William H. Daly Ioan I Negulescu Sreelatha Balamurugan Department of Chemistry Louisiana State University

Transcription

1 Intermediate Temperature Fracture Properties of Asphalt Mixtures Containing RAS: Impact of Recycling Agents Louay N. Mohammad Sam Cooper, Jr. Department of Civil and Environmental Engineering LA Transportation Research Center Louisiana State University William H. Daly Ioan I Negulescu Sreelatha Balamurugan Department of Chemistry Louisiana State University FHWA Asphalt Binder Expert Task Group Fall River, MA April 9, 2015

2 The Story! Background Objective/Scope Methodology Mixture Experiment Fracture Properties at Intermediate Temperature Binder Experiment Binder Fractionation by MW Results Summary

3 Asphalt Mixture Design Optimum asphalt cement content Asphalt Binder from RAS and/or RAP Availability Quality VOLUME air MASS Total Volume asphalt aggregate aggregate Total Mass

4 Use of RAS in Asphalt Mixtures AASHTO MP AASHTO MP Use of RAS as an Additive in Hot Mix Asphalt (Asphalt) Provides Standard definitions for RAS Process RAS 100% passing 12.5-mm sieve Allows blending of RAS with fine aggregate Prevent agglomeration Addresses deleterious materials

5 How to incorporate RAS in Asphalt Mixtures AASHTO PP53 AASHTO PP Standard Practice for Design Considerations When Using RAS in Asphalt Mixtures Design Considerations When Using RAS in Asphalt Mixtures Determining the Shingle Aggregate Gradation and Specific Gravity Determining Adjustment to the New Asphalt Binder Grade RAS asphalt binder availability factor is

6 Objective Laboratory Performance at intermediate temperature mixtures containing RAS and/or RAP Effect of recycling agents (RAs)

7 Scope 12.5 mm Asphalt Mixture RAS: Post-Consumer Binder: PG 70-22M Mix ID Mix Code RAP RAS Recycling Agent Mix 1 70CO 0 0 None Mix 2 70PG5P 0 5 None Mix 3 52PG5P-RA PG Mix 4 70PG5P-RA % V. D. O. Mix 5 70PG5P-RA % N.O. Mix 6 70PG5P-RA % S.A. Mix 7 70PG5P15RAP-RA (0.75% + 5%) V. D. O. Mix 8 70PG5P_B-RA % REOB

8 Scope 12.5 mm Asphalt Mixture RAS: Post-Consumer Binder: PG 70-22M Mix ID Mix Code RAP RAS Recycling Agent Mix 1 70CO 0 0 None Mix 2 70PG5P 0 5 None Mix 3 52PG5P-RA PG Mix 4 70PG5P-RA % V. D. O. Mix 5 70PG5P-RA % N.O. Mix 6 70PG5P-RA % S.A. Mix 7 70PG5P15RAP-RA (0.75% + 5%) V. D. O. Mix 8 70PG5P_B-RA % REOB

9 Scope 12.5 mm Asphalt Mixture RAS: Post-Consumer Binder: PG 70-22M Mix ID Mix Code RAP RAS Recycling Agent Mix 1 70CO 0 0 None Mix 2 70PG5P 0 5 None Mix 3 52PG5P-RA PG Mix 4 70PG5P-RA % V. D. O. Mix 5 70PG5P-RA % N.O. Mix 6 70PG5P-RA % S.A. Mix 7 70PG5P15RAP-RA (0.75% + 5%) V. D. O. Mix 8 70PG5P_B-RA % REOB

10 Scope 12.5 mm Asphalt Mixture RAS: Post-Consumer Binder: PG 70-22M Mix ID Mix Code RAP RAS Recycling Agent Mix 1 70CO 0 0 None Mix 2 70PG5P 0 5 None Mix 3 52PG5P-RA PG Mix 4 70PG5P-RA % V. D. O. Mix 5 70PG5P-RA % N.O. Mix 6 70PG5P-RA % S.A. Mix 7 70PG5P15RAP-RA (0.75% + 5%) V. D. O. Mix 8 70PG5P_B-RA % REOB

11 air Design Consideration OAC=5.3% asphalt 6.0 Virgin Binder Recycled Binder aggregate aggregate Asphalt Binder, % Mix 1 = 70CO 0.0 Mix 1 No RAP/RAS Mixture type

12 air Design Consideration OAC=5.3% asphalt 6.0 No Recycling Agents Virgin Binder Recycled Binder aggregate aggregate Asphalt Binder, % Mix 1 = 70CO Mix 2 = 70PG5P 0.0 Mix 1 No RAP/RAS Mix 2-B 5% RAS Available RAS Binder=28%*0.05=1.4% RA 1 RA 2 RA 3 RA 4 RA 2 Mixture type

13 Mixture Design Concerns Classes of Recycling Agents REJUVENATING AGENTS RAS Type %RAS Total AC Content %RAS in Mix Design %RAS AC Binder Available PCWS SOFTENING AGENTS Lube Extracts Extender Oils (aromatic oils) Anti-Stripping Agent Naphthenic Oil (RA-3) Vegetable Derived Oils (RA-2) Lube Stock Lubricating or Crankcase Oil REOB (RA-5) Asphalt Flux Oils Soft Asphalt Binders (RA-1) Purpose of Recycling Agents Softening Agents lower the viscosity of the aged binder Rejuvenators help restore physical and chemical properties of aged binder contain a high proportion of maltene constituents

14 Mixture Design Concerns Classes of Recycling Agents REJUVENATING AGENTS Lube Extracts Extender Oils (aromatic oils) Purpose of Recycling Agents Softening Agents lower the viscosity of the aged binder Rejuvenators RAS Type %RAS Total AC Content help restore physical and chemical properties of aged binder contain a high proportion of maltene constituents %RAS in Mix Design %RAS AC Binder Available PCWS SOFTENING AGENTS Lube Stock Lubricating or Crankcase Oil Anti-Stripping Agent REOB RA 5 Naphthenic Oil (NO) RA 3 Asphalt Flux Oils RA 4 Vegetable Derived Oils (VDO) RA 2 Soft Asphalt Binders RA 1

15 air Design Consideration OAC=5.3% asphalt 6.0 No Recycling Agents Recycling Agents Virgin Binder Recycled Binder aggregate aggregate Asphalt Binder, % Mix 1 = 70CO Mix 2 = 70PG5P Mix 3 = 52PG5P-RA 1 Mix 4 = 70PG5P-RA 2 Mix 5 = 70PG5P-RA 3 Mix 6 = 70PG5P-RA 4 Mix 7 = 70PG5P15RAP-RA Mix 1 No RAP/RAS Mix 2 5% RAS Mix 3 5% RAS Mix 4 5% RAS Mix 5 5% RAS RA 1 RA 2 RA 3 Mixture type Mix 6 5% RAS RA 4 Mix 7 5% RAS + 15%RAP Mix 8-B 5%RAS RA 2 RA 5

16 air Design Consideration OAC=5.3% asphalt 6.0 No Recycling Agents Recycling Agents Virgin Binder Recycled Binder aggregate aggregate Asphalt Binder, % Mix 1 = 70CO Mix 2 = 70PG5P Mix 3 = 52PG5P-RA 1 Mix 4 = 70PG5P-RA 2 Mix 5 = 70PG5P-RA 3 Mix 6 = 70PG5P-RA 4 Mix 7 = 70PG5P15RAP-RA Mix 1 No RAP/RAS Mix 2 5% RAS Mix 3 5% RAS Mix 4 5% RAS Mix 5 5% RAS RA 1 RA 2 RA 3 Mixture type Mix 6 5% RAS RA 4 Mix 7 5% RAS + 15%RAP Mix 8-B 5%RAS RA 2 RA 5

17 Louisiana Balanced Asphalt Mixture Design High temperature Performance Loaded Wheel Tracking Test Rutting Intermediate temperature Performance Semi Circular Bend Test Cracking

18 l Fracture mechanics l Temperature: 25 C l l Half-circular Specimen Laboratory prepared Field core 150mm diameter X 57mm thickness simply-supported and loaded at mid-point Notch controls path of crack propagation 25.4-, 31.8-, and 38.0-mm l Aging: 5 days, 85 C l l l Semi Circular Bend (SCB) Test Loading type Monotonic 0.5 mm/min To failure Record Load and Vertical Deformation Compute Critical Strain Energy: Jc Load (kn) Peak Load U Deflection (mm) notch a1

19 Results

20 Semi-Circular Bend Test Results, 25 C RAP and/or RAS No Recycling Agents Recycling Agents 0.4 Mix 1 = 70CO Mix 2 = 70PG5P Mix 3 = 52PG5P-RA 1 Mix 4 = 70PG5P-RA 2 Mix 5 = 70PG5P-RA 3 Mix 6 = 70PG5P-RA 4 Mix 7 = 70PG5P15RAP-RA 2 J c, KJ/m RBR = 0 % Mix 1 No RAP/RAS RBR = 9.4 % Mix 2 5% RAS RBR = 13.2 % Mix 3 5% RAS RBR = 26.4 % Mix 4 5% RAS RBR = 22.6 % Mix 5 5%RAS RBR = 26.4 % Mix 6 5%RAS RBR = 41.5% Mix 7 15% RAP+5% RAS RBR = 18.9.% Mix 8-B 5% RAS RA 1 RA 2 RA 3 RA 4 RA 2 RA 5 Mixture type

21 Objective / Scope Binder Experiment Correlate the molecular structure of asphalt binders to fracture property of asphalt mixtures Asphalt mixtures: Conventional Asphalt mixtures: RAS with and without RAs Gel Permeation Chromatography (GPC) Fourier Transform Infrared Spectroscopy (FTIR) Binder extracted from aged HMA mixtures 5 days, 85 C

22 GPC data of Blown asphalt and MWS (RAS M) extracted binders RI (Relative Units) MWS BLOWN ASPHALT 14K 17.5% 28K 6.5% 53K 1.15% 3K 45.0% 0.8K 29.85% Binder of RAS M is practically identical to blown asphalt VHMW Asphaltenes Associations MW (Daltons x 10-3 ) 0.2

23 Oxidation of Asphalt Matrix Dispersed asphaltenes Oxidative aging Polar groups stabilize aggregation COOH COOH Polar groups may enhance adhesion to binder HOOC Asphaltene aggregation Asphalt aggregates reinforce matrix

24 Typical MW Distributions of RAS, RAP and of PG M 5 100k 10k 1k RI (Relative Units) RAS-M RAP RAS-M RAP PG M 100k 10k MW (Daltons ) 1k 100 RAS M contributes with higher conc. of associated asphaltenes of much higher molecular weights than that of RAP

25 Typical MW Distributions of Asphaltenes Separated from RAS-P and from PG Binder RI (Relative Units) ASPHALTENES* SEPARATED FROM POST CONSUMER WASTE SHINGLES (PCWS) 32.2 % MW 12, % MW 24, % MW 3, *Fraction Insoluble in n-heptane RI (Relative Units) *Fraction Insoluble in n-heptane 10 ASPHALTENES* SEPARATED FROM PG BASE ASPHALT CEMENT % MW 2, % MW 6, % MW 0.3-2K 1 0 RAS-P ASPHALTENES 0 PG ASPHALTENES MW (Daltons x 10-3 ) MW (Daltons x 10-3 ) 0.2

26 MW distribution of molecular species of extracted binder: HMA mixture containing 0% RAS and PG70-22M binder RI (Relative Units) % MW CO 50 MALTENES ASPHALTENES 21.5 % MW 8, % MW 3, % POLYMER MW 50, J c = 0.5 kj/m MW (Daltons x 10-3 ) 0.2

27 MW distribution of molecular species of extracted binder: HMA mixture containing 5% RAS-P and PG70-22M binder PG5P % MW 930 MALTENES RI (Relative Units) ASPHALTENES 12.6 % MW 12, % MW 33, % MW 4,300 J c = 0.5 kj/m MW (Daltons x 10-3 ) 0.2

28 Semi-Circular Bend Test Results, 25 C 70PG5P_B-RA 1 (15% REOB) RI (Relative Units) % MW 11, % MW 41,720 70PG5P_B-RA1 ASPHALTENES % MW 9, % MW 1, % MW 3,640 REOB MALTENES J c = 0.23 Kj/m MW (Daltons x 10-3 )

29 Semi-Circular Bend Test Results, 25 C RAS - RA 1 (PG 52-28) RI (Relative Units) ASPHALTENES 52PG5P-RA1 RA-1 18,65.0% MW 4, % MW 8, % MW 24, % MW % MW % MW 3,370 MALTENES -10 J c = 0.2 Kj/m MW (Daltons x 10-3 )

30 Semi-Circular Bend Test Results, 25 C RAS RA 2 (0.75% + 5%) V. D. O RI (Relative Units) PG5P-RA2 ASPHALTENES % MW 10, % MW 30, % MW 13, % MW 1, % MW 3,940 MALTENES MW (Daltons x 10-3 ) RI (Relative Units) RA % MW 1, % MW 1, % MW % MW < J c = 0.3 Kj/m MW (Daltons) 100

31 Semi-Circular Bend Test Results, 25 C RAS RA 3 (12% N.O.) RI (Relative Units) % MW 33, % MW 13,600 70PG5P-RA3 ASPHALTENES % MW 4, % MW 925 MALTENES MW (Daltons x 10-3 ) J c = 0.4 Kj/m 2

32 Semi-Circular Bend Test Results, 25 C RAS RA 4 (20% S.A.) RI (Relative Units) MW 11, % MW 13, % MW 35,650 70PG5P-RA4 ASPHALTENES % % MW 4, % MW 1,140 MALTENES MW (Daltons x 10-3 ) J c = 0.3 Kj/m 2

33 Semi-Circular Bend Test Results, 25 C RAS & RAP RA 2 (5% V. D. O.) % MW 1,081 RI (Relative Units) % MW 45, % POLYMER ASPHALTENES % MW 18,970 28,28.0% MW 6,337 MALTENES PG5PHG15RAP-RA MW (Daltons x 10-3 ) J c = 0.4 Kj/m 2

34 Estimation of Extent of Aging by FTIR C=O FTIR spectra of the aged samples show a peak around 1700 cm -1, characteristic of C=O species. The carbonyl index was calculated from the band areas measured from valley to valley as shown above*: Area of the carbonyl centered around 1700 cm-1 Carbonyl index (%) = Area of the spectral bands between 1490 and 1320 cm-1 *J. Lamontagne et al., FUEL, 80(4), (2001)

35 Correlation of VHMW, Carbonyl Index, and Jc Mixture Type Total VHMW % Polymer & Highly Associated Asphaltenes >20K C=O Index x10 3 J c KJ/m 2 70CO PG5P PG5P-RA PG5P-RA PG5P-RA

36 Remarks Effect of Recycling Agents REOB and other RAs evaluated enhanced the extraction of the asphaltenes from the RAS. Use of soft binder (RA 1) did not improve fracture properties. Molecular fractionation through GPC of RAS samples confirmed the presence of associated asphaltenes in great concentrations. High concentrations of HMW asphaltenes decrease the fracture resistance of the asphalt mixtures Presence of SBS additives enhances the compatibility with the HMW asphaltenes. C=O is not reliable indicator of intermediate fracture resistance performance. Use of Recycling Agents evaluated in this study did not reduce the concentration of the highly associated asphaltenes Did not improve the cracking resistance

37 Thoughts! Is 100% blending of available RAS binder desired? Consideration of Addition of ADDITIVES that enhance the compatibility with the HMW asphaltenes.

38 Semi-Circular Bend Test Results, 25 C 70PG5P_B-RA 1 (15% REOB) & Additive RI (Relative Units) % MW 11,675 70PG5P_B-RA1 ASPHALTENES % MW 9, % MW 41, % MW 1, % MW 3,640 MALTENES -10 J c = min 0.50 Kj/m MW (Daltons x 10-3 )

39 T H A N K Y O U