Wetting/Compatibility

Transcription

1 Wetting/Compatibility NCHRP Project 9-43; Mix Design Practices for Warm Mix Asphalt Troy Pauli Julie Miller James Beiswenger Will Grimes Janet Wolf PAVEMENT PERFORMANCE PREDICTION SYMPOSIUM 2008 Warm Mix and Recycled Asphalt Pavements-RAP Session 2 University of Wyoming Washakie Center Rendezvous Room, Laramie, Wyoming, July 16-18

2 OVERVIEW MIXTURE MODELING OF EFFECTIVE PHYSICAL PROPERTIES RAP-WMA COMPATIBILTIY TESTING FILM-ON-FILM WETTING EXTERIMENTS OBSERVATION OF MIXING AT MICRO- SCALE CONCLUDING REMARKS

3 A LOOK AT THE MASTIC SCALE (μm to nm) Kandhal, et al., 1998, Kandhal and Chakaraborty, 1996.

4 MIXTURE MODELING OF EFFECTIVE PHYSICAL PROPERTIES, X eff n ( 1 ) X χ X = χ X + χ X eff i i i i i i i= 1 Queimada, et al n i= 1 χ 1 = χ + χ i i j χ = i n M i= 1 i M i M : mass( g) 1/2 1 ( ) ( ) ( ) X : δ MPa, μ kj mol, η Pa s,... Solubility parameter, chemical potential, viscosity, χ : x, φ,... Mass fraction, volume fraction,

5 Example: FH Mix Model Applied to Spinodal Decomposition F = f ( ) ( ) 0 ϕ + κ ϕ V 2 dv Velázquez Sánchez. M.E ( + ) 0 0 ϕ 1 ϕ ξ ε11 ε22 f0( ϕ) = ϕμ1 + ( 1 ϕ ) μ2 + kt ln( ϕ ) + ln( 1 ϕ ) + ε12 ϕ ( 1 ϕ ) N 1 N 2 kt spinodal Chemical Potential, μ(φ) Free Energy metastable unstable molar concentration, φ Conserved Order Parameter, mole concentration

6 DIFFERENTIAL EFFECTIVE MEDIUM THEORY, D-EMT, APPLIED TO PAL-RHODES EQUATION φla, φ K = = = c 0 φc φ KK 0 αφ φ Kφ φla, 1 α dηr η 1 φ c [ η] dv dφ c = [ η] + O( dvc ) = + O V V 1 φc = V T ( dvc ) 2 c 2 r T c Pal and Rhodes, 1989, Garboczi and Berryman, 2001, Bullard, et al. submitted 11 June η η η r r r ( ) [ η 1 Kφ ] = ( 1 K ) = K[ η ] φ ( ) [ η 1 Kφ ]/ = K ηr : K : φ : [ η] : Relative viscosity Solvation constant Suspended phase volume fraction Einstein constant, 2.5

7 Relative Viscosity Plotted as a function of Asphaltene Content 1.0 Relative viscosity function: (η/η n-c7 ) ν group A, ν = [η] (η/η n-c7 ) ν = 1-3.5χ iso-c8 group B, ν = [η]/k isooctane asphaltene mass fraction, χ iso-c8

8 Phase Angle Plotted as a function of Asphaltene Content 90 Phase Angle, δ = tan -1 G"/G' ( δ 90 ) 0 δ ( 1 ) = χ isoc isooctane asphaltene mass fraction, χ iso-c8

9 A Nanoscopic view of asphalt

10 Experimental Approach Compatibility A sample of SHRP asphalt AAD-1was RTFO-PAV aged at 100 C for 144hr (homemade-rap) SHRP asphalts AAB-1, AAG-1, and field asphalt YNP(Yellowstone National Park), were mixed with Fisher-Tropes hard wax, Sasobit (1.5% by mass) (@130 C, 60-min, lab mixer in oven) SHRP asphalts AAB-1, AAG-1, and field asphalt YNP WMA samples were mixed with homemade-rap at different mass concentrations (@130 C for an additional 60-min) Compatibility Testing of RAP-WAM mixtures employing the Automated Flocculation Titrimeter Estimates/measurements of maltene viscosity and asphaltene content were made to conduct mixture calculations

11 MIXTURE MODEL OF RAP-WMA MIXTURE VISCOSITY η = η χ ( 1 K ) [ η ] asphalt n C iso C 7 8 Barrufet and Setiadarma, 2003, Ha, H. Z., and P. Koppel, mix (,, ) 8 7 [ η] η χ η χ asphalt isoc nc RAP 0 η 1 K χ eff isoc 8 eff ( ) δ = 90 1 χ isoc 8 ( ) ( ) ( ) 0 ln ηmix χrap ln ηnc + 1 χrap ln ηnc RAP 7 7 ( ) ( 1 )( ) χ = χ χ + χ χ eff isoc RAP isoc RAP RAP isoc asphalt asphalt

12 PREDICTED VISCOSITY FOR RAP-WMA MIXTURES Predicted ln( ) AAB-1-waxWMA/AAA-1-(RAP-1) AAB-1-waxWMA/AAD-1-(RAP-2) AAG-1-waxWMA/AAD-1-(RAP-2) YNP-waxWMA/AAD-1-(RAP-2) RAP Mass Fraction, χrap

13 PREDICTED PHASE ANGLE FOR RAP-WMA MIXTURES AAB-1-waxWMA/AAA-1-(RAP-1) AAB-1-waxWMA/AAD-1-(RAP-2) AAG-1-waxWMA/AAD-1-(RAP-2) YNP-waxWMA/AAD-1-(RAP-2) Predicted Phase Angle, δ RAP Mass Fraction, χ RAP

14 Koehler Instruments brand Automated Flocculation Titrimeter (AFT) Schematic of a reversible AFT apparatus; a. sample circulation loop, flow cell housed in a UV visible spectrometer [ASTM D6703, 2008, Heithaus, 1962], b. metering pump, c. reaction chamber, sample vial and cap, e. stir plate, f. titrant dispersion assembly, back-titrant dispersion assembly.

15 Plot of the asphaltene compatibility index versus the reversible asphaltene peptizability parameter for twelve SHRP asphalts. 4 χ ( K ) = + 2 p 2 χ rev iso C8 a nc7 ( 1 ( 2) rev ) K K p 2 [ η ] η = η + χ asphalt n C a nc 7 7 f = a*x+ y 0 = 5.5x-2 Pauli and Branthaver, χ iso-octane /χ n-heptane p a 25 o C

16 Heithaus compatibility parameter, p a ; asphaltene peptizability, measured via reversible AFT analysis, plotted versus the mass percent RAP-representative material present in a RAP-WMA(wax) mixture AAB-1 (WMA) with RAP-1 AAB-1 (WMA) with RAP-2 AAG-1 (WMA) with RAP-2 YNP (WMA) with RAP Asphaltene Peptizability, pa Mass Fraction RAP per mix

17 Heithaus compatibility parameter, p a ; asphaltene peptizability, measured via reversible AFT analysis, plotted versus the mass percent RAP-representative material present in a RAP-WMA(zeolite) mixture AAB-1-ZEO-RAP AAG-1-ZEO-RAP 0.75 YNP-ZEO-RAP 0.70 Asphaltene Peptizability, pa Mass Fraction RAP per mix

18 Experimental Approach Wetting SHRP asphalt AAD-1, RTFO aged at 100 C for 144hr (homemade- RAP) was prepared in solution (toluene, 1g/10mL) and spin-cast as a thin-film (1.0 μm) on microscope slides (Borosilicate glass) SHRP asphalts AAB-1, AAG-1, and field asphalt YNP prepared as WMA samples were prepared in cyclohexane(1g/10ml) then spincast onto RAP films. (i.e., a film-on-film system) Film-on-Film systems were images using atomic force microscopy In certain cases, films were heated in a 130 C oven for min then re-imaged to observe changes in the film morphology

19 EXPERIMENTAL METHOD: Solvent Spin-Casting

20 Film Thickness, h, as a function angular velocity of spin-coating,ω Film Thickness, h, nm Angular Velocity, ω, rpm

21 r P - z η r ρω = υ 0 + Π P = κγ / r h r h r h r r h = κ DYNAMIC WETTING: Lubrication Theory Applied to Spin Coating h h rh rh r t r r r r r r ρω γ η = + : : : : : : : h η ρ ω υ κ Π Viscosity Density Angular velocity Velocity Disjoining pressure Curvature Film thickness Melo et al., 1989.

22 EXPERIMENTAL TECHNIQUE: Film-thickness, and refractive index determination via Spectral Reflectance

23 EXPERIMENTAL TECHNIQUE: AFM w/ heating-cooling Solidification sample stage

24 Projected views (photograph-to-light microscope-to-afm image) of a contact interface between a WMA spin-cast thin-film coating spin cast on top of a spin-cast thin-film coating of a RAP-representative PAV-asphalt originally spin-cast on a glass microscope slide

25 AFM scans at the interfacial contact line (upper-left), at the WMA surface toward the center of the top film (upper-right), and the RAP film toward the edge (lower-left) for WMA spin-cast thin-film coating spin cast onto the top of a spin-cast thin-film coating RAP-representative PAV-asphalt after annealing films in a 130 C oven for 60 minutes.

26 AFM profile topography (left), and microscopic photograph view (right) depicting the interfacial contact line between a WMA spin-cast thin-film coating (AAB-1/wax) spin cast onto the top of a spin-cast thin-film coating RAP-representative PAV-asphalt (AAD-1).

27 AFM profile topography (left) and phase-contrast (right) scans of an interfacial contact line between a WMA spin-cast thin-film coating spin cast onto the top of a spin-cast thin-film coating RAP-representative PAV-asphalt PAV Aged AAD-1 (RAP) AAB-1 w/ft wax (WAM)

28 Photograph image of two WMAfilm-on-RAPfilm AAB-1/WMA(wax) on RTFO-aged AAD-1) samples spin cast onto glass microscope slides, (left, prior to thermal annealing), (right, thermally annealed for C).

29 AFM scan at the interfacial contact line, between the WAM film and the RAP film, imaged after annealing the film in a 130 C oven for 60 minutes.

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31 The chemist s rule of: Like dissolves Like Like mixes/associates with Like RAP-wax mixes with neat wax RAP asphaltenes associate with neat asphaltenes RAP maltenes mix with neat maltenes Indication of Molecular Ordering? (ENTROPY)

32 AFM topography scan of a WMA spin-cast thin-film coating, AAG-1/WMA(wax) spin cast onto a glass microscope slide, which was thermally annealed 20-min, 130 C.

33 AFM topography image of a thin film of SHRP asphalt AAG-1 (thermally annealed).

34 AFM topography (left) and Friction (right) scan of a AAB-1/WMA(wax) spin-cast thin-film coating spin cast onto a glass microscope slide, Images three days after preparation.

35 AFM topography (left) and Friction (right) scan of a AAB-1/WMA(wax) spin-cast thin-film coating spin cast onto a glass microscope slide, Images 20-min after a 30-min annealing in a 130 C oven.

36 AFM profile topography scan of a WMA spin-cast thin-film coating spin cast onto a glass microscope slide, YNP w/zeolite. Bright spots, Polymer?

37 Heithaus compatibility parameter, p a ; asphaltene peptizability, measured via reversible AFT analysis, plotted versus the mass percent RAP-representative material present in a RAP-WMA(wax) mixture AAB-1 (WMA) with RAP-1 AAB-1 (WMA) with RAP-2 AAG-1 (WMA) with RAP-2 YNP (WMA) with RAP Asphaltene Peptizability, pa Mass Fraction RAP per mix

38 CONCLUSIONS RAP (oxidized, potentially incompatible), when mixed with neat asphalt binders, which range from compatible to incompatible each act differently in terms of mixture compatibility, i.e., compatibility of mixture decreases more rapidly when mixed with less compatible starting asphalt, thus, if high RAP concentrations are used, softer, more compatible asphalts may be preferential. Neat asphalt, when wetting a RAP surface, tend to mix Temperature (or essentially decreasing viscosity) and time (particularly for WMA) of mixing will be important parameters in actual field applications. Is it fair to say that the notion of a Black Rock is essentially invalid for high RAP concentrations.

39 Perceived Gaps in Research The present work is somewhat like putting the cart before the horse: HMA-highRAP systems should be studied in depth, in terms of mixture compatibility, to better understand finding in the present work Lower temperature WMA-highRAP systems require further study in terms of long term mixing/settling/curing at/under inplace temperatures (conditions), AND OXIDATION. Is it fair to say that the notion of a Black Rock is essentially invalid for high RAP concentrations? How will Cold Mix Asphalt-RAP systems perform, Ah-Black Rock Theory may have more merit here? What is the actual mechanism of action of FT wax, zeolite, emulsifiers, in viscosity reduction, long term effects?

40 REFERENCES ASTM D , 2008 Annual Book of ASTM Standards, Section 4, Construction. vol Road and Paving Materials; Vehicle-Pavement Systems ASTM International, West Conshohocken, PA, , Barrufet, M. A., A. Setiadarma, 2003, Reliable heavy oil solvent viscosity mixing rules for viscosities up to 450 K, oil solvent viscosity ratios up to 4 105, and any solvent proportion. Fluid Phase Equilibria 213, Bullard, J. W., A. T. Pauli, E. J. Garboczi, and N. S. Martys, A Comparison of Viscosity-Concentration Relationships for Emulsions. Preprint submitted to Journal of Colloid and Interface Science, 11 June Garboczi, E.J. and J.G. Berryman, 2001, Elastic moduli of a material containing composite inclusions: effective medium theory and finite element computations. Mechanics of Materials, Vol. 33, No. 8, Kandhal, P. S., and S. Chakaraborty, 1996, Effect of Asphalt Film Thickness on Short and Long Term Aging of Asphalt Paving Mixtures. NCAT Report No Kandhal, P. S., K. Y. Foo, and R. B. Mallick, 1998, A Critical Review of VMA Requirements in Superpave. NCAT Report No Ha, H. Z., and P. Koppel, 2008, Accurately Predict Viscosity of Syncrude Blends. Hydrocarbon Processing, Vol. 87(7), Heithaus, J. J., 1962, Measurement and Significance of Asphaltene Peptization. Journal of the Institute of Petroleum, 48: Melo, F., J. F. Joanny, and S. Fauve, 1989, Fingering Instability of Spinning Drops. Physical Review Letters, 63(18): Pal, R., and E. Rhodes, 1989, Viscosity/Concentration Relationships for Emulsions. Journal of Rheology, 33(7), Pauli, A. T., and J. F. Branthaver, 1998, Relationship Between Asphaltenes, Heithaus Compatibility Parameters and Asphalt Viscosity. Petroleum Science and Technology, 16(9&10), Queimada, A. J., I. M. Marrucho, J. A. P. Coutinho, and E. H. Stenby, Viscosity and Liquid Density of Asymmetric n-alkane Mixtures: Measurement andmodelling. Paper presented at the Fifteenth Symposium on Thermophysical Properties, June 22-27, 2003, Boulder, Colorado, U.S.A. Velázquez Sánchez. M.E. 2002, Thesis: Spinodal decomposition in thin films of binary polymer blends. Universiteitsdrukkerij Technische Universiteit Eindhoven, the Netherlands.

41 ACKNOWLEDGEMENTS NCHRP: NCHRP Project 9-43; Mix Design Practices for Warm Mix Asphalt Ray Bonaquist: Advanced Asphalt Technologies, LLC Julie Miller James Beiswenger Will Grimes Janet Wolf

42 Discussion