Fundamental Properties of Asphalts and Modified Asphalts, III

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to crack initiation brought on by fatigue, followed by pavement failure, as a function of environmental conditions and loading cycles? It has also been hypothesized that the process of combining asphalt with aggregate at high temperatures, placing this composite material in a roadway, and then allowing it to cool and cure may be modeled as a solidification process. Solidification processes are generally considered to be non-equilibrium thermodynamic processes where fluxes in composition and thermal gradients are driven by both mechanical and thermodynamic forces (e.g., chemical potential, surface tension and pressure differentials), thereby constituting mechanisms for order-disorder transitions that result in the formation of microstructural grain boundaries. These order-disorder transitions could also be responsible for cohesive failures when, for example, subjected to temperature fluctuations, shear and compressive loading, and exposure to moisture. Thus, a thorough investigation of the “chemical-action” of asphalt binder as it exists in pavements is warranted in order to define the interfacial boundary conditions and kinetic driving mechanisms that describe the formation and destruction of microstructural phases in asphalt when adopted by continuum mechanical modeling approaches used to simulate fatigue damage. Background In this subtask a somewhat simplified view has been taken to describe the composition of asphalt thin-films in a “pavement structure.” This is particularly true at the mastic level, which may be viewed as if one were building sandcastles with asphalt in place of water as the binding agent to adhere and maintain structural form to the system. While constructing such a system, many different forces can be considered that could contribute to the strength of the system. These forces may include the capillarity and adhesion between asphalt and aggregate fine particles, the viscoelastic response of the asphalt thin-films between aggregate particles to compression and shear forces, and breakdown of both the cohesive strength of the asphalt and the adhesive bonds between asphalt and aggregate in the presence of moisture. For the sake of the present discussion, figure 2-3.1 depicts a volume element slice of an 8-μm thick asphalt thin-film adhering three aggregate fine particles together in a mastic sub-structure of a pavement structure. If the presence of the aggregate particles in this system have an influence on the ordering of the asphalt molecules at the interface (e.g., first monolayer, first 200-nm, first 1.0-μm, etc) at what distance away from this interface would long-range molecular ordering subside? At what effective distance away from this interface would the asphalt layer have properties similar to a bulk phase state? In the present scenario, asphalt “molecules” present at the interface would experience the strongest interactions with the aggregate surface. Four microns out into the film, approximately halfway between two of these particles, the asphalt should exhibit properties more closely resembling that of asphalt in the “bulk” state. Based on AFM surface imaging it has been observed that thicker thin-films of asphalt (>4.0 μm) do not differ that much in appearance from films that are 10’s of microns or even 1.0-mm in thickness. As these films are decreased to
to the aggregate fine particle interface influence the flow properties of the molecules farther away from the interface and the adhesive properties of the molecules in direct contact with the interface? Figure 2-3.1. Pictorial of a volume element slice of an 8μm thick film adhering three Aggregate fine particles together in a mastic sub-structure of a pavement structure D > d = 8μm. 49
Page 1: Fundamental Properties of Asphalts
Page 5: TASK 1. COORDINATION The goals of t
Page 8 and 9: Support of FHWA Strategic Goals The
Page 11 and 12: SUBTASK 2-2. AGING SUBTASK 2-2.1. I
Page 13 and 14: To further evaluate how water influ
Page 15 and 16: SUBTASK 2-2.2. SUPPORT OF THE MECHA
Page 17 and 18: Work Conducted This Quarter Introdu
Page 19 and 20: greater than 100 micrometers are co
Page 21 and 22: limestone. Major RA elemental oxide
Page 23 and 24: Log G* at 10 rad/s 8 7 6 5 25°C y
Page 25 and 26: Table 2-2.2.3b. Experiment status m
Page 27 and 28: Table 2-2.2.4b. Experiment status m
Page 29 and 30: (a) (b) PA Intensity (arbitray unit
Page 31 and 32: PA - Carbonyl total peak ht. (1700
Page 33 and 34: SHRP RA (granite) PA spectra of RA
Page 35 and 36: Mastics Several asphalt mastics wer
Page 37 and 38: 4000.0 3600 3200 2800 2400 2000 180
Page 39 and 40: • LTA1 (long term aging Level 1):
Page 41 and 42: The increase in carbonyl at the cen
Page 43 and 44: figure 2-2.2.19 to show the correla
Page 45 and 46: The majority of the results were pr
Page 47 and 48: Hirschfeld, T., 1976, Computer Reso
Page 49 and 50: SUBTASK 2-3. NANOTECHNOLOGY: AFM AN
Page 51: comprised of tens of thousands of d
Page 55 and 56: a. Sample, b. cold stage, c. hot st
Page 57 and 58: Problems and Solutions to Problems
Page 59: SUBTASK 2-4. LOW-TEMPERATURE PROPER
Page 62 and 63: Background The addition of polyphos
Page 64 and 65: All different aging times were shif
Page 66 and 67: Log a A 2.5 2.0 1.5 1.0 0.5 AAM-1,
Page 68 and 69: KAO Gripper. The minor resonance wa
Page 70 and 71: Dadey et al. [1988] proposed Scheme
Page 72 and 73: Problems and Solution to Problem No
Page 75: SUBTASK 2-6: VALIDATION SITE MONITO
Page 79: TASK 4. INFORMATION DEPLOYMENT SUBT
Page 83: SUBTASK 4-3. RESEARCH DATABASE—CO
Page 89: SUBTASK 4-5. SUPPORT OF THE MECHANI

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