International Conference on Transportation and Development 2018: Airfield and Highway Pavements

As part of asphalt mix design for flexible airfield pavements, the Federal Aviation Administration (FAA) collects asphalt volumetric mixture properties and aggregate gradations. Binder properties as well as laboratory dynamic modulus |E*| measurements for asphalt mixes are performed for flexible airfield pavements research. An artificial neural networks (ANN) model was developed using collected volumetric properties, aggregate gradation, and binder properties as well as laboratory |E*| measurements from seven hot-mix asphalt (HMA) and warm mix asphalt (WMA) mixtures. ANN model predictions were compared with the modified Witczak predictive model calculations for the same mixtures, and it was found that the developed ANN model successfully predicted |E*| for airfield pavement asphalt mixtures.

A new decision support tool (DST) was developed to model the performance of airfield pavements and plan potential capital expenditure (CapEx) interventions over a 20-year period for London Heathrow Airport (LHR). The valuable contribution of DST for annual airfield maintenance strategy planning is the control of the pavement performance of the total airfield considering the asset criticality and the associated risk of each airfield segment. The strength of the model is in identifying the locations of potential failures and the necessary targeted maintenance interventions. The DST allows the user to plan in advance strategic, targeted maintenance treatments, or replacement at section level. This planned approach can generate capital savings arising from optimising construction costs, minimising operational disruption, and targeting appropriate treatments. Savings of 50% on a 20-year maintenance plan at LHR have been identified. This performance-targeted, airfield pavement asset replacement strategy derived from the DST has identified savings of approximately £70m in the next 5-year capital investment period.

The use of deicing chemical has the potential to cause environmental and safety concerns and pavement deterioration. Hydronic heated pavement systems (HHPS) have been widely used to melt or prevent ice and snow accumulation on paved surfaces. HHPS uses heated fluid circulated through pipes embedded in the concrete pavement to warm the surface of the concrete. The objective of this study is to develop a conceptual design framework and construction guidance for large-scale HHPS using precast concrete pavement (PCP) technology to expedite construction work and minimize air travel disruption. The detailed design and 3-D visualization of construction procedures has been developed for HHPS using PCP technology. The outcome of this study will help contractors and transportation agencies to envision the constructability of different components in HHPS, including tubing patterns and construction procedures.

Real-time monitoring of pavement conditions is beneficial not only to more accurate predictions of airport pavement performance but also to more efficient pavement management activities. Although wireless-based sensing system have shown some advantages compared to wired sensing system, there are just few studies that describe instrumenting wireless sensors in the field for pavement condition monitoring. To bridge this gap, this paper presents case studies describing use of advanced wireless sensing system for airport pavement conditions monitoring at three test sites: the Des Moines International Airport (DSM), the Ohio State University (OSU) Airport, and the Texas A&M University (TAMU) Airport. The wireless sensors communicate through a gateway to collect sensor data and then upload it to the cloud. The wireless sensor instrumentation strategy and design plans, based on the field instrumentation experience, are summarized. The key requirements and potential restrictions for implementing wireless sensing systems in airfield pavement are also discussed.

The concept of overnight construction on runways has been limited to either thin asphalt overlays in nightly segments, replacement of Portland cement slabs with accelerated Type III Portland cements, or calcium sulfoaluminate Rapid Set cement concrete. Thin asphalt overlays have been used frequently with 2-inch (5 cm) lifts that leaves a small grade change that is considered to have negligible effect if using an asphalt ramp that is kept to a maximum of 1-inch per 15 feet (.57% grade). Slab replacements have been relegated to keeping the existing grade because an overlay would be required to be at least 5 inches (13 cm) of concrete. However, what if a rapid setting durable concrete would allow a 6-inch (15 cm) overlay to be constructed at night and opened to traffic in the morning. A ramp would obviously be required, but what would the aircraft response be if a temporary construction ramp of 6 inches (15 cm) was used? Using aircraft simulation, this paper explores the issues of introducing a 1% and 0.5% ramp used for overnight construction and its effect on aircraft response. These ramps will be integrated into three profile types; an artificial “glass smooth” runway, an existing in-service runway with known pavement roughness, and finally, an existing in-service runway with average ride quality. This study identifies parameters that can impact aircraft response: ramp location; profile of the existing surface; and up-ramp vs. down-ramp, etc. The final objective is to provide guidance for the use of temporary ramps that would minimize aircraft dynamic response.

The F/HWD Round-Up project located at the Federal Aviation Administration’s (FAA) National Airport Pavement Test Facility (NAPTF) at William J. Hughes Technical Center near Atlantic City International Airport, NJ, U.S., was constructed to investigate the variation of NDT data and FAARFIELD1.42 based on sound theoretical principles and with models verified from appropriate full-scale test data. This paper presents a case study of how the uncertainty of backcalculated in situ modulus can be assessed and incorporated in the FAARFIELD1.42 design procedure to determine appropriate concrete pavement thicknesses. The mean values and standard deviations of backcalculated modulus were computed using two computer programs: BAKFAA (layer elastic theory) and 1993 AASHTO design guide (plate-on-grade theory), and then input into FAARFIELD1.42 using Rosenblueth’s procedure to predict the reliability of a 20-year pavement design performance. The case study shows that the proposed procedure provides an alternative decision-making tool for airport engineers to predict pavement life more realistically using F/HWD data.

The profile roughness over long distances of the airport runway and taxiway pavement may lead to aircraft fatigue damage, reduced operational safety, and passenger discomfort. The Federal Aviation Administration (FAA) has provided guidelines and procedures for measuring airfield pavement roughness in the Advisory Circulars FAA AC 150/5380-9 and has developed the computer program ProFAA for computing longitudinal pavement profile roughness indexes. In recent years, the FAA has collected many longitudinal and transverse profiles at domestic airports. To process the profile data in a more accurate and effective way, an algorithm of a beam bridging filter has been created to reduce the influence of short dips in the pavement surface. This approach can adjust the effect of a tire’s contact with the road surface by modeling the contact area as a beam element with a series of compressive springs. The application of the beam bridging filter is demonstrated by its incorporation into the computer program ProFAA for processing the data of longitudinal profiles of airport runways.

Between 2014 and 2016 the Federal Aviation Administration (FAA) conducted full-scale traffic tests of flexible pavements at its National Airport Pavement Test Facility (NAPTF) at the William J. Hughes Technical Center, Atlantic City International Airport, NJ, U.S. The purpose of these tests, part of NAPTF Construction Cycle 7 (CC7), was to evaluate the International Civil Aviation Organization’s (ICAO) existing criteria for allowable occasional aircraft overloads on flexible airport pavements. ICAO Annex 14 currently limits such overloads to 10 percent above the published pavement classification number (PCN). The applied traffic consisted of the design gear loads alternating with increasing levels of overloads (2-wheel, 4-wheel, and 6-wheel) in a specific sequence. FAA tests confirmed that the ICAO criteria are highly conservative. While higher traffic loads led to earlier failures, overloads of up to 50% above PCN did not alter the parameters of the failure curve, suggesting that for overloads up to this magnitude, the cumulative damage factor (CDF)-based failure model can be used reliably to compute reduced life. However, very high overloads of 90–100% above PCN caused more rapid acceleration of the failure. The findings of this full-scale test will be used to support future revisions to the existing overload criteria.

The Ernesto Cortissoz International Airport is a commercial service airport that serves the city of Barranquilla, Colombia. This paper details the design and reconstruction using an asphalt overlay of the existing 3,000-meter Portland cement concrete (PCC) runway that was built in 1968. The alternatives to repair the runway and taxiway PCC pavements were evaluated, including the reconstruction of the existing rigid pavement. Since the airport has only one runway, the operational impact had to be considered as a critical factor in the design, to minimize the operational disruptions during construction. The airport concession was awarded to Grupo Aeroportuario del Caribe on June 2015, for a 15-year period. The concessionaire proposed the use of a rubber-asphalt mix, with recycled rubber grain (GRC) as the first layer on top of the existing PCC pavement. This layer would allow aircraft operations on the surface and serve to reduce reflection cracking. The use of rubber-asphalt GRC has not been, in general, used in airfield pavements. Another unique technique used in the reconstruction was the use of geogrid synthetic fabric between the first and second asphalt layer to reduce reflection cracking. This paper describes the design considerations for the airfield pavements rehabilitation project including three layers of asphalt overlay constructed at night with transition ramps. The construction process included daytime taxiway construction and several lessons were learned by the contractor before the nighttime process. The runway was kept open to military and commercial service aircraft during the project. The runway overlay was completed in October 2017.

Many single runway commercial service airports and airports with highly congested multiple runway have a dilemma when trying to rehabilitate their runways. The dilemma is how to minimize the disruption to airlines and passengers by reducing runway closures while keeping the revenue stream constant. We are proposing a new method of nighttime structural overlay of either asphalt or portland cement runways using a fast setting, belitic calcium sulfoaluminate (BCSA) cement. The rapid strength gain properties of BCSA cement concrete make this strategy feasible. The difficulty is not in the concrete placement, but rather in the reconstruction process in short 5 to 8 hour runway closures. Concrete removal is one of the most time-consuming portions of the reconstruction process. If the old concrete or asphalt did not have to be removed but simply overlaid with new BCSA concrete, more production could be accomplished each closure window.

This paper provides an update on the standards, applications, and approvals of end-around taxiways (EATs) and implementation challenges at U.S. airports. It also describes how EATs could potentially reduce aircraft delays by reducing the number of runway crossings and minimizing departure holds for crossing aircraft. Other benefits of EATs described in this paper include reduced risk of runway incursions, reduced controller-pilot communications workload, and reduced emissions due to fewer starts and stops by taxiing aircraft. These benefits have been verified through fast-time airfield simulation, human-in-the-loop simulations, and actual experience at existing EAT installations. The paper also discusses challenges of EAT implementation and potential disadvantages of EATs at constrained airport sites, which include potential reductions in certain runway declared distances that could result in payload-range penalties for certain flights. Examples of existing EATs at Hartsfield-Jackson Atlanta International Airport (ATL), Dallas-Fort Worth International Airport (DFW), and Detroit Metropolitan Wayne County Airport (DTW) are also presented. The paper focuses on (1) recent enablers of EATs, including recent changes to the EAT design standards and airspace obstruction clearance criteria; and (2) the new EATs currently being planned for ATL and Newark Liberty International Airport (EWR).

Concrete median barriers are widely used in state highways to redirect vehicles from entering opposing travel lanes. Different from cable barriers or W-beam guardrails, concrete barriers are very rigid; therefore, their performance relies mainly on their cross-sectional shapes. With the development of high performance computer hardware and software, nonlinear crash simulations can be conducted to evaluate concrete barriers in addition to physical crash tests. This paper presents a reliability-based design optimization (RBDO) approach for the design of concrete barriers under vehicular crashes. This design optimization method combined nonlinear finite element (FE) analyses, a metamodeling technique, Monte Carlo simulations (MCS), and a genetic algorithm (GA). High-fidelity FE simulations were first performed to obtain the crash responses at the sample points; therefore, the performance of the concrete barrier was evaluated. To reduce computational efforts, metamodels were created and used to replace the implicit crash responses requiring expensive numerical simulations in the optimization solution process. Once the metamodels of constraint functions were created, the probability constraints were evaluated using a simulation method such as MCS. A GA was applied as the optimization engine of RBDO. The design of a concrete barrier (Jersey barrier) was studied and numerical results were obtained to demonstrate the RBDO approach.

This research focused on the study of flexural load-deflection behavior of rubber in concrete composite (RCC) up to first-crack load. Specifically, this study involved an experimental method to examine simultaneous flexural load-deflection response measurements on normal Portland cement concrete and rubberized concrete. Other basic tests were addressed to characterize the fresh mix and constituent material properties. Regression models were developed to predict the first-crack load at different mix combinations of crumb rubber. Results from this investigation showed that the incorporation of crumb rubber inherits the elastic property to concrete. The flexural load-deflection response tests showed that RCC beams exhibited a significant increase in net deflection compared to that at 50% of the PCC first-crack load. First net deflection for RCC beams did not show a similar increase due to the lower first-crack load. The results indicate the inclusion of the crumbed rubber in Portland cement concrete will reduce the brittleness of this material and in turn improves the concrete toughness. However, it will reduce the overall compressive as well as the tensile strength. This makes rubberized concrete ideal for non-structural use in cold regions in resisting extreme temperatures and the cycles of freezing and thawing. Using rubberized concrete for structure elements require the inclusion of fiber additives to compensate for the strength reduction and further improve the toughness properties even beyond the first-crack load.

Part-time shoulder use (PTSU) and full-depth paved shoulders are typically implemented in the metropolitan areas due to high traffic demand. Full-depth paved shoulders are beneficial as the shoulder is structural sound. As the population of the United States (U.S.) spread to rural regions, full-depth paved shoulders are not always guaranteed. With increasing populations and limited funding, strategies that have worked in more urbanized regions, such as PTSU, will need to be evaluated for use in these growing rural regions. Partial-depth paved shoulder designs are common in rural regions, a reduced cross-section when compared to the mainline lanes, some not even paved shoulders. This study aims to determine the pavement impacts of PTSU on a selection of partial-depth shoulder designs and approaches to minimize the structural weaknesses for simplified PTSU implementation. The objectives of this research are completed with the use of the American Association of State Highway and Transportation Officials (AASHTO) Guidelines for Design of Pavement Structures 1993 design. This study found that only two of the nine states evaluated can handle PTSU with minimal to no reconstruction.

Sustainable use of reclaimed materials has gained significant traction among the pavement design practitioners in recent decades. This is primarily due to the scarcity of natural mineral resources, increasing waste disposal cost, and increasing the demand for aggregate sources. The purpose of this study was to evaluate the mechanical performance, strength characteristics, and durability of reclaimed asphalt pavement (RAP) and reclaimed concrete aggregate (RCA) incorporated in stabilized pavement layers. To accomplish this objective, several reclaimed sources and virgin materials were subjected to mechanical and durability tests to characterize the performance characteristics of stabilized systems. The results indicate that reclaimed materials significantly underperformed in terms of lower compressive and tensile strengths compared to the stabilized virgin aggregates. Additionally, the degree of plasticity of the specimen increased when reclaimed materials (RAP and RCA) were used instead of virgin materials in the cement stabilized base system. The laboratory results clearly underscored the significance of incorporation of durability tests for reliable characterization of the degradation of the mechanical properties due to moisture intrusion in stabilized pavement foundations.

Traditionally, the tube suction test (TST) has been used to characterize the affinity of the unbound and stabilized aggregate systems to hold and transport moisture. The variation of the dielectric values measured at the top of the specimen is correlated with the change in the moisture state of the stabilized systems. The motivation for this study was to evaluate the applicability of the TST procedure to characterize the durability issues associated with the use of reclaimed materials in cement treated layers. To achieve this objective, several virgin and reclaimed aggregate systems were subjected to multiple curing/conditioning procedures in the laboratory. Based on the laboratory observations, reclaimed concrete aggregates (RCA) significantly underperformed other permutations of the experiment design in terms of higher moisture susceptibility potential manifested by high dielectric values. This information can be beneficial for practitioners and the pavement design engineers considering reclaimed materials as an alternative source for aggregates in base layers.

Fixed and random parameter negative binomial models were employed in this paper to analyze the impact of pavement condition properties on accidents at two bends site categories (based on radius of curvature). Six-years (2005–2010) of accident data were considered at bends site categories on road network of Norfolk County in the U.K. The first objective is to examine the performance of the fixed and random parameter negative binomial model approaches. The second objective is to investigate the effects of skid resistance combined with traffic characteristics (annual average daily flow, heavy vehicles percentage, and speed limit) and geometric characteristics (radius of curvature, gradient, number of lanes, and number of minor access), on accident numbers. The results suggest that there was a significant improvement in log-likelihood when using random parameters models. Regarding the effects of the explanatory variables, the results reveal that the annual average daily flow, percentage of heavy vehicles, gradients and number of minor access, and rut depth are positively associated with more accidents. Speed limit, radius of curvature, number of lanes, skid resistance, and texture depth are found to be significant variables decreasing the numbers of accidents.

Otta seal resurfacing methods have been widely demonstrated for unpaved roads and road rehabilitation in a few states in the U.S. as well as in Scandinavia and Africa. Application of Otta seal over a deteriorated hot mix asphalt (HMA) surface has been considered as the feasible concept that has not been applied for real construction. In this study, a double-layer Otta seal construction over HMA surface was monitored. The applied materials for the construction were introduced. The following performance of the constructed Otta seal layers was evaluated by measuring the international roughness index (IRI) and dust. The road IRI did not significantly change, and the dustometer test results indicated satisfied dust control on Otta seal layer. The findings from this study provide guidance on designing and implementing Otta seal on asphalt concrete pavement as a resurfacing overlay.

The resilient modulus (M_R) of base and subgrade materials is an essential material input in the new AASHTOWare Pavement Mechanistic-Empirical (ME) Design guide which was formerly known as Mechanistic-Empirical Pavement Design Guide (MEPDG). Like many other agencies, New Mexico Department of Transportation (NMDOT) has begun the process of implementing MEPDG by calibrating the local materials such as base, subgrade, and asphalt concrete materials. In order to calibrate the local base and subgrade materials for the purpose of ME implementation, a comprehensive laboratory resilient modulus test should be conducted on these materials. As a part of this effort, base and subgrade materials were collected from five different locations throughout the state of New Mexico and laboratory resilient modulus test was conducted according to AASHTO T-307 test standard. The pertinent material constants (k₁, k₂, and k₃) are evaluated from the laboratory test data using regression analysis for the ME design input Level 1. A pavement section has been analyzed in ME-design software using Level 1 and 2 unbound material input to observe the pavement responses in terms of rutting and fatigue damage. The results obtained from the analysis showed that the total rut depth and top-down damage was found to be higher if laboratory resilient modulus was used than the default M_R values which was based on the empirical relationship. Therefore, the ME design software underestimates the pavement performance in terms of rutting and fatigue damage when it is analyzed for design Level 2.

Coefficient of thermal expansion (CTE) of concrete is a very important parameter in rigid pavement design and analysis because the magnitudes of temperature related distresses are directly proportional to this value during early ages as well as during the pavement design life. With the advent of pavement mechanistic empirical (ME) design procedure, more emphasis is being laid on accurate determination of CTE of paving mixes for accurate design. Coarse aggregate being the major constituent of concrete affects the CTE of resultant concrete. With prior research, it has been established that coarse aggregate mineralogy has a significant impact on the CTE of concrete. This study focuses on the experimental evaluation of CTE according to AASHTO T336 test protocol, for various paving mixes being used in New Mexico cast with coarse aggregates having different mineralogy. The laboratory results were analyzed and it was confirmed that CTE of concrete varies with change in coarse aggregate mineralogy. The CTE of these paving mixes varies over a broad range of 3.71 to 5.40 micro strain/°F. These CTE results were compared with the ME design default database and significant difference was found between the two, which may result in inaccurate pavement design. It was also confirmed with design simulations conducted in Pavement ME Design software version 2.3 that CTE variation affects the pavement performance in a significant manner.

One of the emerging technologies for producing sustainable ice-and snow-free pavements is the use of electrically-conductive surface courses, e.g., electrically-conductive asphalt concrete (ECAC) that can melt ice and snow through resistive heating. Modifying the mastic in asphalt concrete with electrically-conductive materials is a promising approach for producing high-quality ECAC. The objective of this study is to evaluate electrical conductivity and heat generation efficiency of electrically-conductive asphalt mastic (ECAM) specimens at a below-freezing temperature—simulating the harsh weather conditions in North America during the wintertime. To this end, asphalt mastic was electrically modified with carbon fiber (CF) at varying volume contents. The ECAM specimens were then powered by 60V AC during a time window of 10 minutes so that their heat generation capacity could be characterized through infrared thermography (IRT). Based on the resistivity measurements and thermal data analysis, the most reasonable CF content enabling rapid heat-generating ECAM was identified; this has future implications with respect to achieving efficient highway, bridge, and airport pavement operations during wintertime.

The use of high early strength materials minimizes the out-of-service time of the effective repairs. In this research, high early strength fiber reinforced rapid set materials (HES-FR-RSM) were developed for concrete repair applications in transportation infrastructures with low cracking potential. Three types of rapid set prepackaged repair materials were developed. The designed mixtures have included three types of fibers (steel, basalt, and carbon) with different volume fractions. The research also included developing finite element model (FEM) that could describe the real structural behavior. The optimized mixture that includes 0.5% steel fibers showed free shrinkage less than 300 microstrains. The proposed model is capable of computing the time-dependent restrained shrinkage strain and tensile stresses at various depths of repair layer. The model is also capable of predicting the actual time of cracking, representation, and distribution of cracks. Moreover, the prediction of this model showed a good agreement with the conducted experiment.

Styrene-butadiene-styrene (SBS), one of the popular elastomeric polymer is now being used with asphalt binder to enhance the pavement performance. SBS usually blended with binder using a high shear mixture at an elevated temperature. Past studies shows that the SBS polymer does not react with or melt in binder, rather it disperses in binder matrix. Therefore, it is important to know the true stress-strain field under loading in the modified binder matrix. This study uses the florescence microscopy to morphology of the modified binders. Later, florescence images were used in finite element modeling (FEM) to evaluate the stress and strain contours of the modified binder matrix under tensile loading. Results shows that there are stress concentrations at sides of the polymer particles.

Presence of cross-anisotropy in field-compacted asphalt concrete (AC) layer is reported in some recent researches. There is a possibility that AC stiffness along a horizontal plane may not be the same. In that case, AC layer may show orthotropy instead of cross-anisotropy. This study investigates the presence of orthotropy in an AC layer through the evaluation of horizontal strains collected from the embedded strain gages at Milepost (MP 141) on the Interstate 40 (I-40) near Albuquerque, New Mexico, U.S. Horizontal strains, along with both longitudinal and transverse directions, at the bottom of an AC layer were collected under falling weight deflectometer (FWD) test load. From the obtained results it was observed that strain along the longitudinal direction is greater than that along the transverse direction. It is also observed that strain ratio, i.e., the ratio of longitudinal and transverse strains, also varies with temperature. It indicates that an AC layer shows the presence of orthotropy.

Application of mechanically foamed asphalt binder in warm-mix asphalt (WMA) is the most widely accepted WMA technology. This study evaluates the effect of foaming water content (FWC) on high-temperature rheological characteristics of foamed asphalt binder. To facilitate the study, a performance grade (PG) asphalt binder has been foamed at six different FWCs using a laboratory foaming device. Laboratory tests such as dynamic shear rheometer (DSR) and rotational viscometer (RV) have been conducted for rheological evaluation. Change in continuous performance grade has also been evaluated at different FWCs. Analysis of tested results showed that injection of a higher FWC causes a slight reduction in binder stiffness. Statistical analysis revealed that viscous behavior (loss modulus) of the foamed binder is strongly correlated with FWCs. However, elastic behavior (elastic modulus) of foamed binder showed no correlation with FWCs. Finally, the study concludes that changes in rheological characteristics are not statistically significant in terms of FWCs that led foamed binder equivalent to the conventional unfoamed binder in terms of rheology.

This paper investigates the integration of locally calibrated hot-mix asphalt (HMA) and unbound granular material characterization models into the Mechanistic-Empirical Pavement Design Guide (MEPDG) to improve the design of flexible pavements. The MEPDG method, currently known as Pavement ME, recommends using locally calibrated material characterization models based on laboratory testing of local materials under specific environmental and traffic loading conditions. A case study using locally calibrated HMA, base, and subgrade material characterization models in Manitoba were compared to designs using default material values in Pavement ME. The impact of the integrated locally calibrated material models on the predicted pavement distresses for pavement sections with different traffic loadings and subgrade types were compared and presented. The results show that the locally calibrated materials model inputs produce lower pavement structural thicknesses compared to the default materials inputs. The effect of using calibrated inputs was more pronounced for higher traffic loadings. The results of the study demonstrate the importance of developing locally calibrated material models as a means of improving flexible pavement designs.

Lower production temperature and less aging make warm-mix asphalt (WMA) more prone to rutting. This study assessed rutting characteristics of WMA with chemical additives through laboratory experimentation and non-destructive field evaluation. To facilitate the study, three WMA mixtures and one control hot-mix asphalt (HMA) have been experimented. One of the WMA mixtures contained polymer modified binder. Hamburg wheel tracking (HWT) test has been conducted for laboratory experimentation. A recently developed method of HWT test analysis has been applied. Nondestructive field strength evaluation and automated pavement distress survey tools were utilized for field evaluation. It is found that chemical WMA exhibits equivalent or better rutting behavior compared to a HMA with a same binder and aggregate structure. Incorporation of polymer modifier in chemical WMA additives resulted in improved rutting characteristics and field strength.

Instead of decades of research, till today aging of asphalt is one of the major concerns to asphalt researchers, as aging in asphalt shows increase in stiffness and leading to the brittleness of the material. Asphalt oxidation occurs in asphalt concrete through permeable pores of the concrete material as well as oxygen present in impermeable pores of asphalt concrete. The current study attempts to investigate the effects of oxidation aging on the extracted asphalt binder of asphalt concrete as a function of available pores in the concrete sample. The thin film asphalt binder’s property was examined using nanoindentation test. In this study, nanoindentation tests were done on the asphalt binder, a widely known viscous material, to obtain the viscoelastic load-displacement behavior. The load-displacement creep data is analyzed through rheological models to obtain material response under indentation. Varying percentages of concrete air voids are used and twelve indentations were done on each extracted and recovered asphalt binder samples. In the study, all the concrete slab samples were subjected to four years of atmospheric aging. Results show a strong correlation between asphalt oxidation through pore present in the sample with viscoelastic relaxation and retardation behavior of the extracted asphalt binder.

Even though the Hamburg wheel tracking device (HWTD) has been gaining popularity and wide acceptance by some state highway agencies as a fast and reliable method to evaluate the rutting potential and moisture sensitivity of asphalt concrete mixtures, previous studies that correlate laboratory test results with field performance are very limited and not well established. In this study, pavement distress surveys were conducted on twenty-five different highway sections located in the state of New Mexico. In addition, HWTD tests were conducted on collected asphalt concrete (AC) mixtures with the intent of correlating results with field-rutting performance. Based on the Pearson correlation analysis, it was found that HWTD rut depth values obtained from HWTD 5,000 wheel pass level presents a sensible relationship with field-rut values recorded from the 1st year of pavement service life for AC mixtures assessed.

Intelligent compaction (IC), as a powerful tool for quality management of compacted geomaterials, has attracted the attention of a number of highway agencies. IC measurement values (ICMV) are vibration-based measurements that reflect the stiffness of compacted geomaterial through vibration response of the drum in contact with the ground. Different studies have attempted to relate ICMVs with moduli/stiffness values from traditional in situ tests. Weak correlations between ICMVs and in situ spot test measurements have been attributed to variation in material properties such as moisture content, influence depth of spot test device, and the variation in underlying support, in addition to the uncertainty in the spatial location of the nearest ICMV data point. In this study, a geostatistical approach is presented to establish a spatial correlation between ICMV and spot test measurements using a light-weight deflectometer or a dynamic cone penetrometer. The proposed method recommends a fixed interval analysis for the collected ICMVs within a defined sublot size that is suited for remedial construction options. This methodology showed better correlation between the ICMVs and the spot test measurements within the defined sublots.

Fourier transform infrared spectroscopy (FTIRS) is a rapid and nondestructive technique by which oxidative aging in asphalt binder can be evaluated for laboratory, plant, and field condition. In this study, effects of solvent intrusion, aggregate size, laboratory aging, and percentage of reclaimed asphalt pavement (RAP) binder on absorbance values of attenuated total reflectance (ATR) FTIRS were investigated. No significant difference in absorbance values were observed due to solvent (95% evaporation) and aggregate size (#200 passing). In the case of oxidative aging determination, both laboratory aged and RAP induced samples demonstrated a significant increase in oxidation signals. Laboratory aged pressure aging vessel (PAV) samples increased the sulfoxide and carbonyl oxidation approximately 26% and 33% where RAP binder induced samples increased the sulfoxide oxidation 211% (20% RAP) and 378% (80% RAP) and carbonyl oxidation 49% (20% RAP) and 221% (80% RAP) respectively. The results indicated the efficiency, viability, and potential of using ATR- FTIRS in laboratory conditions as well as for aging due to RAP binder in field condition.

Although several laboratory rutting tests are currently in use in different states, very few of the tests use full scale loading conditions. Therefore, current test methods are good to evaluate the effects of different mix parameters, but often do not correlate well with field rutting distresses. The objective of this study is to evaluate a full scale laboratory wheel load tester by comparing the rut depths obtained in asphalt pavement analyzer (APA) test. A full scale wheel load testing will eliminate the need of rigorous field evaluation. Laboratory made hot mix asphalt (HMA) and warm mix asphalt (WMA) have been used in dry and submerged condition for evaluation of this tester. After 1200 wheel passes the rut depth for HMA and WMA was found to be 2.8 and 3.8 mm, respectively, for dry conditions, and 3.3 and 5.8 mm, respectively, for submerged conditions. Binder was extracted and recovered from WMA and HMA specimens, and it was hypothesized that increased rutting and moisture susceptibility of WMA specimen is the result of reduced short term aging of the WMA than that of HMA.

Bangladesh does not use reclaimed asphalt pavement (RAP) materials, but RAP has been using in developing countries for many decades. The primary objective of this study is to investigate the prospect of RAP to be used as a stabilized base material in the context of Bangladesh. Series of laboratory tests are performed to determine the physical properties such as bitumen contents, aggregate gradation, and strength on RAP collected from a segment of a road being excavated for utility shifting. Specimens prepared with 100% RAP at different compaction temperatures are tested for Marshall stability, flow, and compressive strength. Specimens compacted with 130 °C, 140 °C, 150 °C, and 160 °C are found to have stability value more than 8 kN. Also, the study predicts the life of the flexible pavement by the mechanistic-empirical method. The study finds that pavement rehabilitated with a stabilized base with 100% RAP has more service life than that of the conventional overlay. Moreover, by using RAP consumption of virgin materials can be reduced by 40% to 60% than that of the overlay. Hence, using the RAP as a stabilized base will provide a new solution to road rehabilitation works which is economically and technically viable for Bangladesh.

Nanotechnology has been increasingly used in asphalt modification for its remarkable effect in improving the binder performance. Rheological properties of binder play major roles in rutting, fatigue cracking, and low-temperature cracking resistance of hot mix asphalt (HMA) pavement. This study was conducted to investigate the effect of nanomaterials (NMs) on the rheological characteristics of asphalt binders. NMs, nanoclay, and nanoalumina, were mixed separately with performance grade (PG) 58-28 and 64-28 asphalt binder except the control where NM content was 0%. NMs contents were 1, 5, and 7% by binder weight. Rolling thin film oven (RTFO) and pressure aging vessel (PAV) were used to simulate short-term and long-term aging, respectively. Asphalt specimens (un-aged, RTFO-aged, and PAV-aged from each binder) were tested using dynamic shear rheometer (DSR) to determine and compare the viscoelastic behavior of the asphalt binders at different temperatures. Considering the effect of NMs on the un-aged, RTFO-aged, and PAV-aged binders make this study somewhat unique. The results showed NMs improved the rutting resistance of the binders. Nanoclay is more effective than nanoalumina in increasing rutting resistance. Addition of NMs resulted in an increase in the stiffness of the binders. For higher NMs content, the binder’s high temperature grade could increase by one or more grade.

The purpose of this paper is to determine significant design factors leading to the progression of longitudinal cracking in jointed plain concrete pavements (JPCP) that may be considered in changing design standards and policies. The evaluation involved 1,008 segments averaging 1.14 miles in length. The analysis revealed that approximately 60% of the segments exhibited longitudinal cracking while 40% did not. Approximately 56% of 14 ft. wide panels and 84% of 15 ft. wide panels experienced longitudinal cracking, compared to 81% for 12 ft. and 100% of 13 ft. wide panels. A majority of longitudinal cracking across all panel widths was between wheel paths or in the right wheel path. Significant factors explaining the length and/or severity of longitudinal cracking included width-to-thickness ratio, joint spacing, transverse joint orientation, and base gradation. A 1-in thickness increase from 9 in (w/t=1.6) to 10 in (w/t=1.4) reduced both the number of cracks by 25% and the average cracking length within a pavement segment by 45%.

Temperature variations over the last two decades coupled with increased traffic loads, have escalated the rate of defects in bituminous pavements. Trinidad and Tobago generally utilises flexible pavements with bituminous surface layers. Trinidad lake asphalt (TLA) is natural bitumen which can produce a binder material with high resistance. Polymer modified bitumen displays performance benefits for flexible pavements. In this study, conventional 60–70 refinery bitumen has been modified with varying percentages of TLA and rubber latex polymer (RLP). Several binder properties were investigated such as penetration and specific gravity. The rheological response of the modified and unmodified binder blends after short-term ageing was evaluated. Comparative analysis of the results from the dynamic shear rheometer (DSR) indicate greater performance benefits for the polymer modified blends for the test temperature range of 40–50 °C.

Impact hammer compaction has been the most prevalent laboratory method for compaction of granular materials. Factors such as high variability of strength test results and presence of layer interface barrier between lifts can be limiting factors in this compaction technique. This paper studies the potential benefits and effects of using Superpave gyratory compactor on the engineering properties of the unbound base materials. An experimental program was conducted to compare the impact hammer and Superpave gyratory compaction. Unconfined strength tests along with the permanent deformation tests were conducted on the specimens prepared with both the impact hammer and gyratory compactor. Moisture-dry density curves were also obtained for both compaction methods. Results were compared between the specimens made with these two compaction methods using statistical analyses. Results indicate that samples compacted with the gyratory compactor show higher precision in the strength test than the impact hammer. Data show that gyratory compaction results in different engineering properties than those obtained from the impact hammer compaction. Gyratory compaction is a different mechanism of compaction from the impact hammer compaction.

With the availability of historical pavement performance original data and pavement maintenance records in the pavement management system (PMS), it is of great importance to investigate the pavement performance and effectiveness evaluation of different maintenance treatments. Multiple linear regression analysis method was applied to analyze the influence of factors including traffic level, different asphalt mixtures on pavement roughness, rut, pavement damage, and pavement skidding resistance performance. Besides, many new evaluation indexes which differ from national standards in China were applied to evaluate pavement performance. In addition, based on the rutting, roughness, and side-way force coefficient, effectiveness of three different maintenance treatments (ECA overlay, hot in-place recycling, and micro-surfacing) were analyzed. The results show that: ECA overlay treatment has good effect on highway asphalt pavement rutting condition with different traffic levels and different surface types; The effect of hot in-place recycling measure on road sections with poor initial skid resistance is relatively limited; micro-surfacing treatment is restricted in maintaining rutting and anti-sliding performance under heavy, very heavy traffic conditions of highway asphalt pavement, its long-term effect is not ideal too. Therefore, the appropriate maintenance treatments should be taken to achieve greater maintenance benefits.

The morphological characteristics of aggregates have significant impact on the permanent deformation of asphalt mixtures. Various types of asphalt mixtures were selected in this study and all specimens of mixes were all fabricated by Superpave gyratory compactor. The highly precise images of mixes were acquired by scanning technique. The indices of aggregate geometric features including aggregate contact distance, length, orientation, etc. can be obtained from image processing. Through principal component analysis, the principle component Y₁ and Y₂ was used to represent the major impact of the aggregate geometric indicators. In addition, the P_d≤0.5mm, P_d≤1mm, and L_sum showed great correlation among the morphological indices. Flow number obtained from the results of dynamic creep test presented great correlation with the geometric features and the prediction model of anti-rutting behavior was determined.

Traditional measurement of pavement texture is either based on line-of-sight point laser or manual process. A new asphalt pavement texture depth measurement method is presented in the paper based on the laser 3D data, combining section method, and digital image processing technology. The 3D data of asphalt pavement were obtained by using LS-40 equipment scanning three types of rutting plates (asphalt concrete-13 (AC-13), stone mastic asphalt (SMA), open graded friction course (OGFC)). Based on the triangulation measurement principle, a three-dimensional mathematical model of laser vision is established. The design method of calculating asphalt pavement texture depth is adapted to measure texture depth on sub-mm resolution 3D surface of pavements, and the results of the method were compared with the sand-path method. The results show that the relative error between the numerical results obtained by this method and the sanding method is 0.11 mm.

Concrete requires a significant amount of virgin materials to manufacture. To conserve resources and lower construction costs, recycled concrete aggregate can be used as a construction material and replace the use of natural aggregate. However, compared to natural aggregate, there are inherent deficiencies in recycled concrete aggregate such as lower compressive strength, durability and density, higher water absorption, and a weaker aggregate-cement interfacial transition zone. For reutilization in concrete, the weak interfacial properties need to be improved without comprising overall cost of the concrete. In this paper, a recycled and low-cost sub-bituminous coal bottom ash is pulverized and reutilized as a supplementary cementitious material to increase the strength activity of the cement matrix and interfacial zones. The bottom ash is blended with a type I cement at 9% replacement and mixed using a three-stage protocol: (1) dispersing the ash in water-superplasticizer solution with a homogenizer, (2) partially mixing the bottom ash solution with the aggregate, and (3) mixing in the type I cement and remaining bottom ash solution. The concrete is cured and tested at 28 and 110 days. The result of the study indicates that the addition of the pulverized bottom ash can (1) increase the compressive strength of the recycled aggregate concrete by 16% relative to a control, and (2) dispersing the bottom ash within a water-superplasticizer solution can increase the compressive strength of the recycled aggregate concrete by 12%.

The modification of binder using poly-phosphoric acid (PPA) to improve high-temperature properties is not a new concept to asphalt industries. However, there are some concerns over the moisture-induced damage potential of asphalt pavements with PPA-modified binder. The present study was undertaken to explore the effect of PPA modification on the moisture-induced damage potential of an Oklahoma binder. A commercially available PPA was collected and blended with a PG 76-28 binder. The amount of PPA was kept constant at 1.5% by weight of the binder. The surface free energy (SFE) components and the chemical constituents of the binders were determined using dynamic wilhelmy plate (DWP) test and X-ray fluorescence (XRF) test, respectively. The bonding characteristics as well as the moisture-induced damage potential of the PPA-modified binder with a limestone aggregate were evaluated using the SFE technique. The PPA modification was found to increase the moisture-induced damage potential of the asphalt mix with limestone aggregate. In this study, an attempt has been made to explain the changes in SFE components using the results of elemental analysis from XRF test.