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

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in the literature on the use of polymerized asphalt emulsions on trails and parking lots as noted previously. 3.2.2 Task 2B. Identifying and Specifying Polymer Percentages Experience has shown that specifying polymer percentage does not necessarily result in the expected performance because of differences in compatibilities between asphalt and polymers from different sources. Moreover, feedback received from industry participants at the St. Louis meeting in 2006 clearly indicates that suppliers view polymer quantity specifications as a practice which serves to inhibit innovation – a problem which can be remedied with the adoption of appropriate performance specifications. Thus, performance testing rather than recipe specifications should result in the longest lasting, most cost-effective treatments, by affording suppliers the opportunity to prescribe the polymer types, formulation methods, and mix design flexibility to meet agency and end-user requirements. Specific methods which are currently under consideration are discussed elsewhere in this report. Because of the importance of uniformity and compatibility to performance, it is recommended that the polymer not be post-blended with the asphalt emulsion in the field, particularly since both SHA and industry stakeholders have openly discouraged this practice. Low temperature recovery of asphalt emulsion residues will simulate emulsion curing much more effectively than current recovery methods which are performed at temperatures that are far higher than these products will ever experience in the field. The high temperatures associated with currently used recovery methods have been shown to change the residue rheological properties, as the modulus is usually cut in half by heating the sample to 350º C, as opposed to using a low temperature Forced Draft Oven Method. Also, phase angles from high temperature distillation suggest that heating can cause cross-linking and damage to polymer additives. Therefore, it is recommended that a low-temperature method be adopted which is more representative of field curing conditions. Several such methods are under investigation by various 107
esearchers, with the leading candidate being a Forced Draft Oven Procedure similar to a recent European standard which is expected to be presented to ASTM later this year. Rheological performance tests on the residue should identify the polymeric properties as well as high-float gel structures. While there is some concern that performance testing will be more time-consuming and result in shipping, construction and acceptance delays; a supplier pre-certification or delayed-acceptance program should facilitate the process. 3.2.3 Task 2C. Projected Performance and Cost Costs vary significantly from region to region, depending upon the local costs and local availability of emulsified asphalt and aggregate materials, contractors and expertise. Section 2.10 and Table 11 above give more information on the projected costeffectiveness and extended performance of PME. 3.2.4 Task 2D. Further Investigation There are several data gaps in the available information. Nearly everyone in the industry believes that specifications for PME chip and slurry seals need to be changed so that they better predict field performance. While Superpave greatly improved the specifications for HMA, the tests and specifications developed are not necessarily the same criteria needed to specify performance for PME applications, but the tools may prove useful, albeit in some modified form. In fact, there are several studies independently investigating these. A “PG-type” system consistent with the base asphalts used by the binder industry and dependent upon binder rheology and climatic and traffic conditions would be generally acceptable, if it does not disrupt the supply and truly relates to PME surface treatment performance. The “Strawman” specification given in Table 12 suggests a promising series of protocols, but data gaps are significant. When collected for “report only”, these data will be used to validate or adjust these methods as related pavement performance dictates. Most suppliers indicate they would be willing to pay for or perform these tests on upcoming FLH projects. Two or three commercial laboratories (PRI, Paragon, perhaps 108
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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
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1. Compile published research on th
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2.0 LITERATURE REVIEW OF POLYMER MO
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the emulsion solution is termed the
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molecular weights ranging up to 100
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Elastomeric polymers exhibit a low
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The first commercial process that w
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2.2.3 Synthetic Rubber and Latex Sy
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Latex Modified Unmodified 80 Chip R
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of residual asphalt (3). Additional
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Sabbagh and Lesser (1998) note that
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2.2.6 Plastics The plastic polymer
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high temperature performance, but w
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2.2.7 Polymer Blends Select polymer
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Table 2: Polymer Modification Metho
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Forbes et al found that asphalt emu
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Lubbers and Watson (2005) present t
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Takamura and Heckmann (1999) sugges
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Neat Asphalt + 8% LDPE1 + 8% LDPE2
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Figure 16: Effect of SBS Concentrat
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destruction of the polymer modifier
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emulsified and non-emulsified aspha
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However, in developing the SPG, Epp
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• Forced Air-Drying Method - This
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• Wet Track Abrasion Loss - used
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ductility (61). King characterizes
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Polymer modified asphalt emulsions
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3 40-120º F 5.02 12.81 6.04 14.92
Page 63 and 64: emulsions require a much longer set
Page 65 and 66: Figure 20: Chip Seal Aggregate Rete
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Page 69 and 70: Holleran (n.d.) recommends using SB
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Page 75 and 76: Microsurfacing applications by defi
Page 77 and 78: Thus, the cohesive properties of SB
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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
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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
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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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Page 113: traffic areas, as are durable, poli
Page 117 and 118: Table 13 illustrates a draft Strawm
Page 119 and 120: Laboratory Design Procedures • Ch
Page 121 and 122: • Develop/improve performance met
Page 123 and 124: specification tests will cost appro
Page 125 and 126: PROPERTY TEST METHOD SPEC. RESULT B
Page 127 and 128: 14. Takamura, Koichi, “SBR Latice
Page 129 and 130: 38. Turk, Johannes, and Schmidt, Ma
Page 131 and 132: 62. Desmazes, C., Lecomte, M., Lesu
Page 133 and 134: 86. European Standard EN 14895, “
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