ASPHALT WETTING DYNAMICS

Transcription

1 ASPHALT WETTING DYNAMICS Troy Pauli, Fran Miknis, Appy Beemer, Julie Miller, Mike Farrar, and Will Wiser 5 TH Annual Pavement Performance Prediction Symposium Adhesion & Cohesion of Asphalt Pavements Cheyenne, Wyoming June nd and 4 th, 005

2 Comments on Wetting Contact Angle Hysteresis Dynamic Wetting (Current Theories) Asphalt Adhesive Properties Lubrication Theory (Translational Dynamic Contact-line Wetting) Water Interactions (Rotational Dynamic Contact-line Wetting) Adhesion Hysteresis, Friction and Aggregate Surface Roughness A Look at Stripping OVERVIEW

3 Wetting Drop Experiment θ a θ r

4 Advancing Contact Angle, θ a γ s = γ sl + γ cosθ l a θ a θ r

5 Receding Contact Angle, θ r θa θ r γ s f = γ sl + γ cosθ l r

6 Film Pressure, π π = f γ s γ s π = γ ( cosθ cosθ ) l r a θ a θ r γ s = γ sl + γ cosθ l a γ s f = γ sl + γ cosθ l r

7 Dynamic Wetting Hydrodynamic Model Ranabothu, S. R., et al. (005) J. Colloid Inter. Sci., (ARTICLE IN PRESS) 3 3 9ηv [ θ ] [ ] ( ) a ( t) = θ (0) + ln L Ls γ 3 3 9ηv [ θ r ( t) ] = [ θ (0)] ln( L Ls ) γ l l Advancing DCA Receding DCA

8 Dynamic Wetting Hydrodynamic Model Ranabothu, S. R., et al. (005) J. Colloid Inter. Sci., (ARTICLE IN PRESS) 3 3 9ηv [ θ ] [ ] ( ) a ( t) = θ (0) + ln L Ls γ 3 3 9ηv [ θ r ( t) ] = [ θ (0)] ln( L Ls ) γ l l Advancing DCA Receding DCA L = γ l ρg Capillary length L s Slip length

9 Dynamic Wetting Hydrodynamic Model Ranabothu, S. R., et al. (005) J. Colloid Inter. Sci., (ARTICLE IN PRESS) 3 3 9ηv [ θ ] [ ] ( ) a ( t) = θ (0) + ln L Ls γ 3 3 9ηv [ θ r ( t) ] = [ θ (0)] ln( L Ls ) γ l l Advancing DCA Receding DCA L L s = γ l ρg Capillary length Slip length N Ca ηv = γ Capillary number l

10 Dynamic Wetting Molecular-kinetic Model Ranabothu, S. R., et al. (005) J. Colloid Inter. Sci., (ARTICLE IN PRESS) kbt cos[ θ ( t) ] = cos[ θ (0)] m arcsinh( v K λ) w λ γ l v: velocity λ: distance between adsorption/desorption sites K w : quasi-equilibrium rate constant

11 Lubrication Theory (Translational Dynamic Contact-line Wetting)

12 Roto-Film Solution Spin Casting Device Initial Solution Concentration-0.167g/mL Spin Rate-600 to 800 rpm Volume Deposited to slide-.0μl

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17 Filmetrics Thin-film Measurement System

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19 ω ẑ θˆ rˆ

20 ω ẑ θˆ rˆ

21 Transverse Wave Equation h( r, θ,t t ) = h n 3 h 3 r ω h = h( r, θ,t )

22 Lubrication Theory Translational Dynamic Wetting υ η = z ρω r Viscous Force/Centrifugal Force Balance (per unit Volume) d z υ = ρω r η dz υ z = ρω rz η + c c = υ ρω r( z = h ) = 0 + z η v dυ = z ρω rz η η 0 0 ρω rh + dz

23 Lubrication Theory (cont.) Translational Dynamic Wetting υ 1 1 ρω rhz ρω rz η = Radial Velocity of Film Q h 1 1 = υdz = ρω rhz ρω rz η 0 h 0 dz = ρω rh 3η 3 r h t = ( ) rq r Continuity Equation in terms of Radial Flow per unit Circumference, Q h t = 1 r r ρω r h 3η 3

24 ( ) h H r r r r r t H + + = κ γ ρω η ω υ h H

25 Neat AAD-1 at constant concentration Increasing angular velocity 666

26 Neat AAD-1 at constant concentration Film Thickness, h, nm Angular Velocity, ω, rpm

27 Neat AAD-1 at 4 concentrations Increasing angular velocity 666

28 AAM-1 AAK-1 AAD-1 AAF-1 AAG-1 Asphalt Designation AAC-1 AAB-1 AAA c3-600 c3-700 c3-800 Average Film Thickness (h), nm

29 AAG-1 AAK-1 AAM-1 AAD-1 AAF-1 Asphalt Designation AAC-1 AAB c4-600 c4-700 c4-800 AAA-1 Film Thickness, nm

30 Neat AAD-1 at constant concentration Increasing angular velocity 666

31 AAD-1 PAV-Aged at 60EC, 40-hr Increasing angular velocity 666

32 AAD-1 PAV-Aged at 60EC, 480-hr Increasing angular velocity 666

33 1600 Film Thickness, h (nm) Neat AAD-1 AAD-1, 60 C Aged, 40hr AAD-1, 60 C Aged, 480hr h = a ω + a 1 ω +a Angular Velocity, ω (RPM)

34 AAD-1(w/1.5%ppa) PAV Aged at 60EC, 96-hr Increasing angular velocity 666

35 AAD-1(w/1.5%ppa) PAV Aged at 60EC, 184-hr Increasing angular velocity 666

36 AAD-1(w/1.5%ppa) PAV Aged at 60EC, 60-hr Increasing angular velocity 666

37 Film Thickness, h (nm) Neat AAD-1 1.5%ppa AAD-1-60 C Aged, 96hr 1.5%ppa AAD-1-60 C Aged, 184hr 1.5%ppa AAD-1-60 C Aged, 60hr 1.5%ppa AAD-1-60 C Aged, 36hr h = a ω + a 1 ω + a Angular Velocity, ω (RPM)

38 Film Thickness, h (nm) % ppa-aad-1. 0hr 1.5% ppa AAD-1-60 C Aged, 96hr 1.5% ppa AAD-1-60 C Aged, 184hr 1.5% ppa AAD-1-60 C Aged, 60hr 1.5% ppa AAD-1-60 C Aged, 36hr h = a ω + a 1 ω + a Angular Velocity, ω (RPM)

39 Film Thickness, h (nm) % ppa-aad-1. 0hr 1.5% ppa AAD-1-60 C Aged, 96hr 1.5% ppa AAD-1-60 C Aged, 184hr 1.5% ppa AAD-1-60 C Aged, 60hr 1.5% ppa AAD-1-60 C Aged, 36hr h = a 1 ω + a Angular Velocity, ω (RPM)

40 Lubrication Theory (Rotational Dynamic Contact-line Wetting)

41 γ w θ = 0 α = 0 Water Drop γ a β ρ w γ aw Asphalt ρ > ρ a w

42 Buoyancy Force Balances Capillary Force γ w β ρ w θ α ρ > ρ a w γ a γ aw F b V g( ρ w ρ a ) = F Ca V ρas ρ z w

43 a aw a a z g S γ ρ = 1 aw w w w z g S γ γ ρ = 1 a w aw z z ρ ρ = ( ) a w a w z z ρ ρ ρ = z Derivation of Half-Space for Spreading Coefficient

44 S z g z g aw w a w a w a = γ γ γ ρ ρ ρ ρ 1 1 aw w a S γ γ γ = At pseudo-equilibrium, S w = S a Spreading Coefficient

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47 F b = gk( ρ ρ w a) = + Fbk ( ),( ρ < ρ w a ) F = b gk( ρ ρ w a) = 0,( ρ = ρ w a) F b = gk( ρ ρ w a) = Fbk ( ),( ρ > ρ w a)

48 r Buoyancy Force Balances Viscous Force V F r g V F vis w a w a a a w b = + + ± = = η η η η η υ ρ ρ 3 3 ) ( k k

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50 Terminal Velocity of falling Liquid Drop In a Second Liquid (ρ drop < ρ liquid ) υ = ρ ρ η r g( w a ) a 3 η η a + a + η w 3η w r

51 3 3 z r S w a w a w a a ρ ρ η η η η η υ = + + w a a w a w a a a, ' η η η η η η η η η >> + + = Viscous Force Balances Capillary Force For Water Drop Traversing the Asphalt-Air Interface ) 0,( ) ( a w a w b g ρ ρ ρ ρ = = k F

52 ' z r N S w a Ca a ρ ρ υη = = 3 z r S η a υ Hydrodynamic and Geometric Definitions of Capillary Number & Terminal Velocity For Water Drop Traversing an Interface z r = D /

53 α Angle-α AAA-1 AAB-1 AAC-1 AAD-1 AAF-1 AAG-1 AAK-1 AAM Time, Hours

54 β 90 Angle-β AAA-1 AAB-1 AAC-1 AAD-1 AAF-1 AAG-1 AAK-1 AAM Time, hours

55 Natural Log of Dynamic Viscosity, ln(η a ) AAG-1 AAF-1 AAM AAK AAB-1 AAC AAD-1 AAA Rate of Change in Angle-α, dα/dt, t = 0 to 4hr

56 1000 AAM-1 AAA AAG-1 Film Thickness, h (nm) AAK-1 AAF-1 AAB-1 AAC-1 AAD Spreading Coefficient, S aw (dyne/cm)

57 Lubrication Theory Friction and Aggregate Surface Roughness

58 Model of a Lateral-Action Cantilever Measurement (Frictional Force Microscopy) Bliznyuk, V.N., J.L. Hazel, J. Wu, and V. Tsukruk, Quantitative Probing in Atomic Force Microscopy of Polymer Surfaces (1998). Chapter 15 in Scanning Probe Microscopy of Polymers, Ratner, B.D. and V.V. Tskruk, editors, American Chemical Society Symposium Series 694, Oxford University Press, Oxford. Hookian Force F = k t Δ z Normal Force Constant k n = 3 Et w 3 4l Torsional/Normal Force Constant Ratio k k t n = 4 l 3 cos θ + (1 + ν )sin θ k t = Et 4l 3 w cos θ + l (1 + ν )sin θ

59 Digital Instruments, Inc.

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65 Frictional traces of four SHRP asphalts measured at different cantilever scan rates. Friction Force Response, ξ (volts) AAF-1, k AAK-1, k AAC-1, k 0. AAG-1, k Scan Rate Frequency, ν c (Hz)

66 FRICTION IMAGE OF SHRP ASPHALT AAC-1 50 μm

67 Asphaltene Yield versus Frictional Force Asphaltene Mass Percent, (χ a X 100) Derived from iso-octane asphaltene precipitation Derived from n-heptane asphaltene precipitation Frictional Force Response ξ(@ ν c = 4.0 Hz)

68 1000 AAM-1 Decreasing asphalt friction AAA AAG-1 Film Thickness, h (nm) AAK-1 AAF-1 AAD-1 AAB-1 AAC Spreading Coefficient, S aw (dyne/cm)

69 Aggregate Sliding-Plates: 0-μm X 0-μm (length X width) X 4.0-μm 5% color-contrast scaling of image (AFM TappingMode TM ) Limestone Surface Granite Surface

70 AAB-1 on an RA Granite Plate

71 AAM-1 on an RD Limestone Plate Before and After Sonication in water bath Before After

72 AAD-1 on an RD Limestone Plate Before and After Sonication in water bath Before After

73 AAB-1 on an RA Granite Aggregate After Sonication