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Progress since last RPF
Resolution passed at Nov 07 RPF that a task team be established to:
• to develop best practice guidelines for the use of RAP in HMA
• this follows from 3 SAT seminars & specialty session held at CAPSA07
• first task team meeting held 24 April
Task Team• Client
– Dennis Rossmann– Adreo Brits– Rob Lindsay– Eric Lathlief/
Krishna Naidoo
• Engineers– Derick Pretorius– Tony Lewis– Nico vd Walt– Benoit Verhaege
• Manufacturers & Contractors– Bennie Greyling– Herman Marais– Wynand Nortje– Gary Catin
Plan of action
1. Use draft TRH 21 (1996) as working document2. Update with latest international best practice3. Identify appropriate documents4. Agree on content of new TRH 215. Appoint a consultant/s to rewrite new
document6. Identify specialists from task team to act as
peer reviewers for each section7. Contract specifications to be incorporated into
revised COTO document• SANRAL to include in proforma project specifications
Proposed specification framework
• 3 classes of HMA– < 15% RAP– > 15 < 30% RAP– > 30 % RAP
• Prescribe same mix end properties irrespective % of RAP within each class of HMA
• For each class identify:– risk/application/constraints/protocols
Paradigm shift
• Treat RAP as a valuable asset of the State
• RAP to be regarded as an alternative aggregate source ie linear quarry
• Stockpile RAP for general use on future projects
• Optimise use of RAP• RAP to be seen as
competitive advantage
Handling of RAPDevelop protocol for reclaiming, stockpiling and processing
RAP
• Milling of RAP– Investigate insitu layers– Selected premilling
• Stockpiling of RAP– Demarcate dedicated stockpiles – Minimise moisture content of RAP– Avoid segregation and consolidation
• Processing of RAP– Screen RAP into different sizes– Fractionating of RAP when using >15%– Plant limitations
• Type of plant• Where the RAP is feed into mixing process
Reference documents
• Brock D (2007), Milling & recycling, Technical paper T-127
• Newcomb D (2007), Designing HMA mixtures with high RAP content, QIS 124
• Young T (2007), Processing & handling of RAP, IS 123
• EN 13108-8 (2005), Bituminous mixtures – materials specifications for reclaimed HMA
• Austroads (2000), Framework specifications for HMA recycling, AP-T02
• Rebbechi J (2005), Austroads guide & commentary series on HMA recycling
• PIARC (2007), Review of the growth & development of recycling in pavement construction
Content
1. Introduction2. Pavement recycling3. Use of RAP in HMA plant recycling4. Feasibility of recycling5. Mix design6. Reclaiming of RAP7. Stockpiling of RAP8. Mixing & plant