Corporación de Desarrollo Tecnológico Conferencia Tecnológica: Asfalto Espumado; la experiencia australiana y su aplicación en Chile 28 de agosto de 2013 Foamed bitumen mix design and thickness design: research to improve current processes Geoff Jameson Investigador en ARRB Group www.cdt.cl Corporación de Desarrollo Tecnológico 45 páginas
Foamed bitumen mix design and thickness design : research to improve current processes Geoff Jameson Chief Scientist, Pavements ARRB Group Chilean Construction Chamber Wed 28 August 2013 www.arrb.com.au Advancing safety and efficiency in transport through knowledge research consulting technology
Presentation Outline Objectives of the foamed bitumen research Development of mix design method Improve thickness design method Field performance studies 3
Australia Population: 23 million 7 states 2 territories 4
National highway: 18,600 km Total road length: 813,000 km Population: 23 million Sealed: 323,000 km Unsealed: 490,000 km 5
Climate and Rainfall Dry interior Wet along coastline 6
95% Australian sealed road network, thin bituminous surfaced granular pavements Bituminous binder & aggregate Unbound granular base Unbound granular subbase Subgrade 7
Unbound granular base 8
In situ foamed bitumen stabilisation increased over last 10 years typically 3.5% bitumen and 1.5% quicklime limited use of cement, concerns about cracking now trialling 2.5% bitumen 9
Four year national research project (2012-2016) The purpose of this project is: To improve and harmonise national mix design procedures To improve thickness design procedures does material fatigue crack? 10
Foamed Bitumen Stabilisation Working Group A very important element in the success of the project is the close collaboration between road agencies, contractors and the researchers Project guided by a Working Group comprising: State road agencies Stabilisation industry contractors Researchers ARRB Group 11
Mix design mix design test methods vary throughout Australia need for harmonisation need to relate mix design properties to field performance 12
Mix design based on indirect tensile modulus 13
National working group developing test methods T301 T305 Determination of Foaming Properties of Bitumen Mixing of Foamed Bitumen Stabilised Materials (includes method of establishing mixing moisture content) T310 Compaction of Test Cylinders of Foamed Bitumen Stabilised Mixtures : Part 1 Dynamic compaction using Marshall drop hammer T311 Compaction of Test Cylinders of Foamed Bitumen Stabilised Mixtures : Part 2 Gyratory compaction T313 Compaction of Test Slabs of Foamed Bitumen Stabilised Mixtures T320 T321 T330 T340 Curing of Test Cylinders of Foamed Bitumen Stabilised Mixtures Curing of Test Slabs of Foamed Bitumen Stabilised Mixtures Resilient Modulus of Foamed Bitumen Stabilised Mixtures Deformation Resistance of Foamed Bitumen Stabilised Mixtures by the Wheel Tracking Test 14
Lack of national test methods hindering progress 50 blows Marshall hammer Gyratory compaction to field density 15
Compaction method major influence on modulus 16
Research in 2013/14 Effect of compaction method (Marshall, Standard drop hammer, gyratory) on modulus and density Effect of mixing moisture content on compactibility and modulus 17
Also the link between laboratory and field properties not well understood 18
Coring pavement in early life measuring comparing modulus with laboratory mix design results 19
Calder Freeway example 20
Improve modulus specifications usefulness of initial modulus in terms of the rutting on opening to traffic selecting a design modulus is bitumen stripping an issue and how useful is retained modulus ratio 21
Thickness design 22
Mechanistic approach Assumption is that foamed bitumen stabilised material is susceptible to fatigue cracking 23
Thickness design of FBS layers current thickness design based on modified asphalt fatigue relationship need to verify 24
Field performance monitoring Monitoring of in service roads six existing pavements were identified heavily trafficked roads Construction and monitoring of under-designed roads constructed three pavements designed such that they are predicted to fatigue crack with in 3 years another under-designed pavement will be constructed early 2014 foamed bitumen stabilisation thicknesses 150-200 mm 25
Performance under-designed pavements, colder climates more susceptible to fatigue Kwinana Freeway Port Wakefield Road Calder Freeway 26
1. Calder Freeway constructed March 2013 collaboration between road agency, contractors and researchers 27
4 th March FBS construction 100 m length 4.8 m width slow lane and part shoulder 2 x 2.4 m widths crushed rock base stabilised to depth of 150 mm 3.5 % bitumen & 1.5% quicklime 28
Mix design Research task compare modulus of material sampled from road bed and compacted in lab with laboratory-manufactured materials compare field core moduli with moduli of laboratorymanufactured specimens Compaction test specimens in the field? 29
Research task Early-life characteristics rutting and ravelling strength gain surface deflections modulus of field cores usefulness of initial modulus 30
Research tasks Performance over 3 years rutting roughness cracking modulus 31
Condition after 1 month of trafficking 2 coat chip seal surface 32
FWD deflections were measured 8 days & 1 month after FBS construction Deflections measured in loaded and unloaded areas of pavement to estimate modulus changes with time and loading: on the edge line in the outer wheel path between the wheel paths 33
Curvatures low and consistent There is a need to develop a temperature adjustment procedure 0.10 Calder Freeway Woodend foamed bitumen stabilised material 8 days post construction pavement temperature 29 C 0.10 Calder Freeway Woodend foamed bitumen stabilised materials 1 month post construction pavement temperature 12 C 0.09 0.09 0.08 0.08 0.07 0.07 0.06 Curvatures (D0-D200) 0.05 at 566 kpa (mm) 0.04 Outer wheelpath Between wheelpaths 0.06 Curvatures (D0-D200) 0.05 at 566 KPa (mm) 0.04 0.03 0.03 0.02 0.02 0.01 0.01 Outer wheelpath Between wheelpaths 0.00 0 10 20 30 40 50 60 70 80 90 100 Chainage (m) 0.00 0 10 20 30 40 50 60 70 80 90 100 Chainage (m) 8 days, 29 C 1 month, 12 C 34
Coring along edge line at 8 days & 1 month after FBS construction 35
Predicted to fatigue crack with 3 years 36
2. Port Wakefield Road constructed early 2011, as part of 1km long project heavily trafficked road 75 m section stabilised to 150 mm depth 950 m section stabilised to depth of 200 mm 3% bitumen + 1% hydrated lime 37
Port Wakefield Road fatigue cracking fatigue cracking observed after 18 months of trafficking in reasonable agreement with thickness design model 38
Monitoring measured deflections 39
Field cores 40
3. Kwinana Freeway Perth Constructed in 2011 100 m trial section with reduced thickness, 150 mm FBS asphalt surfaced with underlying geotextile reinforced seal 41
No cracking apparent yet surface deflections regularly being measured may identify fatigue damage prior to surface cracking 42
Adding another project early in 2014 Newell Highway 43
4 year national research project involvement of road agencies, contractors and researchers objectives Summary four year national research project (2012-2016) development of national mix design procedures refinement of modulus specifications using field performance data calibration of thickness design procedures 44
Gracias! 45