Patch condition is a standard inspection item in airport and highway pavement condition surveys. Well-performing patches indicate good maintenance practices; failed patches become new distresses requiring further repair. Patch inspection evaluates edge bonding, surface condition, settlement or shoving, and deterioration of the patch material itself across both asphalt and concrete pavements.
Patch condition inspection is the systematic evaluation of previously repaired areas on pavement surfaces to assess their current performance, identify deterioration mechanisms, and assign severity ratings for inclusion in Pavement Condition Index (PCI) calculations and maintenance management systems. According to ASTM D5340 — Standard Test Method for Airport Pavement Condition Index Surveys and the PAVER distress identification manuals developed by the U.S. Army Corps of Engineers Construction Engineering Research Laboratory (ERDC-CERL), a patch is defined as an area where the original pavement has been removed and replaced by a filler material. Per the PAVER methodology, a patch is always considered a defect, regardless of how well it is performing.
The rationale for treating all patches as defects stems from the fundamental nature of patching as a discontinuity in the pavement structure. Even a perfectly executed patch introduces a material interface where the patch material meets the original pavement — this interface represents a plane of weakness where water infiltration, differential movement, and future distress initiation are most likely to occur. The patch material itself, whether hot mix asphalt (HMA), cold mix, Portland cement concrete (PCC), or proprietary rapid-setting materials, will have different thermal expansion properties, stiffness characteristics, and aging behavior compared to the surrounding pavement. These differences create the potential for bond failure, reflective cracking, differential settlement, and material incompatibility that can compromise both the patch and the adjacent pavement.
FAA Advisory Circular 150/5380-6C — Guidelines and Procedures for Maintenance of Airport Pavements emphasizes that timely maintenance and repair of pavements, including patching, is essential for maintaining adequate load-carrying capacity, good ride quality necessary for the safe operation of aircraft, good friction characteristics under all weather conditions, and minimizing the potential for Foreign Object Debris (FOD). Patch condition surveys provide direct feedback on whether maintenance repairs are achieving their intended service life and whether underlying pavement problems remain unresolved.
The patch inspection process is a standard element of all major pavement condition survey protocols, including:
The PAVER Asphalt Surfaced Airfields Distress Identification Manual (PAVER distress code 50) defines patching and utility cut patches for asphalt-surfaced pavements with three severity levels based on patch condition, performance, and Foreign Object Debris (FOD) potential. These criteria are applied during visual pavement condition surveys conducted in accordance with ASTM D5340.
A low severity patch is in good condition and is performing satisfactorily, with little or no FOD potential. The patch material is intact, well-bonded to the surrounding pavement along all edges, and shows no signs of settlement, shoving, raveling, cracking, or material deterioration. The surface texture of the patch is consistent with the adjacent pavement, and there is no noticeable difference in ride quality when traversing the patch. Low severity patches do not require immediate maintenance intervention and may continue to perform adequately for several years.
Special rating modifications for low severity patches:
A medium severity patch is somewhat deteriorated and affects riding quality to some extent, with some FOD potential. The patch exhibits one or more of the following conditions: partial edge bond failure where the patch has separated from the surrounding pavement along portions of its perimeter; visible cracking in the patch material; light settlement of the patch surface relative to the surrounding pavement (typically less than 13 mm / 0.5 inches); surface raveling with aggregate loss; or a noticeable but not severe roughness when traversed. Medium severity patches should be scheduled for repair or replacement in the near-term maintenance program.
The medium severity rating is also the minimum mandatory rating for:
A high severity patch is badly deteriorated and affects riding quality significantly or has high FOD potential. The patch needs replacement. High severity conditions include: complete edge bond failure with gaps between patch and surrounding pavement; severe cracking of the patch material with pieces loose or dislodged; significant settlement exceeding 25 mm (1 inch) creating a tripping hazard or hydroplaning potential; shoving or lateral displacement of the patch; extensive raveling with coarse aggregate loss; or material disintegration to the extent that the patch is no longer performing its structural function. High severity patches represent an immediate safety concern for aircraft operations and should be prioritized for urgent repair.
Patching is measured in square feet (square meters) of surface area. If a single patch contains areas of differing severity levels, these areas must be measured and recorded separately. For example, a 25 ft² (2.3 m²) patch may have 10 ft² (0.9 m²) of medium severity and 15 ft² (1.4 m²) of low severity — these fractions are recorded as distinct entries in the survey database. Any distress found within a patched area is not recorded separately; however, its effects are considered when determining the patch severity level. This principle prevents double-counting of distress and ensures that the patch distress captures the combined effects of all deterioration present.
A very large patch exceeding 2,500 ft² (230 m²), or a feathered-edge pavement area, may qualify as an additional sample unit or a separate pavement section rather than being recorded as a patch within the original section. This threshold recognizes that extremely large patched areas fundamentally change the character of the pavement section.
For concrete (rigid) pavements, the PAVER Concrete Surfaced Airfields Distress Identification Manual distinguishes between two categories of patch distress based on size. This differentiation reflects the different structural implications of small repairs versus large-area replacements in rigid pavement systems.
Small patches in concrete pavements are surface repairs that do not extend through the full slab depth. These typically address spalls, popouts, or localized surface deterioration. The severity levels are:
Counting rule for small patches: If a slab contains one small patch, it is counted as one slab with small patching, regardless of the patch severity. If a slab contains more than one small patch, the slab is still counted as one slab with small patching, but at the highest severity level present. This slab-based counting method is unique to concrete pavement small patching and differs from the area-based measurement used for asphalt patches.
Large patches and utility cuts in concrete pavements represent full-depth repairs that replace a significant portion of the original slab. A utility cut is a specific type of patch created when the pavement is opened for installation or maintenance of underground utilities. Utility cuts follow the same rating criteria as standard large patches.
Critical rules for concrete patch counting:
Edge bonding is the most critical parameter in patch condition evaluation. The bond between the patch material and the surrounding pavement determines whether the patch functions as an integral part of the pavement structure or as a loose insert that creates FOD hazards and water infiltration pathways.
Debonding occurs when the patch material separates from the vertical face of the surrounding pavement along the patch perimeter. This creates a narrow gap that allows water infiltration into the pavement structure below, accelerates stripping of the tack coat or bonding layer, and enables progressive deterioration from the edge inward. Debonding is typically initiated by:
Assessment method: Edge bonding is assessed visually by examining the entire patch perimeter. A thin metal probe (such as a feeler gauge or knife blade) may be used to detect debonding gaps. The percentage of the total perimeter that has debonded is estimated, along with the maximum gap width. Per PAVER guidelines:
Edge spalling refers to the breakdown of material at the patch boundary, where either the patch material or the surrounding pavement edge fractures and fragments. This is distinct from debonding in that material is actually lost, creating a raveled edge condition. Edge spalling is rated as part of the overall patch severity and significantly increases FOD potential, particularly on airfield pavements where loose material can be ingested by aircraft engines.
Settlement in a patched area refers to downward displacement of the patch surface below the elevation of the surrounding pavement. Shoving refers to lateral displacement or horizontal movement of the patch material, typically manifested as a bulge or ridge at the patch edge.
Settlement is measured by placing a 3-meter (10-foot) straightedge across the patch and measuring the maximum depth of the depression relative to the surrounding pavement. The FAA airfield pavement criteria (AC 150/5380-6C) and ASTM D5340 provide the following guidance for settlement measurement:
| Severity | Runways & High-Speed Taxiways | Taxiways & Aprons |
|---|---|---|
| Low | 3 to 13 mm (1/8 to 1/2 in) | 13 to 25 mm (1/2 to 1 in) |
| Medium | 13 to 25 mm (1/2 to 1 in) | 25 to 51 mm (1 to 2 in) |
| High | > 25 mm (> 1 in) | > 51 mm (> 2 in) |
Settlement in patches is most often caused by:
Shoving in patches occurs when the patch material displaces laterally under traffic loading, typically in the direction of traffic. This is most common in:
Shoving severity is assessed by measuring the height differential between the shoved material and the original pavement surface. The PAVER shoving criteria (distress code 54) provide guidance: less than 19 mm (3/4 inch) height differential is low severity; 19 to 38 mm (3/4 to 1.5 inches) is medium severity; and greater than 38 mm (1.5 inches) is high severity.
The patch material itself can deteriorate through several distinct mechanisms, each of which is assessed during the condition inspection.
Raveling in patches refers to the progressive dislodgement of aggregate particles from the patch surface. In the PAVER methodology, raveling is defined as the loss of coarse aggregate particles from the pavement surface. For patches, raveling is evaluated using the same criteria as for general pavement raveling (distress code 52):
Raveling in patches is typically caused by: inadequate compaction leaving high void content; poor aggregate-binder adhesion in the patch mix; oxidation and hardening of the binder in the patch material; or mechanical damage from snowplows, tire chains, or ground servicing equipment.
Cracking in patches can take several forms:
Cracking severity in patches follows the general crack severity criteria of the PAVER system, with crack width, spalling, and FOD potential as the primary determinants.
Asphalt patch material undergoes oxidation over time as the binder reacts with atmospheric oxygen. This process causes the binder to become harder, more brittle, and less adhesive. The PAVER weathering distress (code 57) provides a framework for assessing oxidation in patches:
Patch condition is one of the most valuable diagnostic indicators in pavement evaluation. The performance of a patch provides direct feedback on whether the original cause of pavement distress was correctly identified and adequately addressed during the repair. A patch that fails prematurely or exhibits specific deterioration patterns points to unresolved problems in the underlying pavement structure.
Recurrent settlement of a patch in the same location strongly indicates that the underlying base or subgrade has not been stabilized. If the original pavement failed due to a weak subgrade, poor drainage, or frost-susceptible soils, simply replacing the surface material without addressing the foundation will result in rapid patch failure. The patch will typically settle progressively under traffic, often at a rate faster than the original pavement deteriorated.
Water-related patch deterioration (pumping stains around patch edges, stripping of the patch binder, frost heave of the patch) suggests that the drainage system is either absent, inadequate, or has been compromised. In airfield pavements, per FAA AC 150/5320-6G, no other factor plays a more important role in the ability of a pavement to withstand the effects of weather and traffic than the drainage system. If patches in a section consistently show moisture-related deterioration, the drainage infrastructure should be investigated.
Structural overloading indicated by patch distress: When patches in primary traffic areas (wheel paths, runway touchdown zones, taxiway centerlines) show consistent structural distress while patches in non-traffic areas perform well, the pavement section may be experiencing loads beyond its design capacity. This is particularly relevant at airports where aircraft fleets have been upgraded to heavier models since the original pavement design.
Differential deterioration between patches and surrounding pavement indicates material incompatibility. Common incompatibility issues include:
In the PCI methodology, if all patches in a section are rated as medium or high severity, the section should be evaluated for potential subdivision into separate sections with distinct condition ratings. If the patching is concentrated in one area of the section, that area may represent a fundamentally different pavement condition that should be rated independently. The ASTM D5340 standard notes that a difference in PCI of 15 or more between parts of a section, resulting in different pavement condition ratings, warrants subdivision.
The Pavement Condition Index (PCI) is a numerical rating on a scale of 0 to 100 (100 being the best possible condition, 0 being failed) determined by a visual pavement survey conducted in accordance with ASTM D5340. Patch distress is one of the standard distress types included in PCI calculations for both flexible and rigid airfield pavements.
In the PCI methodology, each distress type and severity level has a corresponding deduct value that represents the penalty applied to the pavement condition rating. The deduct value for patching depends on both the severity level (low, medium, high) and the density of the distress (the percentage of the sample unit area affected by patching).
Asphalt pavement patching deduct values are determined using the AC Pavement Deduct Curves in ASTM D5340. The PAVER system (as amended by the Air Force Civil Engineer Center / AFCEC) provides simplified deduct value tables that can be used in lieu of the standard curves for contingency PCI surveys. Using these simplified tables, the corrected deduct value for patching is calculated based on the total deduct value (sum of individual deducts) and the number of distress types (q value) in the sample unit.
Concrete pavement patching deduct values are determined using the PCC Pavement Deduct Curves. Large patching and small patching have separate deduct curves, reflecting the different structural implications of these two distress types. A slab with small patching is counted as one slab, and the distress density is calculated as the percentage of slabs in the sample unit affected by small patching. For large patching, the area of the patch relative to the sample unit area determines the distress density.
During a standard PCI survey, sample units are selected for inspection using systematic random sampling. The minimum number of sample units to be surveyed per section depends on the overall size of the pavement section and the desired confidence level. For a standard (project-level) PCI survey, enough sample units must be surveyed to achieve a 95% confidence level. For simplified (contingency) surveys, a reduced number of sample units is acceptable.
The PAVER Field Inspector software application automates the PCI calculation, allowing inspectors to record patch distress directly on a tablet computer in the field. The software calculates real-time PCI values and maintains a database of distress observations for trend analysis.
Foreign Object Debris (FOD) potential is a critical consideration in conducting PCI surveys on airfield pavements. The PAVER distress definitions explicitly reference FOD potential as a severity level determinant for patches. Per ICAO Annex 14 — Aerodromes, aerodrome operators must inspect the movement area (runways, taxiways, aprons) at least daily for FOD. Patch condition directly affects FOD potential in the following ways:
The AFCEC contingency PCI guidance emphasizes that particular attention should be given to pavement distresses that could present safety issues or cause operational limitations, such as potholes, delaminations, and improper or inadequate surface repairs.
Proper documentation of patch condition during inspection is essential for tracking pavement performance over time, justifying maintenance budgets, and developing repair priorities. The FAA Pavement Management Program (PMP) requirements (AC 150/5380-7B) specify that federally obligated airports must maintain records of all pavement inspections and maintenance activities.
The minimum documentation requirements for patch condition inspection include:
Per FAA AC 150/5380-7B, the pavement management program records must include: inspection date, location, distress types found, and any maintenance performed or scheduled. These records must be retrievable for review. The PMP documentation should also include:
Photographs of patch distress should be taken using consistent protocols to enable accurate comparison over time. Recommended photographic documentation standards include:
The performance relationship between patches and the surrounding pavement provides valuable insights into overall pavement health and the effectiveness of the maintenance program.
When patches consistently perform well across a pavement network, this indicates:
In the PCI rating system, a pavement section with well-performing patches (low severity) will have a relatively low deduct value for patching, and the overall PCI may remain in the “good” (86-100) or “satisfactory” (71-85) range. The patches are noted as defects but do not significantly reduce the pavement condition rating.
When patches consistently perform poorly, several conclusions may be drawn:
Patch condition data can be used to establish quantitative maintenance triggers:
| Patch Condition | Maintenance Response | Typical Timeline |
|---|---|---|
| Low severity (all patches) | Monitor at next scheduled inspection | 12-24 months |
| Medium severity (isolated) | Schedule for repair in maintenance program | 3-6 months |
| Medium severity (>20% of section) | Evaluate section for rehabilitation | 1-3 months |
| High severity (isolated) | Urgent repair priority | 1-4 weeks |
| High severity (>10% of section) | Immediate section evaluation | 1 week |
| Recurrent failure at same location | Geotechnical investigation | Before next repair |
The ultimate purpose of patch condition inspection is to inform maintenance and repair decisions. FAA AC 150/5380-6C and the ACRP Report 09-11 Guidebook provide decision frameworks for selecting appropriate maintenance treatments based on patch condition.
Low severity patches — Continue monitoring. If the patch is performing well, no immediate action is required. However, if the patch material is incompatible with the surrounding pavement (dense-graded in PFC, or rigid material in AC), the patch should be scheduled for replacement despite its apparent good condition, due to the differential friction or structural incompatibility concerns.
Medium severity patches — Surface treatment options include:
High severity patches — Full patch replacement is required. The following procedure is recommended per FAA guidance:
Low severity concrete patches — Monitor at regular intervals. Small patches that are functioning well require no immediate action. However, if the small patch is on a slab with other distresses (cracking, corner break), the overall slab condition should be evaluated for possible full-depth repair or slab replacement.
Medium severity concrete patches — Deterioration of the patch edges or surface indicates failure progression. Treatment options include:
High severity concrete patches — Full-depth patch replacement is required. The FAA standard repair procedure for full-depth PCC patches includes:
The most effective maintenance strategy is to minimize the need for patching through proactive preventive maintenance. According to FAA AC 150/5380-6C and the ACRP guidebook, preventive maintenance actions that reduce patching requirements include:
The ACRP Project 09-11 guidebook emphasizes that “the most effective means of preserving airport runways, taxiways, aprons, and other pavement areas is to implement a comprehensive maintenance program” that addresses pavement needs in the good-to-fair condition range, before the deterioration accelerates to the point where patching becomes the primary repair method.
Patch condition data can be aggregated across a pavement network to serve as a key performance measure for maintenance program effectiveness. Agency-level performance measures based on patch condition include:
The International Civil Aviation Organization (ICAO), through ICAO Annex 14 — Aerodromes and the Aerodrome Design Manual (Doc 9157 Part 3), requires aerodrome operators to maintain pavements in a condition that ensures safe aircraft operations. Patch condition assessment and documentation are integral components of the aerodrome pavement management system that supports these requirements. The ICAO Global Reporting Format (GRF) for runway condition assessment, while primarily focused on surface contaminants (snow, slush, water), also recognizes that surface irregularities such as deteriorated patches affect runway condition and should be reported when they impact braking action or directional control.
In summary, patch condition inspection and rating is a critical element of comprehensive pavement management. The systematic evaluation of patches provides direct feedback on maintenance quality, identifies underlying structural problems, quantifies FOD safety risks, and generates the data needed for evidence-based maintenance planning. When performed consistently according to ASTM D5340 and FAA guidance, patch condition surveys enable pavement managers to optimize repair strategies, extend pavement service life, and ensure the safety and operational efficiency of airfield and highway pavements.
TarmacView provides expert airfield and highway pavement condition inspections including patch condition assessment, PCI surveys per ASTM D5340, and detailed documentation of all pavement distress types. Contact our team to schedule an inspection at your facility.
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