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 document 2.Update with latest international best practice 3.Identify appropriate documents 4.Agree on content of new TRH 21 5.Appoint a consultant/s to rewrite new document 6.Identify specialists from task team to act as peer reviewers for each section 7.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 RAP Develop 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 (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.Introduction 2.Pavement recycling 3.Use of RAP in HMA plant recycling 4.Feasibility of recycling 5.Mix design 6.Reclaiming of RAP 7.Stockpiling of RAP 8.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