High Severity - Bahagian Keselamatan Jalan

GUIDE TO THE VISUAL ASSESSMENT OF FLEXIBLE PAVEMENT SURFACE CONDITION By: Norhidayu Hartaty Abdullah Unit Forensik Keselamatan Jalan Bahagian Keselamatan Jalan Cawangan Kejuruteraan Jalan & Geoteknik

Unit Forensik Keselamatan Jalan

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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.Cracks b.Surface Deformations c.Surfaces Defects d.Patches e.Potholes f.Edge Defects Unit Forensik Keselamatan Jalan

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FLEXIBLE PAVEMENT SURFACE CONDITION

CRACKS

SURFACE DEFORMATIONS

SURFACE

Crocodile

Rutting

Bleeding

Edge Break

Block

Depression

Polishing

Edge drop-off

Longitudinal

Corrugation

Ravelling

Transverse

Shoving

Delamination

DEFECTS

PATCH & POTHOLES

EDGE DEFECTS

Edge

Crescent Shaped


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1. PAVEMENT CRACKS

The possible causes of Cracks include: I.Poor construction joints II.Shrinkage III.Reflection of cracks in underlying layers IV.Depression V.Fatigue life of the surface being exceeded VI.Age embrittlement of the surfacing Effects of the Cracks: I.Loss of water-proofing of the pavement layers II.Loss of load spreading ability III.Pumping and loss of fines from the base course IV.Loss of riding quality V.Loss of appearance


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PAVEMENT CRACKS

Types of Pavement Cracks:


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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


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Severity Level of Crocodile Crack

Low Severity • Hairline cracks running parallel to each other • cracks not spalled

Moderate Severity • pattern of articulated pieces formed by cracks may be lightly spalled • cracks maybe sealed

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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


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BLOCK CRACKS also 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 Treatments

1

Joints in underlying layer

Crushed aggregate overlay

2

Shrinkage and fatigue of underlying cemented materials

Replace underlying cemented materials

3

Shrinkage cracks (due to bitumen hardening) in bituminous surfacing

Seal cracks or replace bituminous surface

4

Fatigue cracks in embrittled bituminous wearing course

Cut and patch or crushed aggregate overlay


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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 greater than 3 mm

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Severity Level of Block Cracks

High Severity Severely spalled cracks


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LONGITUDINAL CRACKS also 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 No

Possible Causes

Probable Treatments

1

Reflection of shrinkage cracks

Cut and patch

2

Poorly constructed paving lane in bituminous surfacing

Replace 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 Crushed aggregate overlay base or reconstruction of joints 12

Severity Level of Longitudinal Cracks

Low Severity - Single cracks without any spalling - Mean unsealed carcks width of 3mm or 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


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TRANSVERSE CRACKS

Transverse cracks are unconnected cracks running transversely (perpendicularly to pavement centre line) across the pavement. No

Possible Causes

Probable Treatments

1

Reflection of shrinkage cracks

Cut and patch

2

Construction joint in bituminous surfacing

Crack 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


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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

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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

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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 Treatments

1

Excessive traffic loading at pavement edge

Widen 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


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Severity Level of Edge Cracks

Low Severity - no breakup or ravelling

ModerateSeverity - with some breakup or ravelling

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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


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CRESCENT SHAPED CRACKS or Parabolic, Slippage, Shear Crack

Crescent Shaped Cracks are commonly associated with shoving, often occur in closely spaced parallel group. It is mainly associated with bituminous layer only No

Possible Causes

Treatment Treatments

1

Lack of bond between wearing course and the underlying layers

Cut and patch

2

Low modulus base course

Reconstruction of base

3

Thin wearing course

Bituminous overlay

4

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


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Severity Level of Crescent Shaped Cracks

Low Severity - no breakup or shoving

Moderate Severity - with some breakup or shoving

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Severity Level of Crescent Shaped Cracks

High Severity - with considerable breakup and shoving


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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.Rutting II.Corrugation III.Depression IV.Shoving


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2. SURFACE DEFORMATIONS

The major types of Surface Deformation:


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RUTTING also known as Logitudinal Rut

Rutting is longitudinal deformation or depression in the wheel paths which occur 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. 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

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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

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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


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CORRUGATIONS also 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 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 29

Severity Levels of Corrugation Low Severity -Noticeable (based on observation of its appearance and its effect on riding quality)

Moderate Severity - Cause rough ride

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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

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DEPRESSIONS also 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 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 subgrade due to environmental influences

Improve sub-soil drainage and reconstruct

4

Settlement due to instability of embankment

Embankment stabilization 32

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

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Severity Levels of Depressions High Severity - poor control of vehicles when driving over pavement - driver always having to anticipate depression ahead

Measurements to be taken: • maximum depth under 1.2m straight edge • area of depression

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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 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 Base reconstruction through the surface

4

Stop and start of vehicles at intersections or roundabout

Mill off and replace with stiffer mix35

Severity Levels of Shoving Low Severity - Noticeable swaying motion - effect on riding quality

Moderate Severity - resulting in rough ride

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Severity Levels of Shoving High Severity - resulting in very rough ride - vehicle may loose control because of its presence

Measurements to be taken: • maximum depth of bulge under 1.2m straight edge from high point • area affected

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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. Bleeding II. Ravelling III. Polishing IV. Delamination

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SURFACE DEFECTS


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BLEEDING also 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 binder Effect: 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

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Severity Levels of Bleeding Low Severity -visible colouring of pavement surface

Moderate Severity - distinctive appearance with excess bitumen already free

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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

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RAVELLING also known as Fretting

Ravelling is the progressive disintegration of the pavement surface by loss of binder or aggregates or both No

Possible Causes

Probable Treatments

1

Insufficient bitumen content

Thin bituminous overlay

2

Poor adhesion of bitumen binder to aggregate particles due to wet aggregate


3

Inadequate compaction or construction during wet weather


4

Deterioration of binder and/or aggregates


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Severity Levels of Raveling Low Severity - Wearing away of the aggregates has not progressed significantly

Moderate Severity - Aggregate/binder has worn away - The surface texture is becoming rough and pitted - Loose particles generally exist

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Severity Levels of Raveling High Severity - The surface texture is very rough and pitted

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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 Treatments

1

Inadequate resistance to polishing of aggregates surface

Thin bituminous overlay or use stiffer mix

2

Use of naturally smooth uncrushed Thin bituminous overlay aggregates

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Severity Levels of Polishing Low Severity - smoothening and rounding of upper surface of the roadstone has started

Moderate Severity - coarse aggregates exposed

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Severity Levels of Polishing High Severity - smoothening and rounding of the roadstone has progressed significantly

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DELAMINATION Also 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 Treatments

1

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


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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 around the peeled off area.

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Severity Levels of Delamination High Severity - a group of more than 2 moderate delaminations along a short stretch of road

Measurements to be taken: • thickness of layer peeled off • area of individuall delaminations • number of delaminations

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4. PATCH AND POTHOLES


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PATCH Patch is a repaired section of pavement where a portion of the pavement surface has 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


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PATCH Moderate Severity - patch has moderate severity distress

High Severity - patch has high severity distress

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POTHOLES

Potholes is bowl shaped cavity in the pavement surface, produced when traffic breaches 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

Moderate

25 - 50

Moderate

Moderate

High

> 50

Moderate

High

High


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POTHOLES Low Severity - area < 0.3m2 and depth < 25mm

Moderate Severity - area < 0.3m2 with depth 25 mm to 50 mm

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High Severity - area > 0.1 m2 with depth > 50 mm

No

Possible Cause

Probable Treatments

1

Loss of surface course

patching

2

Moisture entry to base course through a cracked pavement surface

Cut and patch

3

Load associated disintegration of base

Base reconstruction 57

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


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5. EDGE DEFECTS


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EDGE BREAKS

Edge break occur when the edge of the bituminous surface are fretted or broken No

Possible Causes

Probable Treatments

1

Inadequate pavement width

Widen the pavement

2

Alignment which encourage drivers to travel on pavement edge

Pavement widening and realignment

3

Inadequate edge support

Shoulder strengthening

4

Edge drop-off

Strengthening and leveling of shoulder with road surface

5

Loss of adhesion to base

Cut and patch


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Severity Levels of Edge Break Low Severity - edge break has just started

Moderate Severity - edge break with considerable breakup

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Severity Levels of Edge Break High Severity - significant length of edge break and surfacing loss

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EDGE DROP-OFFS Edge drop-off is the difference elevation between the traffic lane and outside shoulder Usually occur when the outside shoulder settles or erodes It is not a defect if the drop-off is less than 25 mm No Possible Causes

Probable Treatments

1

Inadequate pavement width

Widen the pavement

2

Shoulder material with inadequate Replace shoulder material and resistance to erosion and reconstruct abrasion

3

Resurfacing of pavement without resurfacing the shoulder


Leveling the shoulder with road surface

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Severity Levels of Edge Drop-Off Low Severity - slight drop-off

Moderate Severity - significant drop-off

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Severity Levels of Edge Drop-Off High Severity - height of drop > 100 mm and it is danger to traffic

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