Presentation is loading. Please wait.

Presentation is loading. Please wait.

1 The Use of FWD for Pavement Monitoring: Case Studies Bachar Hakim and Martyn Jones Scott Wilson Pavement Engineering Impulsive Matters 2: Impulsive Matters.

Similar presentations


Presentation on theme: "1 The Use of FWD for Pavement Monitoring: Case Studies Bachar Hakim and Martyn Jones Scott Wilson Pavement Engineering Impulsive Matters 2: Impulsive Matters."— Presentation transcript:

1 1 The Use of FWD for Pavement Monitoring: Case Studies Bachar Hakim and Martyn Jones Scott Wilson Pavement Engineering Impulsive Matters 2: Impulsive Matters 2: Use of FWD for quality control Heriot-Watt University, Edinburgh, Scotland 19 November 2003

2 2 The Use of FWD for Pavement Monitoring: Case Studies Contents Unbound Foundation Performance Testing Unbound Foundation Performance Testing Lean Concrete and Pavement Quality Concrete Lean Concrete and Pavement Quality Concrete Crack and Seat Projects Crack and Seat Projects Bond between Pavement Layers Bond between Pavement Layers

3 3 Foundation Performance Testing Main Objectives Main Objectives QUALITY: QUALITY: Ensure design assumption = construction COST & ENVIRONMENTAL SAVINGS: COST & ENVIRONMENTAL SAVINGS: Greater flexibility in use of marginal materials, stabilised, secondary & recycled materials

4 4 Foundation Performance Parameters and Tests:- Strength (CBR%) Strength (CBR%) e.g. Dynamic Cone Penetrometer (DCP) e.g. Dynamic Cone Penetrometer (DCP) Stiffness (MPa) Stiffness (MPa) Dynamic plate (FWD, GDP & Prima) Dynamic plate (FWD, GDP & Prima) Density (Kg/m 3 ) Density (Kg/m 3 ) Nuclear Density Meter (NDM) Nuclear Density Meter (NDM) Rutting (mm) Rutting (mm) Trafficking Trial Trafficking Trial

5 5 Foundation Performance Tests - Unbound & Stabilised Layers Implementation of Highway Agency (HA) ‘Draft Performance Specification for Subgrade and Capping’ Implementation of Highway Agency (HA) ‘Draft Performance Specification for Subgrade and Capping’ Prepared by Consortium, SWPE, Nottingham and Loughborough Universities Prepared by Consortium, SWPE, Nottingham and Loughborough Universities Similar Performance Specification for Similar Performance Specification for Sub-base underway, by TRL

6 6 Implementation Phase Trials Jersey Airport (Taxiway Alpha) Jersey Airport (Taxiway Alpha) First Contractual Use of Specification First Contractual Use of Specification A2 – M2 (Kent) A2 – M2 (Kent) Various Cappings including Cement Stabilised Chalk, Ragstone (local sandstone) and Recycled Crushed Concrete Various Cappings including Cement Stabilised Chalk, Ragstone (local sandstone) and Recycled Crushed Concrete A27 Polegate (Sussex) A27 Polegate (Sussex) Lime/Cement Stabilised Weald Clay Lime/Cement Stabilised Weald Clay A43 Towcester to M40 (Northampton) A43 Towcester to M40 (Northampton) Oolitic Limestone and Planings Oolitic Limestone and Planings Doncaster North Bridge Doncaster North Bridge Urban Widening of Carriageway, granular capping Urban Widening of Carriageway, granular capping A63 Selby Baypass A63 Selby Baypass Sand capping and sand/PFA sub-base Sand capping and sand/PFA sub-base Tilbury Docks: Berths Tilbury Docks: Berths Crushed Concrete capping and sub-base Crushed Concrete capping and sub-base

7 7 FOUNDATION: Design for Permanent Works - Long Term UpperUpper PavementPavement Sub-baseSub-base CappingCapping SubgradeSubgrade Limit rutting in Upper Pavement Limit flexure of Upper Pavement Limit deformation of subgrade (Structural rutting) (Fatigue cracking)

8 8 FOUNDATION: Design for Construction - Short Term CappingCapping SubgradeSubgrade Adequate Stiffness Limit rutting in subgrade to Compact Upper PavementPavement

9 9

10 10 Long Term Capping Thickness Design - A Subgrade CBR (%) For thickness requirements less than 150mm see paragraph 5.20 For very soft subgrades see paragraph 5.19

11 11

12 12 Typical Capping Material Properties ClassDescription Layer Stiffness (MPa) 6F1 Selected granular material (Fine grading) 60 6F2 Selected granular material (coarse grading) 60 (Sand + Gravel) 80 (Chalk) 100 (Other crushed rock) 120 (Recycled crushed concrete) 6F3 Selected granular material 150 9A Cement stabilised well graded granular material 80* 9B Cement stabilised silty cohesive material 80* 9C Cement stabilised conditioned pulverised fuel ash cohesive material 80* 9D Lime stabilised cohesive material 80* Type 1 Sub-base 150 * The stiffness quoted is conservative. Depending on the soil type and level of stabilisation used much higher values can be obtained. stabilisation used much higher values can be obtained.

13 13 Correlation of German Dynamic Plate (GDP) with FWD:- Stiffness Testing

14 14 Prima Dynamic Plate:- Stiffness Testing

15 15 Dynamic Plate Tests: Stiffness Performance Requirements Finished surface of capping shall:- Finished surface of capping shall:- >40MPa 8 from 10 consecutive tests >40MPa 8 from 10 consecutive tests 25MPaabsolute minimum 25MPaabsolute minimum Minimum 50 tests / trial area Minimum 50 tests / trial area Representative trial areas Representative trial areas Cut, Fill, Material Changes Cut, Fill, Material Changes Routine testing at 10m intervals in each lane Routine testing at 10m intervals in each lane

16 16 Rutting Tests - Requirements If capping used in a haul route, and subsequently included in the works, then rutting under construction traffic needs to satisfy:- If capping used in a haul route, and subsequently included in the works, then rutting under construction traffic needs to satisfy:- Rut depth (mm) Capping Thickness (mm) 30 < > < > 500

17 17 Trafficking Trial: Rutting Tests

18 18 Trafficking Trial: Rutting Measurements

19 19 A Performance Specification for Capping and Subgrade - Summary Extensive testing and verification over 6 years Extensive testing and verification over 6 years Implementation phase has identified minor changes to 1999 Draft Implementation phase has identified minor changes to 1999 Draft Successfully trialled at Jersey Airport, with significant savings Successfully trialled at Jersey Airport, with significant savings Provides a path for greater use of secondary aggregates/marginal materials/stabilised ground Provides a path for greater use of secondary aggregates/marginal materials/stabilised ground Prediction of long-term performance remains an issue, especially with moisture susceptible materials Prediction of long-term performance remains an issue, especially with moisture susceptible materials

20 20 Capping Trial: Case Study

21 21 Capping Trials Capping layer was trafficked 50 times Compaction of capping layer

22 22 FWD and GDPT on Capping Nuclear Density Testing

23 23 Capping Wetting

24 24 Rutting and DCP testing

25 25 Foundation Assessment of Existing Pavements

26 26 A19 DBFO: Foundation Assessment of Existing Pavements Concrete slab failure/settlement in Lane 1 Concrete slab failure/settlement in Lane 1 Replacement with bituminous inlay is required Replacement with bituminous inlay is required Unbound foundation stiffness assessment is needed before laying the bituminous materials to ensure that the pavement design life is achieved Unbound foundation stiffness assessment is needed before laying the bituminous materials to ensure that the pavement design life is achieved

27 27 Concrete Slab Failure

28 28 Removal of PQC Slabs

29 29 Rolling the Unbound Materials

30 30 Performance Evaluation Using Dynamic Plate Tests (GDP & Prima)

31 31 Jersey Airport: Performance Specifications

32 32 Jersey Airport: ALPHA TAXIWAY PROJECT

33 33 Alpha Taxiway Pavement Limited local aggregate performance (quarried granite aggregates with some fine quartz dune sand) Limited local aggregate performance (quarried granite aggregates with some fine quartz dune sand) Uneconomic to import aggregates due to high Harbour Dues Charges Uneconomic to import aggregates due to high Harbour Dues Charges

34 34 Pavement Development Site Investigation Site Investigation Materials Characterisation Materials Characterisation Capping Trials, CBM, PQC Capping Trials, CBM, PQC Design Parameters Design Parameters Performance Monitoring Performance Monitoring Top of Capping: Stiffness (GDPBT), Damage to Subgrade (Rut Limit) and Compaction (Density) Top of Capping: Stiffness (GDPBT), Damage to Subgrade (Rut Limit) and Compaction (Density) CBM and PQC strengths CBM and PQC strengths Additional FWD Tests Additional FWD Tests CBM stiffness CBM stiffness PQC: slab stiffness, joints performance, corner/edge deflections PQC: slab stiffness, joints performance, corner/edge deflections

35 35

36 36 FWD Test Results SectionLayer Thickness (mm) PQCCBM 0150 PQC SectionStatisticsEffective Stiffness (MPa) PQCCBMSubgrade CBM50%ile 15%ile PQC50%ile 15%ile Joint TypeStatisticsJoint Parameters d 3 -d 4 (mm) d 4 /d 3 (%)*  1 (deg x )*  1 -  2  (deg x ) Transverse Joints 50%ile 85 (or 15*) %ile Longitudinal Joints 50%ile 85 (or 15*) %ile

37 37 FWD Slab Edge and Corner Test Results LocationStatisticsNormalized FWD Deflections (mm x ) d1d1 d2d2 d3d3 d4d4 d5d5 d6d6 d7d7 d 1 - d 3 d 3 - d 4 Slab Centres 50%ile 85%ile Slab Edges 50%ile 85%ile Slab Corners 50%ile 85%ile LocationNormalized FWD Deflections (mm x ) d1d1 d2d2 d3d3 d4d4 d5d5 d6d6 d7d7 d 1 - d 3 d 3 - d 4 Slab Edges 49%50% 60%50%46%19%22% Slab Corners 33%31%32% 35%26%28%16%25%

38 COST SAVING HIGHER FLEXURAL STRENGTH CONCRETE DEVELOPED GIVING 10% REDUCTION IN THICKNESS. A £158,000 A COST SAVINGS

39 39 HIGHER FLEXURAL STRENGTH CONCRETE DEVELOPED GIVING 10% REDUCTION IN THICKNESS. SECONDARY AGGREGATES FOR BOUND BASE 30% COST SAVING. A COST SAVING B £158,000 £295, BA COST SAVINGS 150

40 40 HIGHER FLEXURAL STRENGTH CONCRETE DEVELOPED GIVING 10% REDUCTION IN THICKNESS. SECONDARY AGGREGATES FOR BOUND BASE 30% COST SAVING. USE OF MUDSTONE CAPPING FROM EXCAVATIONS IN LIEU OF QUARRY SUPPLIED TYPE 1 SUB-BASE 90% COST SAVING A COST SAVING BC £158,000 £295,000 £237, BCA COST SAVINGS

41 41 HIGHER FLEXURAL STRENGTH CONCRETE DEVELOPED GIVING 10% REDUCTION IN THICKNESS. SECONDARY AGGREGATES FOR BOUND BASE 30% COST SAVING. USE OF MUDSTONE CAPPING FROM EXCAVATIONS IN LIEU OF QUARRY SUPPLIED TYPE 1 SUB-BASE 90% COST SAVING A COST SAVING BC £158,000 £295,000 £237,000 TOTAL £690,000 Materials development costs £30, BCA COST SAVINGS

42 42 FWD Testing on Cracked and Seated Concrete Pavement

43 43 Crack and Seat of Concrete Pavement

44 44 Joints improvement after C+S

45 45 Stiffness Improvement after C+S Ch. (m) Layer Stifness (MN/m 2 ) before C&SLayer Stifness (MN/m 2 ) after C&S Comment PQC *EFMPQC *EFM Joint Joint Transverse Crack Joint Joint > Transverse Crack

46 46 Assessment of Bond Between Pavement Layers

47 47 ‘Bond’ between Pavement Layers Complicated phenomenon and its effect on pavement behaviour not very well understood Complicated phenomenon and its effect on pavement behaviour not very well understood Function of temperature and material type Function of temperature and material type Can develop with time under traffic loading Can develop with time under traffic loading Full bond is commonly assumed in design Full bond is commonly assumed in design

48 48 ‘Bond’ between Pavement Layers (Cont’d) In practice, difficult to achieve ‘full’ bond as specified in SHW In practice, difficult to achieve ‘full’ bond as specified in SHW Deflection testing (FWD, Deflectograph?) Deflection testing (FWD, Deflectograph?) show higher deflections under loading Layers are acting independently Layers are acting independently Lower effective stiffnesses Lower effective stiffnesses Lower bearing capacity and hence life Lower bearing capacity and hence life

49 49 Methods of Bond Assessment Falling Weight Deflectometer Coring Survey Hammer Test Leutner Test De-bonded Cores

50 50 SWPE Experience with Bond Analysis Over 10 Technical Papers 1994 – 2003 Over 10 Technical Papers 1994 – 2003 Practical application on more than 10 projects (UK & Overseas) Practical application on more than 10 projects (UK & Overseas) EPSRC Research Project ( with Nott. University) EPSRC Research Project ( with Nott. University) HA Research Project (SWPE) HA Research Project (SWPE)


Download ppt "1 The Use of FWD for Pavement Monitoring: Case Studies Bachar Hakim and Martyn Jones Scott Wilson Pavement Engineering Impulsive Matters 2: Impulsive Matters."

Similar presentations


Ads by Google