2011_AAPA_Study_Tour.. - Aapaq.org

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5. Binders Questions and Responses AAPA 2011 Study Tour Group ReportQ 17. What properties are required for rubber crumb?The rubber crumbs must comply with the following grading and properties as specified in TG1:Property% mass passing screen:1.18 mm0.6 mm0.075 mmPoly-isoprene content (% mass)Fibre length (mm)Source: TG1Requirement10040 – 700 - 525 min6 maxQ 18. How are modified binders specified? At what point are properties for modified bindersapplied? Point of manufacture or at the point they are delivered to site?PMB’s are specified in accordance with the requirements contained in TG1. They are largelypolymer blind and are based on meeting end binder properties. The properties must comply atpoint of usage. Suppliers are required to provide laboratory certificates tabling specific propertieswith each batch and the other properties on a frequency basis.On large contracts a site laboratory will be established to measure the key binder properties suchas softening point and viscosity. Samples will also be taken and sent for off site testing.Q 19. How is segregation and degradation of modified binders controlled?TG1 provides the following guidelines to manage and prevent degradation of PMB’s on-site:• The tank should be designed with an appropriate circulation system to ensure that there isa constant movement of binder over the flues during heating.• In the event of having to superheat the binder above 180°C it is essential that tanks arefitted with augers or stirrers to prevent localized overheating.• Store the binder at the minimum pumping temperature and not at the applicationtemperature.• The binder should only be heated to the application temperature just prior to use to limitdegradation of the polymer.• Do not allow the binder to solidify in the storage tank as reheating will result in localisedoverheating around the flues. Rather heat the binder intermittently over an extendedperiod to maintain a constant storage temperature.• Avoid rapid heating of the binder. As a rule of thumb the rate of heating should not exceed15°C per hour unless the tank is fitted with an agitation mechanism.V4-2 Page 58
5. Binders Questions and Responses AAPA 2011 Study Tour Group Report• All tanks are to be fitted with calibrated temperature gauges. In the case of a sprayer atemperature gauge should be fitted on the spray bar as well as the tank to ensure that thebinder is sprayed at the correct application temperature.• All established modified binder storage facilities should strive to install temperaturerecording devices with automatic temperature controls for heating.• Obtain a method statement from the supplier on the correct handling and storagetemperatures for the modified binder.Q 20. To what extent are emulsions used in sealing? Is there a push to use emulsions based onenvironmental reasons?Emulsions are use in various forms in the construction of seals. They are used mainly:• For priming granular and crushed bases• In the construction of spray seals in winter especially Cape Seals• In slurries for texture treatments, rutfilling and slurry for constructing Cape seals• For dilute covers sprays on newly constructed spray seals to prevent early stone loss• For rejuvenator and enrichment sprays for aged sealsV4-2 Page 59
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Australian Asphalt Pavement Associa
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Contents1. EXECUTIVE SUMMARY 22. IN
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1. Executive Summary AAPA 2011 Stud
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2. INTRODUCTIONIn the forty year hi
Page 9 and 10: 3. Overview and Recommendations AAP
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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 9.4 - South African Acrony
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Appendix 9.5 - ReferencesAAPA 2011
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Australian Asphalt Pavement Associa
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