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Explore the relations between CEN standards and performance-based operations in the context of European asphalt standards implementation. Understand the challenges, differences in testing, factory control, and the transition from national to European standards.
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Relation between CEN standardsand performancebased operations By JP Michaut Colas’ Group
What are the raised issues by the implementation of the European standards for aggregate and asphalt concrete in tendering ?
Asphalt concrete WG1 /TC227 meeting in Berlin
What asphalt standards ? The figures • 7 European product standards • 1 Reclaimed asphalt standard • 1 Type testing standard • 1 Factory production control standard • 43 test standards
European asphalt standards • Asphalt Concrete 13108-1 • Very Thin Asphalt Concrete 13108-2 • Soft Asphalt 13108-3 • Hot Rolled Asphalt 13108-4 • Stone Mastic Asphalt 13108-5 • Mastic Asphalt 13108-6 • Porous Asphalt 13108-7
European asphalt standards • Reclaimed asphalt or so called RAP 13108-8 • Type testing 13108-20 • Factory production control 13108-21 • and one new European standard for Ultra Thin Asphalt Concrete (BBUM) ?
Asphalt concrete • From thin asphalt concrete to EME, from dense bitumen macadam to HDM and HMB and other AC (from 4 to 15 cm thick by layer) • One only standard for base, binder and wearing courses • 2 approaches: empirical or fundamental For the other standards • One empirical standard per product
Empirical or fundamental ? • Empirical = recipe • Performances related specifications (rutting) • Fundamental = stiffness modulus, fatigue and triaxial • Performances based specifications • But may be we can speak just about performance and specification
What content ? • General requirements (grading, void content, water resistance, rutting, etc.) You can choose • Empirical (range for grading, binder content, Marshall only for airfield, void filled with binder, etc.) You can choose • Fundamental (modulus, resistance to permanent deformation by triaxial test, fatigue) You can choose • But do not forget that european standards does not take into account laying.
Fundamental approach • One specification is the minimum binder content • greater than 3 % • One other is the limit of target composition • range for main sieves (1.4 D, D, 2 mm, 0.063 mm)
With fundamental approach, you can propose design alternative by using the real mix performances such as stiffness and fatigue • But we must have performances for all mixes
What changes due to type testing? Type testing or how to prove that asphalt concrete meets standard requirements
A single mix formulation is valid for 5 years except if changes in aggregate (category, particle density, etc.) or in bitumen • Laboratory validation or Production validation or Production and laboratory validation • List of tests per product to carry out to demonstrate standard conformity • One test for one property
What changes due to the factory production control ? • Systematic production control • More or less control for certain mixing plants
Factory production control • Based on quality assurance (ISO 9001) • Based on detailled analysis of the mix • Depending of non conformities (figures outside tolerances), level of minimum frequency for analysis of finished product • Level fo frequency fixed by the standard (more or less numerous) • Guide for audit by notified body is in the standard
Before works, you have to prove that your mix meets the standard requirements: this is type testing • During works, you have to check asphalt manufacturing : this is factory production control (loose mix) • But for laying, you have to prescribe the controls or the performances you want : this is the contract.
To conclude for asphalt • En asphalt standard will be published in April 2006 • Withdrawal of all national asphalt standards in December 2007 • You have to write your national forewords and also may be a guide to describe your choice
And for aggregate Already applied since July 2003 Withdrawal of national standard Since June 2004 Just one only standard
Four parts • Aggregate characteristics and specifications • Initial type testing or How to prove that the aggregates meet the standard requirements • Factory production control • And a national foreword
Characteristics and specifications • Sieve sizes (3 possibilities) Basic set, basic set + set 1 or basic set + set 2 • Grading • Choice of physical or manufacturing characteristics and choice of specifications or not
Initial type testing • For a new source • Major change in the nature of the raw materials or in the processing conditions • But in fact, tests used are those for factory production control
Factory production control • Based on quality assurance • Minimum test frequency are specified, examples: • Grading: one per week and per size • Shape of coarse aggregate: one per month • And one audit by notified body
What differences ? • Grading : perforated sieves and not wire sieve (adaptation or interpretation issue ?) • Example: 4/6.3 mm control (1.4 D) or 8.82 mm • Close sieves in set 2 are 8 and 10 • But ISO 565 , R20 set: 9 mm ? • Then which one to choose ?
But are they ? • Well known asphalt concrete formulation • Keep the same composition (x% of each constituant) • Grading curve with perforated sieve • New grading curve • But always the same formulation and composition Wide grading : no difference Narrow grading : light difference You have to do your own experience
But also some difficulties • Measurement of aggregate particle density before and after: not the same results • Some standards are already reviewed due to mistake, difficulty for performing test, etc (in progress) • Conformity criterias are missing
Positive and negative effects !!! • In Europe, we will speak the same language and we will use the same test methods (PE) • Each mix has to be checked every 5 years (PE) • Each mix of each mixing plant has to have a type testing (PE) • Factory control more efficient based on regular frequency production (PE)
Positive and negative effects and others !!! • Difficulty to understand european standards and hence the need to have a national foreword (NE) • Need a fundamental approach for each product (porous asphalt, SMA, etc) • Need to describe the performances for laying (in terms of compacity or others)
To conclude • En asphalt standard will be published in April 2006 • Withdrawal of all national asphalt standards in December 2007 • Writing of national forewords in progress for certain countries And good luck for implementation in your contracts