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

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2.9 Impact of Materials Selection The literature review failed to yield significant available research into the compatibility and selection of materials used in conjunction with PME based systems. Indeed, thin surface treatment research in general was found to be lacking overall in this area, with most investigators concentrating on individual component impacts, or “whole system” performance (e.g., chip seals). 2.9.1 Polymer Type A review of the available research indicates no clear empirical evidence that one type of polymer modifier is inherently superior to another with respect to performance, at least between the most commonly used types (i.e., SBR and SBS). A recent study of stone retention in chip seals performed by Kucharek et al (2006) indicates that while latexbased PME may require more curing time than pre-blended PME to fully achieve the aggregate retention benefits associated with polymer modification, performance between the two binder types is comparable after only 24 hours (80). Moreover, Kucharek concludes that “no special benefit has been observed so far from having the SBR polymer both inside and around the asphalt binder;” citing the need for additional research (80). 2.9.2 Surfactants & Emulsion Type Surfactant chemistry is a complex and multifaceted area of study and as such, is well beyond the scope of the current review. Although published literature on the variation in PME thin surface treatment performance with respect to surfactant types is relatively scant (much of these data are proprietary in nature), a few researchers have attempted to identify high level differences between modified anionic and cationic emulsions. Kucharek et al (2006) assessed the chip retention characteristics of a variety of anionic and cationic emulsions modified with different polymers (80). In this study, emulsion and whole system (i.e., chip seal) performance evaluations were accomplished using DSR, the Frosted Marble Cohesion Test, and the Sweep Test for Thin Surface Treatments. Overall, cationic PME mixes demonstrated considerably higher moduli during the first few hours of curing than did similarly modified anionic preparations. 73
Moreover, although the moduli of the anionic group did gain some ground on the cationic test samples as curing progressed, the modulus values of the anionic mixes were not found to reach the same levels as the cationic group, even after a 24 hour cure period (80). Kucharek reports that cationic emulsions consistently demonstrated better chip retention characteristics (as measured in the sweep tests) than anionic emulsions for all the aggregate types studied. Cationic mixes also showed less sensitivity towards the varying chemical composition of the aggregates tested than did those prepared using anionic emulsions (80). 2.9.3 Aggregates One of the few issues identified during the literature review with respect to aggregatepolymer interactions pertains to the use of moisture-sensitive aggregate in thin surface treatments. In this regard, aggregates such as moisture-sensitive gravels may exacerbate the effects of hydrogenesis in arid climates, leading to water film buildup beneath a relatively impermeable polymer modified surface treatment (78). Moreover, in cooler climates pre-existing excess water retention problems can lead to freeze-thaw damage (72). Arguably, these potentially negative interactions are representative of an indirect relationship between aggregates and polymers. That is, the use of PME in certain climates - when placed atop a base course containing moisture-sensitive aggregate or one that already has a pre-existing water retention problem - may be contraindicated. Overall, the impact of polymers on moisture sensitivity is not well understood at this time. Moreover, chemical sensitivity issues between aggregate and various types of polymers could also present some challenges in certain cases. But the literature review presented herein turned-up little to no information regarding chemically sensitive aggregates and the use of PME. Indeed, the available research points overwhelmingly toward the ability of polymers to impede moisture penetration, enhance stone retention, and increase overall pavement durability. However, caution should be used to determine whether the base course has a fundamental water retention problem prior to the application of any PME-based thin surface treatment. 74
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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
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 and 60: Polymer modified asphalt emulsions
Page 61 and 62: 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
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: dimensional polymer network is pres
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
Page 111 and 112: opportunity to evaluate performance
Page 113 and 114: traffic areas, as are durable, poli
Page 115 and 116: esearchers, with the leading candid
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
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62. Desmazes, C., Lecomte, M., Lesu
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86. European Standard EN 14895, “
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