Transcript Document 7422572

Impulsive Matters 2: Use of FWD for quality control
Heriot-Watt University, Edinburgh, Scotland
19 November 2003
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The Use of FWD for Pavement
Monitoring: Case Studies
Bachar Hakim and Martyn Jones
Scott Wilson Pavement Engineering
1
The Use of FWD for Pavement
Monitoring: Case Studies
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Contents

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Unbound Foundation Performance Testing
Lean Concrete and Pavement Quality Concrete
Crack and Seat Projects
Bond between Pavement Layers
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Foundation Performance Testing
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Main Objectives

QUALITY:
Ensure design assumption = construction

COST & ENVIRONMENTAL SAVINGS:
Greater flexibility in use of marginal materials,
stabilised, secondary & recycled materials
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Foundation Performance
Parameters and Tests:
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Strength (CBR%)
 e.g. Dynamic Cone Penetrometer (DCP)
Stiffness (MPa)
 Dynamic plate (FWD, GDP & Prima)
Density (Kg/m3)
 Nuclear Density Meter (NDM)
Rutting (mm)
 Trafficking Trial
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Foundation Performance Tests Unbound & Stabilised Layers

Implementation of Highway Agency (HA)
‘Draft Performance Specification for
Subgrade and Capping’

Prepared by Consortium, SWPE,
Nottingham and Loughborough
Universities
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Similar Performance Specification for
Sub-base underway, by TRL
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Implementation Phase Trials
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Jersey Airport (Taxiway Alpha)
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Urban Widening of Carriageway, granular capping
A63 Selby Baypass
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Oolitic Limestone and Planings
Doncaster North Bridge
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Lime/Cement Stabilised Weald Clay
A43 Towcester to M40 (Northampton)
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Various Cappings including Cement Stabilised Chalk, Ragstone (local
sandstone) and Recycled Crushed Concrete
A27 Polegate (Sussex)
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First Contractual Use of Specification
A2 – M2 (Kent)
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Sand capping and sand/PFA sub-base
Tilbury Docks: Berths 41-43
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Crushed Concrete capping and sub-base
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FOUNDATION:
Design for Permanent Works - Long Term
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Limit rutting in
Upper Pavement
Limit flexure of Upper Pavement
(Fatigue cracking)
Upper
Pavement
Sub-base
Limit deformation of subgrade
(Structural rutting)
Capping
Subgrade
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FOUNDATION:
Design for Construction - Short Term
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Adequate Stiffness
to Compact Upper
Pavement
Capping
Limit rutting in subgrade
Subgrade
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Capping and Sub-base Thickness Design
SUB-BASE
THICKNESS
(mm)
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400
300
SUB-BASE
200
100
0
For low CBR values
see Paragraphs
3.7 - 3.10
CAPPING
600
THICKNESS
500
(mm)
Key :Capping/Sub-base Design
Sub-base only Design for
flexible and flexible
composite pavements,
capping not required
CAPPING
400
300
200
100
0
1
2
3
4
5
8
10
15
20
30
Subgrade CBR (%)
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Long Term Capping Thickness Design - A
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600
For very soft subgrades
see paragraph 5.19
500
400
300
For thickness requirements less
than 150mm see paragraph 5.20
200
100
0
1
2
3
4
5
6
7
8
9 10
Subgrade CBR (%)
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Short Term Capping Thickness Design - C
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600
For very soft subgrades
see paragraph 5.19
500
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Capping Stiffness (MPa)
400
100
120
For thickness designs
less than 150mm
see paragraph 5.20
300
150
200
100
0
0
10
20
30
40
50
Stiffness of Subgrade - Dynamic Plate (MPa)
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Typical Capping Material Properties
Class
Description
Layer Stiffness (MPa)
6F1
Selected granular material (Fine grading)
60
6F2
Selected granular material (coarse grading)
60 (Sand + Gravel)
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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.
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Correlation of German Dynamic Plate
(GDP) with FWD:- Stiffness Testing
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Prima Dynamic Plate:Stiffness Testing
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Dynamic Plate Tests:
Stiffness Performance Requirements

Finished surface of capping shall:
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>40MPa
25MPa
8 from 10 consecutive tests
absolute minimum
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Minimum 50 tests / trial area
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Representative trial areas
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Cut, Fill, Material Changes
Routine testing at 10m intervals in each
lane
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Rutting Tests - Requirements
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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
< 250
40
> 250 < 500
50
> 500
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Trafficking Trial:
Rutting Tests
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Trafficking Trial:
Rutting Measurements
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A Performance Specification for
Capping and Subgrade - Summary
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Extensive testing and verification over 6
years
Implementation phase has identified
minor changes to 1999 Draft
Successfully trialled at Jersey Airport,
with significant savings
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
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Capping Trial: Case Study
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Capping Trials
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Compaction of capping layer
Capping layer was trafficked 50 times
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FWD and GDPT on Capping
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Nuclear Density Testing
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Capping Wetting
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Rutting and DCP testing
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Foundation Assessment of Existing
Pavements
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A19 DBFO: Foundation Assessment
of Existing Pavements
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Concrete slab failure/settlement in Lane 1
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
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Concrete Slab Failure
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Removal of PQC Slabs
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Rolling the Unbound Materials
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Performance Evaluation Using
Dynamic Plate Tests (GDP & Prima)
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Jersey Airport: Performance
Specifications
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Jersey Airport: ALPHA TAXIWAY PROJECT
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Alpha Taxiway Pavement
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Limited local aggregate performance (quarried
granite aggregates with some fine quartz dune
sand)
Uneconomic to import aggregates due to high
Harbour Dues Charges
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Pavement Development

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Site Investigation
Materials Characterisation

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Capping Trials, CBM, PQC
Design Parameters
Performance Monitoring
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Top of Capping: Stiffness (GDPBT), Damage to
Subgrade (Rut Limit) and Compaction (Density)
CBM and PQC strengths
Additional FWD Tests
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CBM stiffness
PQC: slab stiffness, joints performance, corner/edge
deflections
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FWD Test Results
Section
Layer Thickness
(mm)
PQC
CBM
CBM
0
150
PQC
320
150
Joint Type
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Section
Statistics
Effective Stiffness (MPa)
PQC
CBM
Subgrade
CBM
50%ile
15%ile
-
8400
4700
100
80
PQC
50%ile
15%ile
34300
30200
5400
3800
130
120
Statistics
Joint Parameters
d3-d4
(mm)
d4/d3
(%)*
1
(deg x 10-3)*
1-2
(deg x 10-3)
Transverse
Joints
50%ile
85 (or 15*) %ile
12
15
96
95
6.5
8.4
1.7
2.4
Longitudinal
Joints
50%ile
85 (or 15*) %ile
133
259
63
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0.0
-5.0
5.9
10.3
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FWD Slab Edge and Corner Test
Results
Location
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Normalized FWD Deflections (mm x 10-3)
Statistics
d1
d2
d3
d4
d5
d6
d7
d1 - d3
d3 - d4
Slab Centres
50%ile
85%ile
318
364
290
340
265
314
254
302
202
242
153
185
101
124
48
56
12
13
Slab Edges
50%ile
85%ile
472
583
435
550
399
514
381
498
323
400
230
288
148
200
57
79
15
18
Slab Corners
50%ile
85%ile
422
527
379
487
349
451
334
432
273
353
194
265
129
190
56
83
15
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Normalized FWD Deflections (mm x 10-3)
Location
d1
d2
d3
d4
d5
d6
d7
d1 - d3 d3 - d4
Slab
Edges
49%
50%
50%
50%
60%
50%
46%
19%
22%
Slab
Corners
33%
31%
32%
32%
35%
26%
28%
16%
25%
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COST SAVINGS
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A
305
COST SAVING
A
HIGHER FLEXURAL STRENGTH CONCRETE DEVELOPED GIVING
10% REDUCTION IN THICKNESS.
£158,000
38
COST SAVINGS
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A
305
B
150
COST SAVING
A
HIGHER FLEXURAL STRENGTH CONCRETE DEVELOPED GIVING
10% REDUCTION IN THICKNESS.
£158,000
B
SECONDARY AGGREGATES FOR BOUND BASE 30% COST
SAVING.
£295,000
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COST SAVINGS
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A
305
B
150
C
300
COST SAVING
A
HIGHER FLEXURAL STRENGTH CONCRETE DEVELOPED GIVING
10% REDUCTION IN THICKNESS.
£158,000
B
SECONDARY AGGREGATES FOR BOUND BASE 30% COST
SAVING.
£295,000
C
USE OF MUDSTONE CAPPING FROM EXCAVATIONS IN LIEU OF
QUARRY SUPPLIED TYPE 1 SUB-BASE 90% COST SAVING
£237,000
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COST SAVINGS
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A
305
B
150
C
300
COST SAVING
A
HIGHER FLEXURAL STRENGTH CONCRETE DEVELOPED GIVING
10% REDUCTION IN THICKNESS.
£158,000
B
SECONDARY AGGREGATES FOR BOUND BASE 30% COST
SAVING.
£295,000
C
USE OF MUDSTONE CAPPING FROM EXCAVATIONS IN LIEU OF
QUARRY SUPPLIED TYPE 1 SUB-BASE 90% COST SAVING
£237,000
TOTAL £690,000
Materials development costs £30,000
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FWD Testing on Cracked and Seated
Concrete Pavement
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Crack and Seat of Concrete
Pavement
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Joints improvement after C+S
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90
80
70
10.0
60
50
40
30
20
10
0
2100 2106 2112
-3
Slab Rotation (degreesx10
)
Percentage Load Transfer (%)
100
8.0
Load Transfer (Before)
Load Transfer (After)
6.0
4.0
2.0
Load Transfer (Before)
0.0 (After)
Load Transfer
-2.0
2118 -4.0
2124 2130 2136 2142
2148 2154 2160
-6.0 Chainage (m)
-8.0
-10.0
2100 2106 2112 2118 2124 2130 2136 2142 2148 2154 2160
Chainage (m)
44
Stiffness Improvement after C+S
Layer Stifness (MN/m2) before C&S
Layer Stifness (MN/m2) after C&S
Ch. (m)
Comment
PQC *
EFM
PQC *
EFM
0
6900
330
17820
280
1
14580
370
5990
280
2
21410
420
12640
310
3
29020
420
10930
370
4
32480
270
11860
320
5
17500
280
13520
320
6
4320
700
9460
380
7
19360
380
11540
330
8
-
590
16230
330
9
3720
530
9560
210
10
16460
350
12290
390
11
59580
250
15030
360
12
5410
350
12720
750
13
15250
380
11960
390
14
28700
380
16110
310
15
30400
380
15030
290
16
50130
340
16290
420
17
7820
330
16170
310
18
3850
390
12110
340
19
23410
470
17400
350
20
>70000
490
24660
390
21
3490
450
12760
350
22
8540
470
14120
380
23
13460
330
25970
220
Joint
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Joint
Transverse Crack
Joint
Joint
Transverse Crack
45
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Assessment of Bond Between
Pavement Layers
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‘Bond’ between Pavement Layers
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Complicated phenomenon and its effect on
pavement behaviour not very well understood
Function of temperature and material type
Can develop with time under traffic loading
Full bond is commonly assumed in design
47
‘Bond’ between Pavement Layers
(Cont’d)
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In practice, difficult to achieve ‘full’ bond as
specified in SHW
Deflection testing (FWD, Deflectograph?)
show higher deflections under loading
Layers are acting independently
Lower effective stiffnesses
Lower bearing capacity and hence life
48
Methods of Bond Assessment
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Falling Weight Deflectometer
Coring Survey
De-bonded Cores
Leutner Test
Hammer Test
49
SWPE Experience with Bond Analysis
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Over 10 Technical Papers 1994 – 2003
Practical application on more than 10 projects
(UK & Overseas)
EPSRC Research Project ( with Nott. University)
1999-2002
HA Research Project (SWPE) 2003-2004
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