Recycled Unbound Base Pooled Fund Study

Transcription

1 Recycled Unbound Base Pooled Fund Study Tuncer B. Edil Recycled Materials Resource Center Geological Engineering Program University of Wisconsin-Madison

2 !! Recycled Concrete Aggregate (RCA)! Demolition and reprocessing of existing concrete structures (buildings, roads, runways, etc.)! Produced by crushing! Particle size distribution depends on crushing methods! Cementitious coating increases water absorption! Un-Hydrated cement increases strength and durability Recycled asphalt pavement (RAP)! Removal and reprocessing of existing asphalt pavement! Produced by milling and crushing! High fines due to milling and crushing in production! Bituminous coating reduces water absorption

3 A suggested nomenclature for RAP!Recycled asphalt pavement (RAP)! Hot mix asphalt (HMA) layer!full depth reclamation (FDR)! HMA and entire base course!recycled pavement material (RPM)! HMA and part of base course layer! HMA, entire base course layer, and part of underlying subgrade!collectively referred to as RAP

4 RESULTS OF SURVEY BY RMRC 2009 The Usage, Storage and Testing of Recycled Materials

5 Material Use and Storage

6 Survey Parameters! Addressed practices involving usage, storage and testing of recycled materials! Sent to 82 materials engineers!54 agencies! 43 U.S. states, Puerto Rico, and Washington D.C.! 4 Canadian provinces! Replies from 41materials engineers!34 agencies! 31 U.S. states, Puerto Rico, and Washington D.C.! 1 Canadian province 6

7 Material Usage! RCA most common, followed by RAP and RPM!Combined RAP and RPM greater than RCA! Stockpiling most common, use-in-place less common! Annual usage!rca: No clear majority!rap: Majority uses 50,000 tons or more!rpm: Majority uses less than 25,000 tons! Materials commonly used for more than 107 years

8 Material Testing! Grain size analysis most common test! Common aggregate quality tests!shear strength: California bearing ratio!toughness: Los Angeles abrasion!durability: Sulfate soundness! Not tested for quality or inconclusive:!stiffness, frost susceptibility, permeability, mineralogical composition, particle geometric properties 8

9 Scaling and Equivalency of Bench- Scale Tests to Field-Scale Conditions

10 ! Scaling depends on: Ð!State of stress Ð!Strain level Ð!Specimen size 10

11 Objective! Determine!Resilient modulus and deformation properties of RAP and RCA!Effect of RCA content on stiffness!effect of layer thicknesses on stiffness!scalability between bench scale, large scale, and field scale test methods 11

12 Test Methods! Bench-scale! Large-scale model experiment! Falling weight deflectometer 12

13 Bench Scale: NCHRP 1-28A! Subjected to sequence of deviator stresses and confining pressures! Cyclic loading! Deflections measured internally and externally! Resilient modulus (M r ) determined by elastic response 13

14 Falling weight deflectometer! Non-Destructive! Determines field modulus! Weight of known mass dropped designated height! Deflection recorded at radial distances from load! Modulus backcalculated from response (FWD) 14

15 Large-Scale Model Experiment! Prototype-scale! Field conditions modeled! Cyclic loading (LSME)! Resilient modulus backcalculated from deflections using MICHPAVE 15

16 LSME Test 16

17 Measured Deflection 17

18 MnRoad Materials! RAP! RCA! Blended RCA/Class 5! Class 5 18

19 MnROAD Test Cells Adapted from Johnson et al

20 Results: Plastic Deformation 20

21 Net Plastic Deflection 21

22 Plastic Strain after 3x10 7 cycles (20 years) 22

23 Rutting Depth Due to Plastic Strain 23

24 Results: Stiffness 24

25 Class 5 25

26 Comparison of Summary Resilient Modulus 26

27 Effect of Layer Thickness on Resilient Modulus 27

28 Results: Scaling Laboratory Tests to Field Tests 28

29 Low Strain Resilient Modulus 29

30 Normalized Resilient Modulus (M r / E s ) Test Method Bench Scale (Ext) M r /E s RAP RCA Blend Class Bench Scale (Int) LSME (0.2 m) LSME (0.3 m) FWD

31 Resilient Modulus Adjusted for Stress Field) and Strain Bench-Scale - Internal) 31

32 ! Plastic deformation!compared to conventional base course (Class 5):!Higher for RAP Conclusions!Lower for RCA and Blend!Decreases with increased layer thickness!decreases with increased RCA content 32

33 ! Resilient modulus!higher for all materials compared to Class 5!RCA highest Conclusions!RAP and Blend approx. equal!increases with increased layer thickness!increases with increased RCA content 33

34 ! Scalability Conclusions!Different test methods result in resilient moduli of different magnitudes.!scaling resilient moduli to the same bulk stress and strain level indicate a reasonable amount of similarity between test methods 34

35 35

36 Materials!! RCA (Recycled Concrete Aggregate)!! Minnesota, Michigan, California, Texas, Colorado, Ohio, Wisconsin, New Jersey!! RAP (Recycled Asphalt Pavement)!! Minnesota, Texas, California, Colorado, Ohio, New Jersey!! RPM (Recycled Pavement Material)!! Michigan, New Jersey!! Class 5 (Natural Aggregate)!! Minnesota!! Blend (RCA/Class5 = 50/50)!! Minnesota 36

37 PSD (RCA)

38 PSD (RAP & RPM)

39 Modified Compaction

40 Int vs Ext Mr (Model 1 & 2)

41 Methodology "! Types and amounts of impurities in RCA, RAP, & RPM weighed and d escribed. "! Evaluate impact of impurities (type & amount) on resilient modulus (M r ) "! Develop predictive method relating M r to fractions of impurities 41

42 Types and Amounts of Impurities "! MnRoad (Class 5) = 0.25% Wood Asphalt Chunks Normal Aggregate 42

43 "! MnRoad (50% Class 5-50% RCA) = 0.36% Geotextiles Plastic Aggregates Wood Aggregates with plastic fibers 43

44 "!MnRoad RCA = 0.87% Normal Aggregate Asphalt Chunks Wood Aggregates with plastic fibers 44

45 "! MnRoad RAP = 0.06% Wood Normal Aggregate Glass Plastic Material 45

46 46

47 Asphalt Content by State 47

48 48

49 Quantitative Assessment of Environmental and Economic Benefits of Using Recycled Construction Materials in Highway Construction

50 Schematic of Two Pavement Designs: Reference-Conventional Materials vs. Alternative-Recycled Materials Reference (Conventional materials) Alternative (Recycled materials)

51 Life Cycle Analysis (LCA) Environmental Metric Conventional Materials Material Productio n Transpor -tation Material Production Recycled Materials Transpor -tation Difference Construction Constructi on CO 2 (Mg) % Energy (GJ) RCRA Hazardous Waste (Mg) 66, , % % Water (L) 17, , %

52 Life Cycle Cost Analysis (LCCA) Categories Reference Alternative Saving Agency Cost ($) 9,044,570 7,107,230 1,937,340 (21%) User Cost ($) 10,570 8,380 2,190 (21%) Total ($) 9,055,140 7,115,610 1,939,530 (21%)

53 Point of Impact Conclusions Extrapolated to a Nationwide Scale Quantity Equivalent to Energy (PJ) Water (million L) CO 2 e (million Mg) LCCA (billion $) ! Annual energy use for 3.67 million householders (EIA 2005 survey)! 68% of annual wind power generation in 2008 (EIA 2009)! 1.4 million persons daily water use for shower (43.9 L/capita)! Equivalent to the removal of 5 million passenger cars per year from roadways! Average annual salary for 1.5 million Americans ($39,500/yr) * Based on an assumption of 150,000 km annual road construction (Carpenter et al 2007)

54 QUESTIONS?! Tuncer Edil, P.E.! Professor! Recycled Materials Resource Center! 1415 Engineering Drive! Madison, WI 53706! ! Image: