Long life concrete pavement


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Long life concrete pavement

  1. 1. Long-Life Concrete Pavements InLong-Life Concrete Pavements InThe WorldThe WorldSubmitted to : Assoc.Prof. Mustafa SAHMARANSubmitted to : Assoc.Prof. Mustafa SAHMARANPrepared BY :Prepared BY : Hazhar HayderHazhar HayderSamadar SalimSamadar Salim1
  2. 2. 2This Search is about LLCP inthese Countries:CanadaGermanyAustriaBelgiumNetherlandsUnited Kingdom
  3. 3. 3The motivation for an international scan of long-lifeconcrete pavement technology:1 - Safety2 - Mitigation of congestion
  4. 4. Aging highway systemHeavier truck loadsHigh maintenance costsCongestionWork Zone SafetyNoise44
  5. 5. 5BackgroundWhy long life?––Reduce future maintenance andrehabilitation requirements–– Minimize traffic disruptions–– Reduce user costs–– Increase safety (fewer work zones)–– Reduce life-cycle costs
  6. 6. 6Solution30--60 year service livesIncludes minor maintenanceand rehabilitation
  7. 7. 77LLCP require:less frequent repairRehabilitationReconstructionand therefore contribute toImproving Highway safetyMitigating congestion
  8. 8. 88Scope of the scan include the following:• Materials evaluation and specification procedures forboth virgin and recycled materials• Design methods of long-life concrete pavements• Construction practices• Maintenance practices
  9. 9. 99Issues of Interest•Materials (cement, coarse & fine aggregates,admixtures, and supplementary cementationsmaterials)•Concrete mixture design•Pavement thickness design (including geometrics,spacing, and location of joints)•Specifications
  10. 10. 10Issues of Interest cont.• Construction procedures• Maintenance procedures• Rapid construction and rehabilitationtechniques• Performance of jointed plain JPCP, jointedreinforced JRCP, and continuously reinforcedconcrete pavements CRCP.• Life-cycle costs
  11. 11. 11Pavement Selection StrategiesLong-life concrete pavements:In every country , "concrete pavement" isconsidered synonymous with "long life.“These countries expect concrete pavements to bestrong and durable, provide service lives of 25, 30,or more years before rehabilitation or replacement.
  12. 12. 12TechnologyChanges
  13. 13. 1313Public and environment:The public is expressing concerns aboutenvironmental issues such as noise, congestion andsafety.Environmental issues, especially noise, arebecoming major concerns to the driving public.
  14. 14. 14Public and environment:In all these countries , there is a heavy emphasison traffic safety, noise mitigation, congestionrelief, and use of recycled materials.In UK , political forces have driven the decision toreduce noise, (all highway pavements must haveasphaltic surfaces).
  15. 15. 15Scan ObjectivesIdentify techniquesused in othercountries, andImplementable in US,for achieving longer-lifeconcrete pavements
  16. 16. 16Pavement type selection factors1. Life-cycle costs2. Functional class3. Truck traffic levels4. Initial cost5. Environmental issues
  17. 17. Pavements optimized for a performanceperiod in excess of 40 years,An extended time to first rehabilitation andminimal interventions for M & R activities.17
  18. 18.  Design catalogs used inAustria, Belgium &Germany Design lives of 30 yearstypically used up to 50 yearsservice expected Truck loadings areheavier than in US,18
  19. 19. Note : Maximum concrete slab thicknesses are a commonfeature of the design catalog.1919Catalog designs (updated regularly) based on:1.Theoretical & lab studies2.Field experiments3.Performance observationsPavement DesignPavement Design
  20. 20. 20Pavement DesignPavement DesignIn Netherlands & United KingdomMechanistic-empirical design software is usedfor project-level design worksThe maximum slab thicknesses appear to bethinner than those designed in US for similartraffic levels and in many cases heavier trucks.
  21. 21. Full-width, full-depth concrete emergencylanes constructed for future capacity needsWidened slabs used to reduce concretestress and deflection (as in US) andextending pavement life.21
  22. 22. Fewer tie bars used in longitudinal joints (about half thenumber used in US).Smaller dowel bars (25 mm diameter) usedJCP and CRCP built to same thickness (as in US)CRCP used for long life in Belgium - technology adoptedfrom the US22
  23. 23. 23 Sealed and unsealed jointsboth perform well Bases: dense HMA and CTB; 5 mm thick Geotextile used toseparate CTB and PCC in Germany Foundations are drainable, stable,protect against frost, and allowrecycling of materials
  24. 24. 24ConcreteHMAUnbound BaseType 5ConcreteHMA LayerCTBType 6Portion of Austria’s design catalog page showing concrete pavement layerthicknesses for different traffic loading levels. Motorways are in the S class.
  25. 25. 25
  26. 26. 26
  27. 27. 271970 -1977PCC t = 20 cm Steel =0.85%1977 -1991PCC t = 20 cm Steel =0.67%1992 -1995PCC t = 23 cm Steel =0.72%Since 1995PCC t = 23 cm Steel =Catalog DesignsCatalog DesignsEX: Class B1EX: Class B1Design lifeDesign life30 years30 years
  28. 28. 28Emergency LaneTop lift w/ exposed aggregateBottom lift w/ recycled aggregates10in.Concrete (combined graded(HMAC or CTB (with AC/geotextile(Thick frost protection layerSubgrade
  29. 29. 29
  30. 30. 30 Lower-alkali cements andblended cements used tomitigate ASR SCMs typically notconsidered in mixtureproportions Attention to aggregatequality and gradation …specially for top layer intwo-lift construction
  31. 31. 31Construction and MaterialsConstruction and Materials Recycled concrete andrecycled asphaltpavement used (ormandated) in lowerlayer in two-courseconstruction Some countries use tiebars coated only inmiddle third
  32. 32. 32Construction and MaterialsConstruction and Materials Coated dowel bars used Intelligent compaction controlused in Austria Small-plate proof testing ofgranular layers used in somecountries Roughness measured withfour-meter straightedge;excellent smoothness achieved
  33. 33. 33ConcreteConcrete Freeze-thaw resistant Flexural strength (28-days)Bottom lift ≥ 800 psiTop lift ≥ 1,000 psi Compressive strength (28days)Bottom lift ≥ 5,000 psiTop lift ≥ 6,000 psi Well graded aggregates – 4bins Two plantsBottom lift concreteTop lift concrete
  34. 34. 34Max. agg. size typicallyused in Europe is (20 mm).AggregatesIn Netherlands, whereprimarily single-liftconstruction is done, (32mm) is the maximumaggregate size.
  35. 35. 35Aggregate BinsAggregate Bins16to 32 mm 8to 16 mm 4to 8 mm 0to 4 mm
  36. 36. 3636InterlayersIn Germany: using (5mm-thick) Geotextile interlayer as abond breaker between concrete pavement and cement-treated base is a recent requirement.German engineers indicated that the mortar is presumed tosaturate the Geotextile during construction, adding justenough stiffness to provide support while still acting as a bondbreaker.
  37. 37. 37Geotextile InterlayersThe required concrete thickness for cement-treated base alternative was increased from(26 - 27 cm) when the design was changed fromone with a bonded base to one with a baseseparated from the slab by a Geotextile.In the other countries , the typical interlayerbetween a concrete slab and a cement-treatedbase is a layer of hot-mix asphalt concrete.
  38. 38. 38
  39. 39. 393939Recycled materials (including concrete and masonry fromdemolition) have been used in the base layers in variouscountries.Austria requires the use of Recycled Concrete and RecycledAsphalt Pavement (RAP) in the lower layer of two-courseconcrete (and for base).Recycled asphalt is allowed up to a maximum of 30 % of thecoarse aggregate in these mixtures.Recycling
  40. 40. 40Recycling Concept for ConcreteRecycling Concept for Concrete
  41. 41. 41
  42. 42. 4242Compaction controlIn Austria : Intelligent compaction control is used.The European countries are strict about control ofcompaction of all layers.In some countries load testing of granular layers tocheck compaction is conducted with a small plate.
  43. 43. 43350 kg/m3 = 590 lb/cy400kg/m3 = 674 lb/cy , 450 kg/m3 = 758 lb/cy
  44. 44. 44Top Lift Concrete PlacementFresh to fresh on bottom lift concrete
  45. 45. 45Placing of the top liftconcreteTie-bar placed by hand (rightbehind first paver(Dowels - placedautomaticallyDensely compacted bottomlift – No sinkage
  46. 46. 46Two-lift pavingTwo-lift construction isthe placement of twowet-on-wet layers orbonding wet to drylayers of concrete, insteadof the homogenous singlelayer commonly placed inconcrete paving.
  47. 47. 4747The bottom layer ( thick & lower quality)(lower durability or strength), locally availableaggregate or recycled aggregate (such asrecycled asphalt, concrete rubble, or localaggregate).The top layer (thin & consists of high-qualityaggregate designed to provide better resistanceto freeze-thaw damage, reduced noise, orimproved friction.The high-quality surface also increases frictionand reduces noise.
  48. 48. Goals of Two-Lift Paving•Improved Surface Durability•Improved Safety (friction)•Reduced Tire/Pavement Noise•Improved Environment by Recycling•Improved Pavement Performance
  49. 49. 49
  50. 50. 50Low-noise exposed aggregate surfacing:The solution to concrete pavement noise popular in someEuropean countries is exposed aggregate surfacing, in whichexceptionally high-quality, durable aggregates are used in the topcourse of the concrete slab, and a process of set retardation andabrasion is used to produce an exposed aggregate surface withgood low-noise properties.Exposed aggregate is also touted as yielding other benefits,including good friction and durability. However, favorable noiselevels may also be achieved by specific pavement texturingtechniques.
  51. 51. 51Exposed Aggregate SurfaceStep 1 - Curing compound + retarder- water-repellent coefficient > 90 % (first 24 h)Step 2 - Curing compound (applied after brushing)- water-repellent coefficient > 85 %
  52. 52. 52Minimal surfaceMinimal surfacefinishing -finishing -longitudinallongitudinalsmoothersmoother
  53. 53. 53BrushingBrushingMachineMachineExposed aggregate surface8 or 11 mm max size
  54. 54. 5454Cement and concrete testing.Workability is evaluated using a compaction test, similar tothe ASTM Vibe test.Ontario and Austria check the air content in hardenedconcrete.In the European countries : alkali-silica reaction (ASR) iscontrolled, if detected by preconstruction testing, usingblended cements or cements with low alkali content.
  55. 55. 5555Pavement testingCountries do not perform quality control testing for noise.Texture measurements are made, both for end-product andpavement management system-based data collection.Only in Germany and Canada MIT-SCAN equipment usedfor detecting dowel bar misalignment for both qualitycontrol and quality assurance purposes.
  56. 56. 56Pavement testingIn EU countries A 4-m straightedge is typicallyused to measure roughness .Belgium also uses APL (length profile analyzer) tomeasure pavement profile.The smoothness of pavements was excellent in allcountries .
  57. 57. 57MaintenanceMaintenance Typically, very little maintenance done on concretepavements Little if any joint resealing done One widely used maintenance technique is a thinasphalt overlay to correct rutting caused bystudded tires or to mitigate tire-pavement noise. Ontario is field-testing precast slab techniques(similar to US) for rapid repair
  58. 58. 58MaintenanceMaintenanceOnly in Canada is diamondgrinding used to improvesmoothness on bare concretepavements (Diamond grindwhole surface and performfull-depth repairs on 1.5% ofsurface area at 25 years)In UK, concrete pavementsoverlaid with asphalt toreduce noise.
  59. 59. 5959Precast slabs for rapid repairCanada is evaluating the use of U.S developed precastconcrete technology for rapid repair.Also panels were used for individual slab & multi slabreplacement.
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  62. 62. 62Overall HighlightsOverall Highlights Standard designsFrost-free foundation & good base(HMAC/CTB) Standard materialsHigher strength concrete than in USBlended cements more common, less SCMsUp to 4 bins for concrete aggregateExposed aggregate surface – lower noise
  63. 63. 63Overall HighlightsOverall Highlights Good construction practicesGood ride, even though no ride specsThey use straight-edge testingLow paste surface (only 1 to 2 mm –brushed off)Joint sawing with very little raveling Very careful approach to introducing newfeatures/techniquesDesign, materials and construction features need tobe well integrated
  64. 64. 64Thank youForYourAttention