The Pre-eminent Supplier– Our People MAKE IT HAPPEN PAPA 54th Annual Paving Conference Hershey, PA...

The Pre-eminent Supplier– Our People MAKE IT HAPPEN

PAPA 54th Annual Paving Conference

Hershey, PA

January, 30th 2014

RAS Best Practices


RAS Best Practices

What is RAS?


RAS Best Practices

Recycled Asphalt Shingles


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


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


Industry Guidance

NAPA IS 136: Guidelines for the Use of Reclaimed Asphalt Shingles in Asphalt Pavements


Where?


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


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


HMA mixtures produced with shingles are 100% recyclable

Saves natural resources Saves landfill space

Environmental Benefits


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


Processing Shingles

Separate out the non-shingle debris before incorporating into HMA

Keep all non-shingle debris separated


Ensure proper sizing of the ground Shingle particlesFiner is better

Oversized Shingle particles impact:Contribution to Pbe

Mat texture

Processing Shingles


Test RAS for gradation & AC Content frequently as they are being shredded

Keep RAS of different AC contents in separate stockpiles

Processing Shingles


Pre-Processing

Processing Shingles

Post-Processing


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


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


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


Ensure the RAS feed system is calibrated and maintained

Plant

Photo courtesy of Astec Industries


Load cells or weigh belts measure the amount of RAS as it is metered into plant

Plant

Photo courtesy of Gencor Industries


Watch for build-up at the RAP collar, especially for plants with smaller throats

Plant


Consider covering conveyors and transfer points

Plant


Test moisture content of RAS often while incorporating into mix – even more frequently if RAS stockpiles are not covered

Plant


RAS has been used successfully in batch and drum facilitiesMay need to increase dry & wet mix time in batch

plants

Plant


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


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


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


Thank you

The Pre-eminent Supplier– Our People MAKE IT HAPPEN PAPA 54th Annual Paving Conference Hershey, PA...

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