Modifications regarding RAS (completed and submitted to AASHTO)

• Development of Technical Information on Shingles to replace the existing standards

MP 15- Specifications

OLD • Grind Size: 100 percent

passes the 12.5-mm (0.5-in.) sieve

• Rates of RAS additions • Deleterious Substances

3% of mass and Non-Metallic 1.5%

• Reference Documents and Terminology

NEW • Grind Size reduced to 100

percent passes the 9.5 mm (3/8-in.) sieve

• Deleted –moved to PP53 • Deleterious Criteria

reduced to: 1% of mass and Non-Metallic reduced to 0.5%

• Reference Documents and Terminology updated

PP 53- Practice

OLD • Shingle Binder

Availability Factor Given 0.70

• Binder Grade Determinations

• Instructions only referred to RAS

• Binder Grade Adjustments Left Open

NEW • Corrected SAF process

Range from 0.70 to 0.85 to be calculated

• BGD process revised

• New Equations for RAS and RAS+RAP

• New Table 1 included Guidelines on when to adjust (see next slide)

PP53, Table 1—Binder Grade Adjustment Guidelines for Mixtures with Reclaimed Asphalt Shingles (RAS) - the percentage of available shingle binder and RAP binder in the design asphalt binder

Binder Grade w/RAS or RAS+RAP No Change in Virgin Binder Selection <15 % Select Virgin Binder Grade, one grade

softer >15% to <25%

Blending Chart Recommendations ≥25

Numbering

OLD • Provisional

Standards • MP15 – 06(09) and PP53 – 06(09) Both To be replaced

• New Provisional Standards

• MP XX (14) and PP XX (14) (XX- TBD)

ASTM Shingles Effort

• Nazli Yesiller, nyesille@calpoly.edu Chair: D18:14 • “We are in the process of preparing the

next version of the specification for ballot. It will be very similar to the AASHTO Version”

NAPA/FHWA 2012 Survey of Recycled

Materials Usage

NAPA WEBSITE: www.asphaltpavement.org

NAPA -RAP, RAS, WMA Usage Survey

• RAP usage 68.3 Million Tons = +22%

• RAS usage 1.9 Million Tons = +56%

• WMA usage 86.7 Million Tons = +26%

• Overall of RAP Usage 19.6% = +3%

RAS Usage in HMA/WMA

701 thousand

1,099 thousand

0200400600800

1,0001,2001,4001,600

2009 2010 2011 20121,192

thousand tons

1.893 Thousand

Total asphalt mix: 358.4 359.8 366.0 (million tons)

Total RAS tons used for mix production

2011 Average RAP Content by State

2011 RAS Reported Usage by State (33 Yes’s)

Victor (Lee) Gallivan, PE Recycled Material Program Coordinator

Victor.Gallivan@dot.gov Ph: 317-226-7493 Cl: 317-605-4704

The secret of a good sermon /presentation is to have a good beginning and a good ending, and to have the two as close together as possible: George Burns

session w62 using reclaimed asphalt shingles (ras) in ...€¦ · using reclaimed asphalt shingles...

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