road and pavement maintenance

7/27/2019 Road and Pavement Maintenance

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KAAF UNIVERSITY COLLEGE

Civil Engineering DepartmentCollege of Engineering

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Highway Engineering 1CIV 368

Lecture 6_Road and Pavement Maintenance

Kwasi Agyeman Boakye ( [email protected])

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Need for Maintenance

The rate of pavement deterioration is directly affected by the standards of maintenance applied

to repair defects on the pavement surface such as cracking, ravelling, potholes, etc., or to

preserve the structural integrity of the pavement (for example, surface treatments, overlays,

etc.), thereby permitting the road to carry traffic in accordance with its design function.

The figure below illustrates the predicted trend in pavement performance represented by the

riding quality that is often measured in terms of the international roughness index (IRI). When a

maintenance standard is defined, it imposes a limit to the level of deterioration that a pavement

is permitted to attain.

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Roughness

Rehabilitation

Time (years) or Traffic Loading

Maintenance Standard

PavementPerformanceCurve

Good

Poor


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Types of maintenance activities

Road maintenance activities can be categorized into 2 main types; Routine and Periodic

maintenance activities.

Routine Maintenance

This is the work that is performed as needed throughout the year. It is the day to day

maintenance of the road. Routine maintenance is carried out on the road once or more timesper year. It aims to prevent degradation of the road service level by maintaining the road surface

condition, and ensuring that the pavement does not weaken. Routine maintenance activities

may be either;

- Cyclic Work Activities: Activities undertaken on a regular basis at a frequency which does

not depend on the character of the road or the amount of traffic but rather depends on the

climatic conditions. eg. grass cutting and desilting.

- Recurrent Work Activities: Activities undertaken on a regular basis but at a frequency which

is dependent on the engineering and traffic characteristics of the particular road.eg. Pothole

patching and edge repair.

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Types of maintenance activities

Periodic Maintenance

Periodic maintenance is the type of maintenance work that is only required over a long time

interval, usually a number of years. Roads deteriorate due to the actions of weather and traffic.

The rate of deterioration depends mainly on the type and quantity of traffic, the weather and the

amount and effectiveness of routine maintenance given to the road.

Periodic maintenance activities are expensive and the objective is to extend the time interval

between periodic maintenance by means of good routine maintenance. For example if the time

interval between reseals can be extended from (say) 6 years to 8 years by effective routine

maintenance the cost savings are substantial.

Periodic Maintenance activities are undertaken also to preserve the structural integrity of the

road. It may include those activities that change the geometry of a road by widening or re-

alignment. eg Resealing , Rehabilitation.

Periodic maintenance should be carried out once the road surface condition has deteriorated to

a level that is difficult or expensive to rectify by routine maintenance.

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Inventory and Condition Survey

There are three useful ways of presenting the information recorded in the inventory:

diagrammatic maps

strip maps

card index systems.

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Strip map

Diagrammatic map


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Inventory and Condition Survey

Road Condition Survey

They are similar to inventory procedures, but their emphasis is on the condition of the road

rather than its basic characteristics. They identify locations where deterioration is occurring,

measure the extent of the problem and define the action needed to put matters right.

Whatever the level of the survey the main objectives of RCS include;- An assessment of the general condition of the road network;

- Identification of sections or sub-sections of the road network which are in critical condition and

those requiring maintenance or structural overlay within the near future.

- Detects the defects on the roads and locate sections where severe damage has or is occurring

which need immediate maintenance action.

- Identify the type and condition of drainage and other structures (shoulders, drainagestructures, culverts, side ditches, etc.)

- Gives estimates of work quantities for the award of tender.

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Road Distresses

Road distresses occur in different forms and can be identified for unpaved and paved roads.

Some of the distresses are illustrated in the table below.

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DEFECTS IN BITUMINOUS

SURFACED PAVEMENT

SURFACES

DEFECTS IN RIGID

PAVEMENTSDEFECTS IN GRAVELED

SURFACES

Alligator CrackingDepressionsRuttingBleedingRavelingTransverse CrackingLongitudinal CrackingEdge CrackingLane Shoulder Drop OffPatching Potholes

Longitudinal CrackingTransverse CrackingFaultingSpallingBlow-UpPumpingScalingDepression

Gravel ThicknessLoose GravelDustPotholesCorrugationsRuttingDepressionsErosion GulliesSlippery Or Rocky SurfaceVegetation EncroachmentSoft Spot


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Road DistressesCracks

Alligator Cracks

Cracks are common defects that occur

mostly on flexible and rigid pavements. They

appear as small fissures in the road surface.

They could occur as alligator cracks,

longitudinal cracks or transverse cracks.

Alligator Cracks: Alligator cracking is a

series of interconnecting cracks caused by

fatigue failure of the pavement under

repeated traffic loading. The cracks initiate

at the bottom of the surface and propagate

to the surface, initially as one or more

longitudinal parallel cracks. After repeatedtraffic loading, the cracks interconnect,

forming many-sided, sharp angled pieces

that resemble chicken wire or the skin of an

alligator. In concrete pavements contraction

and expansion of the concrete slab could

also lead to cracking.


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Road DistressesCracks

Transverse Cracks

Longitudinal Cracks

Transverse Cracks: Transverse cracks run

perpendicular to the direction of traffic

flow. They could be caused by a reflection

of a shrinkage crack or joint in an underlying

base (commonly portland cement concrete

or cemented materials). It can also becaused by construction joint or shrinkage

crack (due to low temperature or bitumen

hardening) in asphalt surfacing. Structural

failure of Portland cement concrete base

can also lead to transverse cracks.

Longitudinal Cracks: These are cracks

that occur parallel to the direction oftraffic flow. Cracks can be relatively short

in length or run the entire pavement section

length. Longitudinal cracks can be caused

by a poorly constructed paving lane joint,

shrinkage of the asphalt surface due to

temperature cycling, or reflection from

cracking beneath the surface course.


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Road DistressesDepressions and Ruts

Depression

Ruts

Depressions: They are localised pavement

surface areas with elevations than those of

the surrounding pavement. In many

instances, light depressions are not

noticeable until a rain, when water creates a

small pond. On dry pavement, depressionscan be spotted by looking for stains caused

by ponding water. Depressions are created

by settlement of the foundation soil or are

the result of improper compaction during

construction.

Ruts: Rutting is characterised bylongitudinal depressions in the pavement

surface that occur in the wheel paths of a

roadway. Rutting may be caused by poor

mix stability, excessive bitumen in the mix,

and repetitive loading on poorly compacted

mix.


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Road DistressesBleeding and Ravelling

Bleeding

Ravelling

Bleeding: Flushing, or bleeding, is a film of

bituminous material on the pavement

surface which creates a shiny, glass

excessive amounts of asphalt cement in the

mix and/or low air void content. It occurs

when asphalt fills the voids of the mix duringhot weather and then expands into the

pavement surface.

Ravelling: Ravelling (also known as

weathering) is the wearing away of the

pavement surface caused by the dislodging

(ravelling) of aggregate particles and loss of

asphalt binder. This generally indicates thatthe asphalt binder has hardened

significantly. Removal of the coarse

aggregate of a sprayed seal leaving the

binder exposed to tyre contact can

happen as the loss of individual stones, or

as the complete loss of stone in a localised

area.


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Road DistressesFaulting and Spalling

Bleeding

Spalling

Faulting: This is a differential vertical

displacement oftentimes at joints and cracks

between abutting slabs resulting in step

deformation. It is usually found in concrete

pavements and can be caused by

differential settlement of adjoining slabs.Also loss of sub-base material through

pumping can lead to this. Poor sub-base or

sub-grade support is also a possible cause.

Spalling: This is the breaking of angular

pieces of concrete material from the edges

of cracks, joints, and corners of the concreteslab or the flaky breakage of material from

the surface of the slab.


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Road DistressesPumping and Blow-Up

Pumping

Blow - Up

Pumping: This is a process by which a

mixture of water, clay and fine-grained soil is

pumped out or exudes from underneath a

rigid pavement slab through cracks, joints

and the edges as the slab is repeatedly

caused to deflect downwards by passingvehicles.

Blow-Up: This is a localized upward

movement of rigid pavement slabs, which

occurs at a transverse joint or crack. The

occurrence of the defect is mostlyaccompanied by transverse edge shattering.

Blow-ups may be caused by excessive

expansion of rigid slabs under hot weather

conditions or inadequate provision for

expansion joints between slabs.


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PAVEMENT MAINTENANCE

MANAGEMENT SYSTEMS

Pavement maintenance management is the process of planning the maintenance and repair

of a network of roadways, in order to optimize pavement conditions over the entire network. It

incorporates life cycle costs into a more systematic approach to minor and major road

maintenance and reconstruction projects.

A pavement maintenance management system (PMMS) is a planning tool used to aidpavement management decisions. It is a computer program that models pavement and surface

deterioration due to traffic and weather, and recommends maintenance and repairs to the roads

surface based on various tests. These tests can be simply visual or employ special software and

databases to provide rankings for roads or road sections. Typical tasks performed by pavement

management systems include:

Inventory pavement conditions, identifying good, fair and poor pavements.

Assign importance ratings for road segments, based on traffic volumes, road functional

class, and community demand.

Schedule maintenance of good roads to keep them in good condition.

Schedule repairs of poor and fair pavements as remaining available funding allows.

In Ghana the tool used for PMMS is known as the Pavement Maintenance Management

Programme (PMMS).


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MANAGEMENT PROGRAMME

The PMMP is a network level tool to collect, store and analyze all relevant data for road

management to assist in decision making. This tool is an integral part ofGHAs RMMS to assist

in finding optimum strategies for the planning and budgeting of road works.

The PMMP requires two main sets of data; Road Monitoring scheme data and Road Traffic

data. The following are required to establish the road monitoring scheme data;Establishment of a location reference system and road inventory

Division of the road network into homogenous sections and subsections

Unique section identification system, coding or numbering system comprising road, section and

subsection numbers

A standardised system of data collection

The PMMP takes the data and processes it for prioritization of maintenance operations,

budgetary allocations and interfacing with other softwares (ARCGIS and HDM-IV).


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MANAGEMENT PROGRAMME

road and pavement maintenance

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