690 likes | 941 Views
Shingles Recycling. A presentation by Dan Krivit at the 49 th Annual Wisconsin Asphalt Paving Conference In Waukesha, Wisconsin Wednesday, November 15, 2006. Definitions. Manufacturers’ Asphalt Shingle Scrap Tear-Off Asphalt Shingle Scrap
E N D
Shingles Recycling A presentation by Dan Krivit at the 49th Annual WisconsinAsphalt Paving Conference In Waukesha, Wisconsin Wednesday, November 15, 2006
Definitions • Manufacturers’ Asphalt Shingle Scrap • Tear-Off Asphalt Shingle Scrap • Recycled Asphalt Shingles (RAS)(Crushed & screened)
History • 15 years + • Multiple research studies in lab and field • Manufacturer shingle scrap in hot-mix asphalt best known, most accepted practice • Still relatively new application
Key Barriers • Lack of clear industry standards and specifications • Inconsistent state regulations • Lack of adequate information / technology transfer • Lack of national leadership by private industry and government
Recent Composition: Weight Ranges of Typical Asphalt Shingles • 32 to 42% Coating filler (limestone or fly ash) • 28 to 42% Granules (painted rocks & coal slag) • 16 to 25% Asphalt • 3 to 6% Back dust (limestone or silica sand) • 2 to 15% Mat (fiberglass, paper, cotton rags) • 0.2 to 2% Adhesives (modified asphalt based)
Multiple Applications • Hot mix asphalt (HMA) • Aggregate / gravel • Dust control • Cold patch • Ground cover • Fuel • New shingles
Factors Affecting HMA Performance • Aggregate gradation of RAS • Properties of final blended binder content within the HMA as affected by: • RAS asphalt binder • Virgin binder
Factors AffectingHMA Performance(continued) • Location RAS is incorporated into HMA drum • Temperature • Moisture content of RAS and other aggregates • Retention time in HMA drum
Potential Benefits • Rutting resistance (especially at warmer temperatures) • Conservation of landfill space • Economic savings to HMA producer due to reduced need for virgin asphalt binder (add oil)
Potential Disadvantages • Contamination (tear-offs) • Added costs of processing and use in HMA • Increased low-temperature / fatigue cracking
Asphalt Grades • PG 64-22 (“PG sixty-four minus twenty-two”) • High temperature for rut resistance 64°C (147°F) • Low temperature for fatigue and cold weather performance(e.g., cracking) -22°C (-8°F)
Mitigating Low Temperature Impacts of RAS • Use less RAS instead of 5%(e.g., use 2% to 3%) • Adjust the virgin binder PG to one grade softer (e.g., PG 52-34)
Deleterious Material • Nails • Other metal • Wood • Cellophane • Other plastic • Paper • Fiber board
U of MN Research • Professor Mihai MarasteanuDept. of Civil EngineeringAsphalt Lab • Adam ZofkaGraduate Student
Missouri HMA Samples • Two recycled sources: • Tear-off shingles (5%) • Recycled asphalt pavement (20%) • Two virgin binders performance grades: • PG 64-22 • PG 58-28 Marasteanu, July 2006
Creep Stiffness (MO: PG 64-22) Marasteanu, July 2006
Creep Stiffness (MO: PG 64-22) Marasteanu, July 2006 Marasteanu, July 2006
Creep Stiffness (MO: PG 58-28) Marasteanu, July 2006
Creep Stiffness (MO: PG 58-28) Marasteanu, July 2006
Strength (MO: PG 64-22) Marasteanu, July 2006 Marasteanu, July 2006
Strength (MO: PG 58-28) Marasteanu, July 2006
Conclusions: Stiffness(MO:At temperatures below -10°C) • PG -22 mixture:addition of shingles increases the mixture stiffness considerably (a) • PG -28 mixture:stiffness difference lessened (b) Marasteanu, July 2006
Conclusions: Strength(MO:At temperatures below -10°C) No significant affects due to shingles for either PG -22 or PG -28 mixtures Marasteanu, July 2006
Minnesota HMA Samples • Three types of recycled materials • 20% reclaimed asphalt pavement (RAP), • 15% RAP + 5% Tear-off recycled asphalt shingles (RAS), • 15% RAP + 5% Manufactured RAS. • Only one virgin asphalt binder: PG 58-28 Marasteanu, July 2006
Creep Stiffness (MN: PG 58-28)(@ 100 seconds) Marasteanu, July 2006
Creep Stiffness (MN: PG 58-28)(@ 500 seconds) Marasteanu, July 2006
Strength (MN: PG 58-28) Marasteanu, July 2006
Creep Stiffness (MO vs. MN)(@ 100 seconds) Marasteanu, July 2006
Creep Stiffness (MO vs. MN)(@ 500 seconds) Marasteanu, July 2006
Conclusions: Stiffness(MN) • Adding tear-offs significantly increases stiffness of the mixtures at all test temperatures (a) • Adding manufactured increases stiffness only at 0°C and -10°C (b) Marasteanu, July 2006
Conclusions: Strength(MN) No significant affects due to either tear-off or manufacturers’ shingles scrap Marasteanu, July 2006
Conclusions: Stiffness(MO vs. MN) • Lower stiffness values for the Minnesota RAP mixtures compared to Missouri mixtures • Lower stiffness values for the MN combinations of RAP + RAS compared to MO mixtures (a) Marasteanu, July 2006
Minnesota Extracted Binder Samples • Bending Beam Rheometer (BBR) (a) • Direct Tension Tests (DTT) (b) Marasteanu, July 2006
BBR (MN) Marasteanu, July 2006
BBR Conclusions (continued) • Addition of shingles changes the properties (a) • The two types of shingles perform differently • The manufactured material seems to be beneficial (b) • The tear-off material affects properties in a negative way (although it also decreases BBR stiffness) (c) Marasteanu, July 2006
BBR Conclusions (continued) • m-value not fully understood (a) • The limited data also shows that binder and mixture results do not always agree (b) • Need further research (c) Marasteanu, July 2006
Mn/DOT Research • Jim McGraw,DirectorMn/DOT Chemistry Lab
AC Impact in Final Mix(at 5% RAS) • RAS binder addition: • Manufacturers’ adds 1.0% binder • Tear-offs adds 1.8% McGraw, July 2006
Final Hot Mix Low Temperature PG (a) • Tear-off -28.8 (b) • Manufacturers’ -26.2 (c) • RAP -29.2 (d) McGraw, July 2006
Conclusions • More mixture testing (a) • Experimental design needs true control • Shingle only study (b) • Field reviews of past projects (c) • Re-evaluate current Mn/DOT spec (d) McGraw, July 2006
Additional National Developments • New AASHTO specification • EPA / CMRA study • www.ShingleRecycling.org • Asbestos data base
States Using RAS(in 1999) Justus, September 2004
AASHTO Specification (continued) • Deleterious material maximum limits (Section 8):(material retained on the No. 4 sieve) • Heavy fraction = 0.50% • Lightweight fraction = 0.05%
Missouri Shingle Spec • Extrinsic Material Allowance Raised • 3.0% Total • 1.5% Wood