RECLAIMED ASPHALT SHINGLES

Use and Operational Considerations

Gerry Huber

Heritage Research Group

∗ Processing shingles ∗ Plant ∗ Laydown ∗ Compaction ∗Design

Phases Considered

∗ Small size ∗ Finer is better

∗ Process in winter ∗ Better than summer ∗ Especially for Manufacturer Waste

Processing Considerations

Previous Grind Specification

Finer Grind

5

∗ Limit water use during processing ∗ Higher the water content allows

faster processing ∗ Limiting water constrains processing

rate

Processing Moisture Content

∗Moisture Limits Maximum Plant Production Rate

∗ Extra fuel to evaporate water

∗ 8% moisture??

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

∗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

∗ Foamed 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

∗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 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

Bill Pine

Heritage Research Group

Bob Forfylow

LaFarge

Lee Gallivan

FHWA