the pre-eminent supplier– our people make it happen papa 54th annual paving conference hershey, pa...
Post on 14-Dec-2015
214 Views
Preview:
TRANSCRIPT
The Pre-eminent Supplier– Our People MAKE IT HAPPEN
PAPA 54th Annual Paving Conference
Hershey, PA
January, 30th 2014
RAS Best Practices
The Pre-eminent Supplier– Our People MAKE IT HAPPEN
Types
2 types of roofing shingle scraps:
Tear-offs generated during the demolition or replacement of existing roofs
Manufactured waste generated when new asphalt shingles are trimmed during production to the required physical dimensions or from "out-of-spec" shingles
The Pre-eminent Supplier– Our People MAKE IT HAPPEN
Shingles typically contain: Asphalt binder
Tear-offs contain 20 – 40% binderManufacturer waste 18 – 22% binder
40 to 60% hard rock granules and fillers 1 to 12 % fiber, felt, and miscellaneous
materials
Composition
The Pre-eminent Supplier– Our People MAKE IT HAPPEN
Industry Guidance
NAPA IS 136: Guidelines for the Use of Reclaimed Asphalt Shingles in Asphalt Pavements
The Pre-eminent Supplier– Our People MAKE IT HAPPEN
Incorporating RAS into HMA began more than 30 years ago
Pennsy Supply began using shingles in PA in 2002
PennDOT currently only allows Manufactured RAS, but may be considering allowing use of Tear-Offs
Experience
The Pre-eminent Supplier– Our People MAKE IT HAPPEN
Similar concerns as for aggregate crushing, RAP processing/crushing & HMA production
Asbestos screening (if using tear-offs)Must comply with local agency
requirements, which vary from state to state
Environmental Concerns
The Pre-eminent Supplier– Our People MAKE IT HAPPEN
HMA mixtures produced with shingles are 100% recyclable
Saves natural resources Saves landfill space
Environmental Benefits
The Pre-eminent Supplier– Our People MAKE IT HAPPEN
Various types of industrial grinders can be used to grind the Shingles into a usable productMost use shredding approachWater is used during processing for dust suppression
and to aid in shredding, but must be controlled
Processing Shingles
The Pre-eminent Supplier– Our People MAKE IT HAPPEN
Processing Shingles
Separate out the non-shingle debris before incorporating into HMA
Keep all non-shingle debris separated
The Pre-eminent Supplier– Our People MAKE IT HAPPEN
Ensure proper sizing of the ground Shingle particlesFiner is better
Oversized Shingle particles impact:Contribution to Pbe
Mat texture
Processing Shingles
The Pre-eminent Supplier– Our People MAKE IT HAPPEN
Test RAS for gradation & AC Content frequently as they are being shredded
Keep RAS of different AC contents in separate stockpiles
Processing Shingles
The Pre-eminent Supplier– Our People MAKE IT HAPPEN
Pre-Processing
Processing Shingles
Post-Processing
The Pre-eminent Supplier– Our People MAKE IT HAPPEN
Processing Shingles
In some cases RAS is blended with a carrier aggregate:Used to keep Shingles from
conglomerating & allows for more efficient flow through cold feed bin
RAP, 3/8” Stone, washed screenings, Natural Sand can be used
The Pre-eminent Supplier– Our People MAKE IT HAPPEN
Store RAS in covered environment to control moisture
Shingles left exposed to rain can have very high moisture contents (12%+)
RAS holds more moisture than RAP
Storage
The Pre-eminent Supplier– Our People MAKE IT HAPPEN
Not always a best practice to keep the shingles bin full
Best practice to empty the shingles bin when production complete or production is stopped for extended period
Plant
Photo courtesy of Astec Industries
The Pre-eminent Supplier– Our People MAKE IT HAPPEN
Ensure the RAS feed system is calibrated and maintained
Plant
Photo courtesy of Astec Industries
The Pre-eminent Supplier– Our People MAKE IT HAPPEN
Load cells or weigh belts measure the amount of RAS as it is metered into plant
Plant
Photo courtesy of Gencor Industries
The Pre-eminent Supplier– Our People MAKE IT HAPPEN
Watch for build-up at the RAP collar, especially for plants with smaller throats
Plant
The Pre-eminent Supplier– Our People MAKE IT HAPPEN
Consider covering conveyors and transfer points
Plant
The Pre-eminent Supplier– Our People MAKE IT HAPPEN
Test moisture content of RAS often while incorporating into mix – even more frequently if RAS stockpiles are not covered
Plant
The Pre-eminent Supplier– Our People MAKE IT HAPPEN
RAS has been used successfully in batch and drum facilitiesMay need to increase dry & wet mix time in batch
plants
Plant
The Pre-eminent Supplier– Our People MAKE IT HAPPEN
Higher plant production temperatures may be needed to ensure all moisture is removed from RAS & to maximize blending of RAS binder with virgin binder
Temperatures
The Pre-eminent Supplier– Our People MAKE IT HAPPEN
Higher plant production temperatures may be needed to ensure all moisture is removed from RAS & to maximize blending of RAS binder with virgin binder
Temperatures
The Pre-eminent Supplier– Our People MAKE IT HAPPEN
Field RAS mixtures can behave differently than virgin
mixtures or RAP mixtures, which doesn’t necessarily make them bad: RAS mixtures tend to be more sensitive to
fluctuations in production temperatures RAS mixtures are typically stiffer so may
require additional effort to compact RAS mixtures may make hand-work more
difficult , so think through paving sequence before you begin paving
The Pre-eminent Supplier– Our People MAKE IT HAPPEN
Summary
Shingles require processing Need consistent stockpiles of RAS Should cover stockpiles of RAS Test gradation & moisture content of RAS often RAS feed must be calibrated & controlled Higher production temperatures may be needed Be prepared to manage deltas in mix
characteristics when placing RAS mixtures
top related