Austin District Perspective

Transcription

1 Austin District Perspective

2 District Experience with RAP/RAS = Motivation for Research Construction Issues RAP/RAS Long-Term Performance Issues RAP/RAS Solutions Overview of FM 973 Research WMA/RAP/RAS Project Goals Chronology Story of partnership

3 With limited funds for pavement preservation: The Department can not afford not to use recycled asphalt and optimize material costs. With that, the Department needs long-term performance from PM measures like overlays because we can t afford to do them twice. We have accomplished the first goal, but not necessarily the second.

4 Construction: Dry low effective asphalt Appears aged or high oxidized

5 Construction: Prone to Ravel and Segregate Low Eff. AC

6 Construction: High air voids Stiff mix prone to segregation and difficult to compact

7 Construction: Tearing Stiff mixture Crushed Aggregate Extra Compactive Effort

8 Construction: Premature Cracking or Failure During Construction Longitudinal Cracking Fatigue Cracking

9 Long-term Performance Premature Cracking Raveling Accelerated Deterioration Increase in Maintenance Costs (in some cases) Reduced Performance Life (in some cases)

10 One of the first overlays with RAP in surface mix July 2009 PG TY C PG with 20% RAP Hamburg = 4 mm.@ 15,000passes Sign of raveling and cracking within 8 months of overlay Cost Saving = $19,500 (grade dumping) Total In-house Maintenance Cost ( )= ~$75,000 Crack Seal and Level-Up 30% Drop in Condition Score in 3 years Performance Life = 3 years

11 One of the first overlays with RAP/RAS May 2010 PG TY C SAC B 15% RAP/5% RAS with PG Hamburg = 2.1 mm.@ 20,000passes Alligator & Longitudinal Cracking Cost Saving = $17,555 (grade dumping) Total In-house Maintenance Cost (2012)= ~$2450 (Crack Seal) Level-Up & Seal Coat RMC FY 14 or 15 ($530,000) 18% Avg. Drop in Condition Score in 2 years Performance Life ~ 3-4 years

12 Analyze PMIS database for trends of cracking versus rutting over past fiscal years Crack/Rut Ratio = Total Percent Cracking per Lane Mile Total Percent Rutting per Lane Mile

13 Ratio: Percent Cracking per Percent Rutting 1 st SP (FRAP) projects let March st SP (RAS) projects let December RUT/CRACK RATIO Austin FY2008 Austin FY2009 Austin FY2010 Austin FY2011 Austin FY2012

14 Increase Target Density to 97% for all mix with recycled asphalt Minimum Rut Depth of 3 mm. Implemented the Austin District Thin Overlay Program for surface courses PM Research FM 973 Project Research

15 Study in WMA/RAP/RAS

16 District Goals for FM 973 test section: Confirm what we, as a District, have observed Calibrate the amount of recycled asphalt allowable without compromising long-term performance Collaborate on other possible solutions in utilizing WMA/RAP/RAS as a cost savings measure Help make a GOOD idea a GREAT idea

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18 April 13, 2011 RAS Workshop TTI, TxAPA, CST & Austin District Discussion about a potential test section in the Austin District Austin District & TxAPA identified potential projects and willing Contractors

19 FM 973: Accelerated Pavement Test Section From FM 969 to SH 71 2 Mill, Seal & Inlay TY C PG SAC B 8 HMA/ 11 FLBS Soft silty/sandy clays marginal subgrade ADT = 10,700 % Truck = 9.1% (ADT-975) Heavy Trucks Ready Mix Plant, Sand & Gravel Pit, ABIA Freight, and other Industrial traffic

20 Study Title PI(s) Organization TxDOT Use of Recycled Asphalt Shingles in HMA Fujie Zhou TTI TxDOT Performance Evaluation & Mix Design for High RAP Mixtures Fujie Zhou TTI TxDOT Evaluate Binder & Mixture Aging for Warm Mix Asphalts Charles Glover TTI NCHRP 9-49 Performance of WMA Technologies: Stage I--Moisture Susceptibility Amy Epps Martin, Cindy Estakhri TTI NCHRP 9-49A Performance of WMA Technologies: Stage II--Long-Term Field Performance Shihui Shen Washington State University

21 First Official Meeting July 7,2011 Determined the matrix of different combinations of WMA/RAP/RAS/PG 9 Test Section Administrative Item Change order Costs ~ $55,000 Schedule Field Testing AUS: FWD/GPR/IRI TTI: Condition Survey Mixture FM 973 Field Test Sections Asphalt Binder Grade RAS, % RAP, % HMA WMA WMA

22 FM 973 Between FM 969 and HWY 71 Section No. Type Binder RAP RAS 1 HMA WMA Foaming WMA Evotherm WMA Evotherm HMA HMA HMA HMA HMA Austin Bergstrom Int. Airport Sections highlighted in yellow being used in this project Type C mix Limestone C, D, F, Mfg. Sand + Field Sand Section length ~ 2,040 ft Sections 1 & 7: 400 tons Sections 2-6, 8, 9: 800 tons

23 September 9, 2011 Mix Design & Trial Batch Testing Plan RTI/TxDOT (AUS)/ TxDOT (CSTMP) Developed plans for sampling at plant and field TTI/RTI/TxDOT(AUS) Developed experimental testing plan TTI/TxDOT(CSTMP)

24 NCHRP 9-49 TxDOT 6613 TEXAS FM 973 Test Sections Raw Materials TxDOT 6614 NCHRP 9-49A Evotherm Loose Plant Mix (5-gal buckets) On-site specimens b No. Type Bin der R A P R A S Agg/ RAP/ RAS (55-gal drum) Binder (5-gal bucket) WMA (gal or lb) a Binder (5-gal bucket) Binder (5-gal bucket) Aggreg ate (5-gal bucket ) Binder (5-gal bucke t) WMA Additi ve (gal or lb) a Binder (5-gal bucket) RAP (5-gal bucke t) RAS (5-gal bucke t) NCHRP 9-49 TxDOT 6613 TxDOT 6614 NCHRP 9-49A Evotherm NCHRP HMA 2 HMA (6 x 3.75 ) 7 (6 x 2.4 ) 3 HMA 4 HMA 5 HMA 6 HMA (6 x 3.75 ) 7 (6 x 2.4 ) 7 WMA Foaming (6 x 3.75 ) 7 (6 x 2.4 ) 8 WMA Additive or or (6 x 3.75 ) 7 (6 x 2.4 ) 9 WMA Additive or (6 x 3.75 ) 7 (6 x 2.4 )

25 TEXAS FM 973 Test Sections Field Cores No. Type Binder RAP RAS NCHRP TxDOT TxDOT WSU Total 1 HMA HMA HMA HMA HMA HMA WMA Foaming WMA Evotherm WMA Evotherm TOTAL 158

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27 PAVE _IR

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29 Met March 28, 2012 Wrap up & Lessons Learned Field Testing TxDOT (AUS) FWD, GPR, & IRI Condition Survey No Distress, but difference in color and appearance Coring - TxDOT (AUS) & TTI 178 January September 2012

30 Rut Depth (mm) Hamburg Test@10000passes OT Cycles Section Type Binder RAP RAS 1 HMA HMA HMA HMA Overlay Test

31 Rut Depth (mm) Hamburg Test@10000passes PG64-22/30%RAP PG58-28/30%RAP OT Cycles Section Type Binder RAP RAS 2 HMA HMA Overlay Test 5 0 PG64-22/30%RAP PG58-28/30%RAP

32 Resilient Modulus ( Room Temperature 25C) HMA Evotherm Foaming HMA +RAP/RAS Evotherm+RAP/RAS" Time (Weeks)

33 Initial findings and conclusions from research RAP/RAS improves early age distresses (rutting, moisture susceptibility) at the expense of fatigue resistance WMA & HMA are different initially, with HMA exhibiting greater fatigue resistance With aging, WMA appears to catch up to HMA (WMA = initial HMA), in term of stiffness Research testing and analysis on-going, but correlates with observed performance

34 With limited funds: The Department can not afford not to use recycled asphalt and optimize material costs. The Department can not afford to maintain and replace poorly performing overlays that last only a few years. Joint ventures, like the FM 973 test section, is the type of partnering between the Department, Industry, and Academia that result in innovations and solutions to bridge these two goals.

35 Specify a minimum virgin AC% Discount the contribution of recycled asphalt to the total asphalt content or lower recycle asphalt ratios Minimum penetration requirement for RAP and RAS Processing RAP or RAS with conditioners or rejuvenators prior to incorporation in HMA Limit use of mixture with recycled asphalt on high deflection roadways FM roads

36 Planning future test section on FM 973 to study new techniques & admixture to improve performance of mixtures with RAP/RAS WMA or rejuvenators to pretreat RAP & RAP stockpiles Nano technology to promote better effective asphalt

37 Ramming Chuck Fuller, David Fuller, Jimmy Whithed TTI Arif Chowdhury, Amy Epps, Jon Epps, Cindy Estakhri, Tom Scullion TxAPA David Kopp, Harold Mullins, Kyle Swaner TxDOT (CSTMP) Robert Lee, Dale Rand TxDOT (AUS) Austin District Lab, Travis East Maintenance Office, Tommy Blackmore

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