Upload
vuongdiep
View
251
Download
2
Embed Size (px)
Citation preview
GUIDE TO THE VISUAL ASSESSMENT OF FLEXIBLE PAVEMENT SURFACE CONDITION
By:Norhidayu Hartaty Abdullah
Unit Forensik Keselamatan JalanBahagian Keselamatan Jalan
Cawangan Kejuruteraan Jalan & Geoteknik
Unit Forensik Keselamatan Jalan 1
Visual Assessment of Flexible Pavement Surface Condition
Assessment of Pavement Surface condition is required:•As a measure of the ability of the pavement to continue to provide the required service to the public• determining the deficiencies and inadequacies of the pavement•The remedial measures to be taken as well the maintenance planning for the pavement
Distresses in Flexible Pavement can be categorized into one of the following types:a.Cracksb.Surface Deformationsc.Surfaces Defectsd.Patchese.Potholesf.Edge Defects
Unit Forensik Keselamatan Jalan 2
FLEXIBLE PAVEMENT SURFACE CONDITION
CRACKS SURFACE DEFORMATIONS
SURFACEDEFECTS
EDGE DEFECTS
PATCH & POTHOLES
Depression
Rutting Bleeding
Polishing
Edge Break
Edge drop-off
Block
Longitudinal
Transverse
Edge
Crescent Shaped
Crocodile
Corrugation
Shoving Delamination
Ravelling
Unit Forensik Keselamatan Jalan 3
1. PAVEMENT CRACKS
The possible causes of Cracks include:I.Poor construction jointsII.ShrinkageIII.Reflection of cracks in underlying layersIV.DepressionV.Fatigue life of the surface being exceededVI.Age embrittlement of the surfacing
Effects of the Cracks:I.Loss of water-proofing of the pavement layersII.Loss of load spreading abilityIII.Pumping and loss of fines from the base courseIV.Loss of riding qualityV.Loss of appearance
Unit Forensik Keselamatan Jalan 4
PAVEMENT CRACKS
Types of Pavement Cracks:
Unit Forensik Keselamatan Jalan 5
CROCODILE CRACKS
Crocodile cracks is the consequences of the :Inability of the structure to support the repeated loads due to a ‘softening’of the material, which will increase the moisture content
No Possible Causes Probable Treatment
1 Inadequate pavement thickness
Strengthen the pavement or reconstruction
2 Low modulus base Strengthen the base/reconstruction
3 Brittle base Base recycling/reconstruction
4 Poor base drainage Improve the drainage and reconstruct
5 Brittle wearing course Replace or treat wearing course
Unit Forensik Keselamatan Jalan 6
Severity Level of Crocodile Crack
Low Severity• Hairline cracks running parallelto each other
• cracks not spalled
Moderate Severity• pattern of articulated pieces formed by cracks may be lightly spalled
• cracks maybe sealed
7
Severity Level of Crocodile Crack
High Severity• pieces more severely spalled at edges and loosened
• pieces rocks under traffic; pumping may exist
Measrument to be taken in assest the crack:• area affected• predominant crack width• predominant cell width
Unit Forensik Keselamatan Jalan 8
BLOCK CRACKSalso known as Ladder Cracks
Blocks cracks are :interconnected cracks forming a series of blocks, approximately rectangular in shapes. Blocks sizes are usually greater than 300mm and can exceed 3000mm
No Possible Causes Probable Treatments1 Joints in underlying layer Crushed aggregate overlay2 Shrinkage and fatigue of
underlying cemented materialsReplace underlying cemented materials
3 Shrinkage cracks (due to bitumen hardening) in bituminous surfacing
Seal cracks or replace bituminous surface
4 Fatigue cracks in embrittledbituminous wearing course
Cut and patch or crushed aggregate overlay
Unit Forensik Keselamatan Jalan 9
Severity Level of Block Cracks
Low Severity• blocks defined by unspalled cracks with- mean width of 3mm or less- cracks with sealant in good condition
Moderate Severity
Cracks with a mean width greaterthan 3 mm
10
Severity Level of Block Cracks
High Severity
Severely spalled cracks
Unit Forensik Keselamatan Jalan 11
LONGITUDINAL CRACKSalso known as Line Cracks
Longitudinal cracks are:- cracks which are usually straight and parallel to the centre line - situated at or near the middle of the lane- can happen singly or as series
12
No Possible Causes Probable Treatments1 Reflection of shrinkage cracks Cut and patch2 Poorly constructed paving lane in
bituminous surfacingReplace bituminous surfacing
3 Displacement of joints at pavement widening
Reconstruction of joints
4 Differential settlement between cut and fill
reconstruction
5 Reflection of joints in the underlying base
Crushed aggregate overlay or reconstruction of joints
Severity Level of Longitudinal Cracks
Low Severity
- Single cracks without any spalling- Mean unsealed carcks width of 3mmor less
Moderate Severity
Crack’s width of greater than 3 mm
Severity Level of Longitudinal Cracks
High Severity
- Multiple spalled cracks
Measrument to be taken in assest the crack:• area affected• length of dominant cracks• width of dominant cracks• spacing
Unit Forensik Keselamatan Jalan 14
TRANSVERSE CRACKS
Transverse cracks are unconnected cracks running transversely(perpendicularly to pavement centre line) across the pavement.
No Possible Causes Probable Treatments1 Reflection of shrinkage cracks Cut and patch2 Construction joint in bituminous
surfacingCrack sealant
3 Structural failure of cement concrete base
Reconstruction of base
4 Shrinkage crack in bituminous surfacing
Seal cracks or replace bituminous surfacing
5 Reflection of joints in the underlying base
Crushed aggregate overlay or reconstrution of joints
Unit Forensik Keselamatan Jalan 15
Severity Level of Transverse Cracks
Low Severity
- crack’s width less than 3 mm without any spalling
ModerateSeverity
- crack’s width is more than 3 mm
16
Severity Level of Transverse Cracks
High Severity
- high severity with spalling
Measrument to be taken in assest the crack:• area affected• spacing• length• predominant crack width
Unit Forensik Keselamatan Jalan 17
EDGE CRACKS
Edge cracks are Crescent shaped or fairly continuous cracks, parallel to, and usually within 300mm to 600mm of the pavement edge.It usually occurs when paved shoulders do not exist.
No Possible Causes Probable Treatments1 Excessive traffic loading at
pavement edgeWiden the pavement or strengthen the pavement edge
2 Poor drainage at pavement edge and shoulder
Improve drainage and shoulder
3 Inadequate pavement width which forces traffic too close to pavement edge
Widen the pavement
4 Insufficient bearing support reconstruction
Unit Forensik Keselamatan Jalan 18
Severity Level of Edge Cracks
Low Severity
- no breakup or ravelling
ModerateSeverity- with some breakup or ravelling
19
Severity Level of Edge Cracks
High Severity
- with considerable breakup or ravelling along edge
Measrument to be taken in assest the crack:• area affected• length• predominant crack width
Unit Forensik Keselamatan Jalan 20
CRESCENT SHAPED CRACKSor Parabolic, Slippage, Shear Crack
Crescent Shaped Cracks are commonly associated with shoving, often occurin closely spaced parallel group.It is mainly associated with bituminous layer only
Unit Forensik Keselamatan Jalan 21
No Possible Causes Treatment Treatments1 Lack of bond between wearing
course and the underlying layersCut and patch
2 Low modulus base course Reconstruction of base3 Thin wearing course Bituminous overlay4 Drangging of paver during laying
when bituminous mix temperature were low
Cut and patch
5 High stresses due to braking and acceleration movements
Bituminous overlay with stiffer mix or use high compaction mix
Severity Level of Crescent Shaped Cracks
Low Severity
- no breakup or shoving
Moderate Severity- with some breakup or shoving
22
Severity Level of Crescent Shaped Cracks
High Severity
- with considerable breakup andshoving
Unit Forensik Keselamatan Jalan 23
2. SURFACE DEFORMATIONS
Deformation is :
- happen when a road surface undergoes changes from its original constructed profile
- occur after construction due to trafficking or environmental influences- influence the riding quality of the pavement- may reflect structural inadequancies- may lead to cracking of surface layer
Major types of Surface Deformation are:I.RuttingII.CorrugationIII.DepressionIV.Shoving
Unit Forensik Keselamatan Jalan 24
2. SURFACE DEFORMATIONS
The major types of Surface Deformation:
Unit Forensik Keselamatan Jalan 25
RUTTINGalso known as Logitudinal Rut
Rutting is longitudinal deformation or depression in the wheel paths whichoccur after repeated application of axle loading.May occur in one or both wheel paths of a lane.The length to width ratio would normally be greater than 4 to 1.
26
No Possible Causes Probable Treatments
1 Inadequate pavement thickness Strengthening overlay or reconstruction
2 Inadequate compaction of structural layers
reconstruction
3 Unstable bituminous mixes Replace or recycle bituminous surfacing or use stiffer mix
4 Unstable shoulder materials which do not provide adequate lateral support
Shoulder improvement and overlay rutted area with bituminous surfacing
5 Overstressed subgrade which deform permenantly
reconstruction
Severity Level of Rutting
Low Severity
Rut depths of less than 12mm (measured under a transverse 1.2m straight edge)
Moderate Severity
•Rut depths of between 12 mm to 25 mm
•May include slight longitudinal cracks
27
Severity Level of Rutting
High Severity
• Rut depths of greater than 25mm• May include multiple longitudinal or crocodile cracks
Measurements to be taken in the assessment:• maximum depth under a transverse 1.2 m straight edge• length
Unit Forensik Keselamatan Jalan 28
CORRUGATIONSalso knows as Rippling
-Are regular transverse undulation, closely spaced alternate valleys and crests with wavelengths of less than 2 m- Will result in a rough ride and will become worse with time
29
No Possible Causes Probable Treatments
1 Inadequate stability of bituminous surface
Replace bituminous surface
2 Compaction of base in wave form Base reconstruction
3 Faulty paver behavior with some mixes
Replace the faulty mixes and correct the faulty paver behavior
4 Heavy traffic on steep downgrade or upgrade
Mill of corrugated surface and replace with stiffer mix
5 Stopping at intersection stop lights or roundabout
Mill off corrugated surface and replace with stiffer mix
Severity Levels of Corrugation
Low Severity-Noticeable (based on observation of its appearance and its effect on riding quality)
Moderate Severity- Cause rough ride
30
Severity Levels of Corrugation
High Severity- Very rough ride. Vehicle may loose control because of its presence)
Measurements to be taken:
• Maximum depth under 1.2m straight edge• Crest to crest spacing• Length of pavement affected
31
DEPRESSIONSalso known as Distortions
Depressions are localized area within a pavement with elevations lower than the surrounding area.It results from : Settlement, Slope Failure, Volume Change due to
moisture changes
32
No Possible Causes Probable Treatments
1 Differential settlement of subgrade or base materials
Subgrade or base reconstruct
2 Settlement of service and/or widening trenches
Reconstruction of services and/or widening trenches
3 Volume change of subgradedue to environmental influences
Improve sub-soil drainage and reconstruct
4 Settlement due to instability of embankment
Embankment stabilization
Severity Levels of Depressions
Low Severity- Noticeable swaying motion- vehicle is still in good control condition
Moderate Severity
- fair control of vehicle when driving over pavement
33
Severity Levels of Depressions
High Severity- poor control of vehicles when drivingover pavement
- driver always having to anticipate depression ahead
Measurements to be taken:
• maximum depth under 1.2m straight edge• area of depression
34
SHOVINGS
Shoving is :• the bulging of the road surface (generally parallel to the direction of traffic, and/or horizontal displacement of surfacing material)
• mainly in the direction of traffic where braking or acceleration movements occur• caused by traffic pushing against the pavement
35
No Possible Causes Probable Treatments
1 Low stability mix Mill off and replace the bituminous surfacing
2 Lack of bond between asphalt surface and underlying layer which may be caused by excessive tack coating
Replace bituminous surfacing with lower binder content mix
3 Unstable granular base reflecting through the surface
Base reconstruction
4 Stop and start of vehicles at intersections or roundabout
Mill off and replace with stiffer mix
Severity Levels of Shoving
Low Severity- Noticeable swaying motion- effect on riding quality
Moderate Severity- resulting in rough ride
36
Severity Levels of Shoving
High Severity
- resulting in very rough ride- vehicle may loose controlbecause of its presence
Measurements to be taken:
• maximum depth of bulge under 1.2m straight edge from high point
• area affected
37
3. SURFACE DEFECTS
• Surface defects cover loss of surfacing materials, micro and macro textures• Influenced on: the serviceability and safety of pavement (skid resistance, Maneuverability and riding quality)
The main types of Surface Defects are:I. BleedingII. RavellingIII. PolishingIV. Delamination
38
SURFACE DEFECTS
Unit Forensik Keselamatan Jalan 39
BLEEDINGalso known as Flushing, Fating, Slick, Black Spot
Bleeding is the presence of free bitumen binder on the surface, most likely to occur in the wheel paths during hot weather.Result from : Upward migration of the binderEffect: cause low texture depth, inadequate tire to stone contact
No Possible Causes Probable Treatments
1 Excessive application of binder with respect to the stone size.
Apply hot sand to blot up the excess ninder
2 Paving over flushed surfaces. Apply hot sand or aggregate seal coat
3 Paving over excessively primed surfaces
Apply hot sand
40
Severity Levels of Bleeding
Low Severity-visible colouring of pavement surface
Moderate Severity- distinctive appearance with excess bitumenalready free
41
Severity Levels of Bleeding
High Severity-Gives the pavement a wet look-Tire marks are evident
Measurements to be taken:
• Area affected• Percentage by area of stone immersed
42
RAVELLINGalso known as Fretting
Ravelling is the progressive disintegration of the pavement surface by lossof binder or aggregates or both
No Possible Causes Probable Treatments1 Insufficient bitumen content Thin bituminous overlay
2 Poor adhesion of bitumen binder to aggregate particles due to wet aggregate
Thin bituminous overlay
3 Inadequate compaction or construction during wet weather
Thin bituminous overlay
4 Deterioration of binder and/or aggregates
Thin bituminous overlay
43
Severity Levels of Raveling
Low Severity- Wearing away of the aggregates has notprogressed significantly
Moderate Severity
- Aggregate/binder has worn away- The surface texture is becoming rough and pitted
- Loose particles generally exist
44
Severity Levels of Raveling
High Severity- The surface texture is very rough and pitted
45
POLISHING
Polishing is the smoothing and rounding of the upper surface of the roadstones,exposing coarse aggregates which are glossy in appearance and smooth to touch.Usually occurs in the wheel paths.
No Possible Causes Probable Treatments1 Inadequate resistance to polishing
of aggregates surfaceThin bituminous overlay or use stiffer mix
2 Use of naturally smooth uncrushed aggregates
Thin bituminous overlay
46
Severity Levels of Polishing
Low Severity
- smoothening and rounding of upper surfaceof the roadstone has started
Moderate Severity
- coarse aggregates exposed
47
Severity Levels of Polishing
High Severity
- smoothening and rounding of theroadstone has progressed significantly
48
DELAMINATIONAlso known as Peeling, Surface Lifting, Seal Break, Flaking
Delamination is the loss of a discrete and large area of wearing course.Clear delineation of the wearing course and the layer below
No Possible Causes Probable Treatments1 Inadequate cleaning or inadequate
tack coat before placement of upper layers
Mill off and re-lay upper layers
2 Seepage of water Replace wearing course or thin bituminous overlay
3 Weak, loose layer immediately underlying seal
Reconstruction of weak layers
4 Adhesion of surface binder to vehicle tyres
Thin bituminous overlay
49
Severity Levels of Delamination
Low Severity
- peeling of the top surface has started
Moderate Severity
- surface area peeled off between 0.1m2 to 2.5m2
- severe crocodiles cracks in and aroundthe peeled off area.
50
Severity Levels of Delamination
High Severity- a group of more than 2 moderatedelaminations along a short stretch of road
Measurements to be taken:
• thickness of layer peeled off• area of individuall delaminations• number of delaminations
51
4. PATCH AND POTHOLES
Unit Forensik Keselamatan Jalan 52
PATCH
Patch is a repaired section of pavement where a portion of the pavement surfacehas been removed and replaced.Effect: Caused further defects, where it raised or depressed below the level
of the pavement surface
Low Severity- patch is in good condition- has low severity distress
Unit Forensik Keselamatan Jalan 53
PATCH
Moderate Severity
- patch has moderate severity distress
High Severity- patch has high severity distress
54
POTHOLES
Potholes is bowl shaped cavity in the pavement surface, produced when trafficbreaches small pieces of pavement surface and allow water entry.Cause by : the loss of wearing course and binder course materials
the weakening of the base course or poor surfacing quality
Severity levels of Potholes:
AREA (square metre)Depth (mm) < 0.1 0.1 - 0.3 > 0.3
< 25 Low Low Moderate25 - 50 Moderate Moderate High
> 50 Moderate High High
Unit Forensik Keselamatan Jalan 55
POTHOLES
- area < 0.3m2 and depth < 25mm
Low Severity
Moderate Severity
- area < 0.3m2 with depth 25 mm to 50 mm
56
High Severity- area > 0.1 m2 with depth > 50 mm
57
No Possible Cause Probable Treatments1 Loss of surface course patching2 Moisture entry to base course
through a cracked pavement surface
Cut and patch
3 Load associated disintegration of base
Base reconstruction
5. EDGE DEFECTS
Edge Defects occur along the interface of flexible pavement and the shoulder,where the shoulder is unsealed
The Effect of edge defects:
• reduction of pavement width• loss of quality of ride, possible loss of vehicle control• entry of water into base• leading to erosion of shoulder
Unit Forensik Keselamatan Jalan 58
5. EDGE DEFECTS
Unit Forensik Keselamatan Jalan 59
EDGE BREAKS
Edge break occur when the edge of the bituminous surface are fretted or broken
No Possible Causes Probable Treatments1 Inadequate pavement width Widen the pavement2 Alignment which encourage
drivers to travel on pavement edge
Pavement widening and realignment
3 Inadequate edge support Shoulder strengthening4 Edge drop-off Strengthening and leveling of
shoulder with road surface5 Loss of adhesion to base Cut and patch
Unit Forensik Keselamatan Jalan 60
Severity Levels of Edge Break
Low Severity- edge break has just started
Moderate Severity
- edge break with considerable breakup
61
Severity Levels of Edge Break
High Severity- significant length of edge break and surfacing loss
62
EDGE DROP-OFFS
Edge drop-off is the difference elevation between the traffic lane andoutside shoulderUsually occur when the outside shoulder settles or erodesIt is not a defect if the drop-off is less than 25 mm
No Possible Causes Probable Treatments1 Inadequate pavement width Widen the pavement2 Shoulder material with inadequate
resistance to erosion and abrasion
Replace shoulder material and reconstruct
3 Resurfacing of pavement without resurfacing the shoulder
Leveling the shoulder with road surface
Unit Forensik Keselamatan Jalan 63
Severity Levels of Edge Drop-Off
Low Severity- slight drop-off
Moderate Severity- significant drop-off
64
Severity Levels of Edge Drop-Off
High Severity
- height of drop > 100 mm and it isdanger to traffic
65