Pavement Surface Evaluation and Rating

PASERManualConcrete Airfield Pavements

RATING5

RATING3

RATING1

This manual is intended to assist airfield managers in understandingand rating the surface condition of rigid Portland Cement Concrete(PCC) pavements. It describes types and causes of distress andprovides a simple system to visually rate pavement condition.

Produced for the Federal Aviation Administration by EngineeringProfessional Development, College of Engineering, University ofWisconsin-Madison.

Contents

Introduction 2

Evaluating pavement condition 3

Surface defects 4

Joints 6

Pavement cracks 7

Pavement distortion 10

Rating pavement surface condition 13

Rating system 13

Rating 5 — Excellent 14

Rating 4 — Good 14

Rating 3 — Fair 15

Rating 2 — Poor 16

Rating 1 — Failed 17

Practical advice on rating roads 19

Airfield Pavement Inventory inside back cover

AC 150/5320-17 Appendix 2 7/12/04

Donald Walker, P.E., University of Wisconsin–Madison, author

Lynn Entine, Entine & Associates, editor

Susan Kummer, Artifax, designer

PASERManual

Pavement Surface Evaluation and Rating

Concrete Airfield Pavements

AC 150/5320-17 Appendix 2 7/12/04

An airport manager’s goal is to use available funds to provide a safe andeconomical pavement surface. This is no simple task. It requires balancingpriorities and making difficult decisions in order to manage pavements. Thismanual offers useful information for planning maintenance and managingPortland Cement Concrete (PCC) pavements. It discusses common problemsand typical repairs and includes a visual system for evaluating and rating PCC pavements.

General aviation airfield pavements are often managed informally, based onthe staff’s judgment and experience. While this process is both important andfunctional, using a slightly more formalized technique can make it easier tomanage pavements effectively.

Experience has shown that there are three steps that are especially useful inmanaging airfield pavements:

1) Inventory all pavements.

2) Periodically evaluate the condition of all pavements.

3) Use the condition evaluations to set priorities for projects and evaluate alternative treatments.

A comprehensive pavement management system involves collecting dataand assessing several pavement characteristics: roughness, surface distress(condition), surface skid characteristics, drainage, and structure (pavementstrength and deflection). Planners can combine this condition data witheconomic analysis, to develop short-range and long-range plans for a varietyof budget levels. However, general aviation agencies may lack the resourcesfor such a full-scale system.

Since surface condition is the most vital element in any pavement manage-ment system, managers may use the simplified rating system presented in thisConcrete Airfield Pavements PASER Manual to evaluate their pavements. APASER Manual for asphalt airfield pavements is also available (see References,page 20).

PASER — Pavement Surface Evaluation and Rating

Concrete Airfield Pavements

AC 150/5320-17 Appendix 2 7/12/043

Rigid pavement performance

PCC pavements are either plain (non-reinforced) or reinforced concrete.Reinforcement is usually provided bysteel wire mesh placed approximately at mid-slab depth. The reinforcement is intended to limit crack opening andmovement in the concrete slab. Mostairfield pavements are not reinforced.

Since concrete slabs need to move(expand and contract) with changes intemperature and during initial cure(drying and shrinkage), pavements areconstructed with contraction joints.These are usually sawn into the pave-ment shortly after initial curing. Thisjoint gives the slab a place to crack andmakes a straight, well-formed groove to seal. Runways, taxiways and aprons(ramps) are sawn to create square slabsranging from 15’ to a maximum of 25’.

Isolation joints are occasionallyprovided. These are wider, full depth,and filled with a material to allowexpansion. If used, they are placedadjacent to structures that cannot movewith the pavement such as buildings,manholes, and other utility structures.These isolation joints are also used atpavement intersections and allowchanges in joint patterns.

Rigid, PCC pavements carry trafficloadings differently than flexiblepavements (asphalt). Concrete pave-ments are designed to act like a beamand use the bending strength of theslabs to carry the load. Therefore, loadtransfer across cracks and joints isimportant, especially on pavements with heavy traffic loading. Hairline andnarrow cracks still have interlockedconcrete aggregate and can effectivelytransfer loads. Because wide cracks and widely-spaced joints open up, theycannot transfer loads and must take

Evaluating pavement condition

higher edge loads. These higher edgeloads can cause further cracking anddeterioration along the joint, or crackedges.

Many concrete pavements usejoints that have load transfer dowels.These are smooth steel bars placedacross the joint. They transfer trafficloads between adjacent concrete slabs while allowing the joint to openand close. These bars can rust andsometimes cause problems. Thecorrosion causes forces on theconcrete which leads to spalling,cracking, and general joint deterior-ation. Epoxy coated dowels may beused to reduce corrosion.

Unsupported slab edges will deflector bend under a load. If the support-ing soil is saturated it can squirt upthrough joints or cracks when theslab bends. This is called pumping.Eventually the loss of supporting soilthrough pumping creates an emptyspace or void under the slab. Theslabs may then crack further underloads and joints will deteriorate more.

Undoweled joints under heavytraffic may fault. This is when oneslab edge is lower than the next slab.Faulting is more likely on pavementswith most of the traffic in one direction. The downstream traffic slabwill be lower than the upstream slab,creating a step. Faulting creates arough pavement.

You can often detect pumping bythe soil stains around pavement jointsor cracks. The resulting voids can begrouted full or sub-sealed. Slabs canbe leveled by slab jacking or mudjacking. Obviously, sealing cracks andjoints and improving subsoil drainagewill help reduce pumping, faulting,and joint failures.

PCC pavement conditions and defects

It is helpful to separate various condi-tions common to PCC pavements.These are described individually insome detail. We include causes fordeterioration and common strategiesfor repair. Some defects are localizedwhile others indicate that problemsmay develop throughout the pave-ment. It is important to distinguishbetween local and widespread defects.Assessing the conditions of actualpavements also involves looking forcombinations of these individualdefects.

There are four major categories ofcommon PCC pavement surfacedistress and condition:

Surface defectsPolishing, map cracking, pop-outs,scaling, spalling.

Joints Longitudinal and transverse joints.

Pavement cracksSlab cracks, D-cracking, cornercracks, meander cracks, manhole and inlet cracking.

Pavement distortion Pavement settlement or heave;blow ups; faulting; utility repairs,patches and potholes.

In reviewing the different defects it is important to consider both theirseverity and extent. Generally, condi-tions begin slowly and progressivelybecome more serious. Slight defectsmay grow into moderate and thensevere conditions. In addition, defectsmight initially be indicated only in afew isolated cases. Examples in therating section will help identify howbad and how extensive a condition is.

EVALUATION — Surface Defects4

AC 150/5320-17 Appendix 2 7/12/04

SURFACE DEFECTS

PolishingA worn or polished surface maydevelop from traffic wearing off thesurface mortar and skid-resistanttexture. An asphalt overlay orgrinding the concrete surface can restore skid resistance.

Map crackingA pattern of fine cracks usually spaced within several inches is calledmap cracking. It usually developsinto square or other geometricalpatterns. Map cracking can becaused by improper cure or over-working the surface during finishing.It may also indicate a problem withthe quality of the aggregate knownas ASR (alkali-silica reactivity). Ifsevere, cracks may spall or thesurface may scale. Repair is usuallylimited to very severe conditions. An asphalt overlay or partial depthpatching may then be necessary.

Pop-outsIndividual pieces of large aggregatemay pop out of the surface. This isoften caused by chert or otherabsorbent aggregates that deterio-rate under freeze-thaw conditions.Pop-outs alone do not usually affectpavement serviceability. However,damage to aircraft from the debrismay occur. For severe areas, apatch, overlay or slab replacementmay be necessary.

▼▼

Extensivepop-outs of large

aggregatefrom surface.

Severalpop-outsin a new

slab.

▼

Map crackinghas hairline

surface cracks,probably

shallow indepth. May

not cause anylong-term

performanceproblems.

▼

Close-up of a polishedpavement surface.

EVALUATION — Surface Defects 5

ScalingScaling is surface deterioration thatcauses loss of fine aggregate andmortar. More extensive scaling canresult in loss of large aggregate. Thecause often is using concrete which has not been air-entrained, making the surface susceptible to freeze-thawdamage.

Scaling can occur as a general conditionover a large area or be isolated tolocations where poor quality concrete orimproper finishing techniques causedloss of entrained air. In severe cases,deterioration can extend deep into theconcrete. Debris from scaling candamage aircraft.

Grinding may remove poor qualitysurface concrete. Partial depth patchingof isolated areas may also prolong thelife of the pavement. Severe scaling mayrequire slab replacement.

SpallingSpalling is the loss of a piece of theconcrete pavement from the surface oralong the edges of cracks and joints.Cracking or freeze-thaw action maybreak the concrete loose, or spallingmay be caused by poor quality mate-rials. Spalling may be limited to smallpieces in isolated areas or be quite deep and extensive. Large pieces ofloose concrete can cause seriousdamage to aircraft.

Repair will depend on the cause. Smallspalled areas are often patched. Spallingat joints may require full depth jointrepair or full slab replacement.

AC 150/5320-17 Appendix 2 7/12/04

Slight scaling.Minor loss ofsurface mortar.

Moderate surfacescaling. Loss of

mortar and finesstarting to exposelarger aggregate.

Severescaling.Some largeraggregate isloose.

▼ ▼

▼

Smallsurface spallthat hasbeenpatched.

▼

Spall at crack.Createsdangerousdebris.

▼

Spallingalong a joint.

▼

EVALUATION — Joints6

AC 150/5320-17 Appendix 2 7/12/04

JOINTS

Construction joints or sawn joints are narrow and usually well sealed. As pavements age and materialsdeteriorate, joints may open wider anddeteriorate further. Cracks parallel to theinitial joint may develop and accelerateinto spalling or raveling. Settlement,instability, or pumping of subgrade soilcan cause joints to fault. One commoncause of cracks parallel to joints iswaiting too long after the pour to sawthe joint. Then, during initial cure theslab will crack near the sawn joint.

Maintaining a tight joint seal canprevent intrusion of water and debrisand reduce freeze-thaw damage andpumping. Debris may accumulate inopen joints which prevents normal joint movement. This will greatlyaccelerate joint deterioration. Severejoint deterioration may require full depth patching and joint replacement.

Taxiway withspalled joint.

Joint sealant in poorcondition. Loss ofbond to edge allowswater into pavement.

New pavement with good joints.

▼

Joint sealant deterioration on apron.Slab is in good condition.

▼

▼

Severe spallingalong joint andcrack. Creates debris.

▼

▼

AC 150/5320-17 Appendix 2 7/12/04EVALUATION — Cracks 7

PAVEMENT CRACKS

Slab cracksSlab cracks divide the slab into 2 ormore pieces. They can be caused bythermal stresses, poor subgrade support,or heavy loadings. They are sometimesrelated to slabs with joints spaced toowidely. Slabs with a length-to-width ratiogreater than 1.25 are more likely todevelop mid-slab cracks.

As with joints, these cracks may deteri-orate further if not sealed well. Slabs can fault at cracks. Cracks can spall and develop additional parallel cracking.Severe deterioration may requirepatching individual cracks. Multipletransverse cracks in individual slabsindicate further deterioration. Extensiveslab cracking indicates pavement failureand the need for complete replacement.

Crack next to joint oftencaused by late sawing. Crackshows early signs of spalling.

Hairline slab crack.Tight with no spalling.

▼

▼

Slab crack with grass,no sealant, and spallsdeveloping.

▼ ▼

Slab crackwith spallingand debris.

▼

Multiple slab cracksand broken pavement.Replacement needed.

▼

Closely spaced, hair-line,transverse cracks indicate slabis broken and needs replacing.

▼

EVALUATION — Cracks8

AC 150/5320-17 Appendix 2 7/12/04

D-cracksOccasionally, severe deterioration maydevelop from poor quality aggregate. So called D-cracks or disintegrationcracking, develop when the aggregate is able to absorb moisture. This causes the aggregate to break apartunder freeze-thaw action which leads to deterioration. Usually, it starts at thebottom of the slab and moves upward.

Fine cracking and a dark discolorationadjacent to the joint often indicate a D-cracking problem. Once this is visible on the surface the pavement material is usually severely deteriorated andcomplete replacement is required.

Joint or crack sealing helps slow D-cracking deterioration. This is a seriousdefect because it may indicate a materialquality problem throughout the pave-ment. Milling and patching has provensuccessful as a short term repair.

Corner cracksDiagonal cracks may develop near thecorner of a concrete slab, forming atriangle with the joint. Usually thesecracks are within a foot or two of theslab corner and are caused by insufficientsoil support or concentrated stress due totemperature-related slab movement. Thecorner breaks under traffic loading. Theymay begin as hairline cracks.

Some corner cracks extend the full depth of the slab while others start at the surface and angle down toward the joint.With further deterioration, more crackingdevelops, and eventually the entirebroken area may come loose. This maybe a localized failure, but it oftenindicates widespread maintenanceproblems.

Partial or full depth concrete patching or full depth joint replacement may beneeded when corner cracking isextensive.

Surface discoloration near jointsand cracks indicates D-crackingand severe slab deterioration.

Multiple crackpatterns adjacent

to joints. Common D-cracking pattern.

▼

Corner cracking inall four slabs.

▼

Cornercracking

withslight

spalling.

▼

Cornercracking,

severespalling,

anddangerous

debris.

▼

▼ ▼

EVALUATION — Cracks 9

AC 150/5320-17 Appendix 2 7/12/04

Meander cracksSome pavement cracks appear towander randomly. They may cross a slab diagonally or meander in a randommanner. Meander cracks may be causedby settlement due to unstable subsoil ordrainage problems. Frost heave andspring thaw can also cause them. Theyare often local in nature and may notindicate general pavement problems.

Minor cracks may benefit from sealingto minimize water intrusion. Extensive or severe meander cracks may requirereplacing the slab, stabilizing thesubsurface, or improving drainage.

Manhole and inlet cracksThe pavement adjacent to a light can,manhole, or storm sewer inlet oftencannot accommodate normal pavementmovement due to frost heaving andtemperature changes. Cracks andfaulting may develop and the concreteslab may deteriorate further. These areoften localized design defects that maynot indicate a general pavementproblem. Sealing and patching may slowthe deterioration. Eventually full depthrepairs may be required.

Inlet with severecracking and

spalling. Full depthslab repair required.

▼

Slabs replaced next toinlet. Good joint design.

▼Meandercrack causedby settlement.Lack ofmaintenanceallows waterto intrude and debris to collect in crack.

▼Faulting andspalling of ameandercrack.

▼

Two spalls at manhole in anew pavement. Partial depthpatching would be beneficial.▼

PAVEMENT DISTORTION

Pavement settling or heaveUnstable or poorly drained subgradesoils may cause pavements to settle afterconstruction. Poorly compacted utilitytrenches may also settle. This may be agentle swale or a fairly severe dip.

Frost-susceptible soils and high watertables can cause pavements to heaveduring the winter months. Extensivepavement cracking and loss of strengthduring the spring can result in severedeterioration. Improved drainage andstabilization of subgrade soils is usuallynecessary, along with pavementreconstruction.

BlowupsConcrete slabs may push up or becrushed at a joint. This is caused byexpansion of the concrete whereincompressible materials (sand, debris,etc.) have infiltrated into poorly sealedjoints. As a result, there is no space toaccommodate expansion. It is morecommon in older pavements with longjoint spacing. Pavements that haveaggregate susceptible to ASR mayexperience more frequent blowups.Pressure relief joints can be installed and blowup areas must be patched orreconstructed. Cleaning and sealingjoints will help prevent blowups.

Internal pressure has partially raised slab atthe joint. Complete replacement is required.

Settlement causedmeander crackwith faulting.

▼

Extensive cracking and patchingcaused by settlement. Pavement wasbuilt on unstable sub-grade soils. ▼

Pavement blowup in progress—concrete is crushed and slab buckled.

▼

▼

EVALUATION — Distortion10

AC 150/5320-17 Appendix 2 7/12/04

EVALUATION — Distortion 11

AC 150/5320-17 Appendix 2 7/12/04

FaultingJoints and cracks may fault or develop astep between adjacent slabs. Faulting iscaused by pumping of subgrade soilsand creation of voids. Heavy traffic canrapidly accelerate faulting. Joints mayfault due to settlement of an adjacentslab.

Faulting creates a rough pavement andmay cause slab deterioration. Minorfaulting can be corrected by surfacegrinding. Voids can be subsealed, orslabs can be mud jacked back to levelposition. Severe cases may need joint orslab replacement.

Faulting of joints.Aggravated by heavytraffic in one direction.Could improve surfaceby grinding.

▼

Severe joint faultand spalling.

Severe joint fault.

▼

▼

EVALUATION — Distortion12

AC 150/5320-17 Appendix 2 7/12/04

Utility repairs, patchesand potholesSlab replacement or repair of utilities will require cuts and slab patching.Patches from previous repairs mayperform like original pavement or mayshow settlement, joint deterioration or distress.

Localized failures of materials orsubgrade soil can cause individualpotholes. Surface spalling or othermaterial defects may develop intolocalized potholes. Full depth patchingor slab replacement is usually required.

Full depth jointrepair. Very good

condition.

▼

Partial depthconcrete patch

to repair cornercracks. Good

condition.

Joint repair with asphalt.Very good condition.

▼

Potholes causedby severe jointdeterioration.

Need repair.▼

Asphalt patches. Poor (top)and fair (bottom) condition.

▼▼

13

AC 150/5320-17 Appendix 2 7/12/04

Using your understanding of pavementconditions and distress, you can evalu-ate and rate airfield PCC pavements.The rating scale ranges from5–excellent condition to 1–very pooror failed. Some pavements will deteri-orate through the phases listed in therating scale. The time it takes to gofrom an excellent (5) to failed condition(1) depends largely on the quality of theoriginal construction, age, and theamount of heavy traffic loading.

Once significant deterioration begins,it is common to see pavements deteri-orate rapidly. This is usually due to thecombined effects of loading and addi-tional moisture. As a pavement agesand additional cracks develop, moremoisture can enter and accelerate therate of deterioration.

Rating system

Rating pavement surface condition

Surfacerating

Visible distress* General condition/treatment measures

None.5Excellent

Hairline or sealed cracks 1⁄8” wide or less. Map cracking. Pop-outs.4

Good

Several slabs broken into two pieces by slab cracks. Cornercracking on several slabs, 1⁄4” wide with no spalling. Jointsealant mostly in good condition, less than 10% needingreplacement. Several patches in fair to good condition. Map cracking or scaling on 10% or less of the surface area.Slight faulting, less than 1⁄4”, in several locations.

3Fair

Many slab cracks, some breaking the slab into three or more pieces. Cracks open 1⁄8” or cracks with spalling. D-cracks at several joints. Sealant failure over 10% of joints.Several patches in fair to poor condition with cracks in patchand uneven surface. Faulting 1⁄4” to 1⁄2” in several locations.Severe or extensive scaling.

2Poor

Many wide cracks with failed sealant and grass. Extensive crack and joint spalling. Slabs extensively cracked or shattered. Many corner breaks with spalling.D-cracks with spalling. Patches in poor condition withspalling. Numerous faults over 1⁄ 2”.

New pavement or recent major concreterehabilitation. Like-new condition. Less than5 years old. No maintenance required.

Concrete over 5 years old. Signs of wear.Minor spot repair of cracks or joint sealant.

First sign of significant slab cracking, corner cracking, scaling, or faulting. Several patches. Joint sealant repairrequired. Isolated repair of joint or patch.

Needs sealant replacement on more than10% of cracks or joints. Partial depth or fulldepth joint repairs or patch replacement.Repair faulted joints. Replace or overlayslabs with severe scaling. Bonded or unbonded concrete overlay.

Extensive full depth joint repairs or slabreplacements. Extensive patching andcomplete overlay. Complete reconstruction.1

Failed

* A given pavement segment may not have all of the types of distress listed for a particular rating. It may have only one or two types.

Look at the photographs whichfollow and become familiar with thedescriptions of the individual ratingcategories. To evaluate an individualpavement, first determine its generalcondition. Is it relatively new, toward thetop end of the scale? In very poorcondition and at the bottom of thescale? Or somewhere in between? Next,think generally about the appropriatemaintenance method.

Finally, review the individualpavement condition and distress andselect the appropriate pavement surfacerating. Individual pavements may nothave all of the types of distress listed forany particular rating. They may haveonly one or two types. Use thecategories in the rating table below.

Each rating also includes a recommen-dation for needed maintenance or repair.This makes the rating system easier to use and enhances its value as a tool inongoing airfield pavement maintenance.

Rating 5 – ExcellentNo maintenance required.

Rating 4 – GoodMinor routine maintenance, crack or joint sealing.

Rating 3 – FairMore crack or joint sealing. Isolated joint repairs or slab patching.

Rating 2 – PoorExtensive crack or joint sealing. Repair severe joint deterioration. Partial and full-depth slab repairs.

Rating 1 – FailedReconstruction.

Rating pavement surface condition14

AC 150/5320-17 Appendix 2 7/12/04

RATING 5

EXCELLENT — No maintenance required

Rating 5 is for new pavementor for recent major concreterehabilitation. Like-newcondition. Less than 5 years old.No maintenance required.

New or like-new

pavementcondition.

▼

▼

RATING 4

GOOD — Little or no maintenance required

Minor spot repair of cracks orjoint sealing required. PCCpavement over 5 years old.Signs of wear: hairline or sealedcracks 1⁄8” wide or less, mapcracking, pop-outs.

Surfacewear andpop-outs.

Partial loss of joint sealant.

▼

Map cracking,but pavementis sound.

Isolatedmeander crack,tight and wellsealed.

▼

▼

Rating pavement surface condition 15

RATING 3

FAIR — First sign of significant slab cracking, corner cracking, scaling, or faulting. Several patches.Joint sealant repair required. Isolated repair of joint or patch.

Several slabs broken into two pieces byslab cracks. Corner cracking on severalslabs, 1⁄4” wide with no spalling. Jointsealant mostly in good condition, less than 10% needing replacement. Severalpatches in fair to good condition. Mapcracking or scaling on 10% or less of the surface area. Slight faulting, less than1⁄4”, in several locations.

Crack breaks slab into twopieces. Well sealed.

Crackbreaks off largecorner of slab.

▼

Crackparallel tojoint. Open1⁄4”. Nospalling.

▼

▼

Severe scaling. Joint andsealant in fair condition.

▼

Isolated spallat manhole.

▼

Moderatescaling.

▼

AC 150/5320-17 Appendix 2 7/12/04

Rating pavement surface condition16

AC 150/5320-17 Appendix 2 7/12/04

RATING 2

POOR —Cracks open 1/8”, D-cracks at joints. Replacesealant, repair joints.

Many slab cracks, some breakingthe slab into three or more pieces.Cracks open 1/8” or cracks withspalling. D-cracks at several joints.Sealant failure over 10% of joints.Several patches in fair to poorcondition with cracks in patch anduneven surface. Faulting 1/4” to1/2” in several locations. Severeor extensive scaling.

Open jointwith

spalling.

Corner cracks with spalling.Full depth patch required.

Open cracks with edgespalling. Corner crackand broken corner piece.

Open joints and cracks.Need sealant on morethan 10% of joints.

Full depth jointrepair required.

▼

Concrete patch inpoor condition.

▼

▼

▼

▼

Faulting of joints aggravated byheavy traffic in one direction.

▼

▼

Rating pavement surface condition 17

AC 150/5320-17 Appendix 2 7/12/04

▼

Severe joint faultand spalling.

▼

RATING 1

FAILED — Extensive repairs, overlay, or complete reconstructionnecessary.

Many wide cracks with failed sealant andgrass. Extensive crack and joint spalling.Slabs extensively cracked or shattered.Many corner breaks with spalling. D-cracks with spalling. Patches in poorcondition with spalling. Numerous faultsover 1⁄ 2”. Extensive full depth jointrepairs or slab replacements, extensivepatching and complete overlay, orcomplete reconstruction needed.

Multiple slab cracks,spalling andshattered slabs.

Failed joint withsevere spallingand pothole.

▼

▼

Inlet with severe crackingand spalling. Full depthslab repair required.

Rating pavement surface condition18

AC 150/5320-17 Appendix 2 7/12/04

RATING 1

FAILED (continued)

Severe scaling overextensive areas.

Reconstructionrequired.

▼

Closelyspaced cracks

and poorjoint.

Reconstruct.

▼

Severedeterioration.

Requiresreconstruction.

▼

19

AC 150/5320-17 Appendix 2 7/12/04

Inventory and field inspection

Most airport owners routinely observepavement conditions as a part of theirnormal work. However, an actualinspection means looking at the entiresystem as a whole and preparing awritten summary of conditions. Thisinspection has many benefits over casual observations. It can be helpful tocompare pavement features, and ratingsdecisions are likely to be more consistentbecause the system is considered as awhole within a relatively short time.

An inspection also encourages areview of specific conditions importantin pavement maintenance, such asdrainage, adequate strength, and safety.

A simple written inventory is useful in making decisions where other peopleare involved. You do not have to trustyour memory, and you can usuallyanswer questions in more detail. Havinga written record and objective informa-tion also improves your credibility withthe funding agencies.

Finally, a written inventory is veryuseful in documenting changing pave-ment conditions. Without records overseveral years, it is more difficult to knowif conditions are improving, holding theirown, or declining.

A sample inventory form is shown onthe inside back cover. It is very helpful to collect background information oneach feature. Pavement thickness, age,and major maintenance are examples of helpful information.

Annual budgets and long rangeplanning are best done when based onactual needs as documented with awritten inventory.

Pavement features

Inventory and pavement condition dataare normally organized by dividing thepavements into segments or features. Aplan or aerial photo of the entire airfieldis most helpful in identifying these

individual features. Runways, taxiwaysand aprons should be considered asseparate categories. Within eachcategory, the pavement should beseparated into features with similarconstruction. For example, pavementswith different thickness, age, or type ofconstruction should be rated separately.

A runway may be all one feature ifconditions are similar. However, if partsof the runway have significantly differ-ent construction details or condition,then separate features will make therating more logical and useful.

Each taxiway, can be considered aseparate feature. You may combineseveral sections of taxiway if conditionsare similar.

Apron areas can be separated intofeatures according to the areas theyserve. For example, aprons serving aterminal, hangers, tie-down area, orfueling area would be separatefeatures. Areas in different conditionsmay also be separated into features.

It is helpful to note the size of slabsor panels as well as the number ofslabs in a feature. The overall area can be calculated and used to preparemaintenance or construction estimates.

Averaging and comparing sections

No pavement feature is entirelyconsistent. Also surfaces in one sectionmay not have all of the types of distresslisted for any particular rating. Theymay have only one or two types.

The objective is to rate the conditionthat represents the majority of thepavement feature. Small or isolatedconditions should not influence therating. It is useful to note these specialconditions on the inventory form sothis information can be used in plan-ning specific improvement projects. Forexample, some spot repairs may berequired.

Occasionally surface conditions varysignificantly within a feature. Forexample, short sections of goodcondition may be followed by sectionsof poor surface conditions. In thesecases, it is best to rate the featureaccording to the worst conditions andnote the variation on the form.

The overall purpose of conditionrating is to be able to compare eachfeature relative to all the other featuresin your airport pavement system. Oncompletion you should be able to lookat any two pavement features and findthat the better surface has a higherrating.

Assessing drainage conditions

Moisture and poor pavement drainageare significant factors in pavementdeterioration. Some assessment ofdrainage conditions during pavementrating is highly recommended. While youshould review drainage in detail at theproject level, at this stage simply includean overview drainage evaluation at thesame time as you evaluate surfacecondition.

Consider both pavement surfacedrainage and lateral drainage (ditches orstorm sewers). Pavement should be ableto quickly shed water off the surface.Ditches should be large and deepenough to drain the pavement andremove the surface water efficiently intoadjacent waterways.

Look at the crown and check for lowsurface areas that permit ponding. Run-ways and taxiways should have approxi-mately a 1.5º% cross slope or crownacross the pavement. Apron areasrequire positive drainage and ofteninclude storm drainage systems.Maintenance of the entire drainagesystem is critical. Ditches, subsurfacedrains and outlets should be inspected

Practical advice on rating airfield pavements

Practical advice on rating airfield pavements20

AC 150/5320-17 Appendix 2 7/12/04

managers use the rating system.However, an individual surface ratingshould not automatically dictate thefinal maintenance or rehabilitationtechnique.

Consider future traffic projections,original construction, and pavementstrength since these may dictate a morecomprehensive rehabilitation than therating suggests.

Summary

Using funds most efficiently requiresgood planning and accurate identifi-

and cleaned regularly.A pavement’s ability to carry heavy

traffic loads depends on both thepavement materials (concrete slab andgranular base) and the strength of theunderlying soils. Most soils lose strengthwhen they are very wet. Therefore, it isimportant to provide drainage to the top layer of the subgrade supportingthe pavement structure.

Planning annual maintenance and repair budgets

We have found that relating a normalmaintenance or rehabilitation procedureto the surface rating scheme helps

cation of appropriate rehabilitationprojects. Assessing pavement conditionsis an essential first step in this process.This pavement surface condition ratingprocedure has proven effective inimproving decision making and usingfunds more efficiently. It can be useddirectly by airport staff and consultantsor combined with additional testing anddata collection in a more comprehensivepavement management system.

References

Asphalt Airfield Pavements PASER Manual, 2003, Engineering ProfessionalDevelopment, College of Engineering, University of Wisconsin-Madison.

Guidelines and Procedures for Maintenance of Airport Pavements, 7/14/03,Federal Aviation Administration, Advisory Circular AC:150/5380-6A.

AC 150/5320-17 Appendix 2 7/12/04

AIRFIELD PAVEMENT INVENTORY

Airfield _______________________________________________________________ Condition survey date _________________________

Done by _____________________________________________________________________________________________________________________________________

Facility (runway, taxiway, apron) __________________________________________________________________________________________________________

Feature description _________________________________________________________________________________________________________________________

Feature location ____________________________________________________________________________________________________________________________

Feature area _________________________________________________________________________________________________________________________________

Construction date __________________________________________________________________________________________________________________________

Pavement type: ■■ Asphalt ■■ Concrete Layer thicknesses: ___________ ___________ ___________

Maintenance history __________________________________________________________________________________________________

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PASER Rating ( 5 = Excellent, 4 = Good, 3 = Fair, 2 = Poor, 1 = Failed) ■■Comments on pavement and drainage conditions _______________________________________________________________________

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Recommended maintenance ___________________________________________________________________________________________

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Recommended rehabilitation __________________________________________________________________________________________

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PASERConcrete Airfields