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Potholes are a common pavement distress, a nuisance to roadway users, and a maintenance problem for state and local agencies. Patching materials are typically cold mix asphalt (CMA), generic or proprietary, in winter seasons and, ideally, hot mix asphalt (HMA) in warm seasons. Although proprietary CMAs generally perform better than generic CMAs, winter repairs with any CMA are usually considered temporary until semi-permanent repairs can be made. However, re-repairing is cost-ineffective to the point the mantra “do it right the first time” has been adopted by some states and researchers. Induction heating has the potential to rapidly heat standard-size containers (e.g., 19 L) of inductive asphalt mixtures to hot mix temperatures (e.g., 150°C) in a matter of minutes (e.g., 5 min), which would allow patching to be conducted with high-quality materials even in winter when conventional HMA is unavailable. The objective of this paper is to investigate the feasibility of this concept. A laboratory investigation evaluated multiple steel aggregates for inclusion in the inductive HMA (iHMA) and designed an iHMA mix that was field-validated by patching simulated potholes. Containers of iHMA were successfully heated in cold weather (–11 to 0°C) to 160°C in 5 min with 15% steel aggregate by volume. During full-scale trafficking tests, iHMA patches exhibited comparable rutting characteristics to control HMA patches.

This study characterises the mechanical, rheological, induced heating, and induced healing behaviour of asphalt concrete containing steel wool fibers (SWFs) as the conductive constituent. Induced h...

A numerical framework is proposed to investigate the effect of steel particles on thermo-electromagnetic response of asphalt concrete aggregate blends. To investigate the effect of microstructural properties on induction heating, aggregates were blended with steel particle with various microstructural characteristics (e.g., size, shape, and geometry). Ampere’s, Maxwell-Faraday’s, Guess’s, Ohm’s and Joule’s laws were coupled to the Fourier’s and Newton’s laws to properly capture heat generation and transfer through conduction and convection mechanisms. Experimental studies were conducted by applying electromagnetic fields to aggregate blends containing inductive particles with different microstructural properties. Microstructural representation of the aggregate blends were reconstructed computationally based on the gradation and properties of aggregates and steel particles. Coupled thermo-electromagnetic simulations were conducted to investigate how microstructural properties of inductive particles affect the induction heating of the aggregate blend. Simulation results as compared to experimental measurements confirm the efficiency and accuracy of the coupled thermo-electromagnetic microstructural simulations. The results are used to determine the optimum design that yields the most efficient inductive aggregate blends.

Rutting is a major distress for asphalt pavements. This paper examines the relationship of laboratory- and field-compaction methods to rutting performance based on aggregate packing charact...

This study presents the rutting performance results of full-scale pavement test sections subjected to F-15E and C-17 aircraft wheels at two different temperatures. Pavement structures for the tests were constructed under shelter in the U.S. Army Engineer Research and Development Center's (ERDC) pavement test facility. The full-scale test results are used to validate viscoelastic, viscoplastic and hardening-relaxation constitutive relationships implemented in the Pavement Analysis Using Nonlinear Damage Approach (PANDA) model. PANDA is a mechanistic-based model which incorporates nonlinear viscoelastic, viscoplastic, hardening-relaxation, viscodamage, moisture-induced damage and ageing constitutive relationships. Results of dynamic modulus and different repeated creep-recovery laboratory tests are analysed to extract the parameters associated with viscoelastic, viscoplastic and hardening-relaxation constitutive relationships implemented in PANDA. Once calibrated, PANDA is used to predict the rutting perfor...

This paper presents an evaluation of the performance of grooved warm-mix asphalt (WMA) under heavy aircraft loading compared with that of grooved hot-mix asphalt (HMA). Runway surface grooving is often required to provide high skid resistance for aircraft braking, particularly in wet conditions where hydroplaning must be minimized. An area of potential concern with the use of WMA on the surface of airfield runway pavements is the material response to surface grooving. If the asphalt binder in WMA is softer than that of comparable HMA because of reduced binder aging during production and placement, the WMA mixture may be more likely to experience groove closure or collapse. This condition could result in hydroplaning issues because of the reduction in water discharge and also in chipping of aggregate from the groove edges, which could increase the potential for foreign object damage. A full-scale experiment was designed to evaluate two pavement curing conditions and three WMA mixtures. Traffic was applied to the pavements with an F-15 load cart, and testing occurred during the summer of 2013. The performance of WMA, measured as the percentage of groove closure, was compared with that of comparative HMA. It was concluded that WMA could perform as well as HMA under different pavement curing conditions. This result indicates that WMA runway surface pavement that is properly cured before grooving should not exhibit groove closure under normal aircraft traffic conditions.

In this study, the Asphalt Pavement Analyzer (APA) was investigated for its ability to detect asphalt paving mixtures designed for airfields that may be prone to rutting. The objective of t...

This study utilizes a computational-experimental method to determine the effective oxygen diffusivity of asphalt concrete based on diffusivities of its constituents, i.e., air void, aggrega...

Cold-applied asphalt mixtures are often used for pavement repair, primarily because of the small quantities involved and/or the unavailability of hot-mixed asphalt. These cold-applied mixtures have poorer rutting resistance than hot mix asphalt because additives, often solvent, are required to provide adequate workability for them to be placed at ambient tempera-tures. This study primarily evaluated the rutting performance of nine commercial cold mix asphalt repair materials. Both laboratory wheel tracking data and field rutting performance were used in the evaluation with the focus on identifying suitable materials for repairing airfield pavements subjected to high-tire-pressure aircraft traffic. The commercial products included traditional cutback cold mixes as well as water-activated repair materials. Results from both laboratory and field rutting measurements showed that the water-activated materials outperform the products containing solvent. However, none of the commercial products achieved the target threshold of less than 1 in. rutting after 100 passes of simulated F-15E aircraft traffic. The laboratory wheel-tracking measurements proved to be a good indicator of field performance.

The results from accelerated pavement testing on warm-mix asphalt (WMA) mixtures designed for airfield pavements are presented. Three WMA mixtures and one hot-mix asphalt (HMA) mixture produced in an asphalt plant were evaluated under simulated heavy aircraft traffic. The evaluation was conducted at extreme traffic conditions, including heavy aircraft loading, high tire pressure, and high pavement temperature. Pavement structural response and rutting were evaluated to assess the susceptibility to permanent deformation of WMA mixtures compared with that of HMA produced with the same aggregate blend. Test results indicated that WMA was a viable product for surface mixtures on airfield pavements.

This paper presents the results of tests of warm-mix asphalt (WMA) mixtures designed for airfield pavements. The study was conducted in two phases. The first phase included laboratory tests on 11 WMA technologies. The tests in Phase 2 were performed on three WMA mixtures and one hot-mix asphalt (HMA) mixture produced in an asphalt plant. The evaluation included performance tests to assess WMA susceptibility to permanent deformation and moisture damage compared with that of HMA produced with the same aggregate blend. Test results indicated that WMA potentially was a viable product for surface mixtures on airfield pavements. Although WMA exhibited poorer performance than HMA in moisture damage tests on laboratory-produced specimens, the plant-produced mix indicated little difference compared with HMA. Rutting potential for WMA was somewhat greater than for HMA for mixtures produced both in the laboratory and in an asphalt plant according to asphalt pavement analyzer and Hamburg wheel tracking tests. Differences in performance of WMA mixtures were not attributed to a specific WMA technology category. Variations in performance test results between laboratory-produced specimens and plant-produced specimens were noted and indicated a need to require performance testing as part of a comprehensive quality assurance plan.

Asphalt concrete pavements for commercial airport applications in the USA are constructed according to guidelines in Item P-401, ‘Plant Mix Bituminous Pavements’, Federal Aviation Administration (FAA) Advisory Circular 150/5370-10E. Item P-401 specifies the material characteristics and construction requirements for airport asphalt pavements, but does not currently provide guidance for using the Superpave gyratory compactor (SGC) in the preparation of specimens used in the design of hot mix asphalt (HMA) mixtures. Nearly all state departments of transportation in the USA use the SGC along with the Superpave mix design procedure. Since most HMA mixes are used in roadways, many asphalt contractors no longer maintain expertise and equipment for conducting the Marshall mix design procedure currently used by the FAA. The lack of contractors familiar with the Marshall method may become a significant problem for the FAA in the future. This paper describes a laboratory study of the HMA mix design for airport pavem...

Hot-mix asphalt (HMA) laboratory mix design is intended to determine the proportion of aggregate and binder that, when mixed and compacted under a specified effort, will withstand anticipated loading conditions. Current mix design procedures that use the Superpave® gyratory compactor rely on the engineering properties and volumetrics of the compacted mixture to ensure reliable performance; however, a definitive performance test does not exist. The asphalt pavement analyzer (APA) was evaluated as a tool for assessing HMA mixtures designed to perform under high tire pressure aircraft following FAA specifications. The APA used in this study was specially designed to test simulated high tire pressures of 250 psi, which are becoming more common for aircraft. Thirty-three HMA mixtures were included in the study. Each was designed with the Superpave gyratory compactor, according to preliminary criteria being developed by FAA. The study included some mixtures that contain excessive percentages of natural sand and that do not meet FAA criteria. These mixtures were included to provide relative performance for mixtures expected to exhibit premature rutting. APA testing with the high tire pressure APA resulted in rapid failure of HMA specimens compared with traditional APA testing at lower pressures. Data were analyzed, with a focus on the provision of acceptance recommendations for mixtures to support high tire pressures. A preliminary 10-mm rut depth criterion after 4,000 load cycles is recommended.

In their study, the authors focused "on the development and description of a dust generation device, measurement of dust generation through gravimetric and optical means, and the application of that device to evaluate the effectiveness of a range of commercial dust mitigation products." They noted that the generation of dust on unpaved roads and airfields has been a long-time concern, from both a safety and an environmental standpoint. An experimental testing protocol was developed to compare the relative effectiveness of chemical dust palliatives. The methods and application simulate field construction using commercial spray components. The test devices were constructed to simulate wind speeds and conditions for rotary wing aircraft. Fifteen chemical dust suppressants were evaluated using this methodology. These commercial products were applied topically to prepared soil specimens and allowed to cure for one and 48 h. Effectiveness was determined from the relative mass loss of the soil samples from erosion when samples were subjected to an air impingement device. An optical dust sensor was installed in the test device to measure airborne dust concentrations as an additional method for quantifying performance. A method to disturb the treated soil surface was also introduced to simulate the effect of traffic. Select application rates of the palliatives were used in sample preparation to identify minimal quantities necessary for the desired performance. The testing equipment and processes provided a rapid screening methodology for selecting potential dust palliatives. Results indicated good correlation between erosion and airborne dust concentrations with higher application rates and complete curing of materials demonstrating reduced dust levels. The traffic simulation test identified products with a propensity to form surface crusts that may be disturbed by traffic.

Two commercially available chemical dust palliatives were evaluated in full-scale experiments in an enclosed, controlled environment to evaluate their effectiveness and to determine impacts to a stabilized surface. The dust palliatives were topically applied at multiple application rates to the surface of a silty sand soil that had been stabilized using a combination of Portland cement and polypropylene monofilament fibers. Simulated traffic was applied to enclosed test sections using the heavy vehicle simulator-aircraft fitted with a C-17 aircraft tire at 15,560 kg (34,300 lb) load. The effectiveness of the dust palliatives was quantitatively measured using both gravimetric and optical detection devices. Results from the experiment show nearly complete reduction in dust for Palliative 2 (a synthetic oil) and heavy applications of Palliative 1 (an emulsion polymer). The methodology used for experimentally determining the dust palliative effectiveness provided a mechanism for reducing environmental influences that often invalidate and confuse the results of field experimentation data.

Because of the high cost of quality construction materials, transportation engineers are often forced to seek alternative designs using substandard materials, commercial construction aids, alternative pavement materials, and innovative design practices. Nontraditional soil stabilization additives are being marketed as viable solutions for stabilizing marginal materials as a low-cost alternative to traditional construction materials. Nontraditional additives are diverse in their composition and the way they interact with soil. Unfortunately, little is known about their interaction with geotechnical materials and their fundamental stabilization mechanisms. The objective of this research was to advance current understanding of the chemical and physical bonding mechanisms associated with selected non-traditional stabilizers. The research consisted of conducting qualitative analyses of hypothesized stabilization mechanisms, examining historical literature for supporting documentation, and performing laboratory experiments to improve the understanding of how these nontraditional additives stabilize soils. Laboratory experiments included image analyses, physical characterization, and chemical analyses to determine the primary constituents of the mineral, soil, stabilizer, and stabilized soil composite. The focus of this effort was to provide insight into the proposed mechanisms by using the laboratory data to examine proposed mechanisms from the historical literature and to provide additional hypotheses for the interaction between nontraditional additives and different soil types.

An evaluation of commercial and experimental dust palliatives was conducted to determine their effectiveness for mitigating fugitive dust on roads in arid climates. Several types of chemicals were tested including polymer emulsions, lignosulfonates, chloride salts, synthetic fluids, an asphalt emulsion, a polysaccharide solution, a polyacrylamide, and a guar gum. Each product was placed in an individual test section at a rate of 3.8 L∕ m2 using an admix construction method (grade/spray/till/compact/spray). Fourteen test sections were constructed and observed at 30-day intervals to monitor product performance. Data from both stationary and mobile particle collectors were analyzed to determine the ability of each product to suppress dust for extended periods. Several products are recommended for use on roads in arid climates as a result of this evaluation.

A performance test, rather than an empirical test, to evaluate rutting susceptibility is needed to accompany current volumetric property requirements of airport hot mix asphalt (HMA) designed using a superpave gyratory compactor. The new performance test will provide a level of confidence that pavement constructed using a selected HMA mixture will function according to its design. This paper presents results from a laboratory study to identify a performance test for accepting hot asphalt mixtures for constructing airport pavements designed for high tire pressure traffic. Performance tests intended to indicate rutting susceptibility were performed on 34 HMA mixtures. Twenty-nine of these mixtures met all aggregate and volumetric property requirements for airport pavement construction; the remaining five mixtures were designed with excessive percentage of natural sand (30%) as rut-susceptible mixtures. Results from asphalt pavement analyzer (APA), triaxial static creep, and triaxial repeated load tests are presented. Statistical analyses performed on the results indicate that the rate of increase in permanent strain and the flow time value determined from triaxial static creep testing provide the strongest correlation to APA simulated traffic rutting.

The Asphalt Pavement Analyzer (APA) is a laboratory accelerated pavement test device that has been used by many researchers and agencies as a tool to assess rutting potential of asphalt mixtures. Typically, the test is performed on cylindrical or beam specimens using a vertical load of 445 N, a hose inflation pressure of 690 kPa, and a test temperature equal to the high binder performance grade (PG) temperature. A simulated wheel load is repetitively applied to test specimens, typically for 8,000 cycles, and the rut depth is measured as a function of load cycles. This study evaluated the sensitivity of the APA to specimen preparation procedures (e.g., mixing, compaction, and volumetrics) and test parameters (e.g., temperature, wheel load, and hose pressure). Results from the study indicate several parameters can have an important impact on APA performance. These influences become important considerations when using the APA as a design or performance assessment tool.

This report presents results from full-scale accelerated pavement testing of warm-mix asphalt (WMA) mixtures designed for airfield pavements. Three WMA mixtures were evaluated and compared to a control hot-mix asphalt (HMA) mixture. Data are presented from instrumented pavement test sections of WMA and HMA trafficked using a heavy-vehicle simulator (HVS-A) configured with an F-15E military jet aircraft wheel with a high load, high tire pressure and at high pavement temperatures. Surface permanent deformation is presented as a function of number of traffic cycles for the different pavement sections. Pavement instrumentation data are presented to show that rutting performance was not influenced by any differences in the structural capacity of the supporting layers. Additional testing was conducted on areas of the test sections not trafficked by the HVS-A to assess any potential problems associated with grooving the surface of WMA airfield pavements and to compare the performance of grooved WMA to that of grooved HMA. The results from this research demonstrated that WMA is a viable alternative to HMA for use on heavily trafficked airfield pavements.

Warm mix asphalt (WMA) technology is steadily gaining popularity due to the environmental, energy, and cost savings it offers as a sustainable alternative to conventional hot mix asphalt (HMA). However, adoption of WMA for commercial and military airfield pavements has been slow due to lack of documented good performance on airfields and concerns about potential rutting problems. This paper presents testing results for 11 WMA technologies, compared with traditional HMA. One unmodified base binder and one aggregate gradation were utilized throughout. Both laboratory full-scale plant-produced materials are tested. Binder performance grade (PG) data and Asphalt Pavement Analyzer (APA) mixture rutting data are presented. Relationships between laboratory and plant produced binder data and APA rutting are explored. The overall conclusion is that WMA is a viable alternative to HMA to improve the sustainability of airfield pavements.

The U.S. Army Engineer Research and Development Center recently began a research project to evaluate pavement preservation techniques for asphalt pavements on Army airfields. Three field sites were selected for testing. Field sites represented the following climatic regions: hot and wet, hot and dry, and cold. Each of the test sites was on a taxiway or parking apron pavement on an Army airfield. Commercially available products marketed for pavement preservation were placed at each site. Existing pavements were in good condition, and all exhibited only minor longitudinal or transverse cracking and limited weathering. Preliminary data were collected by evaluating pavement surface properties and by extracting pavement cores prior to placement of the surface treatment. Additional tests were performed after product placement. Annual evaluations will provide comparable data to quantify the benefit of the treatment based on its ability to reduce environmental distresses. This report provides information on the products placed at each site as well as pavement conditions before product placement.

The U.S. Army and Marine Corps initiated a search for chemical dust palliatives for mitigating dust on helipads. The purpose of this investigation was to evaluate the effectiveness of current technologies for suppressing dust caused by rotor wash during helicopter landings. The study used an air impingement device to simulate wind speeds similar to field conditions. Chemical dust suppressants were applied topically to prepared soil specimens and allowed to cure for 1 and 48 hr. Effectiveness was determined from the relative weight loss of the soil samples from erosion during the test procedure. An optical sensor was installed in the test device to provide an additional method for quantifying performance.

The ERDC was tasked by the U.S. Marine Corps Systems Command to develop expedient dust control systems for helipads for use in constructing and maintaining Forward Area Arming and Refueling Points. The project consisted of evaluating various chemical dust palliatives and application procedures during field tests. The products of this effort include equipment recommendations, palliative recommendations, and complete application guidance. Fifteen helipads were constructed at Marine Corps Air Station, Yuma, AZ, using commercial palliatives for dust abatement. Each chemical was applied using a topical (spray-on) treatment. Each helipad was subjected to multiple landings of UH-1, CH-53, CH-46, and AH-1 rotary-wing aircraft. The chemicals were evaluated on their ability to control dust and prevent foreign object damage. Each evaluation consisted of dust particle collection and soil property measurements. Pertinent conclusions from the testing conducted are noted, and recommendations for selecting dust abatement methods and materials are provided.

The U.S. Army Engineer Research and development Center was tasked by the U.S. Marine Corps Systems Command to develop dust control systems for sustainment use on roads and other large-area applications in temperate climates as part of a comprehensive dust abatement program. The project consisted of evaluating various dust palliatives and application procedures during field tests. The products of this effort include equipment recommendations, palliative recommendations, and complete application guidance. This report addresses testing performed to evaluate commercial palliatives and application processes for constructing and maintaining lines-of-communication. Twenty-five test sections were constructed at Fort Leonard Wood, MO, using commercial palliatives for dust abatement. Several application procedures were evaluated in the process, including topical applications and admixture applications with alternate application rates. Each test section was evaluated at 0, 30, 80, and 220 days after construction. The evaluation consisted of dust particle collection and soil property measurements. Pertinent conclusions from the testing conducted are noted, and recommendations for selecting dust abatement methods and materials are provided.

Among the atmospheric properties that adversely affect laser propagation is air turbulence. One common optical parameter of air turbulence is the refractive index structure constant that quantifies the fluctuations in the refractive index caused by temperature fluctuations and hence air density fluctuations. There is a reason to believe, from theory and from sparse data that, when propagation occurs under widespread cloudy conditions, the refractive index structure constant is significantly reduced. Therefore the intensity of a propagating laser beam will not be degraded nearly as much as would be expected under clear or lightly scattered cloud conditions. New experimental data will be presented that support this hypothesis. The refractive index structure constant was measured for various cloud-cover conditions during daytime with additional factors present, such as changing crosswinds and precipitation. It was possible to observe the apparent pattern of the decrease of the refractive index structure constant by two orders of magnitude during the periods of increasing cloud-cover evaluated by the measurement of solar irradiance. The statistical correlation coefficient between the log of solar irradiance and the log of the refractive index structure constant was found to be around 0.9 (the closer it is to the maximum of 1.0, the stronger the correlation). The measurements were conducted with a commercial scintillometer/anemometer (1 m above ground, 500-m optical path length) in Northern Alabama in late spring and summer. The effect is believed to be due to the reduction of solar radiation, which caused the temperature gradient that initiated convection in the air. The results of this work can find their application in designing free space laser communication systems and military laser systems. Distribution A. Approved for public release; distribution unlimited. 1 Sep 04

The ERDC was tasked by the U.S. Marine Corps Systems Command to develop two dust control systems, one for expeditionary use on Forward Area Refueling Points (FARPs) and one for Sustainment use on roads and other large area applications. The project consisted of evaluating various dust palliatives and application equipment under controlled laboratory conditions and during field tests. The products of this effort include equipment recommendations, palliative recommendations, and complete application guidance. This report addresses testing performed to evaluate commercial palliatives and application processes for constructing and maintaining lines-of-communication. Twenty-four test sections were constructed at Douglas, AZ, using both experimental and commercial palliatives for dust abatement. Several application procedures were evaluated in the process as well. Each test section was evaluated at 0, 30, 60, and 90 days after construction. The evaluation consisted of dust particle collection and soil property measurements. Pertinent conclusions from the testing conducted are noted, and recommendations for selecting dust abatement methods and materials are provided.

One atmospheric phenomenon that adversely affects laser propagation is optical turbulence. From ten months of observation, the refractive index structure constant in the atmospheric boundary layer was found to be significantly reduced under widespread cloudy conditions. The refractive index structure constant (C(n) (2)) depends upon the turbulent flux of momentum, sensible and latent heat. The intensity of a propagating laser beam will not be degraded nearly as much as would be expected under clear or lightly scattered cloud conditions. New experimental data are presented that support this hypothesis. The refractive index structure constant was measured for various cloud-cover conditions.