Airfield and Highway Pavements 2023: Design, Construction, Condition Evaluation, and Management of Pavements

Airport pavement strength reporting is critical to communicate the acceptable pavement capacity of flying operations that a given airport can tolerate. For the past 40 years, the Aircraft Classification Number-Pavement Classification Number (ACN-PCN) method has been the standardized procedure for reporting airport pavement strength. However, with the ICAO’s update of the Aerodrome Manual and the FAA’s recent release of Advisory Circular 150/5335–5D, the standardized method of pavement strength evaluation has been updated from the ACN-PCN method to the Aircraft Classification Rating-Pavement Classification Rating (ACR-PCR) method. This system update intends to increase the accuracy of reporting by incorporating the latest advances in design and evaluation methods in addition to overcoming the limitations of the ACN-PCN method. More specifically, the ACR-PCR method incorporates the predominate airport pavement design methodology of layered elastic analysis (LEA), while ACN-PCN is based on empirical methods. This update of the airport pavement strength reporting method is anticipated to cause challenges for airport authorities because transferability between the two systems appears to be difficult; however, the issue of transferability could be mitigated by developing correlations for standard aircraft types. This paper provides a proposed correlation between cover layer thicknesses needed to calculate ACN and ACR values for the US Air Force C-17 aircraft and offers recommendations for further research on transitional tools for key stakeholders.

Rigid aircraft pavements generally comprise concrete slabs constructed on a bound or granular sub-base layer, over the natural or constructed subgrade or fill. The joints between the slabs induce and control shrinkage cracks during concrete curing, allow for thermal expansion and contraction, provide load transfer between adjacent paving lanes, and isolate slabs from structural penetrations and adjacent pavement sections. Joint performance is critically important to rigid aircraft pavement performance, and multiple joint solutions are available to pavement designers. This research reviewed common joint types, distresses, and maintenance through analysis of United States, United Kingdom, and Australian aircraft pavement practice, and determined that different authorities use different joint types for similar applications. Alternate jointing methods used on non-aircraft rigid pavements were also investigated, and these could improve constructability and performance for aircraft pavements. It is recommended that further research uses finite element modeling to assess any new jointing practice, prior to field validation.

Open-graded friction course (OGFC) mixtures have been used by several agencies as a wearing surface to improve the functionality of the roadway by minimizing splash and spray, increasing wet weather visibility, improving friction resistance, and reducing noise levels. However, thin OGFC overlays can also help maintain or improve pavement condition and extend pavement life when used as preservation treatments. The objective of this study was to evaluate the field performance of five thin OGFC overlays used for pavement preservation. The results obtained after seven years of service show that overall, the sections have exhibited good durability performance and structural health, which are capable of extending the life of the pavement. The functionality of the OGFC layer has decreased over time, suggesting that some of the added benefits of open-graded mixtures, such as permeability and noise reduction, may be lost within the first few years of service.

Many state highway agencies are working to implement the new AASHTOWare Pavement Mechanistic Empirical Design (PMED). The predicted distress models for flexible pavements must be calibrated to local conditions for accurate pavement performance prediction and subsequent design analysis. In the past, there were multiple efforts on local calibration of flexible pavement distress models in Kansas using AASHTOWare PMED versions 2.2 and 2.5. The new AASHTOWare version 2.6 needs to be evaluated for updated local calibration factors. Twenty-one newly constructed flexible pavements were selected in Kansas for evaluating local calibration factors for different distress models, including rutting, fatigue cracking, transverse cracking, and international roughness index (IRI). The local calibration factors that were developed previously using AASHTOWare version 2.5 performed well for rutting and international roughness index distress models when using version 2.6. However, the top-down fatigue cracking model showed unsuccessful performance. This is because the top-down distress prediction model was drastically changed in PMED version 2.6.0.

To assist airports in the assessment of the surface profile roughness of in-service runways the FAA has developed a new Runway Roughness Index (RRI). This index was established under research conducted by the FAA Airport Research and Technology Branch. The RRI was developed based on the Boeing Bump Index (BBI), pilot ratings to simulator testing, International Organization for Standardization (ISO) human vibration discomfort standards, and ProFAA’s aircraft simulation. Two types of the RRI were developed to categorize airport pavement roughness. The first as an average, total length, root mean square (RMS) RRI, and the second is a single event Transient RRI, which is based on moving RMS. Threshold values were validated for the proposed ranges for acceptance, monitoring, and excessive levels of roughness needing immediate remediation. The RRI is shown to compliment the BBI and give a useful total pavement ride quality metric. Roughness events that would not have been identified using the BBI can be located using the RRI application in ProFAA. This paper describes the development of the RRI.

Random cracking is an all-too regular part of concrete pavement projects. In order to determine how to remedy this, I have focused on two design components which I believe have the highest likelihood of causing cracking notwithstanding that the contractor has complied with the design: “joint spacing” and “mix design.” In order to determine whether random cracking arose because of defective construction or design, it is critical that the “cause” of the cracking be investigated. Based on my experience, this is not done. This failure not only undermines any effort to determine who caused the cracking, but also what should be done to remedy the problem for future projects. Absent design changes going forward, as a matter of law, owners may be liable for the repair costs, not contractors.

The current practice of pavement design requires that engineers take an integral approach to develop feasible design recommendations by considering pavement history, condition of the in-place pavement structure, traffic forecast, drainage, and treatment costs. Without a clear methodology, pavement designers could struggle to achieve their project’s objectives within the client’s deadline and budget. This case study details the process followed to develop a final pavement design recommendation for a 0.87-mi long stretch of US 24 adjacent to Interstate I-69 near Ft. Wayne, Indiana. The design was developed using falling weight deflectometer (FWD) test results, pavement management condition data, geotechnical recommendations, and traffic forecasts. Additionally, the design team conducted a field condition survey in March 2022. The final design recommendation was a preventive maintenance overlay treatment of a 2.0-in. mill and 2.0-in. hot-mix asphalt (HMA) overlay, expected to provide 12 years of functional life.

As per Federal Highway Administration (FHWA), climatic factors alone contribute up to 36% and 24% in total damage to flexible and rigid pavements, respectively. Hence, it is important to understand the influence of climatic factors on pavement performance as well as the design methodologies. The existing literature evaluated the sensitivity of individual climatic and traffic factors on pavement performance. However, the sensitivity of interaction between various traffic and climatic factors could be highly significant but is least understood. The objective of this study is to evaluate the sensitivity of individuals and interactions of climatic and traffic factors on predicted pavement performance. This study considers air temperature, precipitation, wind speed, humidity, percentage sunshine, and groundwater table as the climatic factors and annual average daily truck traffic (AADTT) as the traffic factor. A fractional factorial design (2⁷⁻²) is considered to determine the statistical significance of individual and interaction factors on performance prediction. The study concluded that interaction of temperature and wind speed would be highly significant for rutting predictions, while the interaction of AADTT with temperature/windspeed would be prominent for cracking predictions.

Typically, in aircraft pavement design, the subgrade is assumed to be of infinite (semi-finite) thickness and is characterized by a single modulus (E), CBR value, or k value. In poor subgrade conditions a selected subgrade material may be utilized to overlay the subgrade to achieve an improved strength, or to achieve the required finished surface level. In this situation, an analysis of the various subgrade materials is typically undertaken to determine the effective subgrade strength at the top of the improved subgrade for use in the pavement design. The analysis usually considers the strength of the underlying material types, depth of the selected subgrade material, characteristic strength of the selected subgrade material, and the applied design loading. There are many different techniques available for assessing subgrade materials under aircraft pavements to determine the elastic characterization and effective subgrade strength. The methods identified for assessment in this paper include Austroads Guide to Pavement Technology Part 2: Pavement Structural Design (AGPT02-17); Queensland Department of Transport and Main Roads (DTMR); Japan Road Association; UK Defence Estates’ Design and Maintenance Guide 27: A Guide to Airfield Pavement Design and Evaluation (DMG27); and using Design Software analysis. This paper aims to analyze these methods under a theoretical consistent aircraft pavement profile to compare the results. The outcomes of the paper will help guide engineers’ understanding of the different methods available, and assist with making decisions for determining the most suitable method for assessing the effective subgrade strength of selected subgrade material over poor subgrades for pavement design.

Open-graded friction course (OGFC) mixtures are widely known for rapid water drainage, enhanced surface texture, improved driver safety, and reduced splash and spray. The objective of this study was to verify the predictive capability of Pavement ME total rut depth predictions with that of the average rut depth measurements in the field for the same OGFC sections. Mixture volumetric inputs for Pavement ME software, such as air voids, binder content, and aggregate gradation, were gathered from previously conducted studies for six different OGFC sections of Interstate 75 (I-75) south of Atlanta, Georgia. The traffic data was collected from the weigh-in-motion (WIM) stations closest to the field sections, while the climatic data was collected from the MERRA-2 weather station along the I-75 south of Atlanta, Georgia. As these values were well below the failure criteria, an additional analysis was performed for the rut depth after 20 years. Even this result was well within the specified criteria. Within the limitations of this study, Pavement ME software gave a conservative prediction for rut depth when compared to field observed values. Overall, the study highlighted benefits and challenges of using Pavement ME software for OGFC rut depth predictions.

Curling and warping caused by temperature and moisture gradients are well-known issues in concrete pavement slabs. These behaviors are related to both diurnal and seasonal conditions. Excessive curling and warping can produce stresses that increase the potential for concrete cracking under traffic loads and deflections that contribute to pavement roughness that can significantly impact concrete pavement service life and maintenance costs. While previous studies have shown that most curling and warping in concrete pavements occurs during the morning, changes in temperature and moisture that contribute to actual curling-related pavement roughness in field conditions in Iowa are not as well defined. To investigate the effect of temperature and moisture changes on curling and warping behavior, a number of jointed plain-concrete pavements in Iowa were analyzed using a high-speed profiler. A MATLAB algorithm was developed to analyze diurnal and seasonal changes in the pavement profile to characterize the contribution of curling and warping to pavement smoothness. Temperature and moisture gradients in slabs were predicted using the AASHTOWare Pavement ME Design program, and the findings supported an analysis of the sensitivity of roughness caused by curling and warping due to various temperature and moisture conditions in concrete slabs.

Transverse cracking is a major problem in some asphalt pavements in Northwest Oklahoma. Assessment of repair strategies was needed to optimize maintenance and rehabilitation of the existing pavement. Therefore, in this study, the effectiveness of two transverse crack repair methods, namely (1) trenching and patching using hot mix asphalt and (2) trenching and patching using Fibrecrete, was evaluated. The eastbound lane and shoulder of US 270 in Harper County, Oklahoma, were repaired using these repair methods. Performance of these repaired sections was evaluated for a year using physical inspection, falling weight deflectometer, ground penetrating radar, Face Dipstick, and Pave3D 8K. An evaluation of the “do no repair” scenario was considered to document the improvement of the proposed repair methods. In addition, several alternative rehabilitation options were recommended. Furthermore, a life cycle cost analysis was performed, and the most economical solution was identified.

Rut and longitudinal edge depressions are some of the major problems in asphalt pavements near the intersection of I-35 and SH-7 in Oklahoma. Severe rut and longitudinal joint depressions were observed on SH-7. The purpose of this study was to perform a subsurface investigation using the traffic speed deflection device (TSDD), ground penetrating radar (GPR), and fast falling weight deflectometer (FFWD) tests, as well as laboratory performance tests on asphalt cores. The GPR showed an increase in moisture over the longitudinal joint. Low moduli were observed on the east-bound inside lane, where major depressions and ruts were observed. The Hamburg wheel tracking device (HWTD) tests showed excessive rut in the east-bound and west-bound lanes of SH-7 indicating potential for rut failure. Significantly high rut and roughness were observed on the east-bound inside lane of SH-7 from the TSDD measurements.

Over the last few decades, in-place recycling of asphalt pavements has seen increased use by the highway industry, primarily to take advantage of potential cost, logistical, and emissions savings compared to conventional reconstruction. Recycling operations can be conducted only in the asphalt layer (partial depth) or go deeper into the base layer (full depth). The US military does not currently have standard specifications for conducting in-place recycling, so a waiver must be obtained in order for it to be used on airfield rehabilitation projects. The Federal Aviation Administration and US Navy have both utilized this method on airfields with lighter traffic. This paper provides observations, discussion, and conclusions developed from a case study of a US Navy airfield full-depth recycling (FDR) project. The FDR technique appears to have been a suitable solution to address full-depth asphalt cracking that was occurring on the airfield, which caused repeated mill-and-overlay projects to be ineffective. A structural analysis using the Pavement Transportation Computer Assisted Structural Engineering (PCASE) tool is also included, the goal of which is to determine typical stiffness values that recycled layers must achieve to support various types of military aircraft traffic for different pavement structures. Overall, in-place recycling is recommended for consideration as a rehabilitation technique for military airfield pavements with a wide range of traffic levels, but further investigation is recommended before it is implemented into design specifications.

The US Army Corps of Engineers (USACE) currently uses the Layered-Elastic Evaluation Program (LEEP) as part of its airfield pavement structural capacity evaluation procedures that does not explicitly account for asphalt viscoelastic material behavior. This paper evaluates the ramifications of this by comparing computed stress and strain conditions within a pavement structure using current USACE methods and by using a recently developed computer program LEAGL-VE (Layered Elastic Analysis of General Loadings-Viscoelastic). LEAGL-VE provides the response for a multi-layered viscoelastic system under moving normal, horizontal, and rotational loads. Data from operation of an RJ-85 fire tanker aircraft on an instrumented pavement was used for comparison of analysis programs. Results show that LEAGL-VE produces closer estimates to measured aircraft responses than the current LEEP code. Findings suggest that the proposed analytical method be considered in future mechanistic-empirical design and evaluation procedures.

In the Pavement Mechanistic-Empirical Design (PMED) approach, several climatic factors such as air temperature, precipitation, percentage sunshine, and humidity are considered for analyzing and predicting pavement distresses. Current version of AASHTOWare (version 2.6.22) is integrated with Modern Era Retrospective Analysis for Research and Application (MERRAv2.0) database to retrieve these climatic data inputs for prediction of distresses in flexible pavements. This paper compared the predicted distresses of flexible pavements designed for different locations in the state of New Jersey using three climate data sources: (1) MERRA database from the National Aeronautical and Space Administration (NASA); (2) MERRAv2.0, an improved version of MERRA; and (3) North American Regional Reanalysis (NARR) data supplied with the AASHTOWare version 2.3.1. Predictions on permanent deformation in asphalt layer and bottom-up cracking in asphalt layer were found to be the most affected distresses due to change in climatic data source. NARR climatic data set had a lower prediction on permanent deformation in asphalt layer and bottom-up cracking compared to MERRA and MERRAv2.0. Permanent deformations in asphalt layer using MERRA and MERRAv2 were found sensitive to the bias in windspeed data that was specific to certain locations. MERRAv2 had a higher prediction value (up to 40%) for bottom-up cracking compared to that of MERRA climatic data. International Roughness Index (IRI), top-down cracking, and thermal cracking were found to be least affected due to change in climatic data source. Consequently, this could lead to assessing the requirement for recalibration of the performance prediction models for the state of New Jersey.

The shear bond behavior of geosynthetic interlayers has been intensively investigated, aiming to avoid debonding between surrounding asphalt layers and geosynthetic. Different variables have shown to affect the performance of pavement interlayers, such as tack coat type and rate, surface condition, and geosynthetic properties. However, there is no clear consensus for the design tack coat rate. The present study evaluated five geosynthetic interlayers obtained from field and laboratory studies, in which interface shear strength properties were investigated. Results obtained with different tack coat rates showed an interesting behavior of interface shear strength values and the percentage of tack coat concerning index asphalt retention. An approach using a modified design tack coat rate equation is presented. Maximum results of interface shear strength were not related to the design tack coat rate proposed by the existing equation, while the proposed modified equation led to better estimation of an optimum tack coat rate.

During the construction of the BR-419-MS road, an experimental testing segment had been executed where the pavement was designed and executed by Superpave method, whose structure contained the following layer thickness: 6.0 cm of asphalt surface, 20.0 cm of soil-gravel with 3% of cement, and 20.0 cm of sub-base soil-gravel with 6% cement. This structure was designed using the Brazilian new pavement design method named MeDiNa, which determined the following results after 10 years of pavement use: a cracked area in 16.1% and 2.3 mm of wheel track sag. The objective of this study is to present the methodologies used in laboratory tests for the first stage of experimental testing road segments, compare the performance of asphalt designed using the Superpave method, and compare the results with pavement behavior on the field. The laboratory tests were developed by the Transport Laboratory of the Federal University of Mato Grosso do Sul, and the experimental road testing segment will be evaluated in the place and experimentally, analyzing the criteria of cracks and fissures and for signs of wear and fatigue. The empirical-mechanistic studies considered for evaluation consist of permanent deformation, fatigue, resilient modulus, and dynamic modulus tests. With these comparative data, it is possible to obtain a better understanding of paving designs performance, considering two innovative methodologies in Brazil: the Superpave asphalt mix design methodology and the MeDiNa method for designing pavements.

The placement of geosynthetics between the asphalt layers has proved to enhance the pavement performance through functions including reinforcement, separation, and moisture barrier. Several experimental procedures have been adopted to quantify the performance of geosynthetic-reinforced asphalt pavements, including beam fatigue test, wheel tracking test, three- and four-point beam bending, and interface bond strength tests. The objective of this study is to evaluate the cracking resistance potential of geosynthetic-reinforced asphalt specimens using a monotonic cross-shear test. The unreinforced and geosynthetic-reinforced asphalt specimens tested in this study comprised of 19-mm-thick bottom asphalt layer, binder tack coat, geosynthetic interlayer (only in the reinforced specimens), and 19-mm-thick top asphalt layer. Three different types of geosynthetic interlayers, including polyester geogrid composite (PET-C), polyvinyl alcohol geogrid composite (PVA-C), and fiberglass geogrid composite (FG-C), were adopted in this study. Comparison of monotonic cross-shear test results from geosynthetic-reinforced and unreinforced specimens revealed that the geosynthetic interlayers enhanced the cracking resistance potential of the asphalt specimens. Among the reinforcements tested in this study, polymeric reinforcements exhibited a better performance over fiberglass reinforcement.

This paper evaluates the effect of systematic error (positive and negative bias) in WIM systems on predicted pavement performance. The developed approach uses normalized axle load spectra (NALS) with observed systematic errors to predict the long-term pavement performance in the Pavement-ME for a flexible pavement section at 50% and 90% reliability. The results show that positive and negative bias in axle load spectra results in significant over and under-prediction of rutting and fatigue performance. A 6% positive and 8% negative bias in the tandem axle (TA) load spectra resulted in significant over and under-prediction for rutting and fatigue performance. At the end of design life at 20 years (90% reliability), the positive and negative bias resulted in over and under-prediction of bottom-up cracking by 42% and 15%, respectively. The positive and negative bias resulted in 5%, 2.3% over, and under-predictions for the total permanent deformation, respectively.

Lakeland Linder International Airport (LAL) is a public airport located midway between Tampa and Orlando. As part of the master plan update, the Federal Aviation Administration approved a new aircraft activity forecast that included a substantial increase in large traffic for cargo and maintenance/repair/overhaul (MRO) operations. The new aircraft activity was based on an agreement with a new cargo tenant anticipated to bring B767 and occasional B737 aircraft for 2020. The increase in aircraft size and frequency of operations required the runway pavement to be strengthened. Runway 9-27 is 8,499 ft long by 150 ft wide and serves as the primary runway at LAL. The runway strengthening also required to upgrade the instrument landing system (ILS) from CAT I to a special CAT II and perform work for a final CAT III system later after the strengthening of the runway. This work required the installation of a significant number of light cans for centerline and touchdown zone lighting. The project from design to construction had a very aggressive schedule due to a lease agreement with a new cargo tenant and the Sun n’ Fun airshow. The design started in May 2019, and construction was completed in May 2020. The design consisted of a comprehensive pavement investigation concurrent with runway grading and paving alternatives, including several sustainable approaches to minimize the construction time. A complete remove and replacement approach was considered but exceeded the four-month construction period. Due to grade constraints at the runway threshold ends, the runway needed to match the existing elevation at the runway ends. The runway was constructed in two phases with one of the phases including a displaced threshold to maintain a runway open for general aviation operations. The paving construction was successfully completed within the planned project schedule and included existing base regrading, cement stabilization, asphalt paving, and electrical updates. To be able to meet the design and construction schedule, the team implemented several measures which included weekly meetings and active communication among all disciplines, use of non-destructive testing, minimizing demolition, minimizing new pavement layers, optimizing runway profile to pavement section requirements, and conducting construction simulations to verify durations using standard construction methods. This paper will summarize the process for the accelerated construction of the runway pavement identifying all the design steps implemented for the successful construction of this project.

Long-life pavements are generally designed and built to last 30−50 years without major structural rehabilitation and reconstruction. They achieve their design service life with periodic surface renewal due to surface distresses. Recently, two long-life concrete pavement pilot sections were constructed in Michigan. This paper evaluated the design and construction enhancements employed to achieve longer lives. The long-life pavements differ from standard ones mainly for construction materials, that is, having a cement-stabilized permeable base and stabilized subgrade. Laboratory-determined mechanical properties of the concrete used in both projects surpassed their target. The base layer MR values are higher and lower for the subbase layer than their assumed values at the design stage. The as-designed and as-built predicted pavement performance showed that either design alternative would achieve its intended design lives; long-life pavements had a slower rate of progression of IRI and joint faulting. The LCCA comparison revealed that the long-life design pavements are more cost-effective considering the estimated total cost (i.e., agency and user costs).

The work conducted under this study was designed to establish achievable tolerances for DPS-related measurements, break the measurement errors down into their components, and estimate the error propagation impact on the final DPS evaluated in-place pavement density. To determine the repeatability and reproducibility precision in the field, six sensors were used to comply with the minimum number of participants as required in ASTM E691. Pavement sections built at the NCAT Test Track in 2021 were used in this study and included: fine-graded mixes and open-graded mixes; three underlying materials: new asphalt layer, milled asphalt surface, and granular base; thicknesses ranging from 3.8 to 13.9 cm; and two testing locations: within the mat and along the joint. Computed precision statements for the within laboratory and between laboratory in terms of dielectric values were 0.083 and 0.125, respectively. In terms of density the statements were 27.4 kg/m³ and 36.4 kg/m³, respectively.

The bonding of sealants within a sawcut joint is a key to the prevention of incompressible and fine material to limit the buildup on crack faces of joints transported by infiltrating water into the pavement. Blow-up failures, in particular, are likely a result of crack face accumulations that have occurred within a joint due to a lack of bond between the face of the sawcut and the sealant. Maintaining the bond between sealant and reservoir wall is an important part of the successful maintenance of concrete pavement systems. Several studies have shown that joint sealants often suffered from premature adhesive failure between the sealant and concrete pavement. This unexpected adhesive failure may be due to inadequate joint preparations (inconsistency in managing the cleanliness of contacting surface). Measuring and controlling the condition of the reservoir wall in the field is key to improving the bond strength. Current inspection technologies for cleaning the joints used in the field subjectively assess joint face cleanliness. Moreover, in most cases, only visual-based inspection technologies are utilized that are unsuitable or inapplicable to serve as a standard quality assurance test. This paper introduces a camera-based inspection method to ensure joint preparation quality. In this new method, the cleanness of the joint is quantified using an image analysis technique. Several roughness variables from image analysis are used to assess cleanliness. The proposed camera-based inspection method can provide objective indicators for bonding surface cleanliness by overcoming the limitations of the existing cleanliness inspection method.

In recent years, low-activity nuclear density gauges (LNDG) have become available and are used for soils and asphalt compaction testing. These gauges, which are exempt from licensing and other nuclear regulatory requirements in the United States, use gamma-ray scattering technique for measuring density. A new method was developed for using these gauges for agency acceptance testing of finished asphalt pavements. In this method, the gauge is used in transmission mode, placing the gamma-ray source at a depth of 12.5 mm (0.5 in.) in asphalt layer, using a predrilled hole with a diameter of 19 mm (0.75 in.). This paper presents the measurement method and properties of a gauge using this new method (LNDG/TM). The measurement properties were determined from laboratory and field studies conducted in North Carolina. An LNDG/TM was evaluated by side-by-side testing with a thin-lift type conventional nuclear gauge (TL-NDG) that is allowed to use for acceptance testing. These studies showed that the sensitivity and precision of measuring density by an LNDG/TM were similar to those by a TL-NDG. Based on measurements taken on a 100-mm-thick (4-in.) intermediate layer made from a 19-mm Superpave mix, the precision, repeatability standard deviation, for the LNDG/TM was 5 kg/m³ (0.3 lb/ft³). The measurement time including for site preparation was about 2.5 min. When gauge measurements were correlated to the industry-accepted core-extraction method, the agreement between LNDG/TM and a TL-NDG for measuring density was within 32 kg/m³ (2 lb/ft³).

Several test sections at the MnROAD pavement research facility in Minnesota were re-constructed in summer 2022. Roller modulus mapping was performed to assess foundation layer support conditions, with independent calibration using in situ cyclic plate load tests, and the results are compared with the assumed design values. A new approach was implemented to develop field target values that linked the design loading case with the in situ cyclic plate load testing considering geomaterial stress-dependency, realistic stress-state conditions, and the measurement influence depth of the loading plate. e-Compaction reports were generated for the modulus mapping runs in near real-time to proactively address poor support conditions. Spatial maps of resilient modulus and “blob” analysis maps showing contiguous poor support were generated to improve performance ranking of current experiments. The mapping results identified low modulus areas and allowed for analysis of variability, differences in support conditions between the sections, and between passing and driving lanes.

Use of environment-friendly warm mix asphalt (WMA) technologies with reclaimed asphalt pavement (RAP) materials in airfield asphalt concrete (AC) pavement construction is essential to reduce embodied carbon of airport pavements. However, the current Federal Aviation Administration (FAA) advisory circular for airfield construction neither provides a guidance on WMA technologies nor allows the use of RAP in AC surface mixes for airfield construction projects funded by the airport improvement program (AIP). Test Cycle 2 (TC2) at FAA’s National Airport Pavement and Materials Research Center (NAPMRC) studies the rutting and fatigue performances of three different WMA variants alongside one WMA variant with and without 20% RAP in the surface AC mix. Accordingly, six full-scale test lanes were constructed and subsequently trafficked with a 272.7 KN single moving wheel load under the influence of high temperature and tire pressure. Prior to traffic tests to failure, response tests were performed at different wheel loads to measure pavement responses. This paper summarizes the results from response tests, rutting performance of the WMA+RAP mix considering the strains at the bottom of the asphalt concrete layers and compressive stresses on top of the underlying layers. Rutting performance under accelerated pavement tests of WMA+RAP is compared with HMA. The RAP test sections exhibited comparable rutting performance to that of the control P-401 HMA test section.

Failure of in-pavement light fixtures prompted the Port Authority of New York and New Jersey (PANYNJ) to conduct an in-depth evaluation of the in-service light fixtures in their jurisdiction followed by an instrumentation study. For the study, the L-868B light fixture bases were instrumented with four horizontal and four vertical strain gauges. The Federal Aviation Administration (FAA) embarked on a study in 2019 to replicate and verify PANYNJ results using four different configurations of L-850 light fixtures and corresponding bases with the same instrumentation configuration. A total of eight fixtures with varying combinations of spacer rings, studs, and extension were embedded and instrumented in a conventional flexible pavement test bed. The installed fixtures were subjected to impulse, static, and dynamic loading conditions. This paper summarizes the interaction between light fixtures and slow-rolling aircraft wheel load in terms of observed strains. Following a predefined lateral wander, the test items were trafficked at five different incremental load levels using a 3D-gear traversing bidirectionally at a consistent speed of 4 km/h (2.5 mph). Variations in strains along the two axial directions were examined against the nine different wander tracks. The transition of polarity in base strains with loading distance indicated a larger zone of influence than that from the direct impact of the moving wheel loads on the fixtures.

A full-scale pavement test section consisting of two relatively thin jointed plain concrete pavements was constructed and subjected to simulated aircraft traffic to evaluate the performance of thin concrete pavements under heavy aircraft loads. The full-scale test section was constructed to include two relatively thin concrete thicknesses (8 in. and 11 in.) placed over a nominal 6-in. crushed aggregate base course over a fine-grained subgrade with a typical modulus of subgrade reaction of 172 psi/in. The test section was trafficked using the US Army Engineer Research and Development Center’s (ERDC’s) Heavy Vehicle Simulator (HVS) equipped with a dual-wheel gear simulating one side of a Boeing 737-800’s main gear. Heavy-weight deflectometer (HWD) and falling weight deflectometer (FWD) test results were used to characterize the pre-traffic and post-traffic stiffness of the test items. Pavement performance in terms of cracking was monitored periodically throughout the traffic application period to assess the number of passes necessary to meet historical pavement failure criteria. This paper describes the constructed test section, the application of simulated traffic, and the resulting pavement performance in terms of cracking.

This paper presents findings from the ongoing Construction Cycle 9 tests at Federal Aviation Administration’s (FAA) National Airport Pavement Test Facility (NAPTF) with the objective to investigate full-scale flexible pavement test section performance trends under realistic traffic loading with gear/wheel load wander. Inductive coil sensor technology was adopted to investigate the deformation behavior of unbound aggregate base layers instrumented with arrays of coil sensors installed through the full depth. A dual-wheel tridem-axle (3D) gear configuration applied 58,000-lb (26.3-ton) wheel loads to the test sections with a wander pattern consisting of 66 passes arranged in nine lateral wander positions. Throughout the 26,400 passes applied during the traffic testing, permanent deformation trends with depth were collected and analyzed. The depths at which minimum and maximum deformations took place were determined according to the 3 in. (76 mm) vertical intervals measured by vertical coil pairs. Study findings are quite revealing when analyzing the aggregate base course deformations, in comparison to the overall pavement surface deformations, which could identify damage mechanisms in such thick airfield granular layers and help to evaluate thickness design requirements to effectively protect the subgrade.

The falling weight deflectometer (FWD) is the most common nondestructive testing device used to evaluate the structural capacity of highway and airport pavements. While FWD testing is simple and prevalent, the accurate backcalculation of pavement layer properties has been challenging. The use of static modeling for backcalculation has significant limitations, especially for rigid or thick and stiff flexible structures that are common for airport pavements. Research suggests dynamic backcalculation offers significant advantages over static backcalculation by modeling the inertial effects, the viscoelastic behavior of the asphalt concrete layer, and the damping behavior of the subgrade layer. The FWD deflection time histories contain a wealth of information that are unique to each pavement structure. The static backcalculation methods make use of the FWD peak deflections, whereas the traditional dynamic backcalculation methods use the peak deflections and the time delay between the peak deflections and the peak load. In this paper, the authors explore different parameters from the FWD time histories for use in dynamic backcalculation through a parametric study. The dynamic backcalculation is then performed using the recommended parameters for a flexible pavement structure built at the Federal Aviation Administration’s (FAA) National Airport Pavement Testing Facility (NAPTF) at Atlantic City International Airport, New Jersey.

Vehicle dynamics models rely on accurate input to estimate fuel consumption, dynamic loading, and ride comfort. One of those inputs is the tire’s responses to loading, usually given as a linear spring and a dashpot connected in parallel. This paper determines the load response and variation with the excitation frequency of two truck tires—a dual tire assembly (DTA) and a new-generation wide-base tire (WBT). The experimental program included variations in load, tire inflation pressure, displacement amplitude, and frequency. The tire was mounted to an axle frame connected to a 250-kN servo-hydraulic actuator, which applied the load to the tire frame. The experimental procedure was to load the tire assembly to the desired value, hold the load constant for 1 min to avoid residual deformations, and then apply a displacement-controlled sinusoidal wave at angular frequencies of 0.63, 3.14, 6.3, and 15.7 rad/s and three amplitudes (1.27, 2.54, and 5.08 mm). The loads applied to the tires were 26.7, 31.1, 35.6, 40.0, and 44.5 kN, and the tire-inflation pressures were 552, 689, and 827 kPa. Stiffness and damping depended on frequency, and simple equations were proposed to calculate the tire’s dynamic response. Regression analysis of the damping and stiffness was completed using power and polynomial functions. At constant amplitudes, the damping decreased exponentially with an increase in frequency, while stiffness exhibited a peak of around 3.14 rad/s. For a tire pressure of 689 kPa and an applied load of 40.0 kN, the largest difference in dynamic stiffness and damping between the WBT and DTA was 23.3% and 35.9%, respectively.

This study numerically investigated the responses of cold in-place recycled (CIR) asphalt sections in heavy-weight deflectometer (HWD) testing. A 3D finite element (FE) model was built for an instrumented pavement section containing a 71 mm CIR layer. To determine the appropriate mesh size and model dimension, simulation results generated from the elastic model were compared with predictions obtained from BAKFAA and KENPAVE software tools. Then, the linear viscoelastic model was used to capture the deformation of the surface asphalt layer, with its Prony series parameters determined from experimental dynamic complex modulus tests. Good agreements were achieved between the calculated surface deflection at various locations and the measured responses from field HWD testing, which validated this developed numerical model can be used to capture the deformation of CIR pavement sections. This study is expected to provide useful suggestions for innovative pavement design under more complex conditions in future research.

Fiber-reinforced asphalt concrete (FRAC) improves the fatigue and rutting performance of highways. However, the predicted performance of FRAC for airport pavements in various climates is still unknown. Four fiber types (carbon, glass, basalt, and polyolefin/aramid) and two binder grades (PG76-22 and PG58-28) were used for two climates. Typically, airport pavement design models (FAARFIELD) do not account for temperature variations during pavement service life. The laboratory-measured dynamic modulus values for each sub-season were incorporated into PCASE software to evaluate the selected thickness. The damage was evaluated using FAARFIELD rutting and fatigue models. Furthermore, Pavement Classification Rating (PCR) was determined for control and FRAC by using FAARFIELD. The results showed that PFA fibers are equally good in rutting and fatigue life for both regions and binders. However, carbon fibers showed lower damage for PG76-22. Finally, the PCR results showed higher strengths for the pavements in cold climates than in hot climates.

Historically, most pavement design and analysis procedures make simplified assumptions on the tire load-contact pressure-contact area relationship. First, most procedures assume the contact area is circular. It is also assumed that the contact pressure is equal to the tire inflation pressure at the tire-pavement interface. Next, the contact pressure is assumed uniform across the circular contact area. These assumptions lead to the final concluded relationship that the contact area is simply the applied load divided by the inflation pressure. For conventional thick pavements, the manner of loading is less significant since this statically equivalent loading produces similar responses as the true loading at depth. However, for contingency and overloaded low volume roads, the shape of the contact area and contours of the non-uniform contact pressure produce noticeably different near-surface responses. This study presents a numerical procedure for estimating the loaded contact area of a flexible tire coupled with a deformable surface. The tire is represented as a radial spring tire model. Comparisons are made between measured tire imprints of known load and inflation pressure to the proposed model’s predictions under the same simulated conditions. Estimated contact areas made by the model compared well with the measured areas from different loaded aircraft tires. Further investigation also showed that the proposed model indicated that the shape and size of the contact area depended on factors such as the load, inflation pressure, and pavement structures’ overall stiffness. Results showed that the proposed model produced contact areas that necessitated non-uniform contact areas, which caused relatively larger near-surface responses than those produced by the conventional uniform, circular pressure approach.

Matting systems are used for many applications for the military as temporary surfaces to reduce ground pressure exerted by aircraft, heavy equipment, vehicles, and construction material. The US military uses the AM2 airfield matting systems as rapidly constructed airfields to distribute the load on the subgrade pavement to overcome the deformation effect on the pavement. However, most mats are tested and used for soils with a minimum California Bearing Ratio (CBR) range of 5 to 6. However, using airfield mats on softer soils can be challenging. The subgrade needs to be stabilized to transfer the load properly, which requires substantial preparation for the subgrade pavements. The recycled plastic pin (RPP) is an engineered material manufactured using recycled plastic waste and has been proven effective in stabilizing shallow slope failures. RPPs are lightweight and less susceptible to chemical and biological degradation than alternative reinforcing elements. RPPs can stabilize the soil under the matting system and control deformation. The current study presents the effectiveness of RPP in stabilizing the soft soil under the AM2 matting system. The study investigated the performance of the RPP-supported AM2 system using 2D and 3D finite element analysis (FEA). Different RPP length and spacing has been utilized on soils with a CBR range of 1−5. Based on the FEM analysis results, the RPPs with closer spacing created a group effect and can effectively reduce the vertical displacement and support the foundation system under the AM2 mats.

Transportation agencies and DOTs continually strive to provide good-quality pavements for effective transportation of public and goods. It is obvious that pavements experience critical distresses, such as rutting and fatigue. Compressive strain and tensile strain at the bottom of the base and asphalt layers influence major distresses. Adopting geosynthetics is one of the available approaches to limit distresses by introducing reinforcing materials in base layers of pavement structures. The objective is to evaluate the performance of geosynthetic reinforcements in flexible pavements. The computer program, Composite Geosynthetic Base-Course Model, was employed to mimic the pavement layers’ responses, and as a result, various strains at the bottom of asphalt and base layers were recorded. The findings show that the reinforced pavement layers with geosynthetic materials experienced a significant reduction in compressive strain at the bottom compared to the conventional pavement structure. This indicates that the geosynthetic pavement structures can limit rutting, and hence, the service life of pavements could be increased. In addition, the study aimed to quantify the ability of geosynthetic pavement structure to withstand rutting by developing a novel parameter, rutting resistance ratio (RR). Geosynthetic-reinforced pavements can be considered for roads that are not feasible for regular maintenance due to their longer life span. Due to geosynthetic reinforcement, rutting as well as potholes can be reduced, which leads to a reduction in maintenance costs.

Asphalt concrete (AC) overlays improve pavement condition by restoring the structural capacity of aged pavements. Several state agencies have reported significant budget savings by assessing the present condition and predicting the future performance of overlays. The performance of AC overlays is generally characterized by determining indices such as the Pavement Condition Index (PCI), International Roughness Index (IRI), and Random Cracking Index (RCI) during their service life. A review of the traditional pavement index prediction models showed that they are either mechanistic-empirical or purely empirical in nature. In hot and humid climates such as Louisiana, these prediction models are mostly linear, polynomial, or exponential, and are only a function of pavement age, thus masking the contribution of other key variables such as overlay thickness, pre-treatment PCI, etc. The prediction period is also limited to a maximum of five years. With the ever-increasing size of available pavement performance data, supervised machine learning algorithms can be utilized to develop prediction models that outperform traditional performance models. The objective of this study was to develop a machine-learning-based framework for states with a hot and humid climate to predict the long-term field performance (up to 11 years) of AC overlays based on key project conditions. PCI was used as the pavement performance indicator. Two machine learning algorithms, namely, random forest (RF) and CatBoost, were examined. A total of 892 log miles of AC overlay data were obtained from the Louisiana Department of Transportation and Development’s (LaDOTD) Pavement Management System (PMS) database. Based on the collected PMS data, six models were developed to sequentially predict PCI at AC overlay ages 1, 3, 5, 7, 9, and 11 based on highway function classification (C), overlay thickness (OT), overlay age (A), annual cumulative truck traffic (TT), annual cumulative rainfall (R), mean annual temperature (T), and PCI before overlay application (PCI^-). Results indicated that the RF algorithm yielded higher accuracy than the CatBoost algorithm, with R² values ranging from 0.91 at age 1 to 0.87 at age 11 in the training phase, and between 0.72 and 0.65 in the testing phase. Therefore, the RF-based models were considered in the proposed decision-making framework to predict the PCI of AC overlays based on PCI measurement in the pre-treatment stage and other project condition input data.

California has a diverse climate that ranges from desert regions with some of the hottest places in North America to coastal regions with mild climates and cold summers. The selection of the binder’s performance grade (PG) in California is based on a climate map that was developed in 2005 using 1960 to 1990 data from the National Climate Data Center (NCDC) analyzed using the Enhanced Integrated Climate Model (EICM) and the Long-Term Pavement Performance (LTPPBind 2.0) software. Climate change is happening all around the world, and California is no exception. Based on observed pavement performance, there was a need to revise the PG map using updated climatic data from various sources. In this study, the PG binder map for California was updated to better predict pavement performance using the latest available weather data. Thirty years of climate data (1991−2019) were considered to update the current binder’s PG map. The weather data were collected from two main sources: NCDC and Modern-Era Retrospective Analysis for Research and Applications (MERRA). It was found that pavement structure types and thermal coefficients have insignificant effects on the binder performance grade. Also, it is recommended that the binder high PG for the central valley of California be changed based on the results obtained from analysis using EICM and LTPPBind Online.

This paper presents a performance comparison of a relatively new WIM sensor using strain gauge strip sensor (SGSS) technology with some more common sensors currently in practice. The data were obtained from 84 WIM stations located within the United States. The results show that, immediately after the WIM equipment calibration, the gross vehicle weight total error (computed using the mean and standard deviation of WIM measurement error) for all the sites equipped with SGSS was within the ASTM Type I accuracy threshold of ±10%. Additionally, no statistically significant differences were observed in the measurement accuracy of SGSS, and the other two sensors (load cells and quartz) were used in the analyses based on the available data.