Using Polymer Modified Asphalt Emulsions in Surface Treatments A ...

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CSS-1h 20 - 100 -- -- 57% 40 - 90 40 † Applies to liquid asphalt emulsion ‡ Applies to asphalt emulsion residue Table 5 presents the key physical property parameter requirements specified under AASHTO M 208 and M 140 (i.e., ASTM D2397-05 and ASTM D977-05, respectively) for comparison and discussion purposes. As has already been covered in some detail, the literature review unequivocally illustrates that polymer modified asphalt binders (i.e., PME and PMA) exhibit significant performance benefits over unmodified equivalents (4, 12, 14, 20, 21, 24, 25, 31, 33, 48, 49). Demonstrable benefits include increased rutting resistance, improved chip/stone retention, improved elasticity and ductility, increased fracture toughness, improvements in the penetration index, decreased low and high temperature susceptibility, and improved fatigue resistance. Although polymer blending techniques appear to impact mixture performance, all of the methods examined performed better when compared to unmodified binders. 2.4.4 Modified versus Unmodified Asphalts Khosla and Zahran (1988) compared the performance of unmodified and Styrelf® polymer modified mixtures of three commonly used asphalt cements: AC-5, AC-10, and AC-20 (64). Styrelf® is a proprietary blended modified asphalt product produced by Total, which utilizes a cross-linked elastomeric polymer additive. Khosla and Zahran evaluated each asphalt preparation under varying load conditions and operating temperatures using the resilient modulus test, and reported that they were able to predict the fatigue, deformation, and brittleness of each of the binders. These test results were then used to simulate the predicted service life using the VESYS III computer model in each of the four major climatic regions as shown below in Table 6. Table 6: Predicted Service Life (years) After Khosla (64) Region Temp. Range AC-5 AC-5 Styrelf® AC-10 AC-10 Styrelf® AC-20 AC-20 Styrelf® 1 0-90º F 9.83 15.90 11.96 17.13 15.10 19.01 2 40-90º F 6.24 14.39 8.04 16.55 11.94 18.53 53
3 40-120º F 5.02 12.81 6.04 14.92 10.40 16.39 4 40-140º F NA 10.32 NA 12.76 6.63 14.21 As Table 6 suggests, in each case the Styrelf® asphalt mixtures appeared to yield significant improvements in overall predicted service life as compared to their unmodified parent asphalts. The performance impacts of polymer modified binders were further evaluated specifically with respect to predicted rut depth, fatigue cracking, and low temperature cracking for various service year benchmarks. Quantitatively, Khosla and Zahran estimated the approximate resulting magnitude of rut depth and the degree of fatigue cracking (using cracking indices) over time. Additionally, low temperature cracking susceptibility was determined by a stiffness value that was formulated based upon creep tests conducted at temperature benchmarks of -20º F, 0º F, 20º F, and 40º F, respectively. Khosla and Zahran conclude that: 1. Styrelf® mixtures have better low temperature susceptibility than their unmodified counterparts, and are thus, less brittle; 2. Styrelf® asphalts are more resistant to low temperature cracking; 3. The Styrelf® samples exhibited a reduced propensity for rutting deformation at higher temperatures than the unmodified asphalts; and, 4. Polymer modification of Styrelf® asphalts results in improved fatigue life (64). Takamura (n.d.) has compared the rut-resistance performance of unmodified asphalt emulsions in microsurfacing applications as shown in Figure 19 (54). In the early stages of curing, the rutting resistance comparisons between modified and unmodified mixes are unremarkable. However, the modified asphalt emulsion residues show significantly better rut-resistance than unmodified mixtures after just a few days of curing, particularly in mixes where Portland cement is added to the modified emulsion (due to resulting increases in pH). Note also that when compared to unmodified asphalt emulsions, the curing time to achieve optimal rutting resistance is considerably longer in the modified residues (about 20 days versus approximately 7-8 days). This has 54
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Using Polymer Modified Asphalt Emul
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2.10 SURFACE TREATMENTS, DISTRESS,
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EXECUTIVE SUMMARY Needs to be Compl
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DISCLAIMER This document is dissemi
Page 9 and 10: 1. Compile published research on th
Page 11 and 12: 2.0 LITERATURE REVIEW OF POLYMER MO
Page 13 and 14: the emulsion solution is termed the
Page 15 and 16: molecular weights ranging up to 100
Page 17 and 18: Elastomeric polymers exhibit a low
Page 19 and 20: The first commercial process that w
Page 21 and 22: 2.2.3 Synthetic Rubber and Latex Sy
Page 23 and 24: Latex Modified Unmodified 80 Chip R
Page 25 and 26: of residual asphalt (3). Additional
Page 27 and 28: Sabbagh and Lesser (1998) note that
Page 29 and 30: 2.2.6 Plastics The plastic polymer
Page 31 and 32: high temperature performance, but w
Page 33 and 34: 2.2.7 Polymer Blends Select polymer
Page 35 and 36: Table 2: Polymer Modification Metho
Page 37 and 38: Forbes et al found that asphalt emu
Page 39 and 40: Lubbers and Watson (2005) present t
Page 41 and 42: Takamura and Heckmann (1999) sugges
Page 43 and 44: Neat Asphalt + 8% LDPE1 + 8% LDPE2
Page 45 and 46: Figure 16: Effect of SBS Concentrat
Page 47 and 48: destruction of the polymer modifier
Page 49 and 50: emulsified and non-emulsified aspha
Page 51 and 52: However, in developing the SPG, Epp
Page 53 and 54: • Forced Air-Drying Method - This
Page 55 and 56: • Wet Track Abrasion Loss - used
Page 57 and 58: ductility (61). King characterizes
Page 59: Polymer modified asphalt emulsions
Page 63 and 64: emulsions require a much longer set
Page 65 and 66: Figure 20: Chip Seal Aggregate Rete
Page 67 and 68: design specifications are meticulou
Page 69 and 70: Holleran (n.d.) recommends using SB
Page 71 and 72: 22 20 18 Vertical Displacement (%)
Page 73 and 74: seal stone retention, and to provid
Page 75 and 76: Microsurfacing applications by defi
Page 77 and 78: Thus, the cohesive properties of SB
Page 79 and 80: dimensional polymer network is pres
Page 81 and 82: Moreover, although the moduli of th
Page 83 and 84: Numerous decision tools and best pr
Page 85 and 86: 3.0 LABORATORY TESTING AND SPECIFIC
Page 87 and 88: and performance-related specificati
Page 89 and 90: were consistently twice as high as
Page 91 and 92: • Polymer/Asphalt Compatibility a
Page 93 and 94: angle at the lowest pavement temper
Page 95 and 96: damaged by temperature. The problem
Page 97 and 98: Because the industry survey and oth
Page 99 and 100: conforming to the following criteri
Page 101 and 102: with faster curing and longer wear.
Page 103 and 104: Table 17: Comparison of Microsurfac
Page 105 and 106: Emulsion/Aggregate Performance Test
Page 107 and 108: the FLH report-only format be used
Page 109 and 110: leading the negatives. If post-blen
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opportunity to evaluate performance
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traffic areas, as are durable, poli
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esearchers, with the leading candid
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Table 13 illustrates a draft Strawm
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Laboratory Design Procedures • Ch
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• Develop/improve performance met
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specification tests will cost appro
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PROPERTY TEST METHOD SPEC. RESULT B
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14. Takamura, Koichi, “SBR Latice
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38. Turk, Johannes, and Schmidt, Ma
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62. Desmazes, C., Lecomte, M., Lesu
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86. European Standard EN 14895, “
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Using Polymer Modified Asphalt Emulsions in Surface Treatments A ...

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