reclaimed asphalt shingles - purdue universityncaupg/activities/2014/presentation… · reclaimed...
Post on 22-Sep-2020
3 Views
Preview:
TRANSCRIPT
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
top related