Feedback on HMA recycling task team

Trevor Distin

RPF May 2008

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

Way forward

• Appoint consultant/s – June 2008

• Complete first draft – Nov 2008 RPF

• Publish best practice document– Jan 2009

• Workshop best practice document– Feb 2009