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4. Surface Treatments Questions and Responses AAPA 2011 Study Tour Group ReportTable 4.1 Bitumen gradesAfricangrade(pen)Aus Grade (Vis)African use40 - 50 C32060 – 70 C170 Asphalt80 - 100 C80 Sprayed sealAustralia uses one grade for sprayed sealing and one grade harder for asphalt. This could be whydurability is much more important in Australia. This could also explain why cutter is not used (atleast, not added on site. MC3000, a 80-100 grade bitumen with 12% cutter, may be ordered inadvance.The South African Polymer modified binder specification is polymer blind (it does not distinguishbetween polymer types), and a translation of this is offered in Table 4.2Table 4.2 Polymer Modified BindersClassA-E1A-E2A-H1A-H2S-E1DescriptionAsphalt binder, elastomeric, low polymer (SBS & SBR)Asphalt binder, elastomeric, medium polymer (mostly SBS)Asphalt binder, hydrocarbon, 4-5% GilsoniteAsphalt binder, hydrocarbon, 3-4% SasobitSprayed seal binder, elastomeric, low polymer (SBR, SBS)S-E2 Sprayed seal binder, elastomeric, medium polymer (~3%)S-R1Sprayed seal binder, 5% crumb rubberEmulsionEmulsions are also popular and appear to be more widely used than in Australia for resealing andrejuvenation. An application not practiced in Australia is the use of a fog spray; this involves alight application of a 50:50 diluted rapid set cationic emulsion binder (0.3 – 0.4 l/m2 residual)applied over a seal to bind the aggregate particles together and prevent early stone loss (Figure4.5a). In some circumstances it appears this practice is used instead of precoating. Fog sprays arealso employed in lightly trafficked areas such as shoulders and outside wheel paths to provideadditional binder (Figure 4.5b).V4-2 Page 14
4. Surface Treatments Questions and Responses AAPA 2011 Study Tour Group ReportPrimes and primersealsFor new works primerseals are not used, rather a prime and seal is preferred. If building apavement through winter a prime followed by a modified emulsion double seal is employed.When undertaking pavement rehabilitation under traffic it is common practice to build, prime andseal the road in half widths. Access to the road is maintained on the remaining lane through theuse of stop/go traffic control that may operate 24 hours per day for as many days as necessary.This is undertaken on sections up to 4km in length.ResealsReseals are not normally undertaken during an ‘embargo’ period from May to August due to poorperformance. It is considered that the embargo is partly related to the fact that the use of cuttersis discouraged due to the perceived health and safety risks of adding cutter on site and thepotential for bleeding in summer. Measures taken to improve aggregate adhesion and henceavoid the use of cutter include:• Spraying when pavement temperatures are 25°C and rising• Use of emulsion binders• Aggregate precoating• Prevent trafficking of the seal at night. Similar to rehabilitation sealing is performed in lanewidths with traffic control used to prevent access to the fresh seal overnight. Rolling andsweeping is undertaken the following day when the pavement has warmed. Traffic is onlypermitted on the seal when the pavement temperature is above 15°C.It is recognised that cutter is sometimes necessary, particularly with PMB’s (TG1). In these cases itis preferred that the cutter is added at the refinery or plant. If addition of cutter is required on sitethe contractor is required to provide a method statement addressing the risks. Maximum cutterlevels suggested are 5% for light traffic and 3% for heavily trafficked roads (TG1).Figure 4.5a – Diagram of diluted emulsion fog sprayV4-2 Page 15
Page 1 and 2: Australian Asphalt Pavement Associa
Page 3 and 4: Contents1. EXECUTIVE SUMMARY 22. IN
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Page 7 and 8: 2. INTRODUCTIONIn the forty year hi
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6. Improving Pavement Performance A
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6. Improving pavements performance
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7. Sustainability AAPA 2011 Study T
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8. CAPSA’11 & General AAPA 2011 S
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8. CAPSA’11 & General AAPA 2011 S
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8. General - Questions & Responses
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8. General - Questions & Responses
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Appendix 9.1 - Detailed ItineraryAA
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Appendix 9.1 - Detailed ItineraryAA
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Appendix 9.2 - Study Tour Delegates
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Appendix 9.2 - Study Tour Delegates
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Appendix 9.3- Question ListAAPA 201
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Appendix 9.4 - South African Acrony
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Appendix 9.5 - ReferencesAAPA 2011
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Australian Asphalt Pavement Associa
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