COFFEY GEOTECHNICSOutline of This Presentation•   PAVEMENT TYPES (by use)     – Airport     – Container Terminals     – Op...
COFFEY GEOTECHNICSWHY USE DIFFERENT DESIGN METHODS• Wheel loads, tyre pressure and tracking  differ.• Stress affects modul...
COFFEY GEOTECHNICS    Airport Pavements• Wheel Loads>>3 tonne• B717 13.5 tonne per tyre• Very High Tire Pressures•  (Learj...
COFFEY GEOTECHNICS Airport Pavements• Track width varies• Wander is significant• Load varies by a large  margin.• Airport ...
COFFEY GEOTECHNICSMilitary AerodromesForeign Object Debris (FOD)  is a major design factor.No cracking please!.
COFFEY GEOTECHNICSSurfacing for Aerodromes• CASA Circular AC 139-25(0) permits spray seals up to tyre  pressures of 1000kP...
COFFEY GEOTECHNICSContainer Terminals: Highly Channelized Loading WithStraddle Carriers12 tonne pertireGPS controlledstrad...
COFFEY GEOTECHNICSOpen Cut Mines• Wheel Loads>> 3 tonne• 60 tonne + per tire• Pavement is typically  unsealed.• Wander lar...
COFFEY GEOTECHNICSPublic Roads•   Wheel Load < 3 tonne•   Bigger load = more    tires•   Most trucks are the    same width...
COFFEY GEOTECHNICSTRAFFICABILITY FOR CONSTRUCTION EQUIPMENT
COFFEY GEOTECHNICSTRAFFICABILITY OVER CLAY• A simple procedure using Clay moisture  content and Atterberg Limits (concept ...
COFFEY GEOTECHNICSTrafficability over Clay• Liquidity Index (IL) = 1 at Liquid Limit• Liquidity Index      = 0 at Plastic ...
COFFEY GEOTECHNICS Trafficability over Clay• Check that vertical  stress, factored for  repetitions• (1 + Log N)• at the t...
COFFEY GEOTECHNICS Traffickability over Soft Clay• Geo-reinforcement .• Ncu increases• Load spread angle  increases .• Sen...
COFFEY GEOTECHNICSPavement Design MethodsEMPIRICAL METHODSTypically a chart linking thickness to load and subgrade CBR    ...
COFFEY GEOTECHNICSERN 9 (Empirical, Sprayed seals)
COFFEY GEOTECHNICS Origins of Main Roads WA ERN 9 (Empirical Method)• Started with US Army Corp of Engineers (circa 1940) ...
COFFEY GEOTECHNICS
COFFEY GEOTECHNICSOrigins of ERN 9• Porter (1942) assumed that lightly trafficked road is  equivalent to 7000 lb wheel loa...
COFFEY GEOTECHNICSOrigins of Main Roads WA ERN 9 (Empirical Method)• Maclean (1959) assigned numbers of heavy vehicles  pe...
COFFEY GEOTECHNICSMain Roads WA ERN 9 (Empirical Method)• Circa 1977: Commonwealth intervention.• NAASRA (1979)- non linea...
COFFEY GEOTECHNICSVEHICLE LOADSMcAdam (1824)• ...Stage coaches, with their present system of  loading , and velocity of tr...
COFFEY GEOTECHNICSVEHICLE LOADS• Wakelan HT (1916) “The damage which is  undoubtedly been caused to road surfaces,  by mec...
COFFEY GEOTECHNICS    Regulation Axle Loads in WA (single axle dual tyres)•   1919           4.89 tonne                   ...
COFFEY GEOTECHNICS Austroads Method for Assessing Damaging Effects of Different Loads and Axle Groups• Basic data from AAS...
COFFEY GEOTECHNICSLoads other than Reference Load (Austroads Method)• All loads expressed as equivalent repetitions of 80k...
COFFEY GEOTECHNICSWeaknesses in the AUSTROADS Approach to Loads•   Tire pressure not included in load equivalency•   Pore ...
COFFEY GEOTECHNICSFlexible Pavement Design• Flexible pavements on Public Roads are  fairly unique amongst engineering  str...
COFFEY GEOTECHNICSRoad trainin WAhaulingiron ore.Significanttangentialforceapplied bydrive axle.
COFFEY GEOTECHNICSMechanistic Design• Pavement layers typically modelled as elastic or  visco elastic• Transfer function i...
COFFEY GEOTECHNICSMechanistic Design for Public Roads• Numerous Methods• Austroads (2010) is an example.
COFFEY GEOTECHNICSAUSTROADS METHOD• Transfer Function for Vertical Subgrade Strain  (Roads).• N = (9300/microstrain)7•   T...
COFFEY GEOTECHNICSAustroads• From 3 aeroplane  curves to• N = (9300/microstrain)7• By extrapolation,  assumption and two  ...
COFFEY GEOTECHNICSSubgrade Strain (Airport Pavements)• N = ( k/ε)b• The exponent b varies with subgrade stiffness and numb...
COFFEY GEOTECHNICSASPHALT IN AUSTROADS• Austroads method only considers  fatigue.• Development of ruts is as critical as  ...
COFFEY GEOTECHNICSASPHALT IN AIRPORTS• Fatigue of asphalt in airports is relatively  rare.• Rut development is a major iss...
COFFEY GEOTECHNICSComparison of AUSTROADS & South African Mechanistic Methods                          AUSTROADS 2010     ...
COFFEY GEOTECHNICSSAMDM & Austroads                         AUSTROADS 2008          SAMDM   Fatigue model for cemented lay...
COFFEY GEOTECHNICSLIMITATIONS OF AUSTROADS 2010 method• Unbound base course- no transfer function  for shear.• Lightly bou...
COFFEY GEOTECHNICS                                          70mm Thick Asphalt, 800MPa Granular Base                    12...
COFFEY GEOTECHNICSRoad Pavements over Expansive Clay• Granular cover requirements to manage  shrink swell may exceed CBR b...
COFFEY GEOTECHNICSPavement Materials for Rural Roads• Since the  1950s sprayed  seals on  natural gravel  have  dominated ...
COFFEY GEOTECHNICSNaturalGravelWhere do WASpecificationscome from andwhat do the varioustests mean?
COFFEY GEOTECHNICSFactors Leading to WA Selection Criteria• Culture• Climate• Axle loads• Geology• Cost
COFFEY GEOTECHNICSCulture• Engineering training came from UK and USA  (English speaking). Papers in Arabic or Chinese  hav...
COFFEY GEOTECHNICSArid Climate
COFFEY GEOTECHNICSGeologyUK & USA typically use• Crushed Rock• River Gravels• Glacial OutwashWA (outside of Perth) use• Pe...
COFFEY GEOTECHNICS Cost• WA has a small  population and a  large area.• Crude oil suitable  for bitumen  production is  im...
COFFEY GEOTECHNICSWhat do the Tests Mean?Most tests are indirect “indicators”.
COFFEY GEOTECHNICSParticle Size Distribution• Ideal grading based on Wilhelmi or Talbot Curves                     p/P = (...
COFFEY GEOTECHNICSAtterberg Limits• High Plasticity Index (PI) associated with increased  moisture sensitivity.• Specifica...
COFFEY GEOTECHNICSMaximum Plasticity Index Limits from Around the World•   AASHTO           Gravel                  6•   B...
COFFEY GEOTECHNICSPlasticity Index Limits from Around the World•   Portugal         Lateritic Gravel           15•   Ugand...
COFFEY GEOTECHNICSEffect of Sesquioxides and Carbonates• Al2O3 and Fe203 are cementing agents• Allow an increase in PI (co...
COFFEY GEOTECHNICSCracking of Laterite Pavements is Normal.Lateritic gravel base,asphalt surface withslurry seal.Cracks ha...
COFFEY GEOTECHNICSDoes Plasticity Index Matter?• Chose  limits  carefully  and  enforce  them.
COFFEY GEOTECHNICSDoes MDCS matter?• Test has poor reproducibility.• Pavement performance problems due to low  MDCS are ex...
COFFEY GEOTECHNICSRepeat Load Triaxial Test (RLTT)• Cylindrical sample with confining  pressure is subject to many thousan...
COFFEY GEOTECHNICSRepeat Load Triaxial Test• Recent ARRB research has also thrown  much doubt on the value of RLLT for  as...
COFFEY GEOTECHNICSUnsealed Roads• South African•   Max       37.5mm•   Oversize Index 5%•   P0.425 x LS 100 to 365•   Grad...
COFFEY GEOTECHNICSFUTURE TRENDS IN HIGHWAY PAVEMENT DESIGN• Finite element method that includes:•        Estimates of rut ...
COFFEY GEOTECHNICSFuture Trends in Pavement Materials on Public Roads inWA• Less use of natural gravel.• Return to bitumen...
COFFEY GEOTECHNICSAcknowledgements•   A great many people and organisations helped with this presentation by    providing ...
COFFEY GEOTECHNICSLimitationPeople using information from this presentation must apply and  rely on their own skill and ju...
Upcoming SlideShare
Loading in...5
×

Pavement materials and design in western australia by geoffrey cocks

1,583

Published on

Published in: Technology, Business
0 Comments
1 Like
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total Views
1,583
On Slideshare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
Downloads
69
Comments
0
Likes
1
Embeds 0
No embeds

No notes for slide

Pavement materials and design in western australia by geoffrey cocks

  1. 1. COFFEY GEOTECHNICSOutline of This Presentation• PAVEMENT TYPES (by use) – Airport – Container Terminals – Open Cut Mines – Public Roads – Temporary Haul Roads• DESIGN METHODS & VEHICLE LOADS – Empirical – Mechanistic• PAVEMENT MATERIALS – Focus is on natural gravels in Western Australia FUTURE TRENDS
  2. 2. COFFEY GEOTECHNICSWHY USE DIFFERENT DESIGN METHODS• Wheel loads, tyre pressure and tracking differ.• Stress affects modulus.• Performance limitations differ.
  3. 3. COFFEY GEOTECHNICS Airport Pavements• Wheel Loads>>3 tonne• B717 13.5 tonne per tyre• Very High Tire Pressures• (Learjet 60 is 1480kPa)• Low repetitions• No drive through the wheels• Tires rotate independently• Jets land at about 350km/hour
  4. 4. COFFEY GEOTECHNICS Airport Pavements• Track width varies• Wander is significant• Load varies by a large margin.• Airport Pavement Structural Design System (APSDS), uses cumulative damage factors to combine the effect of different aircraft.
  5. 5. COFFEY GEOTECHNICSMilitary AerodromesForeign Object Debris (FOD) is a major design factor.No cracking please!.
  6. 6. COFFEY GEOTECHNICSSurfacing for Aerodromes• CASA Circular AC 139-25(0) permits spray seals up to tyre pressures of 1000kPa.• For higher tyre pressures asphalt is required (except with a concession).
  7. 7. COFFEY GEOTECHNICSContainer Terminals: Highly Channelized Loading WithStraddle Carriers12 tonne pertireGPS controlledstraddle carrier(zero wander).
  8. 8. COFFEY GEOTECHNICSOpen Cut Mines• Wheel Loads>> 3 tonne• 60 tonne + per tire• Pavement is typically unsealed.• Wander large (human drivers) or negligible (GPS controlled, driverless).
  9. 9. COFFEY GEOTECHNICSPublic Roads• Wheel Load < 3 tonne• Bigger load = more tires• Most trucks are the same width• Truck tires at about 700kPa• Equivalent Standard Axles• Single axle• ESA 8.2 tonne on 4 tires• Many repetitions• 105 to 108
  10. 10. COFFEY GEOTECHNICSTRAFFICABILITY FOR CONSTRUCTION EQUIPMENT
  11. 11. COFFEY GEOTECHNICSTRAFFICABILITY OVER CLAY• A simple procedure using Clay moisture content and Atterberg Limits (concept proposed by DeFlice)• Su at Liquid Limit = 1.7 kPa• Su at Plastic Limit = 170 kPa
  12. 12. COFFEY GEOTECHNICSTrafficability over Clay• Liquidity Index (IL) = 1 at Liquid Limit• Liquidity Index = 0 at Plastic Limit• Su = 170 * 10-2IL (Atkinson)
  13. 13. COFFEY GEOTECHNICS Trafficability over Clay• Check that vertical stress, factored for repetitions• (1 + Log N)• at the top of the clay is less than• Ncu * 170 * 10-2IL
  14. 14. COFFEY GEOTECHNICS Traffickability over Soft Clay• Geo-reinforcement .• Ncu increases• Load spread angle increases .• Sensitivity to load repetitions decreases
  15. 15. COFFEY GEOTECHNICSPavement Design MethodsEMPIRICAL METHODSTypically a chart linking thickness to load and subgrade CBR – Main Roads WA Engineering Road Note 9 for highways – ARRB AP –T36/06 for local streets (Australian) – US Army Corps of Engineers CBR method for airportsMECHANISTIC METHODSTypically use elastic models – AUSTROADS for roads – SAMDM for roads (South African) – APSDS 5 for airports (Australian)
  16. 16. COFFEY GEOTECHNICSERN 9 (Empirical, Sprayed seals)
  17. 17. COFFEY GEOTECHNICS Origins of Main Roads WA ERN 9 (Empirical Method)• Started with US Army Corp of Engineers (circa 1940) chart for airport pavement design.• (source: Geoff Jameson)
  18. 18. COFFEY GEOTECHNICS
  19. 19. COFFEY GEOTECHNICSOrigins of ERN 9• Porter (1942) assumed that lightly trafficked road is equivalent to 7000 lb wheel load and heavily trafficked road is equivalent to 12000 lb wheel load.• E H Davis (RRL 1949) assessed 7 roads in UK and compared results to Porter’s curves.• RRL(1955) adapted Porter’s curves to design of roads for new estates.
  20. 20. COFFEY GEOTECHNICSOrigins of Main Roads WA ERN 9 (Empirical Method)• Maclean (1959) assigned numbers of heavy vehicles per day to RRL (1955) chart• Country Roads Board (Victoria) adopted McLean’s chart with minor modification of the traffic curves
  21. 21. COFFEY GEOTECHNICSMain Roads WA ERN 9 (Empirical Method)• Circa 1977: Commonwealth intervention.• NAASRA (1979)- non linear regression analysis on Country Roads Board chart.• 1 ESA per heavy vehicle• 20 year design life to develop chart for thickness CBR and ESA.• Main Roads WA adopted the NAASRA chart in ERN 4 (1981) and later in ERN 9 (1988)• Chart extrapolated by MRWA to 2 x 108 ESA
  22. 22. COFFEY GEOTECHNICSVEHICLE LOADSMcAdam (1824)• ...Stage coaches, with their present system of loading , and velocity of travelling upon very narrow wheels, damage the roads in a much greater proportion than the compensation derived from the toll.
  23. 23. COFFEY GEOTECHNICSVEHICLE LOADS• Wakelan HT (1916) “The damage which is undoubtedly been caused to road surfaces, by mechanically propelled vehicles during the last two or three years, in particular, has been of an extraordinary nature”.
  24. 24. COFFEY GEOTECHNICS Regulation Axle Loads in WA (single axle dual tyres)• 1919 4.89 tonne 15 Leagl Load Single Axle• 1928 5.08 tonne 13 WA (Tonne)• 1947 7.71 tonne 11• 1960 8.16 tonne 9• 1977 8.50 tonne 7• 1988 9.0 tonne 5 3 1900 1950 2000 2050 MRWA allows 12 tonne on a single axle under Year concessional permit.
  25. 25. COFFEY GEOTECHNICS Austroads Method for Assessing Damaging Effects of Different Loads and Axle Groups• Basic data from AASHO Road test• Assumption: Equal surface deflection gives equal pavement damage?????• Single axle with dual tyres 8.2 tonne• Single axle with single tyres 5.4 tonne• Tandem axle with dual tyres 13.8 tonne• Triple axle with dual tyres 18.5 tonne
  26. 26. COFFEY GEOTECHNICSLoads other than Reference Load (Austroads Method)• All loads expressed as equivalent repetitions of 80kn (8.2 tonne, 18000 lb ) single axle load.• N= (Group Load/Reference Load)n• “n” varies from 4 to 12• ESA uses n = 4• SAR use n = 5 to 12
  27. 27. COFFEY GEOTECHNICSWeaknesses in the AUSTROADS Approach to Loads• Tire pressure not included in load equivalency• Pore pressure not considered• Tangential loads ignored• The AASHO Road Test on which the Austroads damage relationship was based had the following limitations: – Straight – Flat – Constant Speed – Largest vehicle was a 5 axle semi trailer (we have up to 27 axles on a road train in WA)
  28. 28. COFFEY GEOTECHNICSFlexible Pavement Design• Flexible pavements on Public Roads are fairly unique amongst engineering structures.• They are unusual in that the design load (single axle, 8.2 tonne) is less than loads routinely applied now (eg 12 tonne under permit)
  29. 29. COFFEY GEOTECHNICSRoad trainin WAhaulingiron ore.Significanttangentialforceapplied bydrive axle.
  30. 30. COFFEY GEOTECHNICSMechanistic Design• Pavement layers typically modelled as elastic or visco elastic• Transfer function is an equation that relates the allowable number of load repetitions to some parameter (eg strain) calculated using the elastic model• N = a (strain) b
  31. 31. COFFEY GEOTECHNICSMechanistic Design for Public Roads• Numerous Methods• Austroads (2010) is an example.
  32. 32. COFFEY GEOTECHNICSAUSTROADS METHOD• Transfer Function for Vertical Subgrade Strain (Roads).• N = (9300/microstrain)7• This is an empirical transfer function for highways. It is not a fundamental equation from physics.
  33. 33. COFFEY GEOTECHNICSAustroads• From 3 aeroplane curves to• N = (9300/microstrain)7• By extrapolation, assumption and two stages of non linear regression.
  34. 34. COFFEY GEOTECHNICSSubgrade Strain (Airport Pavements)• N = ( k/ε)b• The exponent b varies with subgrade stiffness and number of tires on the landing gear( Wardle & Rodway 2010).• 1 tire b = 7 to 11• 2 tires b = 12 to 15• 4 tires Tandem axle b = 17 to 19• 6 tires Triple axle b = 27
  35. 35. COFFEY GEOTECHNICSASPHALT IN AUSTROADS• Austroads method only considers fatigue.• Development of ruts is as critical as fatigue but is not catered for in the AUSTROADS design procedure.• We need wheel tracking tests for rut potential to become routine for asphalt.
  36. 36. COFFEY GEOTECHNICSASPHALT IN AIRPORTS• Fatigue of asphalt in airports is relatively rare.• Rut development is a major issue particularly in holding areas at the end of taxiways.• Consider the use of polymers (EVA) or multigrade binders to improve rut resistance.
  37. 37. COFFEY GEOTECHNICSComparison of AUSTROADS & South African Mechanistic Methods AUSTROADS 2010 SAMDM Linear Elastic model YES YES Sub layering YES IMPLICIT Anisotropy Anisotropic for unbound granular materials Isotropic for all layers Isotropic for asphalt and cemented (bound) layers Fatigue model for asphalt based on YES YES tensile strain
  38. 38. COFFEY GEOTECHNICSSAMDM & Austroads AUSTROADS 2008 SAMDM Fatigue model for cemented layers based YES YES on tensile strain Crushing of lightly Based on ratio of NO bound materials vertical stress to UCS Model for unbound NO Based on principal base course stresses at mid layer of base course. Subgrade based on vertical strain YES YES
  39. 39. COFFEY GEOTECHNICSLIMITATIONS OF AUSTROADS 2010 method• Unbound base course- no transfer function for shear.• Lightly bound materials – no transfer function for crushing.• Asphalt – no transfer function for rutting.• Horizontal loads not adequately addressed.• Mathematical problems.
  40. 40. COFFEY GEOTECHNICS 70mm Thick Asphalt, 800MPa Granular Base 1200 Granular Thickness (mm) 1000 CBR 4 800 CBR 12 600 400 200 0 1.00E+05 1.00E+06 1.00E+07 1.00E+08 Traffic Loading (ESAs)
  41. 41. COFFEY GEOTECHNICSRoad Pavements over Expansive Clay• Granular cover requirements to manage shrink swell may exceed CBR based design• Use AS2870 to estimate soil movement• Rip and moisture condition the subgrade• Avoid compacting much above 92% MMDD• Cover and allow to cure for about 3 months before finalizing pavement construction
  42. 42. COFFEY GEOTECHNICSPavement Materials for Rural Roads• Since the 1950s sprayed seals on natural gravel have dominated the rural road scene in WA.
  43. 43. COFFEY GEOTECHNICSNaturalGravelWhere do WASpecificationscome from andwhat do the varioustests mean?
  44. 44. COFFEY GEOTECHNICSFactors Leading to WA Selection Criteria• Culture• Climate• Axle loads• Geology• Cost
  45. 45. COFFEY GEOTECHNICSCulture• Engineering training came from UK and USA (English speaking). Papers in Arabic or Chinese have had little influence.• WA Gravel Specifications have AASHTO as their starting point.• Influence of the visit by Dr Frank Netterberg in the 1980s.
  46. 46. COFFEY GEOTECHNICSArid Climate
  47. 47. COFFEY GEOTECHNICSGeologyUK & USA typically use• Crushed Rock• River Gravels• Glacial OutwashWA (outside of Perth) use• Pedocretes including• Lateritic gravel• Ferricrete• Calcrete• Silcrete
  48. 48. COFFEY GEOTECHNICS Cost• WA has a small population and a large area.• Crude oil suitable for bitumen production is imported.
  49. 49. COFFEY GEOTECHNICSWhat do the Tests Mean?Most tests are indirect “indicators”.
  50. 50. COFFEY GEOTECHNICSParticle Size Distribution• Ideal grading based on Wilhelmi or Talbot Curves p/P = (d/D) 0.42• Maximum size < 37.5mm (or 19mm)• Larger size increases material strength and stiffness but creates workability issues and may increase permeability.• Smaller maximum size correlates to reduced material strength and stiffness.
  51. 51. COFFEY GEOTECHNICSAtterberg Limits• High Plasticity Index (PI) associated with increased moisture sensitivity.• Specification limits vary with climate and geology.• Sesquioxides (Al2O3 and Fe2O3) and carbonate (CaCO3) affect measurement and modify the effects of plasticity.
  52. 52. COFFEY GEOTECHNICSMaximum Plasticity Index Limits from Around the World• AASHTO Gravel 6• Botswana Calcrete 15• Brazil Lateritic Gravel 15• Ghana Lateritic Gravel 10• Kenya Natural Gravel 15 to 20• Mali Lateritic Gravel 6 to 16• Nigeria Lateritic Gravel 12
  53. 53. COFFEY GEOTECHNICSPlasticity Index Limits from Around the World• Portugal Lateritic Gravel 15• Uganda Lateritic Gravel 16 to 25• USACE (ToW) Lateritic Gravel 10• Zambia Lateritic Gravel 6 to 10• NAASRA Natural Gravel 6 to 10• WA Lateritic Gravel 6 to 16• WA Calcrete 12
  54. 54. COFFEY GEOTECHNICSEffect of Sesquioxides and Carbonates• Al2O3 and Fe203 are cementing agents• Allow an increase in PI (coat the clay during drying) (Moh & Mazhar 1969)• CaCO3 particles are porous.
  55. 55. COFFEY GEOTECHNICSCracking of Laterite Pavements is Normal.Lateritic gravel base,asphalt surface withslurry seal.Cracks have beenlike this for morethan 23 years.
  56. 56. COFFEY GEOTECHNICSDoes Plasticity Index Matter?• Chose limits carefully and enforce them.
  57. 57. COFFEY GEOTECHNICSDoes MDCS matter?• Test has poor reproducibility.• Pavement performance problems due to low MDCS are extremely rare.• Less important with sealed shoulders or kerbed pavement.• Offset by good mechanical interlock.
  58. 58. COFFEY GEOTECHNICSRepeat Load Triaxial Test (RLTT)• Cylindrical sample with confining pressure is subject to many thousands of compression load pulses.• Caution: For materials treated with cement, tensile stress under wheel loads may rupture cementing bonds. This is not modelled in the RLTT
  59. 59. COFFEY GEOTECHNICSRepeat Load Triaxial Test• Recent ARRB research has also thrown much doubt on the value of RLLT for assessing rut performance of unbound granular pavements.
  60. 60. COFFEY GEOTECHNICSUnsealed Roads• South African• Max 37.5mm• Oversize Index 5%• P0.425 x LS 100 to 365• Grading Coef. 16 to 34
  61. 61. COFFEY GEOTECHNICSFUTURE TRENDS IN HIGHWAY PAVEMENT DESIGN• Finite element method that includes:• Estimates of rut depth development Transfer functions for granular base and rutting in asphalt. Provision for tandem and triple axles without the need for ESAs Use of higher design axle loads Allowance for geogrids
  62. 62. COFFEY GEOTECHNICSFuture Trends in Pavement Materials on Public Roads inWA• Less use of natural gravel.• Return to bitumen stabilised limestone.• More stringent requirements for crushed rock.• Concrete pavements on heavily trafficked freeways.• Reduced use of full depth asphalt.
  63. 63. COFFEY GEOTECHNICSAcknowledgements• A great many people and organisations helped with this presentation by providing me with photographs and sharing ideas over the last 40 years. I particularly want to thank the following:• John Atkinson, Bob Andrews, Srijib Chakrabarti, Russell Clayton, Andrew Cray, Tony DeFlice, Phil Dight, Martin Ellam, Stephen Emery, Geoff Faro, Paul Fisher, Gabor Hamory, David Harris, Sean Hayes, Geoff Jameson, Ross Keeley, Landcorp, Reg Leach, Colin Leek,Tony Mansour, Frank Netterberg, Kerry Sanderson, Jacqueline Scott, Weeks White.
  64. 64. COFFEY GEOTECHNICSLimitationPeople using information from this presentation must apply and rely on their own skill and judgement to the particular issue they are considering.
  1. A particular slide catching your eye?

    Clipping is a handy way to collect important slides you want to go back to later.

×