Estimating Effect of RAP and RAS on PG grade of Binders

Transcription

1 Estimating Effect of RAP and RAS on PG grade of Binders Dan Swirtz, E. Mahmoud and H. Bahia University of Wisconsin- Madison RAP ETG, Oklahoma City, October, 2010

2 Topics Testing and Analysis Procedure Define Outcome: % change in grade per 1 % RAP binder Finalize geometry in DSR for High Temp Verification Results Combining Shingles (RAS) and RAP In collaboration with RMRC

3 Procedure Summary - Sample Preparation R100: RAP passing #50 retained on #100 SRAP Mortar RRAP Mortar

4 Hypothesis Two mortars are prepared: RAM Material (Binder + Aggregate) + Fresh Binder RAM Aggregate (No binder) + Fresh Binder If identical gradation and identical total asphalt content are used, the difference in G*, sin, m and S can be attributed to the RAM Binder only.

5 Spreadsheet Analysis Enter 100% mixing Fresh and Binder test data into analysis spreadsheet Grade X% Fresh Binder + Y % RAP Binder Grade Testing Results Maximum BBR Test Results on PAV Aged Fresh Binder Test Temperature 1: 6 Test Temperature 2: 12 Estimation Trial 1 Trial 2 Trial 3 Average COV Trial 1 Trial 2 Trial 3 Average COV Time [sec] Time [sec] percentage S [MPa] S [MPa] S [MPa] S [MPa] S [MPa] S [MPa] S [MPa] S [MPa] S [MPa] S [MPa] Estimation Extrapolation based on RAP m value m value m value m value m value m value m value m value m value m value binder 60 content and mixing BBR Test Results on PAV Aged Fresh Binder + R100 RAP Aggregate (RRAP Mortar) percentages Test Temperature 1: 6 Test Temperature 2: 12 Trial 1 Trial 2 Trial 3 Average COV Trial 1 Trial 2 Trial 3 Average COV Time determined [sec] Time [sec] S [MPa] by S [MPa] S [MPa] Enter S [MPa] Results S [MPa] at 60 S [MPa] seconds S [MPa] S [MPa] or 10 S [MPa] S [MPa] 60 user m value m value m value rad/sec m value m value (Intermediate m value m value and m value High m value m value BBR Test Results on PAV Aged Fresh Binder + R100 RAP (SRAP Mortar) Temperatures). Test Temperature e1: 66 Test Temperature e2: 12 Time [sec] Trial 1 Trial 2 Trial 3 Average COV Trial 1 Trial 2 Trial 3 Average COV Time [sec] S [MPa] S [MPa] S [MPa] S [MPa] S [MPa] S [MPa] S [MPa] S [MPa] S [MPa] S [MPa] m value m value m value m value m value m value m value m value m value m value

6 Outcome: Estimate of Rate of Change of LT Grade (deg C / 1% RAP Binder) Rate Target Low Temperature PG Grade PG PG Extrapolation % RAP Bi inder

7 RAP Source Sensitivity Summary Grade Change Rate RAP RAP Binder Source Percent [%] E.B J.H R.R P.B Fresh Binder Grade True Grade Fresh Binder Blended Binder Grade Change Rate (Deg C/%RAP)

8 Verification Procedure Create and test Artificial RAP 2 PAV aged binder + RAP aggregates Compare results against binder only blends e.g. 20% 2 PAV binder + 80% RTFO binder (High Temp) Compare True-Grade Values Discrepancies could indicate Invalid assumption of complete blending Problems with analytical procedure

9 Verification Experiment Case I Case II Case III Case IV Artificial RAP A 1 : 40 hr PAV aged PG a binder + R100 aggregate from Reno, Nevada mixed at a 10.5% total asphalt content. Artificial RAP A 2 : 40 hr PAV aged PG b binder + R100 aggregate from Reno, Nevada mixed at a 10.5% total asphalt content. Artificial RAP B: 40 hr PAV aged PG binder + R100 aggregate from Wisconsin mixed at a 7.4% total asphalt content.

10 Results and Discussion Verification (BBR) LowTemperature Results Binder Replacement Test Temp. [C] Estimated True Grade [C] Measured True Grade [C] Difference [C] Case I 15% Case II 15% Case III 15% Case IV 25%

11 Verification Intermediate (DSR) Temperature Results Case I Case II Case III Case IV Test Temp. [C] Binder Replacement Estimated True Grade [C] Measured True Grade [C] Difference [C] % % % %

12 Verification High Temp Case I Case II Case III Case IV Test Temp. Binder Estimated True Measured True Difference [C] Replacement Grade [C] Grade [C] [C] % % % %

13 Selection of DSR Geometry High Temperature Trial DSR Testing Geometries Difference in Plate Dia. Gap Strain [%] True Grade* [mm] [mm] [deg C] Standard Geometry Trial Trial Trial *Measured blended binder true grade estimated blended binder true grade

14 Verification Effect of conditioning time Conditioning Time Analysis Summary Standard Geometry Conditioning Time Measured True Grade Estimated True Grade Diff. [C] None [mixing] hr hr mm Gap Geometry Conditioning Time Measured True Grade Estimated True Grade Diff. [C] None [mixing] hr hr

15 Effect of Total Binder Content 2 mm Gap Trial Geometry TG Estimate Total A.C. RAP Binder TG From from Mortar [%] [%] of total AC Plot Testing Diff. [C]

16 Results and Discussion Verification High Temperature > 3 C Discrepancy for all cases with standard geometry. Re-tested to isolate: - Test Geometry (Trial at 2 mm gap setting) - Conditioning time check (Complete blending) - Sample Gradation (Sieve burned aggregates) - Blending chemistry considerations (Change O.B.) - Asphalt Content (Aggregate interlock effect)

17 Results and Discussion Verification High Temperature Discrepancy still exists Example High Temperature Verification Progression Original Difference in True Grade: 3.84 Difference in True Grade after Change Gap Setting Conditioning Time Blend Chemistry Gradation Asphalt Content Negligable 2.97 Note: - Difference in True Grade always conservative: Est <Measured - Increasing total asphalt content results in less RAM binder effects.

18 Comparison with Extraction and Recovery Purdue Samples Comparison with mixture extraction samples: Fresh Binder Grade PG Fresh Binder Grade PG Notes: True Grade of Blended Binder % RAP in Mortar Mixture Mix Procedure Extraction Difference When RAP present Mortar procedure is conservative Change in True Grade for extraction samples (PG 64-22) seem suspect (0.1 C change for 15% RAP)

19 Results and Discussion RAP and RAS Blends Linear trend between RAP alone and RAS alone tests Blend Low Temperature True % RAP % RAS %F Fresh Difference Grade [C] Binder Binder Binder [C] Measured Calculated Create surface plot of results:

20 Results and Discussion Interim Findings Procedure can be use to estimate low and intermediate properties with limited application at high temperature Each RAP, RAS, and fresh binder blend is unique Characterization can not be lumped

21 Further Study Low temperature Fracture Testing and Glass Transition Workability Concerns Variability (RAS) Verification Using Mixes

22 Fracture Testing Modified BBR BBR sample a Notch in the middle Force (mn) P P L = 3 B W K IC 2 a f W Displacement (mm) Notch a W PAV Binder RRAS Mortar SRAS Mortar L b

23 Effect of RAP and RAS on Fracture RRAP: Fresh Binder, SRAP: Blended Binder RAP/RAS Material Max Load Displacement at Tested (mn) Fracture (mm) Stress Intensity Factor (K IC )(kpa*m 0.5 ) Fracture Energy* [mj/mm 2 ] RAP PAV Binder RRAP Mortar C SRAP Mortar RAP PAV Binder RRAP Mortar C SRAP Mortar RAS PAV Binder RRAP Mortar C SRAP Mortar