Section 2: Routine Pavement MaintenanceAnchor: #i1000773
General Objectives of Pavement Maintenance
The general objectives of roadway pavement maintenance are to provide a safe roadway surface, preserve the state's capital investments in the pavement and to maintain a riding quality satisfactory to the traveling public. Maintenance of roadway pavement includes the restoration and repair of both surface and underlying layers. Maintenance of the shoulder and approaches can also effect the pavement and will be discussed in Section 3.Anchor: #i1000790
Pictures and definitions of distress in pavements may be found in the Distress Identification Manual for the Long-Term Pavement Performance Project, SHRP-P-338. Refer to the Pavement Management Information System Rater’s Manual, June 1988, for examples and photographs of distress.Anchor: #i1000802
Flexible Pavement Distress Maintenance
Types of flexible pavement distress are listed below with guidelines for maintenance.
- Alligator cracking is a type of distress that is generally caused by inadequate base support or brittle asphalt surface. Since cracks allow surface water to enter the subgrade and further destroy the stability of the subgrade, sealing should be accomplished as soon as practical. When cracking has progressed to the extent that failure of the roadway surface is imminent, repairs should be made as soon as possible. The alligator cracked surface material approaching failure will normally have to be removed and replaced with asphalt patching material. Where the base is unstable or wet, the base material will need to be removed replaced or stabilized.
- Corrugations are deviations of the pavement surface from its original cross section and are generally caused by excessive bitumen, improper aggregate gradation in the pavement, insufficient compaction of the mix or low interparticle friction to a degree that causes an unstable pavement with low resistance to traffic loads. Grooving, rutting, and shoving will also occur where the pavement is unstable. These distresses cause considerable annoyance to motorists. Repairs should be made as soon as practical when severe corrugations are evident. Repairs will normally involve removing the corrugated material and replacing it with new asphalt concrete.
- Cracks are considered significant when the pavement is cracked to the extent that water or foreign material can cause structural damage. At this point, cracks should be sealed as soon as practical. Efforts should be made to avoid a buildup of crack sealing material.
- Edge cracking frequently happens on narrow pavements at the same time drop-offs occur. This distress can be started by shrinkage of the asphalt at the edge of the pavement or shrinkage cracks in the base or subgrade. Edge loads tend to cause failure of this type by breaking off the pavement edge.
- Failures and potholes are subject to rapid enlargement and may result in considerable pavement loss and objectionable ride and may affect vehicle control. Failures and potholes should be repaired as soon as possible after they are observed or reported. In inclement weather, temporary repairs should be made and permanent repairs scheduled.
- Pavement edge drop-offs frequently
occur on narrow pavement or pavement without paved shoulders where
the wheels of vehicle frequently traverse off the pavement. New
overlay may also leave a drop-off. When drop-offs get deep enough
to cause hazards, repairs should be made as soon as practical. Pavement
edge repairs are made by two accepted methods:
- One method is to bring the natural material from the shoulder or the embankment material up to the level of the pavement surface edge.
- The second method is to bring in asphalt or other material and add it to the edge of the pavement to remove the drop-off.
- Raveling is the progressive failure of the binder and loss of aggregate from the surface by weathering and/or traffic abrasion. When surface raveling begins to impair safety and/or extensive pavement loss is imminent, corrective action should be taken as soon as practical. Less critical raveling should be scheduled for correction on a priority basis.
- Rutting occurs when wheel track depressions have the undesirable effect of trapping water and may make vehicle control difficult. Corrections to the depressions should be made as soon as possible wherever ruts are determined to be a safety problem.
- Slippery pavement is the surface texture of bituminous pavement that is subject to adverse change as a result of aging, excessive asphalt, wearing, etc. Continuous surveillance of pavement texture should be made with particular attention being given to pavements that become slippery. Obvious slippery areas should be corrected as soon as practical to the extent feasible under the prevailing conditions. When additional corrective action is necessary, it should be scheduled and initiated promptly.
- Waves, sags, and humps are surface defects that often result in poor ride quality, and excessive impact loading of bridges and slabs, and may also make vehicle control difficult. Typical causes are fill settlement, unstable cuts, expansive soils and embankment shear failures. This type of defect may not cause any problem at low speeds but would be objectionable or intolerable at high speeds. Corrections to the surface should be made as soon as practical when ride quality is objectionable.
Rigid Pavement Distress Maintenance
Types of rigid pavement distress are listed below with guidelines for maintenance.
- Blowups are caused by expansion of concrete to the point where the stress causes the concrete to be raised. This can result in a problem ranging from a small bump to a shattering of concrete as if an explosion occurred. When blowups occur, the loose material should be removed and temporary repairs should be made until permanent repairs are practical.
- Cracks, both longitudinal and transverse, may occur in concrete pavement. Transverse cracks are meant to occur in continuously reinforced concrete pavement (CRCP) and should not be sealed. These cracks have little effect on ride quality and should not allow moisture to enter underlying layers and lead to other distress. However, transverse cracks on jointed concrete pavement tend to be wider and will allow moisture into the pavement and should be sealed.
- Failures are punchouts, corner breaks and other major distresses that can cause very uncomfortable ride and in severe conditions could result in vehicle damage. Make repairs whenever areas of the pavement become cracked or broken to the extent that ride quality and structural integrity of the pavement is lost.
- Joint failures (jointed pavements) occur at various spacing on jointed concrete pavement and can cause an unpleasant ride if not properly maintained. Joint failures appear in many forms from minor to major spalling to blowups. Deep spalls and failures may affect vehicle contact with the pavement and should be repaired as soon as possible. Joints should be inspected routinely and should be maintained to exclude foreign material and to preserve the integrity of the joint. When excessive foreign material or infiltration of water is evident, cleaning which includes the repairing and sealing of the joints should be scheduled. This should be done in accordance with "Standard Specification Item 438 Cleaning and/or Sealing Joints and Cracks" (Portland Cement Concrete).
- Settlement, heave, and/or faulting can occur in jointed pavement. Settlement and heave are normally gradual changes and can lead to an uncomfortable ride. Faulting can occur rather suddenly when a slab rises or lowers. Repairs should be made as soon as practical when the ride quality becomes objectionable. Severe faulting that may affect vehicle control should be repaired as soon as possible.
- Surface deterioration such as raveling, popouts, joint spalling and other surface type deterioration allows moisture to penetrate to steel reinforcing, causing further distress. Ride quality also becomes uncomfortable. Repairs are to be made as soon as possible when a section of a roadway is considered to have a severe condition of this type.