Airfield and Highway Pavements 2019: Design, Construction, Condition Evaluation, and Management of Pavements

Traffic loading is one of the most critical inputs in the pavement design process. Load characterization includes the magnitude and the number of load repetitions for each axle configuration. Historically, procedures for axle load characterization in pavement design include: (a) fixed traffic load, (b) fixed vehicle/axle, and (c) variable traffic and vehicle/axle. Generally, the first procedure is adopted for airport pavements, the latter both characterizations are used for the design of highway pavements. In a fixed vehicle/axle procedure, the thickness design is based on the number of repetitions of a standard vehicle or axle load, usually the 18-kip single axle load for highway pavements. If the axle load is different from 18-kip or consists of tandem or tridem axles, it is converted to 18-kip single axle repetitions by a load equivalency factor (LEF). Finally, for variable traffic and vehicle/axle, both axles and their repetitions are considered separately and required axle load spectra (ALS) for different axle types. The concept of equivalent single axle load (ESAL) was developed in AASHTO design guide while mechanistic-empirical design method (Pavement-ME) uses ALS to characterize axle loadings and repetitions. The primary objective of the paper is to evaluate the effects of different load characterizations (ESAL versus ALS) on flexible pavement performance. The approach includes analysis of a standard flexible pavement section by using the axle load spectra from 41 weigh-in-motion (WIM) stations across Michigan. The ESALs were estimated from the ALS for all the WIM stations. Subsequently, the traffic load and repetitions were modeled as ESALs in the Pavement-ME. Flexible pavement performance (fatigue cracking, rutting, and IRI) was predicted by using the site-specific ALS and ESALs. Pavement damage and performance measures were compared between ALS and ESALs to establish the impact of load characterization on the flexible pavement performance. The results show that ALS demonstrated different damage and predicted flexible pavement performance as compared to ESALs.

Since its first development in 1960, the AASHTO design guide for flexible pavements design has been widely used by many agencies for the design of a pavement structure. The guide was substantially modified in 1986 to incorporate nationwide requirements and climatic conditions. However, with significant changes in asphalt technology such as the addition of recycled asphalt, modifiers, and change in traffic and climatic condition, the reliability of the empirical equation to predict the performance of flexible pavements has been put into question. However, even with such concerns, it still remains the most prevalent design method used for the design of a pavement structure by many agencies. One of the most significant breakthroughs of the 1993 design guide was the introduction of the concept of structural number (SN). This study investigates the capability of 1993 AASHTO SN to monitor the changes in pavement performance as it relates to roughness (IRI), rutting, and fatigue cracking using measured field data of four sections from the long-term pavement performance (LTPP) database. The backcalculated moduli values from FWD tests corrected at mid-depth reference temperature are used to determine the layer coefficients. Then, the structural strength of the overall pavement (i.e. SN) for the course of a pavement life is compared to the change in pavement performance (i.e. IRI, rutting, and fatigue cracking). The results showed a significant relationship between the change in SN and a change in pavement performance as it relates to rutting and roughness index where with a decrease in SN, the IRI and rut depth increases. The SN assessment also showed that the LTPP database can be used as a valuable source to calibrate the 1993 AASHTO SN equation based on measured field data from LTPP.

The purpose of this study is to predict the service life of flexible pavements in Bangladesh under rampant overloading. For this study, axle load data, international roughness index (IRI), overlay history of several road sections of flexible pavements constructed by Roads and Highways Department were collected. Firstly, survival curves were developed showing that the actual pavement life was about 4.88 years. Secondly, the intersecting point of the superimposed graphs combining damaging factor vs. axle load and pavement life vs. axle load graphs showed that premature failure of flexible pavements occurs at 4.5 years. So, it is appeared that with present level of overloaded traffic condition, flexible pavements sustain for only 5 years which is one-fourth of its design life. Such reduced pavement life expectancy due to overloading is creating a big concern for Bangladesh since it is incurring high maintenance cost as well as hampering funding for new infrastructure development.

This purpose of this paper is to investigate the impact on flexible pavement performance with truck weights up to 98,000 lbs on six axles that transport loads of raw forest products during spring thaw. Prior to passage of a 2011 state law, Wisconsin DOT could suspend overweight permits for the transportation of raw forest products during the spring-thaw suspension period or impose special weight limits on highways. During one spring thaw cycle that allowed the heavier trucks, measurements were taken for load-related pavement distresses including wheel path longitudinal cracking, rutting, and alligator cracking in adjoining lanes of eleven 2-lane, 2-way highway segments known to carry trucks loaded with logs in one direction and no logs on the return trip. The eleven segments were grouped into two paved surface categories: Marshall mix design (4 segments) and Superpave mix design (7 segments). A segment by segment analysis revealed that one Marshall mix segment (age 13 years) exhibited significantly higher rates of progression in alligator and longitudinal cracking in the loaded lane when compared to the adjoining empty truck lane. In general, higher levels of alligator cracking and rutting were associated with the Marshall mix segments compared to the Superpave segments. Levels of longitudinal cracking were, however, not significantly different between the two surface categories.

AASHTOWare Pavement ME Design is a great tool that can be used to study many different aspects of pavements. The software uses structural, material, and climatic data to predict pavement distresses and performance. In addition to the distress predictions, the software performs several other intermediate analyses and calculates data that can be used to make design decisions. For instance, the enhanced integrated climatic model (EICM) within the software uses hourly climate data to model pavement temperature, resilient modulus adjustment factors, and freeze/thaw depths throughout the design life of a pavement. In this study, many Pavement ME Design projects were created to represent geographic locations throughout the U.S. The frost depth data were extracted from EICM outputs and used to establish a maximum frost depths cumulative distribution for the four long-term pavement performance (LTPP) climate regions. Pavement designers can use the cumulative distribution to determine the maximum total pavement thickness that is needed to protect any frost-susceptible subgrade materials beneath the pavement from frost, for a given level of reliability. Additionally, the mean and median frost depths were established for each climate region. Using these results, pavement engineers and designers can improve their decision making during the design stage, especially for regions or agencies that must account for frost.

Unbonded concrete overlay (UBCO) is the most widely used rehabilitation option being used as compared to other types of overlays based on its long-term performance, minimal pre-overlay repairs, and relatively easier construction. The implementation of latest pavement performance prediction tools such as the Pavement ME Design [previously called AASHTOware Pavement Mechanistic Empirical (ME) Design guide or MEPDG] has provided the opportunity for designing and performance analysis of UBCOs. The levels of design inputs, for concrete mechanical properties, range from time series data (time series means tested data from 7 to 90 days) of elastic modulus (E_c) and modulus of rupture (MOR) to 28-day compressive strength. This study focuses on evaluating the impact of design input levels for concrete strength and stiffness properties on performance predictions of UBCO using Pavement ME Design. Previous studies have shown that concrete strength properties including compressive strength, E_c, and MOR have significant effects on UBCO performance. The effects of these input levels on predicted faulting and transverse cracking are evaluated for three different paving mixes. The results show that the combination of measured 28-day MOR and E_c yielded predicted distresses that were consistently in close agreement with the predictions using time series data. It became evident that accurate 28-day MOR and E_c values can be used as a less challenging and less expensive alternative to the time series characterization of concrete mechanical properties for UBCO design and performance evaluation.

For long-term planning and operation of pavements, an efficient and effective mechanistic analysis engine serves as the key component of a modern pavement evaluation and design platform. Layered elastic analysis based on closed-form and integral solutions with many assumptions and idealizations is not sufficient to properly consider advanced material characterization and damage model input requirements of flexible pavements. A new two-dimensional (2D) axisymmetric finite element method (FEM) based analytical tool is being developed for the U.S. Army Corps of Engineers by incorporating state-of-the-art analysis techniques and material characterization into pavement designs and evaluations. This advanced analytical tool, which is described in this paper, includes modules or components, such as advanced layer material response characterization models that can be selected to allow the required details warranted for different levels of input properties. The tool is designed to feature the capability of considering the cross-anisotropic and nonlinear elastic behavior of unbound aggregate layers and subgrade soils as well as the viscoelastic behavior of hot mix asphalt.

For a realistic estimation of stresses and strains in the pavement, it is necessary to consider the dynamic normal load transferred from a truck to the pavement. The roughness of the pavement, and driving maneuver influences the dynamic load transferred. This study investigates the role of acceleration for a given pavement roughness profile. The realistic acceleration values considering transmission gear shifting, tractive efforts, and resistance forces for a given road surface profile and truck are required when one is interested in the dynamic load transferred. In this investigation, a commercial vehicle dynamics software, TruckMaker, was used for computing dynamic load transferred prescribing only the target speed from a given starting speed on a pavement having a roughness profile corresponding to Grade A as per ISO:8606 standard. The influence of changes in truck load was studied by considering unladen, fully-laden, and overloaded conditions. It was found that the dynamic load during acceleration, quantified using a dispersion index, was significantly high for the front axle under all the three loading conditions. The corresponding dispersion index for the rear axle was still significant, although lower than that of the front axle.

The mechanistic analysis of rigid pavements is based on either closed-form solutions developed by Westergaard or numerical solutions based on the finite element (FE) modeling. Since most FE models consider that the concrete slabs are supported by a bed of spring elements, they may not accurately model the supporting layers and are limited in their ability to predict pavement responses with depth within the pavement foundation structure. A 3-D FE modeling tool developed at The University of Texas at El Paso can be used to analyze the response of jointed concrete pavements (JCPs) comprehensively under different geometric configurations, foundation models, temperature profiles, and traffic loads. The behavior of the underlying layers can be modeled either as a Winkler foundation, as a Vlasov foundation, or as a 3-D FE solid elastic foundation. This study presents an analysis of the behavior of rigid pavements as well as a comparison between the Winkler and 3-D Foundation models. In an effort to determine what model can simulate pavement behaviors more accurately, the results were compared with TxDOT’s FPS21 stress analysis tool. The 3-D FE model provided an assessment of the critical stresses and strains for all pavement layers. Moreover, it was determined that 3-D FE method can be a useful tool to optimize pavement structures, in terms of layer material properties and PCC thickness, that handle maximum vehicle loading.

Layered elastic theory (LET) has been the preferred method of analysis of asphalt pavements in highways and airports since its introduction by Burmister in 1943. In the last decade, several authors proposed new developments for the numerical solution and software implementation of LET by making improvements in the number of layers, number of loads, and number of analysis points. The new developments consider complex-load combinations and enhance the numerical integration procedure of the Bessel product functions. The accuracy of near-to-surface structural responses and the speed of computations are critical in the use of LET in the new MEPDG and any future design methods related to surface responses and damage prediction. The authors developed UNLEA, a Scilab program script for the solution of the multilayered system based on the stress function proposed by Huang. The authors apply spline integration instead of the conventional integration-summation (ISE) to solve the Hankel inverse transforms. Also, the authors apply spline interpolation in an independent module based on the Ahlvin and Ulery solutions to improve the near surface responses with the half-space transformation proposed by Khazanovich. The obtained results appear satisfactory compared with other software like KENPAVE and JULEA. The script may be implemented in other Scilab-based solutions for highways and airport pavements or geotechnical engineering.

Because of the dynamics of vehicle-pavement interaction, the magnitude of the load transferred to the pavement can be significantly higher than that transferred in static conditions. However, the dynamic loading history is usually such that loads of relatively higher magnitude occur over shorter periods of time, and hence have shorter residence times at any given location. While this may not have a consequence on the response of elastic materials, the duration of the loading can significantly influence the response of viscoelastic materials. In this study, a linear viscoelastic model was used to capture the response of the HMA layers to short-duration high-magnitude loads. The resulting response was compared with that obtained by assuming the HMA layers to be elastic. The results show that the strain at the bottom of HMA layer is considerably lower when the viscoelasticity of the pavement layers are taken into account.

Life-cycle service time of concrete pavement, strongly governed by the coupling of water and cracks, is known as the inevitable issues of ambient-environmental effects on the fatigue life of concrete pavement. This couple is a key determinant for the long-term durability and maintenance in the current design codes. In this study, three-dimensional nonlinear analysis was conducted by integrating the constitutive laws for concrete and cracked reinforced one, modelling of pore water inside cracks, and the multi-yield surface plasticity for soil foundation to examine the fatigue life under high-cycle moving loads of traffic. The behavioural simulation is discussed with emphasis on the prodigious water pressure in narrow spaces surrounded by a pair of crack planes under the repetitive loading of wheel passages and the drastically shortened fatigue life is focused on in view of the maintenance strategy.

Pervious pavement is gaining popularity in pavement industry because of its extraordinary water permeability, traffic noise reduction, and wet driving safety. However, the larger air voids of pervious pavement bring high susceptibility to damage resulting from environmental and traffic stresses. Therefore, focusing on the service performance of permeable pavement under various moisture and loading conditions is of critical importance. This paper presents a study which aims to investigate the service behavior of water permeable pavement topped with polyurethane-bounded pervious mixtures (PUPM) under various loading and environmental conditions. To achieve this objective, a full-scale test track was constructed in Germany. The performance of pervious pavement test track was evaluated under accelerated loading with three loading speeds at different environmental conditions. During the loading process, vertical total stress of each pavement layer were recorded as the response to hydro-mechanical loading. Analyses show that the response of different pavement layers to hydro-mechanical loading is varied. The water table inside the permeable pavement as well as the water scouring effect on the pavement is affected by the loading speed. Water permeable pavement could be an effective way to help mitigate the heat island effect.

The state-of-the-art testing facility presents a significant step towards expanding the full-scale testing capabilities of pavement laboratories to better simulate field conditions. A comprehensive experimental program was recently designed and implemented at the University of Nevada, Reno, as part of a Federal Highway Administration project on “Analysis Procedures for Evaluating Superheavy Load Movement on Flexible Pavements.” This comprehensive program included five full-scale experiments with different objectives and characteristics. These experiments contained layered pavement systems of asphalt concrete, crushed aggregate base, and subgrade. The key element in the experiments was a square large-scale box, referred to as PaveBox. The internal dimensions of the PaveBox were 10.3 ft by 10.3 ft, with a 7 ft adjustable height. A hydraulic static and dynamic actuator was used to apply surface loads on a Falling weight deflectometer (FWD) loading plate. FWD tests at different load levels were applied while each experiment was extensively instrumented to provide a comprehensive database of the system response. This paper presents the detailed description of the PaveBox design, fabrication, and instrumentation. The efforts undertaken to construct the pavement structures, as well as, special considerations to address several concerns during the application of the FWD loading are presented, such as the reflection of waves at the PaveBox boundaries.

This paper integrates in-service hot mix asphalt pavement data from several typically available but disconnected data sources to inform pavement policy and specification development. Leveraging the resultant large amount of connected cost, mix design, construction, and performance data can supplement existing laboratory experimentation, field trials, and test sections. Specifically, Washington State Department of Transportation (WSDOT) data from 2007 to 2017 are manually integrated to address a range of relevant policy and specification questions. While integration is done manually for this paper, recent advances in data storage capabilities can automate such integration. For this paper, WSDOT pavement performance questions regarding (1) 9.5-mm versus 12.5-mm nominal maximum aggregate size (NMAS) mixtures, (2) the influence of elevated in-place density mixtures, and (3) the influence of high reclaimed asphalt pavement (RAP) mixtures (>20%) are analyzed. Ultimately, the integrated data analysis approach exhibits the potential to show in-service performance trends supporting current pavement practices.

Highway agencies have often used quality assurance specifications that specify end product quality for assuring construction quality. Also, agencies are increasingly incorporating performance-related specifications (PRS) in construction contracts to specify quality in terms of parameters related to desired long-term performance. The PRS also provide a means to account for the value lost or gained by the variances of these parameters from the specified target values. Although such PRS have seen limited use in the construction of new pavements, their use for pavement preservation treatments (e.g., chip seals) has been generally non-existent. The objective of this paper is to establish pay adjustment factors based expected performance of chip seals (aggregate loss and bleeding). The percent embedment (PE) of aggregates into emulsified asphalt was selected as the acceptance quality characteristic (AQC). Relationships were further developed between quality measures, service life, and pay adjustment factors. The expected pay curves were developed based on the quality measures and were used to establish acceptable and unacceptable quality levels. The pay adjustment factors were evaluated to ensure fair payments for the quality of work produced. The paper also documents the process to develop pay adjustment factors based on AQC and performance relationship and evaluate the risks associated with receiving appropriate pay for predicted percentage within limits (PWL).

This study was conducted to review the current acceptance schedules of payment for asphalt pavements used by the Alabama Department of Transportation (ALDOT) and determine if they are representative of the current contractors’ performance. Contractor quality control (QC) and state verification data of forty-five Superpave HMA projects across all nine ALDOT divisions were compiled into a database and analyzed using statistical analysis tools. The statistical analysis was conducted to determine the overall mean deviation and standard deviation of contractor QC and state verification data for asphalt content (AC), voids in the total mix (VTM), and in-place density, and compare with those in the current ALDOT acceptance schedules of payment. In addition, the two-population differences between the contractor QC versus state verification data as well as validated versus unvalidated contractor QC data of AC and VTM were evaluated. Statistical analysis shows that contractor QC and state verification data have statistically equal means for both AC and VTM, but the standard deviation of contractor QC data is significantly lower than that of state verification data. In addition, the variability of AC, VTM, and in-place density data of the database was found to be significantly lower than those considered in the current ALDOT acceptance schedules of payment. Based on the overall standard deviation values determined from the current database, the allowable deviations from the specified target values would be reduced by approximately 50 percent for AC and VTM, and by about 34 percent for in-place density.

Improving asphalt concrete (AC) performance entails designing mixes that can withstand various environmental and traffic loading conditions. Rutting and thermal cracking are distresses associated with high and low temperatures, respectively, while fatigue cracking is a result of heavy load repetitions. These distresses can be considered during the AC mix design through laboratory testing. Current balanced mix design (BMD) approaches focus mainly on two traffic-related distresses: rutting and fatigue cracking, and their results are presented in a two-dimensional interaction diagram. Limited attention has been directed towards thermal cracking, which is an environmental related distress. This paper establishes a three-dimensional (3-D) interaction diagram to include material properties for AC mixtures that would yield exceptional performance against rutting, thermal cracking, and cracking at intermediate temperature. The interaction diagram was constructed using three tests: Hamburg wheel tracking test (HWTT), Illinois flexibility index test (I-FIT), and indirect tensile test (IDT Creep). The tests were performed on three AC mixes, typically used in Illinois (N90-0, N70-0, and N70-10). Based on the 3-D interaction plot, N90-0 performed best on the I-FIT and IDT tests making it the overall highest performing mix. N70-0 on the other hand, performed the least in all the tests earning it the lowest overall performance.

Micro surfacing is a pavement preservation treatment that can be used to protect the pavement structure from moisture and correct minor surface defects. As with other preservation treatments, performance of treated sections depends in great part on proper candidate selection and timely intervention. Estimates for pavement life extension typically range from 4 to 7 years; however, the criteria for defining performance varies among sources. As part of the NCAT-MnROAD Pavement Preservation Study, micro surfacing test sections were placed on Lee County Road 159, a low traffic volume road located in Auburn, Alabama. A total of six test sections were treated in the summer of 2012, including single, double, and cape seal applications, and have been monitored periodically to assess structural condition, surface distress, and ride quality. This paper describes the observed performance of a subset of test sections over the first 6 years of the study.

Over the past decades, several studies have been performed on prolonged pavement life and low-cost preservation and rehabilitation techniques. Cold recycling of asphalt concrete pavements is a widely practiced technique adopted by different agencies over the United States. Thin overlays are popular due to their long-life, low life cycle cost, engineered material selection, smooth surface finish, low noise, and minimum closure time. The National Center for Asphalt Technology (NCAT) has constructed several test sections as part of its Pavement Preservation Study along highway US-280 near Opelika, Alabama. These high-traffic volume test sections were constructed in 2015 and have been in service for approximately 36 months. In this paper, combinations of cold recycled bases and thin overlays were subjected to deflection testing over time and the effect of the treatments over the structural response parameters are analyzed. For the pavement responses, deflection basin parameters, composite pavement modulus, and effective structural number were analyzed for thin overlays placed on cold central plant (CCPR) and cold in-place (CIR) recycled bases, both using emulsion and foaming technologies. All the observed values were compared to control (untreated) sections. The study demonstrates the suitability of thin overlays on cold recycled bases by evaluating the structural performance and overall condition of the pavement test sections over time.

Performance models are the key components in a pavement management system (PMS). A weak link of today’s PMS is the lack of reliable estimates on life-extending benefits of preservation treatments. To address the gap, the National Center for Asphalt Technology (NCAT) started a preservation study in 2012 with laying out preservation treatments on a low-volume county road in Auburn, Alabama. Performance measures including rutting, cracking, roughness, and texture are being collected on a regular basis to this date. The present study aims to implement the survival analysis technique to develop performance curves for preservation treatments. The study confirms that preservation strategies significantly increase survival life of a pavement section when compared with a “do-nothing” scenario. It was found that initial conditions, recycled material usage, crack sealing, and the number of layers have an impact on future deterioration. It is concluded that survival techniques are valuable analysis tools for the assessment, comparison, and prediction of future performance of pavement preservation strategies.

The concept of performance-based mixture design is gaining popularity among the asphalt pavement community. The popularity of this concept stems from the fact that the performance characteristics of new and innovative materials can be readily included, helping to assure the long-term service life of the pavement network. As a result of successful research studies, several agencies in the U.S. have already developed performance-based design procedures for hot asphalt mixtures. Integrating a performance-based design concept into cold recycling mix design process would also provide similar benefits. One of the important components of employing a performance-based mixture design concept for cold recycled mixtures is the availability of a test method(s) to characterize mixture performance. Through this study, the versatility of several cracking-related performance tests and analysis methods was explored. Cold recycled mixtures were prepared in the laboratory with different emulsion types and a range of cement contents and were subjected to the selected tests. The test results were analyzed in terms of the test methods’ ability to rank the expected trends of performance as well as their capability in providing a range of performance discerning potential. The test results confirmed the feasibility of a performance-based design concept for cold recycling mixtures. Based on test results, further research should be conducted to establish a performance evaluation framework for cold recycling mixtures.

In recent years, cold in-place recycling (CIR) researchers have been looking more and more to dense graded asphalt (DGA) testing principles, particularly in relation to cracking. More advanced tests like the disk-shaped compact tension (DCT) require modest-to-intensive specimen sawing procedures and instrumentation, which can present challenges for more friable materials like CIR. Simpler DGA cracking tests [e.g. IDEAL cracking test, indirect tensile (IDT) N_flex factor] have become a recent focus, and these types of simpler tests should be investigated for CIR. If specimen preparation and testing complexities can be alleviated, simplified tests may have value for CIR. This paper’s objective is to investigate simple CIR brittleness and cracking index parameters that can be obtained from non-instrumented IDT testing. Multiple CIR blends encompassing a range of cracking behaviors were tested, and results indicated cracking properties could be sufficiently characterized by energy index (EI), a simplified fracture energy term, and IDT strength.

Cost effective secondary road reclamation is critical given the current budget limitations that many smaller governmental agencies are facing. Several counties in the Midwest have been successfully utilizing steel furnace slag as a key component in full and partial depth pavement reclamation projects. The utilization of the steel slag, along with the techniques developed, have reduced the cost of these projects by up to 50% while also providing better utilization of an agency’s work force. These projects have been on-going for ten (10) years and now have a proven performance record. Due to the limited budgets/resources of these agencies, alternative methods for assuring appropriate quality during construction and compaction have been explored. One of these methods is the use of a light weight deflectometer (LWD). The LWD was utilized both before and after remediation to provide guidance as to its level of success. The presentation will include: 1) an overview of the techniques used; 2) proper characterization of the sustainable steel slag materials; 3) specifications, test results, and comparisons to other materials; 4) a review of one agency’s decision-making process, construction phases, and cost comparisons; and 5) an overview of the field results obtained utilizing the light weight deflectometer (LWD).

Incorporating cold-recycling technologies such as full-depth reclamation (FDR) in pavement rehabilitation strategies reduce environmental impacts, construction costs, and time. FDR construction methods involve pulverizing and reusing materials from the same distressed pavement structures, ultimately reducing the use of new resources and measurably increasing project value. Some state transportation agencies (STAs) have actively sought to implement these technologies, but realizing the full benefits of these asphalt mixtures requires that local state data on material properties be available, in order to optimize these pavement designs. A key challenge is that local and reliable data is limited, leading STAs to use non-representative design values and coefficient modulus that yield overly conservative designs. As STAs across the U.S. have adopted the mechanistic-empirical (M-E) pavement design, their main focus has been on calibrating default M-E coefficients to local design parameters and pavement characteristics. The literature review, however, indicates that STAs have mainly prioritized on optimizing pavement designs other than those constructed with FDR. This study aims to bridge this existing gap by analyzing stiffness modulus values of various FDR materials. To accomplish this, falling weight deflectometer (FWD) measures were taken at 11 FDR project sites throughout Colorado. This study analyzes the stiffness modulus backcalculated from FWD measures and compares the values obtained from different FDR stabilization technologies, namely non-stabilized and emulsion-stabilized FDR. Since using reliable and accurate design input is paramount to a cost-effective design, the findings offered herein are expected to assist STAs in designing FDR pavements utilizing M-E pavement design.

The long-term performance of in situ recycled pavements under service loads has rarely been documented. A number of performance-related questions remain unanswered as to how different pavement recycling methods compare to traditional techniques, such as mill and overlay. This research investigated and compared the structural and functional condition of three full-depth reclamation (FDR) projects. Rutting, fatigue cracking, transverse cracking, and international roughness index (IRI) performance were used to assess the pavement’s functional condition. FDR is a deep in situ pavement recycling method involving pulverizing and reusing existing materials from distressed pavements. Trial sections were constructed in 2008 as part of a Virginia Department of Transportation (VDOT) FDR demonstration project. Foamed asphalt (2.7% with 1% cement), asphalt emulsion (3.5%), and Portland cement (5%) were used as stabilizing treatments for the base layers. Several distress surveys were conducted for the pavement sections, both before and after construction. An automated road analyzer was used to collect distress data over a period of 8 years. Rutting was higher for the foamed asphalt and emulsion sections, but remained well below the maximum allowed by VDOT. The structural and functional capacities of the pavements improved irrespective of the stabilizing treatment used. The load-related distresses seemed to be more critical to the overall condition of the asphalt sections, while the non-load related distresses played a key role in the cement sections. The IRI was better for the cement-stabilized sections compared to the asphalt-stabilized sections. The FDR sections performed better compared to their corresponding reference sections.

This paper presents a new methodology, which enables streets, roads, highways, bridges, and airfields to use an advanced fiber-reinforced concrete material, which can delay or prevent the deterioration of these transportation infrastructure when subjected to traffic and environmental loadings. The major problem of plain concrete is that its service life can considerably reduce due to weather and loading. As a result, it requires frequent repair and eventual replacement, which consumes more natural resources. Ultra-high-performance fiber-reinforced concrete (UHP-FRC) introduces significant enhancement in the sustainability of concrete structures due to its dense microstructure and damage-tolerance characteristics. These characteristics can significantly reduce the amount of repair, rehabilitation, and maintenance work, thereby giving the transportation infrastructure a longer service life. This research addresses the strong need to develop fast and sustainable UHP-FRC materials for pavement repair that can be easily cast onsite without special treatments. This avoids any major changes to current concrete production practice and accelerates the use of UHP-FRC materials. This research investigated a new method for concrete repair by combining precast UHP-FRC panels with a small quantity of cast-in-place UHP-FRC for pavement repair without any dowel bars. Experimental results proved the feasibility of using this new method for fast pavement repair.

As part of the Long Term Pavement Performance SPS-2 (Strategic Study of Structural Factors for Rigid Pavements) Program, a total of 19 sections of jointed concrete pavements were constructed on STH 29 in Wisconsin in 1997. Variables included in the program were slab thickness, slab width, concrete strength, and base type. These sections have been continuously monitored since then. This paper focused on the 20-year performance of transverse joints. The performance was correlated with design variables and materials testing results. It was found that the main contributing factors to joint spalling are (in descending order of significance) air content, slump, slab thickness, lane width, load transfer efficiency, dowel bar diameter, and PCC flexural strength. The risk of joint spalling could be minimized by reducing air content, increasing slab thickness, widening slab, and increasing load transfer efficiency.

Pavement deflection has been widely utilized as a nondestructive technique to evaluate the structural capacity of pavement structures at network and project levels. One of the most widely utilized devices is the falling weight deflectometer (FWD). This study aims to run an advanced computer simulation analyses to mimic the FWD deflection bowl obtained from the field. Transportation agencies utilize various indices based on FWD deflection data. However, this study will utilize newly developed deflection parameters based on the entire deflection bowl in the remaining service age prediction. The newly developed normalized comprehensive area ratio parameter (CA_r’) was successfully related to the tensile strain at the bottom of the asphalt layer and the number of load repetitions to fatigue failure (N_f). The parameter was utilized to predict the remaining service life of thirty-five long term pavement performance (LTPP) sections in Texas. CA_r’ can be easily implemented in pavement management systems that would help state departments of transportation (DOTs) and local highway agency officials to make more informed decisions about most suitable maintenance and rehabilitation strategies.

High ambient flexible pavement temperature, traffic loading, and abrasion caused by studded tires contribute to pavement rutting. The aim of this research is to identify the most significant factors that affect pavement rutting in Alaska, especially change in asphalt surface temperature following winter and during summer. Pavement rutting was simulated in the lab using the wheel–tracker machine based on AASHTO Designation T 324-11. Samples were tested under two different temperatures that approximate Alaska’s summer driving conditions. A ceramic belt was incorporated into the wheel to simulate studded tires. Additionally, rubber tires were used to simulate actual pavement friction forces. The wheel-tracker machine results showed no significant rutting from traffic loading simulation under cold temperatures. Lab results were compared with actual field wear rates collected from pavement resurfacing projects in Alaska. Field results showed higher average wear rates due to studded passenger vehicles (0.006 in. per 100,000 studded vehicles) than the average rut rates due to heavy wheel loads (0.003 in. per 100,000 trucks). Increased temperature of asphalt samples showed significant influence of both thermal and heavy loading effect on pavement rutting especially in summer time. In addition, results vary based on type of mix and testing wheel used. Furthermore, results showed that higher temperature provides higher average rut depth ranges from 2–2.6 inches/20,000 passes.

Continuous evaluation of pavement performance is critical to ensure that the pavement survives its design life. However, collection of cores from different layers to evaluate the pavement condition can be costly and time-consuming. To overcome this limitation and monitor the pavement performance continuously, this study uses the response from an instrumentation section. The instrumentation section has a total of 32 sensors and it is located at Milepost (MP 141) on the Interstate 40 (I-40) near Albuquerque, New Mexico, USA. It has strain gages at the bottom of the asphalt concrete (AC) layer, and earth pressure cells (EPCs) at base, subbase, and subgrade layer. From 2012 to 2017, regular falling weight deflectometer (FWD) test was conducted on the designated locations at the instrumentation section. During this time, pavement responses at different layers were also collected under traffic loads. To evaluate the condition of the unbound layers, base damage index (BDI) and base curvature index (BCI) were measured. Furthermore, combining the FWD modulus, instrumentation sensor response, and layer elastic analysis (LEA), an in situ k₁-k₂-k₃ resilient modulus (M_R) model, used in Pavement ME (mechanistic-empirical), were developed. This FWD test derived M_R model was used to determine unbound layer resilient modulus under moving loads. From the results, it was observed that stress in the unbound layers is decreasing and damage index is increasing over time. It was also observed that developed M_R can predict the resilient modulus under the tandem axle of class 9 vehicle with an average difference of around 15%.

The assessment of composite pavements is an important activity in the pavement management system due to its capability of carrying significant traffic volumes. The objective of this study is to assess the performance of in-service composite pavements to better design and provide long-life structural capacity. Eight long-term pavement performance (LTPP) composite pavement sections [flexible layer over a rigid layer: jointed plain concrete pavement (JPCP) and continuously reinforced concrete pavement (CRCP) with unbound subbase from wet-freeze climate zone] are selected for this study. AASHTOWare Pavement ME simulations are performed to predict the performance of the selected LTPP composite pavement sections using the layer thickness, material properties (Level 1 and 2 Pavement ME inputs), traffic volumes, climatic data, and national calibration prediction models. The measured field performance, in terms of rutting and international roughness index (IRI), of the selected sections, are compared with those predicted from Pavement ME over time to determine the effectiveness of AASHTOWare Pavement ME for predicting the accurate performance of composite pavements. AASHTOWare Pavement ME results overestimated the measured rut depth and IRI. The study recommends conducting additional research to develop local calibration factors for each state based on the data collected from each state LTPP and pavement management systems (PMS).

Forecasting of pavement condition and roughness is essential for optimization of pavement rehabilitation and treatment programs. The objective of this research is to develop a new set of pavement condition index (PCI) and international roughness index (IRI) models for road networks in the city of St. John’s, Newfoundland. For this purpose, road sections that represent freeway, arterial, and collector road systems are selected. On these road sections, pavement distress survey was conducted after collecting video footage and photographs of the roads. In-field measurement of various distresses including rutting, load related and transverse cracking, potholes, and patching was performed in accordance with ASTM standard D6433-07. The survey data is then used to develop a PCI model. Results from the PCI model are validated using pavement service rating (PSR) data obtained by surveying driver behaviour in the city. IRI data is collected on all the road sections using a smartphone app called TotalPave. This data is then used to develop a new IRI forecasting model for the road networks. The IRI model output is validated using PCI and PSR data.

Network level pavement management system (PMS) helps state highway agencies predict future condition scenarios, optimize treatment actions, and estimate funding needs. Most current PMS relies on the assessment and modeling of pavement surface distresses in supporting these activities. Recently several devices, commonly termed as traffic speed deflection devices (TSDDs), have been introduced that can collect pavement structural condition data in a safe and cost-effective manner while traveling at traffic speed, making network level pavement structural evaluation practical. This study summarizes research efforts to-date by authors on developing analysis methodologies, and procedures for incorporating network level pavement structural evaluation in pavement management activities using traffic speed deflectometer (TSD) measurements. A field case study was used to demonstrate the developed methodologies that 1) adjust measurements to a reference temperature, 2) backcalculate pavement layer moduli, and 3) calculate structural number as an indicator of remaining structural capacity of in-service pavement sections.

The New Jersey Turnpike Authority (NJTA) is not unlike other agencies that are challenged to determine and find the appropriate funding required to maintain its infrastructure in a state of good repair. The NJTA operates and maintains two vital National Highway System routes in New Jersey: the New Jersey Turnpike and the Garden State Parkway. The NJTA has implemented a strategic asset management approach to leverage the value of its geospatial database. HNTB, the NJTA’s General Consultant Engineer, created a decision support system (DSS) for the NJTA using results of pavement performance and lifecycle analyses. The results of the lifecycle analyses were incorporated into the database and allows the staff to quantify the current level of service provided on each route and receive guidance on optimizing pavement performance and the allocation of repair funds.

Agencies are trying to improve efficiency of their paving operations, capture accurate pavement and asset history to transition from corrective to preventive maintenance, and lower pavement lifecycle costs. Existing pavement evaluation methods are performed at a section level that yield estimated quantities of work at approximate locations. However, this is not sufficient to generate design plans and calculate the true repair costs. Using advanced global positioning system (GPS) and geographic information system (GIS) techniques, this asset management solution solves these challenges by allowing inspectors to capture the precise location of defects which are then immediately and spatially associated to the assets based on geo-fenced pavement inventory. Repair crews are able to navigate directly back to the reported defect with accuracy (up to 2 cm horizontal and vertical positioning) to eliminate any potential superfluous repairs. The data captured in the end-to-end process allows the back-office to perform quality control and analyze and monitor asset lifecycle developments in real time to enable proactive and predictive airfield repair decision making. A pilot airport project focused on pavement inspection, design, and construction process. During the inspection phase, the data captured included everything contractors needed for bids and was available immediately when the inspections were completed which greatly reduced the time to create work estimates. The defect dimension data, along with the defect images captured during the inspection, helped make the re-inspection process more efficient by providing a “before and after” view of the repair site. Improvements in each step in the design and construction process led to an overall reduction in closure time and an efficient and cost-effective process.

The AM4INFRA project, funded by the European Union's Horizon 2020 research and innovation programme, has delivered an integrated, systematic, common approach for asset management on transport infrastructure networks that is readily implemented, including a supporting toolbox on critical elements (data, methods, and models). The approach enables systematic, consistent translation of policy decisions on the network level into the operational management and maintenance of the various assets in the infrastructure networks, such as pavements, rails, bridges, and runways. The project was structured into three principal work packages. The first work package provides a common language framework that enables transport infrastructure managers to determine what synergetic benefits their mutual cooperation would bring. This is supported by a number of methods and models for whole life cycle and risk management that enables transparent and fact-based decision making across the line of sight (work package 2). This in turn is supported by a set of data and information structures and tools, a common core model for an asset information management system facilitating the exchange and interoperability of data (work package 3).

Rolling wheel deflectometer (RWD) devices are increasingly being used for structural condition evaluation. However, the response of a pavement to a moving load generated by an RWD is different from the response to an impact load as generated by the commonly used falling weight deflectometer (FWD). Thus in order to fully understand deflections obtained by an RWD device, it is important to establish a proper comparison between the two types of equipment. This research presents a dynamic and viscoelastic finite element model able to simulate both impact load and moving load. The model is used for backcalculation of RWD measurements and then forward simulation of an impact load to obtain the corresponding FWD deflections. The “corresponding FWD deflections” refer to the deflections an FWD would have measured at the same location on a pavement as the RWD measurements were conducted. Experimental tests were conducted on a 10 km highway using both a Dynatest Raptor (RWD) and an FWD for measuring. The experimental data from the Raptor measurements was given as input to do backcalculation of pavement parameters, followed by a forward simulation of corresponding FWD deflections. The corresponding FWD deflections compared well with the experimentally measured FWD deflections.

The state highway agencies summarize the overall pavement condition using a pavement condition index. Most of these pavement condition indices only account for the pavement surface distresses and do not accurately consider for the existing pavement structural condition. Even though some states have started using the pavement structural condition into their pavement management decision making process, collecting network level structural condition data at a network level remains a challenging task. The traffic speed deflectometer being a continuous deflection measuring device, allows for network level pavement structural condition assessment, eliminating limitations from the traditionally used stationary devices. This paper investigates the relationship between the pavement surface and structural condition at a network level. Comparison between the surface and structural condition obtained from the traffic speed deflectometer showed that the surface condition is not necessarily a good indicator of the structural condition.

Heavy weight deflectometer (HWD) backcalculated moduli for subgrade materials appear from experience to be always overestimated in comparison with commonly expected values used in design methods. This can be explained by the dynamical loading applied to the pavement whereas the tests used during the construction phase for the characterization of those materials in the frame of a new pavement design are static plate tests. In order to better understand the relationships between the apparent bearing capacity of the subgrade under respectively static and dynamic solicitation, the French Civil Aviation technical center (STAC) decided to build a specific test facility, in partnership with the French Road and Research Center (CER). It consists in an airfield flexible pavement comprised of a subgrade, a UGA subbase, and bituminous materials. It presents two test areas, one with a subgrade presenting regular water content, and the other with a water-saturated subgrade. Static and dynamic bearing capacity tests were performed during the construction for each constitutive layer. This paper focuses on the subgrade moduli backcalculated from HWD tests. Two backcalculation methods are compared: a full backcalculation where all layer moduli are backcalculated under HWD tests performed at the surface of the bituminous materials, and a step by step process using the HWD test performed on each layer, the modulus backcalculated for the underlying layer being fixed and injected in the next one-modulus backcalculation process, until the top of the pavement is reached. Both results are compared with the bearing capacities obtained during construction, for both subgrades.

The state of the art for pavement evaluation has advanced significantly in the last 25 years. New technology allows for rapid relative profile measurement with extreme precision, as well as true profile measurement relative to an external elevation reference, such as sea level, that can accurately capture all grade changes regardless of amplitude or wavelength. However, regulatory agencies have the difficult task of maintaining and enforcing existing specifications using older testing equipment while industry strives to move forward to utilize the newer technologies. This paper presents the results of an FAA study that compares new profile measurement devices and the data that they record versus the California profilograph and 12-foot (3.66 m) straightedge. The purpose of the study was to determine if the stake-holders can benefit from the advantages of using this newer technology without compromising the integrity of existing smoothness specifications. In addition to the use of the California profilograph and 12-foot (3.66 m) straightedge, this evaluation incorporated the use of two different walk-behind inclinometer type profilers, a walk-behind external reference type profiler and two types of inertial type profilers. In addition to smoothness acceptance testing of new pavements, these newer devices can also be used for pavement management purposes or to evaluate roughness concerns for in-service pavements. Ultimately, this study demonstrated that there was agreement regardless of the profiler technology used, and that new technology may be suitable alternatives to the profilograph and 12-foot (3.66 m) straightedge for construction acceptance.

Slurry seal surfacing is a preventive pavement maintenance method to correct surface erosion and irregularities, fill the cracks, and improve the skid resistance. Slurry seal can increase the efficient life of asphalt pavements with a low initial cost. One of the most important parameters affecting performance of a slurry seal is the percent of abrasion (aggregate and bitumen loss) over the service life of the layer. This study investigates the wearing performance of slurry seal mixes using an image processing technique. Performance of various slurry seal mixtures made with virgin and RAP aggregates were evaluated using wet track abrasion test (WTAT). WTAT samples were image analyzed to see the effects of large aggregate, bitumen, and small aggregate loss. High-resolution images were taken from WTAT samples before and after the abrasion test. Applying proper filters and thresholds, images were converted to the binary format to distinguish two material phases, i.e., aggregate and bitumen. After image processing, two loss parameters were compared with the results of wear values. The results showed that bitumen loss and large aggregate loss are the driving factors for abrasion of virgin slurry seals and RAP slurry seal, respectively in its initial service life. It is crucial to use compatible emulsion bitumen and aggregate material for both the virgin and RAP slurry seals. RAP slurry seals should be lightly rolled after lay-down to improve the friction life and the aggregates embedment into the slurry seal mat.

Ride quality of a pavement is important to the travelling public, and highway agencies strive to provide a smooth road network. A common strategy that is used to improve the ride quality of flexible pavements is to place an asphalt concrete overlay. In some instances, the overlay is placed on the existing asphalt concrete surface, while in other instances, a portion of the existing asphalt concrete surface is milled before placing the overlay. The reduction in roughness in terms of the International Roughness Index due to single-lift overlays placed on flexible pavements is presented in this paper using data obtained from a highway agency. The analysis considered 780 and 1,120 segments that were 0.1-mile long on non-milled and milled projects, respectively. The average IRI values for 0.1-mile long segments that was achieved for a single lift overlay on non-milled and milled pavements was 62 and 54 in./mi., respectively. The 85^th percentile IRI values for 0.1-mile long segments after an overlay for non-milled and milled pavements were 77 and 66 in./mi. The percent reduction in IRI that is achieved when placing an overlay was seen to increase with increasing values of before overlay IRI. A percent reduction in IRI of over 40 percent was observed for 0.1-mile long segments having an IRI before overlay greater than 100 in./mi.

The major objective of this research study was to develop a methodology to evaluate tire-pavement noise, in addition, investigating the effect of the pavement surface characteristics on the generation and propagation of noise of the asphalt concrete (AC) and portland cement concrete (PCC) at varying traffic speeds. Field noise measurements were performed using a noise trailer developed in this study and attached to the parent vehicle. Overall, PCC sections with higher skid resistance and lower average texture depth produced the highest noise levels compared to the conventional AC sections; PCC type had an average difference of about 1dB(A) compared with the AC pavement. The presence of surface distress led to increasing the tire-pavement noise level by 7 dB(A). There was an increment of about 1 dB(A) and 7 dB(A) to change vehicle speed from 20 to 40 km/hr and from 40 to 60 km/hr, respectively. Regarding the measurement period effect on the tire-pavement noise level, tire-pavement noise had an increment of about 7 dB(A) during daytime compared with night.