A Guide to the Visual Assessement of Flexible Pavement Surface Conditions - JKR 20709-2060-92

JKR 20709-2060-92

A Guide To The Visual Assessment of Flexible Pavement Surface Conditions 7.0m

5.0m

Roads Branch Public Works Department Malaysia Jalan Sultan Salahuddin 50582 Kuala Lumpur

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A Guide To The Visual Assessement Of Flexible Pavement Surface Conditions

A GUIDE TO VISUAL ASSESSMENT OF FLEXIBLE PAVEMENT SURFACE CONDITIONS FOREWORD

ACKNOWLEDGEMENT

In Malaysia as well as in most other countries in the world, the road network remains the predominant mode of transportation facility. To ensure its continued efficiency and accessibility, the road network has to be maintained to a high standard. Research work carried out at Institut Kerja Raya Malaysia (IKRAM) has enable Jabatan Kerja Raya (JKR) Malaysia to understand and develop improved techniques for the maintenance of the road network.

This guide is prepared by the Pavement Research Unit (Head: Ir Mohamed Shafii Mustafa). The authors of this guideline are Ir Koid Teng Hye, Ir Mohamed Shafii Mustafa, Mohd Sabri Hasim, Abd. Mutalif K. A. Abd. Hameed and Ahmad Fauzi Abdul Malek. The document forms part of a series of guidelines on the design, construction and maintenance of flexible pavements which the Pavement Research Unit produces as part of their studies.

It is the aspiration of JKR to be able to share this knowledge with those that are involved in road building and maintenance activities. It is therefore my pleasure to introduce this first edition of A Guide to Visual Assessment of Flexible Pavement Surface Conditions.

The guide was reviewed by a Committee headed by the Director of IKRAM, Ir Ng Chong Yuen. Other members of the Committee were

This guide, which is the first part of a series of guidelines on road maintenance techniques has a two fold purpose. Firstly, it is to encourage the usage of common nomenclature for the various pavement conditions and secondly it hopes to promote more effective maintenance works with the indication of the possible causes of each different type of pavement distress and their probable treatments.

Ir. Aik Siaw Kong - Road Maintenance, Roads Branch

It is my hope that this guideline will be of help to all who are involved in road maintenance activities and contribute significantly towards better maintenance techniques.

Ir. Han Joke Kwang - IKRAM

Ir. Tai Meu Choi - Road Maintenance, Roads Branch Ir. Zainol Rashid Zainuddin - Road Maintenance, Roads Branch; Ir. Lee Swee Kee - Road Design, Roads Branch. The authors thank the Director General of Public Works Malaysia for his permission to publish the guideline.

(Tan Sri Dato' Ir. Wan A. Rahman Yaacob) Director General of Public Works Jabatan Kerja Raya Malaysia

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Page 1

A Guide To The Visual Assessment Of Flexible Pavement Surface Conditions.

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CONTENTS Page FOREWORD ACKNOWLEDGEMENT 1.0. INTRODUCTION

2

CATALOGUE OF DISTRESSES IN BITUMINOUS SURFACES

3

2.0. PAVEMENT CRACKS

3

2.1. 2.2. 2.3. 2.4. 2.5. 2.6.

4 5 6 7 8 9

Crocodile Block Longitudinal Transverse Edge Crescent Shaped

3.0. SURFACE DEFORMATIONS 10 3.1. 3.2. 3.3. 3.4.

Rutting Corrugation Depression Shoving

11 12 13 14

4.0

SURFACE DEFECTS

15

4.1. 4.2. 4.3. 4.4.

Bleeding Ravelling Polishing Delamination

16 17 18 19

5.0. PATCH

used in one form or another by most road departments and/or highway authorities as a measure of the ability of the pavement to continue to provide the required service to the public. More importantly, it is used in determining deficiencies and inadequacies of pavements, the remedial measures to be taken, its fiscal needs, planning and programming of pavement maintenance and/or rehabilitation. This guide is for the assessment of flexible road pavements only. Concrete pavements and unpaved roads are not covered by this guide. The aims of this guide are :i)

To provide a uniform nomenclature for the description of visible pavement distresses.

ii) to provide a comprehensive catalogue of the major visible distress types. iii) To promote the usage of distress recognition as an aid to the diagnosis of pavement deficiencies. Pavement distresses are categorized and quantified. Illustrations of each category are provided to lend uniformity to reporting and interpretation. Description of the severity of the particular distress is made to conform with standard words that express the relative severity on a low, moderate or high scale.

20 The following data are also provided for each distress type :-

6.0. POTHOLE

21

7.0. EDGE DEFECTS

22

i) Common synonym(s).

7.1. 7.2.

22 23

ii) Description of the essential features of the distress.

GLOSSARY

24

iii) Photographs of typical examples.

REFERENCES

25

iv) List of probable or most likely causes.

Edge Break Edge Drop Off

1.0. INTRODUCTION

v) List of probable treatments.

Assessment of pavement surface conditions is Cawangan Jalan, Ibu Pejabat JKR, K.L

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CATALOGUE OF DISTRESSES IN FLEXIBLE PAVEMENTS Manifestation of Distresses in flexible pavements can be categorized into one of the following types : a) Cracks

A Guide To The Visual Assessment Of Flexible Pavement Surface Conditions.

i) Depression. ii) Fatigue life of the surfacing being exceeded. iii) Age embrittlement of the surfacing. iv) Reflection of cracks in underlying layers.

b) Surface deformations v) Shrinkage. c) Surface defects vi) Poor construction joints. d) Patches e) Potholes f) Eedge defects

This section includes the following types of cracks: i) Crocodile cracks. ii) Block cracks.

2.0. PAVEMENT CRACKS iii) Longitudinal cracks. Cracks are fissures resulting from partial or complete fractures of the pavement surface. Cracking of road pavement surfaces can happen in a wide variety of patterns, ranging from isolated single crack to an interconnected pattern extending over the entire pavement surface. The detrimental effects associated with the presence of cracks are : i)

iv) Transverse cracks. v) Edge cracks. vi) Crescent shaped cracks. The general form of the various types of cracks is illustrated in Fiqure 1.

Loss of water-proofing of the pavement layers.

ii) Loss of load spreading ability of the cracked material. iii) Pumping and loss of fines from the base course. iv) Loss of riding quality through loss of surfacing. v) Loss of appearance.

FIGURE 1 : TYPES OF CRACK

The loss of load spreading ability and waterproofing will usually lead to accelerated deterioration of the pavement condition. The possible causes of cracks include :

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CROCODILE CRACKS

DESCRIPTION Crocodile cracks are interconnected or interlaced cracks which form a network of multisided blocks resembling the skin of a crocodile. The block size can range from 100 mm to about 300 mm.

Low severity with interconnected hairline cracks

Crocodile cracks is a consequence of the inability of the structure to support the repeated loads due to a "softening" of the material normally associated with increase in moisture content. The cracks in the subbase or subgrade tend to spread rapidly under rain and traffic causing blocks of surfacing to be displaced and broken up. SEVERITY LEVELS

Moderate severity with lightly spalled cracks

Low Interconnected or interlaced hairline cracks running parallel to each other; cracks not spalled. Moderate A pattern of articulated pieces formed by cracks that may be lightly spalled. Cracks may be sealed.

High severity with severe spalling

2.1. CROCODILE CRACKS

High Pieces more severely spalled at edges and loosened; pieces rock under traffic; pumping may exist.

SYNONYMS

MEASUREMENTS TO BE TAKEN

Alligator, chicken wire, fish net, polygonal, fatigue cracks.

a) area affected. b) predominant crack width c) predominant cell width.

NO.

POSSIBLE CAUSES

PROBABLE TREATMENTS

1.

Inadequate pavement thickness

Strengthen the pavement or reconstruction

2.

Low modulus base

Strengthen the base or reconstruction

3.

Brittle base

Base recycling or reconstruction

4.

Poor base drainage

Improve the drainage and reconstruct

5.

Brittle wearing course

Replace or treat wearing course

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BLOCK CRACKS

2.2. BLOCK CRACKS SYNONYM Ladder cracks.

DESCRIPTION

Low severity with cracks' width < 3 mm

Block cracks are interconnected cracks forming a series of blocks, approximately rectangular in shape. Block sizes are usually greater than 300 mm and can exceed 3000 mm. SEVERITY LEVELS Low Blocks defined by unspalled cracks with a mean width of 3 mm or less; cracks with sealant in good condition.

Moderate severity with cracks' width > 3 mm

Moderate Blocks defined by moderately spalled cracks; cracks with a mean width greater than 3 mm. High Blocks well defined by severely spalled cracks. MEASUREMENTS TO BE TAKEN

High severity with severely spalled cracks

NO.

POSSIBLE CAUSES

a) area affected. b) predominant crack width. c) predominant cell width.

PROBABLE TREAMENTS

1

Joints in underlying layer

Crushed aggregate overlay

2

Shrinkage and fatigue of underlying cemented material

Replace underlying cemented materials

3

Shrinkage cracks (due to bitumen seal hardening) in bituminous surfacing

Seal cracks or replace bituminous surfacing

4

Fatigue cracks in embrittled bituminous wearing course

Cut and patch or crushed aggregate overlay

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LONGITUDINAL CRACKS

2.3. LONGITUDINAL CRACKS SYNONYM Line cracks DESCRIPTION

Low severity single crack without any spalling

Longitudinal cracks are cracks which are usually straight and parallel to the centre line, situated at or near the middle of the lane. It can happen singly or as series of almost parallel cracks or with some limited branching. SEVERITY LEVELS Low Cracks with low severity or no spalling; mean unsealed crack width of 3 mm or less.

Moderate severity with crack's width > 3 mm

Moderate Cracks with moderately severe spalling; mean unsealed crack width of greater than 3 mm; sealant material in bad condition. High Cracks with high severity spalling. MEASUREMENTS TO BE TAKEN

High severity with multiple spalled cracks

NO

POSSIBLE CAUSES

a) width of dominant crack. b) length of dominant crack. c) spacing. d) area affected.

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 or reconsstruction base of joints

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TRANSVERSE CRACKS

2.4. TRANSVERSE CRACKS Transverse cracks are unconnected cracks running transversely (relatively perpendicular to pavement centre line) across the pavement. SEVERITY LEVELS

Low severity with crack's width < 3 mm without any spalling

Low Cracks with low severity or no spalling; mean unsealed crack width of 3 mm or less; sealant material in good condition. Moderate Cracks with moderate severity spalling; mean unsealed crack width of greater than 3 mm; sealant material in bad condition.

Moderate severity with crack's width > 3 mm

High Cracks with high severity spalling.

MEASUREMENTS TO BE TAKEN a) b) c) d)

predominant crack width. spacing. length. area affected.

High severity with spalling

NO.

POSSIBLE CAUSES

PROBABLE TREATMENTS

1.

Reflection of shrinkage cracks

Cut and patch

2.

Construction joint in bituminous surfacing Ccrack sealant

3.

Structural failure of portland cement concrete base

Rreconstruction 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 reconstruction of joints

. Cawangan Jalan, Ibu Pejabat JKR, K.L

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EDGE CRACKS

2.5. EDGE CRACKS DESCRIPTION Edge cracks are crescent shaped or fairly continuous cracks, parallel to, and usually within 300 mm to 600 mm of the pavement edge. It usually occurs when paved shoulders do not exist. SEVERITY LEVELS

Low severity with no breakup or ravelling

Low Cracks with no breakup or ravelling. Moderate Cracks with some breakup or ravelling. High Cracks with considerable breakup or ravelling along edge.

Moderate severity with some breakup

MEASUREMENTS TO BE TAKEN a) predominant crack width. b) area affected c) length

High severity with considerable breakup

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 Widen the pavement forces traffic too close to pavement edge

4.

Insufficient bearing support

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Reconstruction

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CRESCENT SHAPED CRACKS

2.6. CRESCENT SHAPED CRACKS SYNONYMS Parabolic, slippage, shear cracks. DESCRIPTION

Low severity with no breakup

This type of cracks are half moon or crescent shaped cracks, commonly associated with shoving, often occurring in closely spaced parallel group. It is mainly associated with bituminous layer only. SEVERITY LEVELS Low Cracks with-no breakup or shoving.

Moderate severity with some breakup

Moderate Cracks with some breakup or shoving. High Cracks with considerable breakup or shoving. MEASUREMENTS TO BE TAKEN a) predominant crack width. b) area affected.

High severity with considerable breakup and shoving

NO.

POSSIBLE CAUSES

PROBABLE 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.

Dragging of paver during laying when bituminous mix temperatures were low

Cut and patch

5.

High stresses due to braking and acceleration movements

Bituminous overlay with stiffer mix or use high compaction mix (HCM)

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FIGURE 2 : TYPE OF SURFACE DEFORMATION

3.0. SURFACE DEFORMATIONS Deformation takes place when a road surface undergoes changes from ifs original constructed profile. It may occur after construction due to trafficking or environmental influences. In some cases, deformation may be built into a new pavement owing to inadequate control during construction. It influences the riding quality of a pavement and may reflect structural inadequacies. It may lead to cracking of the surface layer.

The general form of the various types of surface deformation is illustrated in Figure 2.

The major types of surface deformation covered in this section are : i) ii) iii) iv)

rutting. corrugation. depression. shoving.

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RUTTING

3.1. RUTTING SYNONYMS Longitudinal rut. DESCRIPTION

Low severity with rut depths < 12 mm

Rutting is longitudinal deformation or depression in the wheel paths which occur after repeated applications of axle loading. It may occur in one or both wheel paths of a lane. The length to width ratio would normally be greater than 4 to 1. SEVERITY LEVELS Low Rut depths of less than 12 mm (measured under a transverse 1.2 m straight edge)

Moderate severity with rut depths between 12 mm to25mm

Moderate Rut depths of between 12 mm to 25 mm (may include slight longitudinal cracks). High Rut depths of greater than 25 mm (may include multiple longitudinal or crocodile cracks). MEASUREMENTS TO BE TAKEN

High severity with rut depths > 25 mm NO.

POSSIBLE CAUSES

a) maximum depth under a transverse 1.2 m straight edge. b) length.

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/HCM

4.

unstable shoulder materials which do not provide adequate lateral support

shoulder improvement and overlay rutted area with bituminous surfacing

5.

Overstressed subgrade which deforms permanently

Reconstruction

6.

Unstable granular bases or sub-bases

Base or sub-base strengthening

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CORRUGATIONS

3.2. CORRUGATIONS SYNONYM Rippling DESCRIPTION

Low severity - noticeable

Corrugations are regular transverse undulations, closely spaced alternate valleys and crests with wavelengths of less than 2 m. Generally, it will result in a rough ride and will become worse with time. SEVERITY LEVELS Low Noticeable (based on observation of its appearance and its effect on riding quality). Moderate Rough ride.

Moderate severity causing rough ride

High Very rough ride. Vehicle may lose control because of its presence. MEASUREMENTS TO BE TAKEN a) maximum depth under 1.2 m straight edge. b) crest to crest spacing. c) length of pavement affected.

High severity causing very rough ride NO. 1.

POSSIBLE CAUSES

Inadequate stability of bituminous surface

2.

Compaction

3.

Faulty paver behaviour with some mixes

4. 5. 6.

of base in wave form

PROBABLE TREATMENTS Replace bituminous surface Base reconstruction

Heavy traffic on steep downgrade or upgrade Stopping at intersection stop lights or roundabout

Replace the faulty mixes and correct the faulty paver behaviour mill off corrugated surface and replace with stiffer mix or use HCM Mill off corrugated surface and replace with stiffer mix or use HCM

Inadequate stability of base course

Base reconstruction

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DEPRESSIONS

3.3. DEPRESSIONS SYNONYM Distortions. DESCRIPTION

Low severity with noticeable swaying motion

Depressions are localized areas within a pavement with elevations lower than the surrounding area. They may not be confined to wheel paths only but may extend across several wheel paths. Generally, it results from settlement, slope failure, or volume changes due to moisture changes. SEVERITY LEVELS

Moderate severity with fair control of vehicle

Low Noticeable swaying motion. Good control of vehicle still present. (Based on the interaction between vehicle and pavement surface depression). Moderate Fair control of vehicle when driving over pavement. High Poor control of vehicle when driving over pavement with driver always having to anticipate depression ahead.

High severity with poor control of vehicle

NO. 1. 2. 3. 4.

POSSIBLE CAUSES differential settlement of subgrade or base materials settlement of services and/or widening trenches volume change of subgrade due to environmental influences settlement due to instability of embankment

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MEASUREMENTS TO BE TAKEN a) maximum depth under 1.2 m straight edge. b) area of depression.

PROBABLE TREATMENTS subgrade or base reconstruction reconstruction of services and/or widening trenches improve sub-soil drainage and reconstruct embankment stabilization

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SHOVINGS

3.4, SHOVINGS DESCRIPTION

Low severity with noticeable swaying motion

Shoving is the bulging of the road surface generally parallel to the direction of traffic and/or horizontal displacement of surfacing materials, mainly in the direction of traffic where braking or acceleration movements occur, caused by traffic pushing against the pavement. Transverse shoving may arise with turning movements. SEVERITY LEVELS Low Noticeable. (Based on observation of its appearance and its effect on riding quality). Moderate Rough ride.

Moderate severity resulting in rough ride

High Very rough ride. Vehicle may lose control because of its presence. MEASUREMENTS TO BE TAKEN a) maximum depth of bulge under 1.2 m straight edge from high point. b) area affected.

High severity resulting in very rough ride NO. 1. 2. 3. 4. 5.

POSSIBLE CAUSES Low stability mix Lack of bond between asphalt surface and underlying layer which may be caused by excessive tack coat acting as lubricant Ustable granular base reflecting through the surface Stop and start of vehicles at intersections or roundabout Inadequate pavement thickness

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PROBABLE TREATMENTS Mill off and replacehe bituminous surfacing Replace bituminous surfacing with lower binder content mix Base reconstruction Mill off and replace with stiffer mix or use HCM Bituminous overlay or reconstruction

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FIGURE 3 : TYPES OF SURFACE DEFECTS

4.0. SURFACE DEFECTS Surface defects cover loss of surfacing materials, loss of surface micro and macro textures. While they do not usually indicate pavement structural inadequacy, they have a significant influence on the serviceability and safety of a pavement, especially with regard to skid resistance, maneuverability and riding quality. Some defects, if not corrected, may lead to subsequent loss of pavement structural integrity. The major types of surface defects are: i) ii) iii) iv)

bleeding. ravelling. polishing. delamination.

The general form of the various defect types is illustrated in Figure 3.

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BLEEDING

4.1. BLEEDING SYNONYMS Flushing, fatting, slick, black spot. DESCRIPTION

Low severity with visible colouring of pavement surface

Bleeding is the presence of free bitumen binder on the surface resulting from upward migration of the binder, causing low texture depth and inadequate tyre to stone contact. It is most likely to occur in the wheel paths during hot weather. SEVERITY LEVELS Low Colouring of pavement surface visible.

Moderate severity with excess bitumen already free

Moderate Distinctive appearance with excess bitumen already free. High Free bitumen which gives the pavement surface a wet look. Tyre marks are evident. MEASUREMENTS TO BE TAKEN a) area affected. b) percentage by area of stone immersed.

High severity which gives the pavement surface a wet look NO.

1.

2. 3.

POSSIBLE CAUSES

PROBABLE TREATMENTS

Excessive application of binder with respect to the stone size. On hot days, the binder expands into air Apply hot sand to blot up the voids; if volume of air voids is too low, continued expansion results in lower stability of the mix with the excess binder consequence that traffic will force out excess binder to the surface. Paving over flushed surfaces. The excess bitumen on Apply hot sand or aggregate the old surface may coat be pumped up through the seal coat new paving over a period of time Paving over excessively primed surfaces

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Apply hot sand

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RAVELLING

4.2. RAVELLING SYNONYM Fretting. DESCRIPTION Ravelling is the progressive disintegration of the pavement surface by loss of binder or aggregates or both.

Low severity where wearing away of the aggregate has not progressed significantly

SEVERITY LEVELS Low Wearing away of the aggregate or binder has started but has not progressed significantly. Moderate Aggregate and/or binder has worn away and the surface texture is becoming rough and pitted. Loose particles generally exist.

Moderate severity with worn away aggregate and binder

High Aggregate and/or binder has worn away and the surface texture is very rough and pitted. MEASUREMENT TO BE TAKEN a) area affected.

High severity with rough and pitted surface

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

Thin bituminous overlay

3.

Inadequate compaction or construction fduring wet weather

Thin bituminous overlay

4.

Deterioration of binder and/or aggregate

Thin bituminous overlay

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POLISHING

4.3. POLISHING DESCRIPTION Polishing is the smoothening and rounding of the upper surface of the roadstone, exposing coarse aggregate which are glossy in appearance and smooth to the touch. It usually occurs in the wheel paths.

Smoothening and rounding of the upper surface of the roadstone has started

SEVERITY LEVELS Not applicable. However, the degree of polishing may be reflected in a reduction of skid resistance.

MEASUREMENT TO BE TAKEN a) area affected.

Coarse aggregate exposed

Smoothening and rounding of the roadstone has progressed significantly

NO.

POSSIBLE CAUSES

PROBABLE TREATMENTS

1.

Inadequate resistance to polishing of surface aggregates, particularly in areas of heavy traffic movements or where high stresses are developed between surface and tyres

Thin bituminous overlay or use of stiffer mix or use HCM

2.

Use of naturally smooth uncrushed aggregates Thin bituminous overlay

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DELAMINATION

4.4. DELAMINATION SYNONYMS Peeling, surface lifting, seal break, flaking DESCRIPTION

Low severity where peeling of the top surface has started

Delamination is the loss of a discrete and large (minimum 0.01 square metre) area of the wearing course. Usually there is a clear delineation of the wearing course and the layer below. SEVERITY LEVELS Low Peeling of the top layer has started but has not progressed significantly. Surface area peeled off is less than 0.1 m2.

Moderate severity with surface area peeled off between 0.1 m2 and 2.5 m2

Moderate Surface area peeled off is between 0.1 m2 to 2.5 m2. Severe crocodile cracks in and around the peeled off area. High A group of more than two (2) moderate delaminations along a short stretch of road. MEASUREMENTS TO BE TAKEN a) thickness of layer(s) peeled off. b) area of individual delaminations. c) number of delaminations.

High severity with group of delaminations

NO. 1. 2. 3. 4.

POSSIBLE CAUSES Inadequate cleaning or inadequate t coat obefore placement of upper layers Seepage of water through asphalt, especially in cracks, to break bond between surface and lower layers Weak, loose layer immediately underlying seal

PROBABLE TREATMENTS Tack mill off and re-lay upper layers Replace wearing course or thin bituminous overlay Reconstruction of weak layers

Adhesion of surface binder to vehicle tyres Thin bituminous overlay

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PATCH

5.0. PATCH DESCRIPTION

Patch with low severity distress

A patch is a repaired section of pavement where a portion of the pavement surface has been removed and replaced (see FIGURE 4). It may or may not be associates) with either a loss of serviceability (apart from a loss of appearance) or structural capacity. The `extent and frequency of patching can be useful indicators of the structural adequacy of the pavement. Defects can occur within a patch or the patch can be a further defect where it is raised or depressed below the level of the pavement surface. SEVERITY LEVELS

Patch with moderate severity distress

Low Patch is in good condition or has low severity distress of any type. Moderate Patch has moderate severity distress of any type. High Patch has high severity distress of any type. MEASUREMENTS TO BE TAKEN a) area of patch at each severity level. b) number of patches at each severity level.

Patch with high severity distress

FIGURE 4 : PATCH AND POTHOLE Cawangan Jalan, Ibu Pejabat JKR, K.L

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POTHOLE

6.0. POTHOLE DESCRIPTION

Low severity with area < 0.3 m2 and depth < 25 mm

Pothole is bowl shaped cavity in the pavement surface resulting from the loss of wearing course and binder course materials (see FIGURE 4). They are produced when traffic breaches small pieces of the pavement surface allowing the entry of water. These spots disintegrate because of the weakening of the base course or poor quality surfacing. Free water collecting in the hole and the underlying base accelerates its development. SEVERITY LEVELS MEASUREMENTS TO BE TAKEN a) depth of pothole. b) area of pothole. c) number of potholes at each severity level.

Moderate severity with depth between 25 mm to 50 mm and area < 0.3 m2

.

Group of potholes with depth > 50 mm and area > 0.1 m2 AREA (square metre) DEPTH (mm) < 25 25-50

< 0.1 Low Moderate

0.1 -0.3 Low Moderate

> 0.3 Moderate High

> 50

Moderate

High

High

NO.

POSSIBLE CAUSES

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

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A Guide To The Visual Assessment Of Flexible Pavement Surface Conditions EDGE BREAKS

Edge break has just started

FIGURE 5 : TYPES OF EDGE DEFECTS

7.0. EDGE DEFECTS Edge defects occur along the interface of flexible pavement and the shoulder, and are most significant where the shoulder is unsealed. The detrimental effects of edge defects include : i)

Edge break with considerable breakup

reduction of pavement width.

ii) loss of quality of ride and possible loss of control of vehicle. iii) channelling of water at the edge of the pavement leading to erosion of shoulder. iv) entry of water into base.

Significant length of edge break and surfacing loss

The defect types covered in this section are 7.1. EDGE BREAKS i) edge break. DESCRIPTION ii) edge drop-off. The general form is illustrated in Figure 5.

Edge break occurs when the edge of the bituminous surface are fretted, or broken. SEVERITY LEVELS Not applicable. MEASUREMENTS TO BE TAKEN a) length over which break occurs. b) maximum width of surfacing loss.

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NO 1.

POSSIBLE CAUSES

A Guide To The Visual Assessment Of Flexible Pavement Surface Conditions PROBABLE TREATMENTS

Inadequate pavement width Alignment which encourages drivers totravel on pavement edge

Widen the pavement

3.

Inadequate edge support

Shoulder strengthening

4.

Edge drop-off

5.

Loss of adhesion to base

2.

EDGE DROP-OFFS

Pavement widening and realignment

Sstrengthening and levelling of shoulder with road surface Cut and patch or bituminous overlay 7.2. EDGE DROP-OFFS DESCRIPTION Edge drop-off is the difference in elevation between the traffic lane and outside shoulder; typically occurs when the outside shoulder settles or erodes. It is not usually considered a defect if the drop-off is less than 25 mm.

Slight drop-off

SEVERITY LEVEL Not applicable. However, severity levels can be defined in relation to the height of drop. MEASUREMENTS TO BE TAKEN a) height of drop. b) length affected.

Significant drop-off

Height of drop > 100 mm. It is a danger to traffic

No. 1 2 3

POSSIBLE CAUSES Inadequate pavement width Shoulder material with inadequate resistance to erosion and abrasion Resurfacing of pavement without resurfacing of shoulder

Cawangan Jalan, Ibu Pejabat JKR, K.L

PROBABLE TREATMENTS Widen the pavement Replace shoulder material and reconstruct Levelling of shoulder with road surface Page 23

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A Guide To The Visual Assessment Of Flexible Pavement Surface Conditions

GLOSSARY Binder Brown or black adhesive mate rial Bituminous overlay A method of treat ment where the existing pave ment surface is overlaid with bituminous materials Bleeding Identified by a film of bitumi nous material on the pavement surface that creates a shiny, glass-like, reflective surface that nay be tacky to the touch Block crack The occurrence of cracks that divide the bituminous surface into approximately rectangular pieces, typically 0.1 m2 or more in size Centre line The white/yellow separating traffic travelling in opposite direction Construction joint The point at which work is concluded and reinitiated when building a pavement Corrugation Regular transverse undulations, closely spaced alternate valleys and crests with wavelengths of less than 2 m. Crescent shaped crack Crack which is half moon or crescent in shape, normally associated with shoving Crocodile crack Interconnected or interlaced crack which form a network of multisided blocks; the block sizes are smaller than 300 mm. Cut and patch A treatment where the distressed area is excavated and patched back with bituminous materials

Cawangan Jalan, Ibu Pejabat JKR, K.L

Delamination Loss of a discrete and large (minimum 0.01 m2) area of the top bituminous layer Depression Localized area within a pavement with elevations lower than the surrounding area Edge break Broken or fretted pavement edge Edge crack Fracture along the pavement edge Edge drop-off The difference in elevation between the traffic lane and the shoulder Hairline crack A fracture that is very narrow in width Longitudinal Parallel to the centre line of the pavement Patch An area where the pavement has been removed and replaced with a new material Polishing Smoothening of the upper surface of the road stone, exposing coarse aggregate, which are glossy in appearance and smooth to the touch Pothole A bowl-shaped cavity in the pavement surface Pumping The ejection of water and fine materials under pressure through cracks under moving loads Ravelling The wearing away of the pavement surface caused by the loss of binder or the dislodging of aggregate particles or both Rutting The occurrence of longitudinal surface depression/deformation in the wheel paths

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Shoving Permanent, longitudinal displacement of a localized area of the pavement surface caused by traffic pushing against the pavement Spalling Breaking or cutting off small pieces from the pavement surface Transverse Perpendicular to the centre line of the pavement

REFERENCES 1. A Guide to the Visual Assessment of Pavement Condition, National Association of Australia State Road Authorities, 1987. 2. Distress Identification Manual for the Long-Term Pavement Performance Studies, SHRPLTPP/FR-90-001, Strategic Highway Research Program, National Research Council, Washington, D.C. 1990. 3. Manual for Condition Rating of Flexible Pavements - Distress Manifestation, G.J. Chong, W.A. Phang and G.A. Wrong; Reprinted January 1982. 4. Various Research Findings at IKRAM.

Cawangan Jalan, Ibu Pejabat JKR, K.L

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