ASTM & AASHTO Specifications for Recycling Shingles (RAS)

Transcription

1 7TH ASPHALT SHINGLES RECYCLING FORUM ASTM & AASHTO Specifications for Recycling Shingles (RAS) Victor (Lee) Gallivan, P.E. Asphalt Pavement Engineer Gallivan Consul=ng, Inc. Chicago- O Hare, Illinois October 30, 2015

2 Todays Outline Ø AASHTO Current Specifications Ø ASTM Developing Specifications Ø Developing Changes to RAS Specifications by AASHTO/FHWA

3 STANDARDS l M323 Modifications; Binder replacement revisions for RAP and/or RAS (part 1 completed) l MP15/PP53 Modifications regarding RAS (completed and submitted to AASHTO) l Development of Technical Information on Shingles to replace the existing standards l Further revisions to Standards underway

4 MP 23- Specifications Old l Grind Size: 100 percent passes the 12.5-mm (0.5- in.) sieve l Rates of RAS additions l Deleterious Substances 3% of mass and Non- Metallic 1.5% l Reference Documents and Terminology NEW l Grind Size reduced to 100 percent passes the 9.5 mm (3/8-in.) sieve l Deleted moved to PP53 l Deleterious Criteria reduced to: 1% of mass and Non-Metallic reduced to 0.5% l Reference Documents and Terminology updated

5 PP 78- Practice EXISTING l Shingle Binder Availability Factor Given 0.70 l Binder Grade Determinations l Instructions only referred to RAS l Binder Grade Adjustments Left Open NEW l Corrected SAF process Range from 0.70 to 0.85 to be calculated l BGD process revised l New Equations for RAS and RAS+RAP l New Table 1 included Guidelines on when to adjust (see next slide)

6 PP23, Table 1 Binder Grade Adjustment Guidelines for Mixtures with Reclaimed Asphalt Shingles (RAS) - the percentage of available shingle binder and RAP binder in the design asphalt binder Binder Grade w/ras or RAS+RAP No Change in Virgin Binder Selection <15 % Select Virgin Binder Grade, one grade softer >15% to <25% Blending Chart Recommendations >25

7 ASTM Shingles Effort l Nazli Yesiller, nyesille@calpoly.edu Chair: D18:14 l We are in the process of preparing the next version of the specification for ballot. It will be very similar to the AASHTO Version l 2015 It is..

8 ASTM Shingles Effort Highlights l Covers Roadway Applications including unbound materials such as granular fill l Covers material quality, material quality control, operator and facility operations and qualifications l Contains both manufactures and tear-offs sources l Testing for (A) at 1000 tons of delivered materials installed prior to Used to be 20 years l Grinding to meet 95 percent passing the 9.5 (3/8) sieve l Extraneous waste materials (Non-RAS) allowed is at 1.0% l Moisture limitations and cautions when >15% l Operator and Facility Qualifications l Recommended Facility and Material Certification Form l RAS Material only specifications. No usage recommendations

9 FHWA Recycling Policy 3 E s l ENGINEERING Use Good Engineering Design to Design to Assure Long-Life Pavements. l ECONOMICS Use Life-Cycle Cost Analysis for Project Selection. l ENVIRONMENT Consider Recycling First Be Good Stewards of the Environment

10 Proposed Changes to AASHTO Specifications l FHWA Mixtures Expert Task Group Subtask group on Recycling is proposing changes to AASHTO Specifications. Jim Muscleman (FDOT Taskforce Leader) presented the following

11 Background l Previous Asphalt Mixture ETG Task Team reviewed 2007 PP 53 and MP 15; made a number of revisions PP 53 Design Considerations When Using Reclaimed Asphalt Shingles (RAS) in Asphalt Mixtures MP 15 Reclaimed Asphalt Shingles for Use in Asphalt Mixtures l Provisional standards were modified and subsequently sunset by AASHTO; Reissued as PP 78 and MP 23 l Main issues to be addressed by the Task Team: RAS asphalt binder availability Binder grade adjustment guidelines

12 Issues l How to address the stiffness/ brittleness of the RAS binder? Quality of binder l How much of the RAS binder becomes effective asphalt binder? Quantity of binder

13 Existing Approach l Current approach: Use a RAS Binder Availability Factor of Use Binder Grade Adjustment Guidelines: Recommended Virgin Asphalt Binder Grade RAS or RAS + RAP Binder Percentage No change <15 One grade softer 15 to 25 Use blending charts >25

14 Alternative Approach l Focus on the brittleness of the blended binder: Estimate brittleness of the blended binder with the Bending Beam Rheometer (BBR) Stiffness (S) and Relaxation (M-value) BBR testing is done at two temperatures bracketing the specification requirements from which the temperature where the criteria are met can be interpolated.

15 BBR Data S&M Determination For S=ffness (S): T c = T 1 +[ Log(300) Log( S 1 )/Log( S 1 ) Log( S 2 ) x ( T 1 T 2 )] 10 For Relaxa=on (M- value): T c = T m 1 / m 1 m 2 x ( T 1 T 2 ) 10

16 Critical Temperature Difference (ΔT c ) ΔT c = S'ffness cri'cal temp (S) the Relaxa'on cri'cal temp (m- value) Previous work by Mike Anderson, Tom Bennert, etc. indicates that when ΔT c exceeds -3-5 C there is a significant loss of cracking resistance in asphalt pavements.

17 Assumptions l Assumes worse case scenario (from a binder perspective) If blending is less than complete, the impact of the aged binder on stiffening and relaxation is less than the laboratory would predict If blending is completely homogeneous, the impact on stiffening and relaxation would be accounted for.

18 Pro s l Relatively simple approach l Easy for States to make an informed decision on setting RAS limits based on available virgin binders and existing RAS materials

19 Con s l Doesn t address mixture issues (VMA) if the RAS binder does not become fully blended Binder volume would be less than calculated Binder availability of 0.70 would result in a VMA reduction of ~ 0.50% Could have a mix with better quality binder but not enough of it l Some potential issues with virgin binders meeting the -3/4 C criteria

20 Proposal To simplify the process further, the Task Team is looking at setng maximum Recycle Binder Ra=o (RASBR) for mixtures with RAS Possibly a RASBR of ~0.10 Corresponds to roughly 3% RAS with ΔT c = - 3/4 C l States that want to exceed this amount would need to evaluate ΔT c l Possible Tiered approach

21 Summary l ΔT c is a rela=vely simple way of addressing impact of RAS on binder quality l -3/4 C is a possible recommended starting point l Task Team looking at setng maximum Recycle Shingle Binder Ra=o (RASBR) for mixtures with RAS Based on ΔT c Possibly 3% RAS with RASBR of 0.10 l RAP complicates things l Need feedback and data to refine the idea further.

22 Action Items/Timeline l Task Team to revise PP 78 and MP 23 to reflect the ΔT c criteria Include Tiers? Y/N? Target date March 2016 l Task Team to con=nue to address: Volume of effec=ve binder issue Recommended performance test (maybe)

23 Using RAS First, do no harm

24 25% RAP w/pg 76-22

25 20% RAP, 5% RAS w/pg 76-22

26 Summary Work con=nues to address and determine cri=cal limits Ini=al work on RAS mixtures only. RAS/ RAP combina=ons has to be included Proposed AASHTO revisions/specifica=ons to be developed and presented to ETG March 2016.

27 Victor (Lee) Gallivan, PE Asphalt Pavement Engineer Ph: