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7. Sustainability - Questions & Responses AAPA 2011 Study Tour Group ReportQuestions (#1, 2, 3, 13)Q 1. What percentages of recycled asphalt is used in South Africa? Estimated tonnage? Does itvary by urban / regional and by Province.In the 80’s to 90’s significant qualities of RA was used on project work including use as sub base toconcrete pavements. This dropped off in the late 90’s with the total of RA as a percentage of newHMA estimated at 5% in 2005. The increased cost of raw materials and the relatively higher costof bitumen resulted renewed attention with the publication of the TRH21 in 2009.The use of RA in South Africa is limited by its availability. Most road pavements and surfacingsconsist of granular layers with thin bitumen seals. Thick asphalt pavements are limited to majormetropolitan areas, their major connecting highways and in some of the major airports. In themetropolitan areas the RA is included at percentages generally around 5 to 15% depending onavailability. Most projects where RA is available will have that either stockpiled for future worksor included in the mix for that project.The total production of asphalt is South Africa is approximate 4.5 million tonnes which at the 2005RA % would equate to 225 000 tonnes annually.Q 2. What percentages of RAP are allowed in wearing course, binder course and base course?The use of RA is permitted in the most widely used specification, COLTO Series 4200: Asphalt baseand surfacing which provides not limits on the percentage of RA permitted in hot mix asphalt. Thespecification does require that the asphalt meets all the specification criteria and conforms toadditional handling and QC criteria. This includes the evaluation of the RA, testing frequencies andstockpiling requirements.TRH 21 provides a range of permitted amounts as per Table 8.5In practice each project is evaluated against the amount of RA available and the maximumpercentages that can be included in the mix. When RA is fractionated into aggregate sizes theproportions of the resulting RA will vary in residual binder content and this will influence themaximum percentages in Table 8.5.V4-2 Page 98
7. Sustainability - Questions & Responses AAPA 2011 Study Tour Group ReportThe introduction of Warm Mix Asphalt Technologies using foamed bitumen, organic waxes,surfactants & zeolites and has seen the inclusion of higher percentages of RA in all layers due tothe less hardening of the bitumen with the lower mixing temperatures and improved coatingachieved. This has particular relevance to wearing courses.For cold in-place and cold in-plant recycling 100% of the existing material is reused with theaddition of foamed bitumen or bitumen emulsion. Whilst not currently used in South Africaanymore, hot in-place recycling makes use of only small additions of virgin aggregate resulting invery high percentages of RA in the final pavement.Q 3. Are their restrictions on the use of modified binders in RAP? Are their restrictions on theuse of RAP in modified binder mixes?RA from asphalt including EVA and SBS modified binders is permitted and is not considered aproblem for recycling. Additional care is recommended in the preliminary mix design stage whenusing this RA in excess of 30%. RA that is derived from bitumen rubber modified asphalt should betreated with extra caution where the RA content exceeds 15%.There is no guidance given or specific exclusion in the use of RA in modified binder mixes. Indiscussion with South African practitioners less that 15% RA is added to modified asphalt mixeswhich continue to achieve the mix design criteria.Q 13. How do they manage RAP from milling of the City &Urban projects? Is SANRAL or Sabita(members) responsible for transport, storage and processing of RAP?The ownership of RA varies by project and jurisdiction. Typically the RA is preserved for use by theroad authority and then made available for inclusion in given projects. The evaluation andsubsequent processing of the RA is undertaken as part of the project development and execution.The Sabita hot mix asphalt producers collect and process RA for incorporation into normal asphaltoperations as percentages varying from 5 to 15%.Recycling and in-plant foam stabilization – eThekwini / Durban MunicipalityIn the example of the eThekwini / Durban municipality the RA (and other reusable constructionmaterial) is planned and managed from project inception to material usage, with the pavementmanagement system used to monitor and manage the value / status of the materials. The councilV4-2 Page 99
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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
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3. Overview and Recommendations AAP
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3. Overview and Recommendations AAP
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4. Surface Treatments Questions and
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5. Binders AAPA 2011 Study Tour Gro
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Page 122 and 123: Appendix 9.1 - Detailed ItineraryAA
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Page 126 and 127: Appendix 9.2 - Study Tour Delegates
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Page 131: Appendix 9.3- Question ListAAPA 201
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Australian Asphalt Pavement Associa
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