Current and future developments in asphalt technology

Transcription

1 Current and future developments in asphalt technology Erik Denneman For presentation at AAPA and QTMR Workshop 5 April 2013, Eagle Farm

2 Structure of short presentation Conventional asphalt mix design Current directions in asphalt technology Current Austroads related work Improved design procedures for asphalt pavements High modulus asphalt Maximising the re-use of Reclaimed Asphalt Pavement 2

3 Conventional mix design Differs per road authority, bot nationally and internationally but typically: Focus on volumetrics and specification of components (grading, binder) Advantages: Straightforward Decades of experience Fairly reliable determination of optimum binder content Disadvantages: No direct link to pavement design methods Empirical, reactive specifications 3

4 Directions in asphalt technology Strong international trend towards performance related design Concept of performance specifications: Evaluate mix properties based on field loading conditions (climate, traffic) relevant to site. Describe required performance, rather than prescribing mix composition. Testing mostly mix and binder type blind. Simplification: fewer, but more reliable tests, only one test per performance parameter. Reduces barriers to innovation and promotes efficient use of natural resources, without sacrificing performance. 4

5 Directions in asphalt technology SUPERPAVE in the US Performance Grade (PG) binder selection, based on traffic loading and field temperature Performance related testing for permanent deformation, fatigue cracking and low temperature cracking EN and EN standards series in Europe Second generation to be completely performance related Performance related tests for: workability, elastic modulus, permanent deformation, fatigue and durability CE Marking of performance properties for asphalt designs Performance related design in Austroads guide part 4B State of the art at time of introduction Link with pavement design could be improved No plans to revisit the design method at this stage 5

6 Vision of performance related design Pavement analysis Vertical plane parallel to Y-Z at X = 0 Shear Strain YZ Structural requirements Property value E* [GPa] > 5 Fatigue [με to 10 6 ] > 300 Perm. def. [ε p ] < 2% Mix selection Property Mix 1 Mix 2 Mix 3 E* [GPa] Fatigue [με to 10 6 ] Tender specification Property value E* [GPa] > 5 Fatigue [με to 10 6 ] > 300 Perm. def. [ε p ] 0.8 % 1.5 % 4.2 % Workability [voids] Durability [TSR] Perm. def. [ε p ] < 2% Workability [voids] < 6% Durability [TSR] > 80%

7 Note: The previous slides showed an overview of international trends, there are currently no Austroads projects planned to further the implementation of performance related asphalt design in Australia. 7

8 Current related Austroads projects TT1353: Asphalt properties and mix design procedures SMA design procedures Restructuring of Part 4B High modulus asphalt: Best practice review and limited laboratory testing TT1826: Improved design procedures for asphalt pavements Review US work on healing and fatigue in asphalt Review potential application of E* master curves (flexural, dynamic, other) TT1817: Maximising the re-use of reclaimed asphalt pavement materials Characterisation of the binder blend containing RAP Characterisation of performance of mixes containing RAP 8

9 High modulus asphalt Origin: France early 90s Enrobés à Module Elevé (EME) Typical characteristics: High binder content 6% by mass of aggregate, Hard grade binder: Pen 10-25, Low air voids content, High Modulus > 14 GPa at 15 C, 10 Hz, High resistance against permanent deformation, Good fatigue resistance, Impermeable, High mixing temperature. 9

10 Modulus 10

11 Improved design procedures for asphalt pavements Pavement temperature prediction: 11

12 Maximising the use of RAP 12