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International Road Maintenance Handbook 3

International Road Maintenance Handbook 3

 Bahasa : Inggris
 Halaman : 277 Halaman
 Format : Pdf
 Sumber : -
 Sifat : GRATIS


Part A - General Repairs
General repairs are routine maintenance tasks. Sometimes they are preliminary tasks, carried out before periodic maintenance operations.

Part B - Surface Dressing (Mechanised)
Surface dressing is a periodic maintenance task. It is used to reseal the road surface and improve the riding quality/safety. Usually it is necessary to do general repairs before carrying out surface dressing.

Part C - Resealing Options 
Mechanised surface dressing is the most common type of periodic maintenance reseal. However in certain circumstances other techniques, such as Labour Based surface dressing, Fog spray or Slurry seal are more appropriate.

Part D - Thin Overlays 
A thin overlay is a periodic maintenance task. It is used to reseal the road surface, cover minor depressions or strengthen the road pavement. As with surface dressings, it is frequently necessary to do general repairs in preparation. An existing road surface that is cracked should not be overlaid without an investigation of the cause by the engineer.

Each Part A, B, C, and D describes tasks concerning exclusively paved roads*. Roads of that category have been given a surface course, generally containing bitumen or tar, because of their importance and their higher traffic. 

Maintenance of the paved surface has the following objectives :
To maintain the impermeability of the road surface, preventing water penetrating the surface or edge of the road pavement and weakening the pavement layers or foundation.

To retain or renew the road surface quality and therefore good riding and safety conditions.

General Repairs are normally a routine maintenance activity. however they are also carried out in advance of some periodic maintenance operations.
The term General Repairs covers all types of work on the road pavement*:
- of a localised nature
- of limited size.

The Object is to :
- improve the surface condition of the road
- improve the pavement* structure
- prevent water penetrating the pavement structure

General Repairs must be carried out in good time in order to prevent further deterioration resulting in danger to traffic and leading to disintegration of the pavement.

General Repairs employ simple methods but cover a large range of small work operations.

Due to the materials, skill and safety requirements, this task is usually carried out by a mobile gang.

A particular General Repair technique is involved for each type of defect.
This Part of the Handbook deals with the following techniques*:
In the case of surface repairs, use is made of bituminous binders, sands and aggregates.

In the case of repairs to the pavement structure, use is made of natural or crushed materials and sometimes of cold bituminous mixtures.

Often when work is carried out on pavement General Repairs, it is also necessary to repair defects on the shoulders* and side ditches when the pavement defect is due to them. This will help to prevent the problem recurring. e.g.,
- construction or cleaning out of ditches,
- construction or cleaning of drainage outlets,
- patching and reshaping of shoulders.

Defects can occur in: 
The road surface (a)
- wear of the surface layer of the road,
- cracking of the surface layer,
- fatting-up of binder to the road surface.

The pavement structure (b)
- deformation,
- potholes.

Information follows on the different types of defect with respect to: 
- Location: parts of the pavement where the defect usually appears,
- Main Causes of the defect,
- Development: consequences if maintenance is not rapidly carried out,
- Remedies: usual repair treatments.

List Of Defects :
- Bleeding
- Cracks
- Cracks (continued)
- Ruts and depressions
- Edge subsidence and rutting
- Edge damage (degradation of pavement structure)
- Local aggregate loss
- Potholes (degradation of the pavement structure)
- Shoving (defects in the surface or pavement structure)

May involve a part or the whole of the road surface.

Main causes
- too much binder,
- unsuitable binder.

Development, if neglected
- the road surface becomes slippery when wet,
- separation and break-away of surface layer under the action of traffic.

- sanding (Page III - 51),
- surface dressing (Page III - 83).

(in the surface and in the pavement structure)

a. longitudinal: parallel to the centre line (often along the wheel tracks or along the edges of the surfacing).

b. transverse: perpendicular to the road direction (across the whole or part of the cross-section).

c. mesh cracking: intersecting cracks dividing the pavement surface into isolated elements of differen sizes down to the small elements involved in crazing.

Main Causes
- poor quality materials,
- poor workmanship,
- insufficient pavement thickness for the traffic being carried,
- shrinkage (see Note),
- pavement age.

DEFECT CRACKS (continued)
Development, if neglected
- a general or local destruction of the pavement.

- surface cracking: local sealing (Page III - 53) or fillingin of the cracks (Page III - 57).
- cracks in the pavement structure: local sealing (Page III - 53) or filling-in of the cracks (Page III -57), and patching in cases of severe cracking (Page III - 71).

- in the wheel tracks of vehicles (ruts),
- local areas (depressions*).

Main Causes
- insufficient foundation or pavement strength for the traffic being carried,
- inadequate stability of the bituminous* surfacing materials.

Development, if neglected
- if water is able to penetrate into the body of the pavement, then there will be a rapid increase in the degree of rutting often leading to cracking and breakup of the pavement.

- slight rutting (less than 5 cm): filling in of the ruts and depressions (Page III - 63),
- deep rutting: local restoration of the pavement structure (Page III - 71).

Location : 
Usually along the edges of the pavement where it borders unsealed shoulders.

Main Causes 
- inadequate or badly maintained shoulder,
- penetration of water into the pavement structure or foundation and resulting loss of bearing strength,
- poor drainage,
- narrow carriageway.

Development, if neglected
- rapid during the rainy season leading to the disintegration of the edges of the pavement.

- slight subsidence (less than 5 cm): filling in of ruts and depressions (Page III - 63) and restoration of shoulder (see Volume I),
- deep subsidence: local restoration of the pavement structure (Page III - 71) and restoration of the shoulder (see Volume I),

DEFECT EDGE DAMAGE (degradation of pavement structure)
Along the edges of the pavement*.

Main Causes
- wear of the shoulder* (formation of step),
- action of water,
- insufficient compaction of the edges of bituminous pavements,
- road too narrow.

Development, if neglected
- rapid during the rainy season.

- local restoration of the pavement structure (Page III - 71).

Small areas or strips of the road surface.

Main Causes
Loss of surface aggregate due to: 
- insufficient binder due to faulty spray jet,
- aggregate dirty when laid,
- insufficient penetration of aggregate,
- poor premix quality or workmanship.

Development, if neglected
- minor stripping/fretting/streaking*.

- surfacing patching (Page III - 67).

DEFECT POTHOLES (degradation of the pavement structure)
No particular location but often in areas showing cracks, deformation or aggregate loss.*

Main Causes
- poor quality of material used for the construction of the pavement,
- infiltration of water,
- break away of material under the action of traffic,
- final stage in the development of crazing* or of a depression*.

Development, if neglected
- progressive enlargement of the hole and formation of additional potholes.

- local restoration of the pavement structure (Page III - 71).

DEFECT SHOVING (defects in the surface or pavement structure)
Usually on either side of the wheel tracks. The irregularities are usually associated with deformation and subsidence.

Main Causes
- ingress of water: reduced bearing capacity of the pavement,
- materials: of poor quality,
- workmanship: insufficient compaction,
- traffic: passage of vehicles which are too heavy for the pavement structure.

Development, if neglected
- forcing up of weak materials as deformation occurs,
- progressive disintegration of the pavement.

- small irregularities: filling in of irregularities (Page III - 63),
- large irregularities together with cracks: local restoration of the pavement structure (Page III -71).

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