Airfield and Highway Pavements 2015: Innovative and Cost-Effective Pavements for a Sustainable Future

Premature cracking of Superpave pavements with higher proportion of Reclaimed Asphalt Pavement (RAP) materials is a major concern in Kansas. This research was done to assess the suitability of the Semi-Circular Bending (SCB) test for evaluating cracking potential of Superpave mixture with high RAP content. Three sources of RAP and three RAP proportions (20%, 30% and 40%) were used in this study. Static and repetitive load SCB tests were conducted on samples compacted with the Superpave gyratory compactor. The peak load to cracking, time to crack initiation, and maximum strain in these tests were measured. The Analysis of Variance (ANOVA) was used to find out statistically whether cracking resistance of a certain mix varies with the RAP proportion used in the mix. ANOVA results showed that higher amount of RAP decreases cracking resistance of HMA mixes. RAP source is also an influencing factor in determining cracking resistance of HMA mixes with RAP.

With an increase in the price of asphalt binder, the asphalt paving industry has searched for its recycling resources. Recently, using tear-off asphalt roofing shingles in pavement systems have gained large amount of attention by transportation agencies. Beneficial use of tear-off shingle as road construction materials is an attractive option. In this laboratory study, in line with the Florida recycling regulation target, tear-off roofing shingles were used as additives in Hot-Mix Asphalt (HMA) ranged from 0% to 6% with 1% increment. Aged asphalt binder was extracted from the tear-off shingle and its physical properties were tested. Subsequently, mechanical characterization of the asphalt mixtures with respect to strength, moisture susceptibility, and rutting resistance at different RAS (Recycled Asphalt Shingle) ratios were evaluated. Lastly, the optimum mix design for the use of shingle in HMA has been established.

Warm mix asphalt (WMA) technology presents a wide potential to be successfully used in road works construction projects. Although its most salient advantage is to be environmental friendly, it has technical and economic assets. Another widely mentioned advantage of WMA technology is the opportunity to be used in the production of recycled mixtures (recycled or reclaimed asphalt pavement, RAP). This paper describes a laboratory effort that studied WMA mixtures with 20%-50% RAP contents using Marshall, resilient modulus, tensile strength ratio (TSR) and rutting tests. WMA and RAP samples were mixed using a chemical product which foamed asphalt. The chemical product was added to the asphalt binder AC 60-70 (PG 58-22) during the mixing process of the WMA-RAP. Using the additive, the mixing temperature of RAP mixtures can decrease 30°C, reaching similar volumetric composition with respect to traditional hot mix asphalt (HMA). WMA-RAP mixtures developed greater resistance to moisture damage as well as resistance to high temperature of service under monotonic and repeated loading in comparison with HMA control mixture.

Within the scope of this study, variants of titanium dioxide (TiO₂)-containing aggregates were produced and optimized in terms of their strength, polishing resistance, wearing resistance and the durability of the photocatalytic performance. The aggregates were spread on the asphalt pavement surface coated with epoxy resin in order to decompose the emitted nitric oxides (NO_x) in the exhaust gas of the vehicles as quickly and effectively as possible. From the results, it was ascertained that durable NO_x degradation can be achievable by using the TiO₂ in the spreading materials on asphalt road surface following the developed procedure. Thus, an important step of building environment-friendly road surfaces with NO_x degradation is taken.

There is a growing need to improve the performance properties of asphalt binders in order to minimize the occurrence of failure mechanisms such as permanent deformation, fatigue, adhesiveness and moisture damage. Nano-structured materials have taken a scientific-industrial boom as asphalt modifiers due to their mechanical, thermal and electrical properties, among others. The chemistry of the nano-material, and thus their inherent physical properties, ends up in each one having specific effects on the asphalt and variable blending forms depending on their nature. This paper evaluates the effect of the incorporation of nano-silica into a PG64-22 binder at various contents from 0.5% to 6.0%. Morphological, rheological and thermal analysis techniques were used to quantify the effect of asphalt binder modification. Such techniques were Differential Scanning Calorimetry (DSC), thermogravimetric (TGA) analysis, as well as Fourier transform infrared spectroscopy (FTIR) and Atomic Force Microscopy (AFM). Selection of the optimum modifier content was mainly based on DSR asphalt fatigue and rutting tests and work of adhesion analysis.

The sustainability of pavement projects can be improved by incorporating locally available materials. It has been shown that successful utilization of local materials is beneficial for the local economy, the environment, the contractor, and the owner. However, the use of innovative materials is often inhibited by current method-specifications. The objective of this research was to use performance-based testing and modern mix design tools to develop a special provision allowing for the use of oil sand in a bituminous pavement. Oil sand is a naturally occurring petroleum deposit comprised of heavy bitumen, sand, clay and water. The largest oil sand deposits, located in western Canada, are well known for crude oil production from oil sand. Oil sand is also available throughout the United States in smaller deposits where converting oil sand to crude oil is not feasible. In certain areas immediately surrounding oil sand deposits, contractors have been paving with oil sand asphalt mixtures for over a century; even though, modern mix-design methods have not been used to characterize these mixtures. To address this need and allow for contractors to use oil sand pavements on state funded jobs, a special provision was created for the Utah Department of Transportation utilizing oil sand from eastern Utah. The steps followed to create this provision were: oil sand characterization, volumetric-mix design, and laboratory testing. The oil sand was characterized by determining the bitumen content, the gradation, and temperature susceptibility. The mix design was created following a procedure similar to the method used to gap-graded hot mix asphalt. The special provision created from this research outlines the required oil sand characterization and laboratory testing that must be completed to design an oil sand asphalt pavement. Although this research concentrated on incorporating oil sand into bituminous mixtures, the methodology developed could be extended to provide a performance based testing framework to any innovative material.

Asphalt binder supplies are shrinking, while the demand for it is increasing rapidly; this in turn has led to an increase in the price of asphalt. As the price of asphalt binder increases, the demand for alternative and renewable binder resources increases. Therefore, this paper investigates the effects of introduction of four different bio-binders (made from Corn Stover, Miscanthus Pellet, Swine Manure, and Wood Pellet) on the aging susceptibility of asphalt as measured by the change in rheological and chemical properties of a selected asphalt binder (PG64-22) as a result of oxidative aging. The results of Rotational Viscometer (RV) and Dynamic Shear Rheometer (DSR) were used to evaluate the rheological behavior of the various bio-modified asphalt binders. Overall, the rheological characterization showed that bio-binder from Wood Pellets had the most desirable properties in unaged status among all bio-modified specimens. However, this trend was reversed after aging, indicating Pellets bio-binder has thehighest susceptibility to oxidative aging. In order to quantitatively measure and compare the extent of aging, the chemical composition of each sample was obtained using the FTIR spectra. Oxidative aging was demonstrated through tracking the formation of carbonyl and sulfoxide groups due to aging. The results showed that aging susceptibilities varied significantly depending on the source of the biomass. The experimental results indicates that bio-binder from Swine Manure was least susceptible to aging, followed by bio-binder made from Corn Stover, Miscanthus Pellets, and Wood Pellets.

In this study, two asphalt binders are blended with four particulate types; one natural filler and three Coal Combustion By-Products (CCPs), to make mastics at different concentrations. This initial study aims to evaluate the compatibility of different asphalt binders with these particulates in terms of damage and aging resistance. High and intermediate temperature testing is conducted while varying the aging level. Results show tha the particulates, at all concentrations, improve high temperature rutting resistance of mastics. At intermediate temperature, the results show significant dependency on particulate, binder and polymer modification types. In general, results show that CCP mastics with unmodified binders increase damage resistance at high temperature, with no determinate effect on aging related stiffness. For the polymer modified binder, Spray Dryer Absorber (SDA) appears to enhance its properties significantly as noticed by increase damage resistance, recovery, and significant retardation in aging related stiffness.

The process control for the hot-mix asphalt mixtures (HMA) by the Kansas Department of Transportation (KDOT) requires each lot of HMA be produced within ±0.6% of the design binder content. Recent reviews indicate that HMA lots are being produced consistently with lower binder contents. This situation has been exacerbated by the use of higher proportion of Reclaimed Asphalt Pavement (RAP) materials in the HMA mixtures. This project evaluated two moisture susceptibility test methods to assess the effect of asphalt content on the moisture resistance of HMA. Two different commonly used mixtures for overlaying and four varying asphalt contents, optimum and lower, were selected. The Hamburg Wheel Tracking Device (HWTD) test was used to predict moisture damage potential of these mixes. All specimens tested were prepared with the Superpave gyratory compacter. Results indicate that within the tested range, deformation decreases as the binder content decreases. This trend was verified by studying the correlation of the number of wheel passes with the asphalt binder film thickness.

Polymer-modified asphalt have been proven to improve mechanical characteristics of asphalt mixes, however there are concerns that mixes become drier and more difficult to compact. This study aims to develop compaction indices using routine laboratory compaction procedure to evaluate the workability and compactability of hot and warm mixes prior to laydown. Workability is reflected in the ease of blending while compactability is reflected in the mixes’ stability and resistance to densification. To quantify thresholds for the indices, laboratory and accelerated field testing were implemented. The workability index was tentatively found to be a minimum of 4.5 while the compactability indices were tentatively found to be a maximum of 0.5 and a minimum of 20. The compactability indices were capable of predicting mix resistance to permanent deformation.

This study aims to address the effect of filler materials (passing no. 200 sieve) on performance of hot mix asphalt mixtures. The Marshall mix design procedure was followed to prepare laboratory specimens using various types of filler materials to determine the optimum asphalt content. Furthermore, three different gradations with various amount of filler contents were selected to estimate the performance of asphalt mixture in laboratory conditions in terms of Marshall stability and flow. It was observed that more filler content, increases the plasticity of the mix and thus the permanent deformation. Moreover, adding the hydrated lime as filler improves the functional properties of the asphalt mixtures. A nonlinear genetic programming algorithm was developed to predict and formulize the Marshall stability results using material characteristics. The prediction power of the employed soft computing technique deemed satisfactory as compared to the experimental results.

In general, asphalt binder used in various paving applications needs to be heated and kept in a liquid state in order to achieve the good workability of a binder required for these applications. This study would examine the use of pelletized binders instead of those conventional binders in various pavement types. The pelletized binder materials are produced by first mixing virgin asphalt binder (e.g., PG 64-22) and various crumb rubber modifiers (CRM) together to produce the polymerized binders. After the reaction between the CRM and virgin binder has taken place, the hot binder is introduced into the pelletizing machine along with a stiffener (e.g., hydrated lime) to produce the pellets. Then, these pellets are cooled, and a coating is applied to prevent coagulation. The final binder matrix is polymerized asphalt (e.g., PG 76-22). The paper discusses major properties of pelletized mixtures used in many laboratory and field projects.

Moisture susceptibility of asphalt mixtures is a commonly addressed concern in mixture designs. As the industry shifts toward the use of warm mix asphalt (WMA) technology from the traditional hot mix asphalt (HMA) there has been increased concern regarding the performance of WMA technology in regards to moisture susceptibility. This concern is primarily driven by the decrease in required production temperatures of the asphalt mixtures which may result in aggregates that have not been dried thoroughly prior to being coated with asphalt binder. To assess this concern, 87 mixtures were evaluated for their resistance to moisture damage using the most common laboratory test for assessing such damage: AASHTO T 283. As a result of this study, it was determined that there was no statistical difference between field compacted specimens versus laboratory reheated specimens for tensile strength ratio (TSR). WMA consistently showed statistically lower TSR values compared to HMA control mixtures.

One of the effects of climate change is the drop in the extreme temperature during winter season. The impact that this phenomenon has on pavement performance is a concern, especially for the Hot Mix Asphalt (HMA) surface layers. The increasing use of sustainable techniques, like the addition of Reclaimed Asphalt Pavement (RAP), poses a challenge to enduring extremely low temperatures. This study examines the performance of typical Ontario Superpave surface course HMA to thermal cracking. Thermal Stress Restrained Specimen Tests (TSRST) and Disk-Shaped Compact Tension Tests (DC(T)) were conducted on six laboratory prepared hot mixtures with varying RAP contents and Asphalt Binder Performance Grade (PG). The results suggest that the Recycled Hot Mixtures (RHM) do not always withstand the expected critical temperatures, but they could exhibit a lower impact in fracture strength when the extreme low temperature drops by 6°C.

The motivation of this study is using plasma modification to significantly increase the performance of the hot mix asphalt. The surface of mineral filler was modified by using three different components: tungsten disulphide under peroxide (WS₂ – H₂O₂), tungsten disulphide under water (WS₂ – H₂O) and silicon dioxide (SiO₂) nano powders. Hot mix asphalts prepared with plasma modified mineral fillers were evaluated by Marshall Stability (MS) test. According to the results of modified SiO2 plasma samples were showed higher stabilities and better properties. Eco-friendly plasma modification technique provided homogenous, single step and fast processing for the modification of the asphalt materials.

This study evaluated the laboratory bond strength and moisture susceptibility of a nanotechnology (derived from organosilane) modified emulsion against a control CSS emulsion. This additive is designed to convert the surface of the treated material (untreated aggregate, soil, or HMA) from a water loving (hydrophilic) surface to a water repelling (hydrophobic) surface while providing equivalent bond strength compared to an unmodified emulsion with a higher residual AC content. Two-layer slabs were produced in the laboratory with the following variables: emulsion type, surface type (new HMA or milled), and application rate (three different rates). Cores were obtained from each slab to evaluate the effect of the critical variables using a monotonic shear bond strength test. The results of the bond strength evaluation showed the modified emulsion provided equivalent bond strength to a control emulsion with 3 times the residual AC content. Additionally, an experimental evaluation was conducted to assess the moisture susceptibility of the tack coat materials. Additional slabs were fabricated at the optimum application rate for each surface type and emulsion application. The AASHTO T283 procedure was utilized to condition these specimens with one or two freeze-thaw cycles prior to determining their bond strength. The results of this evaluation were mixed. The data suggested moisture damage was occurring in the new HMA surface specimens, but not in the specimens with a milled surface interface. For the new HMA specimens, the control and nanotechnology modified emulsions had equivalent resistance to moisture damage as freeze-thaw cycles were applied to the specimens.

One of the imperative components contributing to longevity and performance of asphalt concrete overlays is sufficient bond strength between the new overlay and existing surface. If the multi-layered asphalt pavement does not have ample bond strength to endure dynamic loads from traffic, surface distresses may develop. Surface distresses may occur in areas of, but not limited to, stopping, starting, and turning. These surface distresses are, but not limited to, de-bonding, delamination, slippage, or fatigue cracking. Therefore, the objective of this study was to develop a test method and testing device for measuring the bond strength between pavement layers. The research evaluated tack coat materials and HMA mix designs commonly used by West Virginia Division of Highways. The project was conducted in both laboratory and field. The effects of mix design, tack coat type, surface condition, and moisture damage were evaluated. Initial testing concluded that laboratory compaction using Superpave Gyratory Compactor affected bond strength. It was also found that the cut face which represents the worn surface and the new HMA face of the sample exhibit different bond strengths. Increased nominal maximum aggregate size of the mix design increased bond strength, but not a significant amount. Cut faced samples exhibited higher bond strength than milled samples on average. The bond strengths of samples with or without tack coat were not statistically different. For milled and cut faced samples, trackless tack coat was superior to a standard SS-1h emulsion. Set time from 0.25 to 2.0 hours, was statistically significant for both milled and cut faced samples. The difference in bond strength for moisture damage was statistically significant.

The effectiveness of a hot-mix asphalt (HMA) overlay is largely dependent on the quality of its bond to the existing surface. A good bond will evenly disperse traffic loads from one layer into the next, while a poor bond will concentrate stresses within relatively thin upper layer. This condition will expedite premature distresses like fatigue cracking, slippage cracking and delamination. All of these problems are then exacerbated by moisture accumulating at the bonded interface. Non-tracking tacks, recently introduced to the paving industry, bond asphalt layers together while avoiding the tracking problems under traffic associated with traditional tacks. While traditional tack has been well studied, these new products require further evaluation. Of particular concern is the loss of adhesion between exposed aggregate on the existing road and asphalt binder. The objectives of this study were to characterize existing non-tracking products, and measure the bonding potential of different types of aggregate from a chemo-mechanical perspective. For this purpose, the rheological properties of the emulsion residues and base binder of five non-tracking tacks and one conventional tack were characterized. The bonding potential between the tack and different aggregate substrates was measured with a pneumatic adhesion tester. The results show significant differences in bond strength of aggregates with rough surface and the control binder or emulsion residue at different testing temperatures. The control binder and emulsion residue at different testing temperatures were also found to develop different bond strength with any given aggregate. The results show that the control binder and emulsion residue have different degrees of sensitivity to aggregate type in terms of their bond strength.

Non-tracking tacks, recently introduced to the paving industry, bond pavement layers while avoiding the tracking problems associated with traditional tacks. Initially, there was only one supplier of non-tracking tack in Texas, but now multiple producers are bringing products to the market. Performance to date has been good, but there are no established methods to test tackiness/tracking resistance of current and new products. The objective of this research, therefore, was to develop and assess three tests for measuring tracking resistance: the modified no-pick-up time test, the TTI sand adhesion test, and the modified DSR tackiness test. These methods were evaluated on four tack materials, three curing temperatures, and at 10-minute curing time intervals. The results from the modified no-pick-up time test were clearly influenced by curing time and curing temperature. The TTI sand adhesion test could discern among different tack materials. Track free time may be defined as less than 2 g of sand adhesion. The modified DSR tackiness test showed measurable differences among the tack types and different temperatures and times. Of these test methods, the researchers recommend adoption of the modified no-pick-up time test for routine tracking resistance testing. “Track-free time” should be defined as less than 10% tracking in 40°C curing. Testing of this and other tests should continue, especially with other conventional and non-tracking tacks.

The necessity for cost-effective and more sustainable replacements for virgin paving materials is becoming more pressing in recent years especially with the asphalt binder and aggregate economics and obligations for using greener alternatives. Hot in-place recycling (HIR) is a process that preserves or maintains distressed asphalt pavements while minimizing the use of virgin binder and aggregates. The final quality of HIR mixture depends on the characteristics of the original binder, aging during service, and new binder or the asphalt rejuvenating agent (ARA) added. While the recycling process will make the existing asphalt binder age even further, HIR mixture should maintain desired properties for another service period. Aged asphalt binder modifications are done by adding an ARA in the HIR process. However, there is a concern that ARA may adversely affect the qualities of new HIR pavement especially the rutting and creep performance since the ARA is known to soften the binder. In this study the effects of adding ARA were investigated on samples obtained from three HIR projects in Kansas. The HIR mixture performance in rutting and creep, with and without ARA, was studied by conducting flow number tests.

Current management practice, existing regulations, and environmental consequences of municipal solid waste incineration (MSWI) ash utilization were comprehensively reviewed. Efforts were made to physically and mechanically characterize MSWI bottom and fly ashes and also to evaluate their influence on the structural properties of Portland cement concrete (PCC) and hot-mix asphalt (HMA) when part of fine aggregate is replaced with the MSWI bottom ash. Fundamental properties of MSWI bottom ash and fly ash were studied by conducting physical, microstructural, and chemical tests. Concrete cylinders were cast with various amounts of ash additions and their strength and durability were investigated as the replacement ratio of ash increases. The MSWI bottom ash was also used to replace fine aggregate in HMA. Varying proportions of bottom ash and fine aggregate were tried in an effort to determine the optimum ratio of bottom ash to fine aggregate, as determined by performance tests such as the Marshall Stability and Flow test and the moisture susceptibility test.

Infrared thermography technologies are rapidly developing for thermal measurement and control of hot mix asphalt (HMA) pavement and airfield construction. Two technologies currently used and/or specified include hand-held thermal imaging cameras for discrete measurement and paver-mounted temperature sensors for continuous measurement. A field evaluation of these new technologies was conducted on three asphalt paving projects by collecting thermal readings in the truck box, paver hopper, and behind the paver screed. Analysis of the field data concluded these technologies are capable of detecting HMA temperature variability during construction that can lead to process adjustments and other quality control actions. The HMA temperature ranged from 100°F to 160°F in the truck box, while material behind the screed ranged from 8°F to 53°F. The HMA temperature standard deviation behind the paver was reduced from 9.4°F to 5.5°F when a material transfer vehicle (MTV) was included in the paving operation. When a pass/fail criteria is set at a range of 25°F in a transverse section behind the screed, locations having a material transfer vehicle (MTV) are able to pass this requirement in 10 of 11 tests, while not having an MTV failed this requirement in 4 of 4 tests.

Fundamental purpose any of construction specification is to ensure the expected long-term performance of the final product. Performance Related Specification (PRS) incorporates the economic implications associated with superior or inferior pavement construction practices since it translates to extended or reduced pavement service life. Generally, earlier PRS development studies were based on performance data collected from either pilot pavement construction projects or the models built based on experimental pavement sections such as MEPDG. This study primarily focuses on constructing PRS framework utilizing field performance data and actual quality control measurements obtained during road construction projects. Laboratory density of plant-mix and placement density of compacted hot mix pavement and as-constructed ride quality of both hot mix and concrete pavements are identified as performance-sensitive parameters. A performance related pay adjustment scheme that is governed by these performance-sensitive quality control parameters is developed.

The objective of this case study was to document an unanticipated pavement failure, the subsequent identification of the failure mechanism, the rapid redesign, and successful reconstruction of an experimental section containing higher-than-normal amounts of reclaimed asphalt pavement at the National Center for Asphalt Technology Test Track. The failure mechanism was identified as debonding between the base and intermediate asphalt concrete lifts, which led to middle-up cracking. Although the section was designed to develop distresses within the two years of trafficking, with the intent to evaluate the entire pavement structure, layer interface debonding inhibited that goal. A laboratory tack coat study was promptly conducted to determine the optimal amount of tack necessary to provide a bond between layers that would withstand the accelerated loading applied at the Test Track. Multiple corrective actions were taken during reconstruction to ensure that this premature failure would not recur. The tack coat application rate was doubled and the mix temperature of the intermediate lift was increased. Since reconstruction, performance evaluations that included falling weight deflectometer testing, instrumented pavement responses and surface distress monitoring have indicated that the section is performing well. This paper compiles the performance evaluations (original and reconstructed), with laboratory testing, and construction quality control results to disseminate the lessons learned.

Inertial-based roadway longitudinal profiling technology has been widely used since the 1990s in the US for providing a key benchmark on road surface ride quality. For the traditional profilers, point laser rangers or Roline sensors are widely employed to measure the height data between the vehicle body and the pavement. In this paper, a profiler system was designed and implemented to combine pavement height information from a new generation of 3D sensors and the vehicle’s vertical displacement information to yield longitudinal profiles of the pavement. The advantage of the 3D sensor is that it can collect the height information of the complete pavement lane which can provide pavement engineers the complete roadway profiles at any line of sight. Analytical results show that the profiler system is able to provide repeatable profile data and reasonable IRI results. Further development of the presented system is on-going.

In order to best prioritize road maintenance, the level of deterioration must be known for all roads in the network. International Roughness Index (IRI) is a key standardized and widely used parameter to quantify road roughness and to aid officials in making road maintenance decisions. A low IRI value indicates smooth road and a high value indicates road has distresses such as severe cracking, potholes, and rutting, etc. IRI measurement using laser profilometers with accelerometers mounted on the front or rear bumper of a vehicle along the wheel path is commonly used at a driving speed of above 40 mph. IRI values measured through laser are questionable below this speed and will not work when road is wet. This paper discusses an alternative method to estimate IRI using a dynamic tire pressure sensor (DTPS) inside the tire as vehicle is moving. This method is working at a speed of above 15 MPH suitable for both interstate highways as well as urban roadways which required a driving speed of below 40 MPH. It works at all weather conditions since the measurement is the tire pressure change inside the tire through road and tire interaction. A feasibility and repeatability test on highway and airport through a certification test which was administered by Massachusetts Department of Transportation is therefore reported. The accuracy is equivalent to laser based IRI values.

The comparison of macrotexture values estimated from different measuring techniques, usually provides poor agreement and unsatisfactory confidence on the real macrotexture estimates by means of the Mean Texture Depth (MTD) Index. For this reason a new algorithm, to evaluate a more reliable 3D macrotexture index evaluated directly from 2D profile, has been proposed. This algorithm includes a profile data cleaning process, developed to detect and remove invalid laser readings present on pavement profile data recorded by means of a high speed laser device (HSLD). Preliminary results obtained on pavements of Virginia Smart Road seem promising.

The evolution of the skid resistance of asphalt road surfaces was simulated in a laboratory. Asphalt plates were taken from a test track. They were polished using the self-developed Aachen Polishing Machine with real tires under various conditions followed by the measurement of their skid resistances using the Wehner/Schulze machine. The differences between summer and winter with regard to water and the dust composition were simulated and their influence on the skid resistance was analyzed. The process of removing the binder, polishing the aggregate and a periodical fluctuation of the skid resistance can be accurately described by a skid resistance prediction model. One could conclude that for the asphalt samples the change of the polishing conditions entailed a fluctuation of the skid resistance coefficient between two final states.

The impact of pavement texture on bicycle ride quality has not been explored and fully understood. This paper summarizes the results of measurements of texture on a set of California Department of Transportation (Caltrans) and local government pavement surface treatments with different measurement methods. The results with a survey of bicycle ride quality on most of those sections are also presented. Correlations between MPD, IRI, bicycle vibration, and bicyclists’ perception of ride quality and pavement acceptability for use by bicycles are developed. The effect of traffic on the pavement texture and the effect of remedial treatment on rough surface are also evaluated. This study will help Caltrans Districts and other state DOTs to continue using the cost-effective surface treatments to preserve their pavements while maintaining a bicycle-friendly surface.

This paper presents the technical guidance released in 2014 by the STAC (Service Technique de l’Aviation Civile : French Civil Aviation Technical Center), relative to Flexible Airfield Pavement Assessment using Heavy Weight Deflectometer (HWD) which aims at providing all airport technical managers with a methodology for pavement testing using HWD. It gathers recommendations relative to operational survey and data analysis, based on an advanced dynamic modeling which overcomes the limitations encountered with the usual static analysis methods. The operational recommendations include all information about airport platform survey and the carrying out of the tests whereas the recommendations relative to the data analysis gather the description of the mechanical modeling and its parameters, as well as the one of the associated backcalculation process developed. All parts of the guide have been validated, numerically or using in-situ measurements. The last part of the document is dedicated to illustrations through real case studies. This paper describes the content of this guide and particularly points out the new main developments compared with usual HWD test protocols and analysis methods.

This paper describes the design, construction, and verification testing of a mass stabilization project in south Florida as part of a taxiway and apron expansion for Marco Island Executive Airport. Resulting from a preconstruction value engineering analysis by the geotechnical specialty contractor, Dry Mass Stabilization (DMS) was used to support new taxiway and apron structures on coastal marsh soils. The soil profile included a thick stratum of very weak and wet peat and organic silt extending to a maximum depth of 6.1 m (20 feet) below the existing ground surface. Left untreated, this material would have resulted in excessive total and differential settlement of the new pavement systems. During a preconstruction site visit, such distress was observed on the existing taxiway in the form of undulating pavement surface and deep ponding of rainwater. Conventional soil replacement and deep foundation solutions were considered, but ultimately rejected due to their significant technical challenges and high costs associated with these options concerning this particular project. Instead, the specialty geotechnical contractor improved the existing subgrade soils using DMS, a dry soil mixing technique. The DMS program increased the shear strength and stiffness of the treated soil, creating a stable mass suitable for long-term support of the new pavement systems. Performance was verified using in-situ shear strength measurements and settlement monitoring of several test embankment sections during construction.

As part of the Capital Improvement Program at Tulsa International Airport, reconstruction of the runways 18-36 and 8-26 intersection was conducted to address Foreign Object Debris (FOD) caused by D-cracking deterioration of the concrete in the form of joint and corner spalling and popouts. Detailed planning and design for the reconstruction of the intersection was conducted to meet the Airport’s requirements of having at least one runway open for passenger and cargo traffic during weekdays. To limit interruptions to traffic operations, reconstruction of the runway intersection was conducted over weekend closures with limited night week closures for minor work. The concrete pavement was constructed with dowels but it was designed assuming no load transfer at the joints to provide a conservative approach. The approach allowed using the existing non-stabilized aggregate base since stabilized bases are required under rigid pavements serving aircraft weighing 100,000 lbs or more. To limit damage of the existing aggregate base/clayey subgrade system the slabs were to be removed by the lift method only. The design required removing the existing 25 foot concrete slabs and replacing them with 18.75 foot by 20 foot concrete slabs at a slightly different grade than existing. To accomplish this and to minimize the number of weekend closures, the new concrete was to be placed in 37.5 foot paving lanes with a saw cut in the middle. This required careful considerations during demolition since the runway intersection was to be operational during weekdays. The contractor paved 38.5 foot lanes to provide grade transition to existing. The transition portion was saw cut during removal of the adjacent lane. The design also required the use of conventional concrete mixes with dense graded aggregates mixes to attain a flexural strength of 550 psi after 24 hours and 650 psi at 28 days. This was accomplished by using dense graded aggregates, and 7.5 sacks of cementitious material which included 25% fly ash replacement. The proposed mixture was considered adequate for the cold to moderate air temperatures expected during construction. Construction details included measures for avoiding sympathy cracking, thermo-cracking impact due to temperature variations, transitions from existing to new grades, requirements for back-up equipment, etc.

Runway 10L-28R is the main runway at the Niagara Falls International Airport (NFIA) and is critical to the operation of the airport due to the airport’s use by the New York State (NYS) Air National Guard, the United States Air Force (USAF) Reserves, and the recent re-entry of scheduled commercial air carrier operations. A January, 2011 technical pavement assessment indicated that the runway had less than 5 years of structural and functional remaining life due to sections being deficient of thickness and various surface distresses witnessed. The distresses included but were not limited to: reflective cracking, spalling, and surface raveling of the asphalt concrete (AC) surfaced Portland cement concrete (PCC) or asphalt on concrete (APC) pavements. The deficient AC surface material was defined as the primary cause of the excessive foreign object debris (FOD) found on the runway and was generally caused by aggregates raveling out of the surface. Other pavement issues included non-standard longitudinal profiles and cross-section slopes changing from a center crowned section to a continuous cross fall from one side to the other. The airport also required the installation of a centerline and Touchdown Zone Lighting System (28R end) per a recent Master Plan Study. This paper will discuss the rehabilitation strategies considered, cost analysis findings, the decision process for utilizing sustainable methods such as rubblization and the use of milled/recycled asphalt as a P-209 leveling base course, the construction test results, and a follow-up evaluation of the pavements to review their performance after two full winter seasons.

As part of the airport expansion program at Fort Lauderdale International Airport, Broward County selected a team to replace the old runway and design a new south runway and associated taxiways. The runway and the parallel Taxiway J extend over the existing Florida East Coast Railway and US Route 1 by using an earth embankment and an elevated bridge structure. During construction, Fort Lauderdale International Airport was the busiest airport in the country operating with a single runway. The earth embankment was a major challenge due to the expected vertical and horizontal displacements. An extensive geotechnical investigation was conducted to define the characteristics of the subsurface stratums. The P-152 earthwork and other associated specifications were modified to minimize the primary settlement in the embankment to allow for the construction of the new pavement within a reasonable timeframe. The secondary settlement was monitored to promptly address any issues that could affect the integrity of the new airfield pavement. The life-cycle cost and settlement analyses indicated that under a controlled embankment construction and surcharge process, a portland cement concrete pavement was advantageous over an asphalt pavement. The transition slabs to the approach slabs were reinforced and dowelled so that they could be slabjacked if significant differential settlement is obtained between the embankment and the bridge structure. Due to the extensive area of concrete pavement to be constructed, it was decided to modify the P-501 specification by requiring slip form paving with a dedicated on-site batch plant. The mixture required dense graded aggregate mixtures, and other material requirements to improve the quality of the end product. Construction of the concrete pavement was a learning curve since concrete pavement construction of this magnitude and process was a first to South Florida. This paper summarizes key design elements affecting the construction and long term performance of the airfield pavements.

The new French rational procedure for flexible airfield pavement design was recently released (2014). This method includes the consideration of a phenomenon observed in aviation that is aircraft lateral wander, corresponding to the lateral offset of aircraft from the centerline of the pavement. Little data are available regarding the characterization of this parameter, especially on runways for take-offs. However, it is important to know it since its effect on flexible pavement design calculations is impactful. That is why the French Civil Aviation Technical Center decided to launch an experimental program aiming at characterizing lateral wander with the use of optical strain sensors embedded in the runway pavement. For each aircraft, a transverse profile (i.e. perpendicular to the runway centerline) of the strain basin is recorded and the landing gear position can thus be determined. Data processing is performed by correlating several databases: optical sensors database, aircraft traffic data provided by the air navigation services (essential for aircraft identification), and geometrical landing gear data from the French Civil Aviation’s “FICAV” database. An automated routine was developed to process the data quickly, which is necessary since the amount of data may be substantial. This paper describes the experimental setup as well as the methodology implemented for data analysis. After enough data is collected, refinement of the lateral wander parameter of the design procedure will be considered.

A method and the corresponding indexes based on laboratory test were proposed for evaluating the performance of strain gauges used in asphalt pavement. Two types of strain gauges were used to develop the method and the indexes. Firstly the life cycle performance of asphalt strain gauges was divided into three different stages: construction stage, pre-cracked stage and cracked stage. Then six evaluation indexes were proposed for evaluating the comprehensive performance of the asphalt strain gauges in these three stages. The “collaborative deformation characteristic” and long-term performance were emphasizedly explored. Two different types of strain gauges were then embedded into asphalt mixture beams and evaluated by these indexes. Results show that the performance of different strain gauges can be clearly characterized and differentiated through the evaluation indexes and methods proposed. The findings provide useful insights on selecting proper strain gauges for asphalt pavement.

Concrete pavement rehabilitation due to joint-related flaws at young-age is a usual procedure on highways, airports, and urban corridors in Brazil. As a more sustainable (in terms of longevity) alternative to jointed plain concrete pavements, a continuously reinforced concrete pavement (CRCP) was constructed in São Paulo. The length of the four sections was 50 meter each, short in contrast with traditional CRCP. Due to the lack of anchorage at the slabs end, the short CRCP cracking behavior was very different from traditional CRCP. This paper presents the updated crack map and the results of a dynamic load testing. The tests were conducted with a loaded truck at constant speeds of 10 km/h and 50 km/h, as well as during braking. Results pointed out that increasing the average speed does not affect the stresses values; however, it was observed that the braking action increases the stresses caused by the front axle and the opposite effect was recorded concerning the rear axle.

Roller Compacted Concrete (RCC) is an economical and durable candidate for many pavement applications. Properly designed RCC mixes can achieve outstanding compressive strengths similar to those of conventional concrete. The objective of this study was to evaluate the structural performance and load carrying capacity of RCC over soil cement pavement structures through accelerated pavement testing. Six full-scale RCC pavement test sections, each of 71.7 ft long and 13 ft wide, were constructed at the Louisiana Accelerated Loading Facility (ALF) site. The test sections included three RCC thicknesses: 4-, 6-, and 8- in., respectively and two soil cement base types: an 8.5-in. cement stabilized base and a 12-in. cement treated base. A heavy vehicle load simulation device, ATLaS30, was used in the accelerated loading of RCC test sections. Load-induced pavement responses (e.g., stresses and strains) were measured with embedded dynamic sensors, and the variations of temperatures of RCC slabs and subgrade moistures were monitored during the ATLaS30 loading. This paper will present the findings of RCC pavement performance as well as the experience learned during the mix design and the construction of RCC test sections.

Roller compacted concrete (RCC) is a concrete mixture with a low cementitious material and water content and a dry consistency. It is placed using an asphalt paver and consolidated using roller compaction. This zero-slump concrete does not require slip-form conventional concrete paving equipment for placement. It does not contain reinforcement, tie-bars, or dowels. RCC can be placed and opened to traffic in a short period of time. All of these factors combined make it a relatively low-cost roadway compared to either asphalt or conventional concrete pavements. However, RCC may lack the smoothness required for high-speed roadways and can ravel and/or crack; an asphalt overlay may remedy the smoothness and raveling issues. Although cracks may occur in the RCC and potentially reflect through the asphalt layer, such cracks should stay tight because of the low shrinkage of RCC. A composite pavement with RCC and an asphalt overlay has the potential to be a cost-effective long-lasting pavement system. The Virginia Department of Transportation (VDOT) has implemented RCC technology to rebuild a section of Route 684 (Staffordboro Boulevard) and roads leading to a commuter parking lot in Stafford, Virginia. Approximately 2 lane-miles of the pavement were reconstructed or built using RCC with a 2-inch asphalt overlay. This paper summarizes the construction procedures and provides information on the lessons learned. After initial difficulties, the project is progressing successfully. Although the majority of the roads were open to traffic in 48 hours, a portion of Staffordboro Boulevard was opened to traffic in 6 hours. The mixture used had 15% fly ash for improved durability and sustainability. An issue with compaction occurred because the equipment had to be adjusted to provide the required density. Compaction was dependent not only on the equipment but also on the mixture consistency, which relates to the moisture content. Continuous determination of density and moisture was essential in the quality control of RCC.

Roller-compacted concrete (RCC) is re-emerging as an alternative pavement type to asphalt concrete and even slip-form concrete pavements because of its rapid construction, early opening to traffic, and its economic benefit. The lower cement content of RCC requires careful selection of the aggregate structure to ensure adequate structural performance of the pavement. Recommended gradation bands have been proposed in the literature with few studies systematically investigating aggregate gradation effects on the fresh and hardened properties of RCC. A laboratory study was conducted to quantify the effects of aggregate gradation on the moisture-density relationships and the strength properties of RCC with low fines content. Low fines content RCC mixtures represent the direct application of existing concrete aggregates found in most ready-mixed concrete plants. Optimized moisture-density relationships for nine RCC mixtures with different aggregate gradations and fixed cement content were determined using the modified Proctor test. The compressive and splitting tensile strengths were measured at 14 days and compared with a conventional concrete paving mixture.

Pervious concrete is a specialty mix consisting of coarse aggregate and cementing agents used primarily to improve drainage in parking lot applications, roadway shoulders, and low volume roadways. The porosity of the concrete is typically in the range of 10%-35%, which allows for rapid absorption of surface runoff. Although beneficial for this purpose, it is susceptible to raveling and typically has lower peak strength than conventional concrete. However, the residual strength, i.e. total fracture energy, characteristic length, brittleness ratio, and size effect are relatively unknown and have yet to be investigated thoroughly. This information can prove beneficial because it provides insight into the materials resistance to fatigue fracture, and its ductility and energy absorptiveness under impact. In this study, a series of geometrically similar three point bending single edge notch beams of three different sizes were tested under quasi-static loading. In addition, dynamic drop impact tests were carried out on pervious concrete disks to assess energy absorptiveness. The mode I residual behavior was observed to be ductile due to significant crack bridging and tortuosity. In addition, the characteristic length was quite large which precipitated strength domain response and not LEFM (Linear Elastic Fracture Mechanics). The total fracture energy for the largest size beam was approximately 110 N/m and the absorbed energy under impact was approximately 1.4 Joules. In addition, the excellent residual energy absorptive properties of the pervious concrete as shown in this paper, may lead to expanded use of this material for energy absorptive applications like highway median wall barriers upon further enhancement and optimization of the material constituency.

The Federal Aviation Administration (FAA) recommends that design flexural strength of portland cement concrete (PCC) should be between 600–700 psi for “most airport applications.” In Construction Cycle 6 at the FAA’s National Airport Pavement Test Facility (NAPTF), slabs were constructed at flexural strengths outside this range and subjected to full-scale aircraft traffic. In conjunction with the full scale tests, the FAA conducted fatigue tests on concrete beams from the same mixes. Fatigue loads were applied to beams at stress ratios from 70% to 90% of the rupture modulus. Beams from the high-strength concrete performed in fatigue similar to lower-strength concrete. The laboratory tests did not indicate reduced fatigue life for strengths above the normal design flexural strength range. Results of this study do not rule out the possibility that some high-strength mixes may perform poorly in fatigue. Further research is recommended to identify what mixes may be susceptible to poor fatigue performance.

A Continuously Reinforced Concrete Pavement (CRCP) design was prepared for a non-uniform pavement section of a dedicated guided bus route in the United Kingdom. The non-uniform section required full-depth thickness along the channelized wheel path and reduced thickness in the middle section which serves as drainage path. Using the current CRCP standard design method for UK presented a challenge because it was assumed that the method intrinsically accounts for lateral wander and therefore not applicable for channelized traffic. It was decided that a project specific design approach was needed for this project. Two structural models were used to understand the impact of reduced thickness in the middle section on the wheel path portion of the pavement. The first structural model is a generic finite element program that could simulate the response of any type of geometry. The second structural model is the pavement program EVERFE which was used to calibrate the generic finite element program for a uniform pavement thickness. Once the generic program was calibrated, the generic program with non-uniform thickness was used to understand the reduced pavement thickness in the middle portion of the section and its influence on the traffic path portion. This paper summarizes the structural analysis and the final design prepared for the project. The non-uniform section also includes an integrated curb as part of the guided bus route, which has tight horizontal spacing requirements to meet the operation demands of the guided bus system. The approach for developing the longitudinal and transverse reinforcement was similar to current state of art CRCP design methods.

The influence of traffic as an input parameter for mechanistic-empirical (M-E) pavement analysis on the percentage of fatigue cracks on slabs or the required slab thickness for jointed concrete pavements (JPCP) was investigated. Site-specific traffic data from Illinois weigh stations exhibiting different axle load and vehicle class distributions were compared against the default traffic inputs used in the M-E pavement design program. The load spectra for several sites were adjusted by changing the annual average daily truck traffic (AADTT) volumes to produce the same equivalent single axle loads (ESALs) for a typical interstate highway design in Illinois. The influence on the required JPCP thickness varied less than 2.0 inch (50 mm) for combinations of all traffic distributions and climate regions given the same level of ESALs. For a given climate station with a fixed ESAL level, there was no significance in cracking level for the load spectra data gathered at different stations across Illinois. Only in extreme overload traffic cases, where a significant percentage of the single axle weights were 50 percent greater than the legal limit, did the distribution of traffic significantly influence the slab cracking performance for a fixed number of ESALs and climate. For JPCP design, the difference between using an ESAL-based design and load spectra design for fatigue cracking prediction was determined to be negligible when using the M-E pavement design program with existing Illinois traffic inputs and a realistic magnitude of overloads.

The surface roughness in terms of International Roughness Index (IRI) captures variation in vertical surface elevations along the pavement length. Diamond grinding is a rigid pavement preservation treatment which is typically utilized to increase pavement smoothness by eliminating the surface undulations. The focus of this study is to evaluate the impact of diamond grinding on rigid pavement performance by using the mechanistic-empirical procedure. The effectiveness of a diamond grinding was assessed by evaluating the IRI before and after the treatment. Generally, smoother pavements will have lower IRI, which will result in less vehicle body and axle bounce. Consequently, the pavement will be subjected to reduced dynamic loads which may cause less pavement damage or vice versa. The longitudinal profile and axle load data from the Long-Term Pavement Performance (LTPP) in the SPS-6 experiment were utilized to evaluate the impact of diamond grinding on pavement performance. These experiments were designed to evaluate the effectiveness of rigid pavement rehabilitation treatments. The data for pavement sections from two climatic zones were evaluated before and after diamond grinding. The axle distributions for each pavement section were utilized to generate truck gross-vehicle weight (GVW) distributions. Subsequently, the truck GVW distributions were used to generate truck response on different pavement surface profiles by using TruckSim software. The impact of surface roughness on dynamic loads was evaluated by comparing axle load spectra before and after diamond grinding. The variations in the axle load spectra are used to explain the differences in the predicted pavement performance in terms of cracking, faulting and IRI.

Erosion in rigid pavements is defined as the loss of material of the base layer near the joints of the slabs that is caused by the combined effect of the presence of water, traffic loading and the use of certain base materials. This material loss forms a cavity under the joint areas, which produces a lack of support of the concrete slabs and causes the initiation and propagation of cracking processes. This work presents the results of two experimental efforts conducted to better characterize this phenomenon: 1) a new test to quantify the erosion susceptibility of stabilized base materials, and 2) a full-scale experimental set-up to evaluate the initiation and progression of erosion. The results suggest that the erosion test provides reliable information to quantify the erodability of stabilized materials, and that the full-scale set-up is useful to evaluate the relative impact of different factors in determining the development of this phenomenon.

Innovative thermochromic asphalt concrete incorporated with thermochromic materials have been designed to modulate the surface temperature of asphalt pavement (i.e., reduce pavement surface temperature during summer and increase the surface temperature during winter). Both aspects potentially improve the durability of pavement. A three-dimensional finite element model was proposed to simulate temperature characteristics of asphalt pavement using measured weather data in Cleveland, OH. The temperature simulation indicated that the surface temperature of asphalt concrete could be reduced up to 5.3 °C in May and increased up to 1.1 °C in February, respectively compared to conventional asphalt concrete. The corresponding temperature gradient across the pavement could be reduced up to 17 K/m and 14 K/m respectively. These effects concrete are beneficial to reduce high temperature related performance degradation of the pavement, to potentially enhance durability and safety of asphalt pavement, and to alleviate urban heat island effects.

A study of the in-place thermal cycling of asphalt pavements containing select sustainable technologies, such as reclaimed asphalt pavements (RAP), recycled asphalt shingles (RAS), and ground tire rubber (GTR) was performed using multiple test sections built at the National Center for Asphalt Technology (NCAT) Test Track. For a period of six months, hourly measurements of the pavement temperature were taken at different depths within the asphalt layers. Simultaneous hourly measurements of the ambient air temperature, wind velocity and solar radiation were also obtained. The results were used to estimate the energy absorbed by the pavements and the heat conducted through the asphalt layers. An unconventional parameter, based on heat transfer theory (termed “field thermal conductivity” for the purpose of this study) was proposed to compare the heat conduction characteristics of the three sustainable pavement systems included in the study. A statistical analysis of the results revealed that the use of RAP, RAS, and GTR-modified binders affected the in-situ thermal properties, warranting further investigation.

A field experiment is carried out by operating vehicles (passenger car and commercial truck) on two roadway sections (flexible pavement and rigid pavement) along Interstate Highway 95 in Florida. Statistical comparison is first performed and revealed that the average fuel consumption differences between vehicles operating on flexible pavement and rigid pavement at given test condition are 4.04% for truck and 2.25% for passenger car, in favor of rigid pavement. The differences are proven statistically significant regardless of the vehicle type at 95% confidence level for southbound average fuel consumption and overall average fuel consumption, but not for northbound average fuel consumption. The truck test data are then used to calibrate the two coefficients given in HDM-4 fuel consumption model. Calibration result shows that the model is well response to the field data and can be adequately applied to predict the truck fuel consumption given pavement and environment information. In turn, the result further confirms the necessity of adjusting/calibrating models before their application to local condition. Finally, the effect of wind speed on vehicle fuel consumption is investigated and equation is recommended for calculating the truck aerodynamic resistance for Florida’s condition.

This paper presents an independent evaluation of the accuracy and precision of high-speed field measurements of pavement surface distresses taken by three different 3D systems that represent the state-of-the-practice of automated distress collection equipment. The analyzed distress data was collected from a field experiment that comprised twenty 550-ft test sections that included both flexible and rigid pavements. The high-speed measurements produced were compared to manual measurements taken statically by experienced raters. The paper also presents a qualitative comparison between the crack maps produced at highway speeds and digital crack maps collected statically by manual measurement of the cracks. In addition, before-and-after analyses were conducted to assess for the change in accuracy achieved after conducting a visual inspection, and manual corrections, of the automated measurements.

A total of 137 runways from 107 general aviation airports across the state of Kansas were surveyed in 2008 to assess runway pavement condition in terms of the Pavement Condition Index (PCI). Approximately 68% of the sections surveyed were in “good” to “satisfactory” condition. About 21% of the sections studied were in “fair” condition. Overall, the condition of the network can be rated as “satisfactory.” Deterioration prediction models were developed for the asphalt and concrete surface types. The results show that as much as 44% of the network could have a “fair” rating by 2013 if the sections receive only routine maintenance. The budgeting report developed show that the 108 runways of the 78 general aviation airports eligible for federal funding could be brought to a “satisfactory”rating or above (i.e. average PCI ≥ 70) by spending approximately $15 million annually for five years.

The U.S. military typically operates its aircraft on traditionally surfaced pavements such as Portland cement concrete (PCC) or asphalt concrete (AC), for which there are well-established methodologies for evaluating their surface conditions and structural performance. There is, however, a lack of pavement evaluation guidance for nontraditionally surfaced airfield pavements that may be encountered around the world. Aircraft operations, such as training exercises, humanitarian relief missions, or personnel evacuations may be conducted in remote regions of developing countries where access to traditionally paved airfield infrastructure meeting International Civil Aviation Organization standards is not available. Nontraditionally surfaced airfield pavements of particular interest include those with wearing surfaces comprised of sand asphalt, penetration macadam, bituminous surface treatments (applied over prepared bases), and stabilized soils/aggregates. These pavement types may be encountered in regions where airfield quality AC or PCC are either not readily available or they are too cost-, labor-, or equipment-intensive to use. Additionally, these surface types may have been used at airfields designed to support lighter aircraft with fewer operations. This paper presents evaluation procedures for predicting the performance of these pavement types for aircraft. The identification of key surface distresses and recommendations for the visual and structural assessment of each pavement type are also presented. Recommendations for improving the evaluation procedure through field verification tests are discussed.

Incineration of municipal solid waste (MSW) is a common technology that converts solid waste into energy. In European and Asian countries, municipal solid waste incineration (MSWI) ash has been beneficially utilized by separating the bottom ash from fly ash and using them as road construction materials. Generally, MSWI bottom ash, classified as nonhazardous materials, is used to replace either cement or fine aggregate in asphalt and concrete mixtures. In this study, chemical and microstructural analyses of MSWI bottom ash (‘as received’ samples) produced from a Refuse Derived Fuel (RDF) plant in Florida were conducted. The characterization method included energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) methods. Subsequently, leaching behaviors of bottom ash-mixed asphalt and concrete mixtures (for milled asphalt and crushed concrete applications) were investigated. The Synthetic Precipitation Leaching Procedure (SPLP) testing method was used for the leaching investigation.

The performance of subgrade stabilization with cement, lime or lime/fly ash are extensively studied. However, the use of recycled materials for subgrade stabilization is yet to be properly studied. If proper mix designs and construction specifications for subgrade stabilization with recycled materials are available, those materials can be used for pavement construction. Recycled materials not only provide cheaper alternatives for subgrade stabilization, they also alleviate landfill problems. Most of the previous studies were related to subgrade modification with recycled materials, limited to quantify immediate benefit through construction facilitation. However, there is a need to identify the long-term benefits and/or associated risks to use recycled material for subgrade stabilization. With satisfactory long-term benefits, subgrade stabilization can be potentially used for optimizing pavement designs that will result in cost effective pavement sections. If this study reveals any long-term risks associated with subgrade stabilization, those will be addressed by either remedial actions or by limiting usage of those stabilizing materials. This paper examines the preliminary results of a laboratory testing program to determine benefits and risks of using recycled materials such as Cement Kiln Dust (CKD), Lime Kiln Dust (LKD), Fly Ash (FA) and Concrete Fines (CF) for subgrade modification as well as stabilization.

Long-term aging of recycled asphalt binders was studied through Superpave binder performance grade (PG) tests with extended aging time. Rejuvenation is an important component of asphalt recycling. Effectiveness of recycling agents (rejuvenators) is often evaluated by softening curves established based on viscosity and penetration tests. A shortcoming of these criteria is that they do not take long-term performance into account. This study aims at looking beyond initial performance and evaluating long-term aging of recycled binders. The aging rates of virgin and recycled asphalt, measured by PG tests, were compared. Virgin binder was aged using Pressure Aging Vessel (PAV). Aged binder was rejuvenated by mixing with four different rejuvenators and then was aged again. The PAV aging time it took each sample to reach the failure point was considered as a measure of binder longevity. Results showed significant difference in long-term aging of samples recycled with different recycling agents. While some samples aged significantly slower than the original binder, others aged faster. Analysis of aging rate of binders showed that selecting a proper recycling agent can extend the service life up to 10 years. Results from this study can be implemented to develop performance specifications for recycling agents in order to take long-term aging into account.

As part of ongoing efforts to reduce initial construction costs, the Indiana Department of Transportation sponsored research to explore the possibility of increasing the use of locally available, polish-susceptible aggregates in asphalt surface courses for moderate and high traffic volume roadway surfaces. Increasing the use of local materials could also reduce the haul distance to bring in premium, high friction aggregates from limited sources in and outside the state, which would in turn reduce fuel usage and vehicle emissions. This increased use would also benefit local economies by creating markets for underutilized resources. This paper summarizes the results of a study to investigate the effects of various quantities of local, polish-susceptible limestones blended with high friction slags and sandstone on surface friction. The study led to increased use of local aggregates and a testing procedure now implemented in Indiana to evaluate aggregates for use in asphalt surface courses.

This paper studied the performance and economic efficiency of test perpetual pavement in Jiangsu Province, China. The method of this study is combing the FEM calculation and performance comparison to determine which structure is fitter for this site. The tool for economic evaluation is Life Cycle Cost Analysis (LCCA). Perpetual pavement without Rich Binder Layer (RBL) has better cracking and rutting resistance ability than its counterpart with RBL, but perpetual pavement without RBL is less economical than the perpetual pavement with RBL. Higher asphalt content in RBL could promote cracking resistance ability, but would at the same time decrease rutting resistance ability. Traditional semi-rigid base asphalt pavement has best rutting resistance ability, but this structure is the least economical in the life cycle.

To accurately estimate the cost for crack sealing on airport runway shoulders, an automatic approach using 3D line laser imaging technology, automatic crack detection, and width measurement algorithms is proposed. Based on their widths, cracks can be categorized in terms of the routing depths. Then, accurate cost estimation can be made according to the total length in each crack category using different routing depths. Other than the cost estimation, the detected crack maps and the crack classification information can also be used to guide construction operations and provide a means for agencies’ quality checking. Using the proposed method, a case study has been performed on a 30.5-m (100-ft) runway shoulder at Hartsfield-Jackson Atlanta International Airport. The results show that the proposed method is very promising for providing an automatic approach that cost-effectively and reliably generates categorized crack maps with different crack sealing methods and accurately estimates crack sealing cost.

This paper presents a rational approach for determination of permit fees for truck traffic based on consumption of service life of highways. The prescribed approach uses mechanistic-empirical design philosophy for estimation of deterioration of the pavement structure. The methodology uses permanent deformation, load-related fatigue damage, and roughness scores as primary descriptors for estimation of the service life consumption. The experiment factorial included flexible pavement sections with varying structural numbers and sampled across Texas to account for climatic and geographical differences. Each of the pavement sections were simulated under different loading conditions to reflect the full spectrum of axle weights that are characteristic of single, tandem, tridem, and quad axles. The aforementioned exercise provided the basis for developing the group equivalency (GEF) and axle load factors (ALF) for individual axle groups. The determination of axle specific parameters enabled adoption of a modular approach towards determination of gross load equivalencies for any truck category without any restriction on axle weights or configuration. The consumption of the service life was calculated as the additional pavement structure that would be required to accommodate traffic in excess of the design truck volume. The cost incurred in the process of providing the additional structure was assigned to the responsible truck fleet in proportion to the marginal load equivalency over the legal gross vehicle weight (GVW) and axle weight tolerances. Results indicate that a permit fee of 3.7 ¢/mile/ESAL is equitable based on the findings from this study.

This study developed a methodology to allocate asphalt pavement damage cost induced by truck using mechanistic-empirical (M-E) pavement analysis procedure. Load equivalency factors (LEFs) were developed from M-E analysis and used to convert truck traffic to the number of equivalent single axle loads (ESALs) that would yield the same impact on pavement. Pavement life was predicted using Weigh-in-Motion (WIM) data and typical pavement designs in New Jersey. Life-cycle cost analysis was performed to derive the unit pavement damage cost in average. The results indicate that the unit pavement damage costs are in the range of $0.005-$0.04 per ESAL-mile for the Interstate highway and $0.05-$0.61 per ESAL-mile for the minor road, depending on discount rate, pavement structure, and rehabilitation strategy. The analysis of pavement damage cost caused by an individual truck clearly indicates that a truck having the same gross vehicle weight (GVW) but different axle configurations could cause significantly different pavement damage cost. The developed methodology allows allocating costs to different trucks that commensurate with their respective contributions to pavement damage and developing an axle-weight-distance based road charge structure.

Pavement preservation has become a common practice in the management of pavement network across the country. However, the effectiveness of the preservation treatments vary depending on numerous factors e.g., construction practices, traffic, climate and pre-existing surface conditions and structural capacity. The purpose of this paper is to determine the impact of the site factors on the effectiveness of flexible pavement preservation treatments in terms of service life extension (SLE). The data from the Long-Term Pavement Performance (LTPP) SPS-3 experiment were utilized to compare the pavement SLE among different preservation treatments (slurry seal, chip seal, crack seal, and thin overlay) based on structural and functional performance measures. The SLE is a measure of treatment effectiveness and can be obtained by comparing the performance between treated and untreated control pavement section. The flexible pavement performance measures considered were structural and thermal cracking, rutting, and surface roughness, bleeding, raveling, and friction. The impact of various site factors (e.g., traffic, climate and pre-existing surface conditions) was determined by performing statistical analyses including analysis of variance (ANOVA) and multiple linear regressions. The comparison of SLEs among different treatments showed the most effective preservation treatment under different site conditions. The results from statistical analyses elaborated the significance of site factors in defining the efficacy of various preservation treatments.

Advances in concrete technology have allowed Flowable Fibrous Concrete (FFC) inlays to be an option for pavement preservation through rapid placement, thin-lift construction, durability, and material ductility. By incorporating titanium dioxide (TiO₂) cement, these FFC inlays can also mitigate vehicular greenhouse gas emissions and the Urban Heat Island (UHI) as well as meet structural requirements. A concrete mix incorporating this modified FFC was lab-tested for strength and fracture properties at 7 days and was found to be acceptable for pavement preservation applications. The FFC albedo was measured as 0.26 and the predicted hourly surface temperatures of hypothetically-aged asphalt concrete pavements with and without the FFC inlay were compared over a ten-year period using weather data from Chicago, IL. With a lower surface temperature in 94% of daytime hours, the inlay was effective in mitigating daytime UHI but less effective in nighttime.

For the design of new jointed plain concrete pavements (JPCPs), three national calibrations of the AASHTOWare Pavement ME have been necessary due to updates in either the prediction models or the calibration database. Local calibration is recommended to further refine predictions so that they better match a state’s experience. To date, local calibration efforts resulted in eight states changing one or more coefficients to a local value, while eleven states have decided to directly adopt national calibration coefficients. To determine the impact of local calibrations relative to the national calibration, a review of the national and local calibration efforts was completed. Local and national calibration coefficients were compared in two scenarios. In the first scenario, Pavement ME was employed to evaluate the performance of a hypothetical JPCP section. In the second scenario, Pavement ME was used as a tool for determining the thickness of pavements with various design features. It was found that for most states the pavement performance differed quite significantly between the local and national calibrations. However, in terms of design thickness, no evident difference could be statistically concluded for most of the states. In comparing designs developed using AASHTO 1993 Guide for Design of Pavement Structures, it was found that the Pavement ME yielded thinner designs regardless of the calibration coefficients used.

Empirical procedures based on the CBR method for the design of flexible airfield pavements have shown many limitations in the past decades. Much effort has been made to overcome them, leading to the development of new methodologies associated with new computer programs (APSDS, FAARFIELD, PAVERS…). The French Civil Aviation Technical Center released its new pavement design guide Rational Design Method for Flexible Airfield Pavements (STAC, 2014) describing the complete procedure based on rational principles. A dedicated software, Alizé-Airfield Pavement, was developed for its implementation. This French procedure is based on the computation of resilient stresses and strains in the pavement structure using a multi-layer linear elastic model. Two failure criteria are taken into account: permanent deformations of the subgrade, and fatigue of asphalt mixtures. Damages induced by each aircraft of the traffic mix are cumulated over the design period. The failure models used are derived from laboratory testing on pavement materials, observation of in-service airfield pavements, as well as experimental programs carried out in the early 2000s in Toulouse-Blagnac airport with a full-scale heavy simulator. This procedure fulfils many of the ambitions that were raised by the limitations of the former empirical method. For instance, it is now adapted to any type of landing gear including the most complex configurations. The most advanced developments that are implemented allow describing in a complete manner some effects such as successive loadings induced by 6 or 4-wheel landing gear, or lateral wander of aircraft, which makes it an optimizing tool. This paper describes the content of the design guide and its field of application, including a design example with the Alizé-Airfield Pavement software. The method has now become the recommendation of the French Civil Aviation Authority.

The paper presents the fundamental basis of an analytical design methodology for roads with thin asphalt surfaces in Germany. A new mechanistic-empirical design approach was developed which is focused on limiting the main sources of rutting of thinly sealed pavement structures: 1) excessive plastic deformation in the subgrade and 2) excessive plastic deformation of the unbound granular materials in the basecourse in the vicinity of the wheel load. The procedure is based on two steps: first, a response step is carried out where the response of the structure is calculated due to traffic loading, taking into account the effect of climatic conditions on material properties. Thereafter, a distress prediction is undertaken to evaluate the accumulated damage in terms of rutting originated in the subgrade and granular basecourse.

In this study, a model has been developed, calibrated, validated, and verified for rigid airfield pavements constructed at the National Airport Pavement Testing Facility. After the model had been validated and verified, it has been used to predict the performance of the pavement under two different wheel loading configurations, the Airbus A320 and the Boeing B737. Based on the analysis, it was determined that these two wheel configurations cause significantly lower stress and strain responses in the pavement than the dual tandem configuration. It was also determined that the dowel joints transfer more load between adjoined slabs under these wheel configurations, than the field tested configuration.

The dynamic modulus tests on 24 specimens of AC-20 were performed at six loading frequencies, three confining pressures and four temperatures, respectively. The values of parameters were obtained by fitting the K–θ model based on test results. A user subroutine incorporating stress-dependent behavior of asphalt concrete for the ABAQUS finite element (FE) model was written and validated. Then a three-dimensional (3D) FE pavement model was developed to investigate the pavement responses. The study analyzed the effects of stress-dependency coupling with temperature-sensitivity of the hot-mix asphalt (HMA) layer on pavement responses, including surface deflection, shear stress and tensile strain in the HMA layer, maximum principal stress at the bottom of the base layer, and compressive strain on top of the subgrade. The results showed that surface deflection and tensile strain in the HMA layer had significant temperature-sensitivity. Compared with loading frequency, the effects of temperature on stress-dependent modulus of the HMA layer and predicted pavement responses were greater. It was found that stress-dependent model resulted in greater predicted pavement responses in comparison to the linear model.

A computational program SAFEM was developed based on semi-analytical finite element (FE) method to analyze asphalt pavement structural responses. It is a three-dimensional FE program that requires only a two-dimensional mesh by incorporating the semi-analytical method using Fourier series in the third dimension. The parallel computing technology can be applied easily in this code. These advantages could significantly reduce the computation time. The reliability and efficiency of this FE program was proved in previous studies. In order to further reduce the computational time yet still maintain high accuracy, the infinite element was added to this program. The results of the finite-infinite element coupling analysis were firstly compared with those of finite element analysis derived from the verified SAFEM program. And then the two computational programs were verified by comparing the predicted deflection with the measured data from a falling weight deflectometer (FWD). The study showed that finite-infinite element coupling analysis has higher reliability and efficiency, which has great feasibility to form a calculation basis for predicting the service life of new and existing asphalt pavement.

Geomaterials are often in unsaturated condition during their service life and their resilient modulus is influenced by several factors including moisture content, density, void ratio, plasticity, and etc. There are various constitutive models to predict the nonlinear resilient modulus of unbound materials as a function of the aforementioned factors—particularly moisture and stress states based on empirical equations or theoretical unsaturated soil mechanics concepts. In this study, seven existing constitutive models and two predictive models were evaluated using eight different soil databases with different properties including cohesive and non-cohesive soils. The constitutive models were calibrated based on the data at optimum moisture content and maximum dry density. Consecutively, the calibrated models were used to predict the resilient modulus at other moisture or density conditions. The models were compared in terms of their rationality, accuracy of prediction, and applicability to the widest range of soils.

The light-weight deflectometer (LWD), which is the portable version of the common falling weight deflectometer (FWD), has been gaining popularity due to the ease of use and familiarity of pavement community to the deflection-based concepts. LWD imparts a pulse load to the surface of a soil layer through a circular plate to measure the soil surface deflection and to estimate the effective modulus of the underlying system. An extensive finite element modeling was performed to study the mechanism of two common types of LWDs during quality control of unbound pavement materials. The performance of the LWDs was evaluated under various loading conditions, different plate sizes and a diverse range of geomaterial properties. The influence depth was studied using both stress and strain criteria. The nonlinear constitutive model parameters seem to have significant influence on the measured influence depth of both devices. However, different functional properties of each device found to be the source of variations in the results.

Full-depth asphalt concrete pavements are generally designed to control fatigue cracking and reduce potential rutting when subjected to repeated heavy traffic loads. A particular interesting question is whether a limit load exists below which excitation shakedown in the sense that the granular layer does not accumulate further deformation. Although pavement design guides give more weight to asphalt concrete layer failures, granular failure may not be ignored; especially for thin layers and/or heavy load. The behavior of granular layers used in base and, sub-base layers of flexible pavement is complicated due to its nonlinear elastoplastic response when subjected to dynamic traffic loading. The objective of this paper is to present a new simplified simulation model for the Shakedown behavior of granular layer in flexible pavement. This method is integrated with Mohr-Coulomb criterion, which is used and applied to simulate the response of unbound granular layers to dynamic loading in a numerical analysis. The results of analysis are then compared to simplify the results of modeling without considering shakedown effects and then, the conclusions are drawn.

Despite the fact that aggregates are used in all pavement applications and other branches of construction, only limited life-cycle inventory database compatible with ISO 14040:2006 guidelines exist for the aggregate industry. This paper introduces a life-cycle inventory assessment approach that can be used in the environmental assessment of mineral aggregates production processes. Such an approach requires building a more reliable and representative inventory database in the U.S. As a preliminary screening to assess the present status of the crushed aggregate production, a case study is presented to calculate energy consumption and greenhouse gas emissions from aggregate production and compared to other sectors included in the mineral industry. An initial screening type case study was also conducted using a generic inventory database (energy and greenhouse gases) reported in the literature. According to the results obtained from the screening LCA, crushed aggregate production contributes approximately 2.3 million metric tons CO₂-equivalent, merely 2.15% of the mineral industry.

In order to provide adequate support to the surface layer of airfield pavement, the base, subbase and subgrade must be compacted to high density. Generally, the pavement materials are compacted by roller in the longitudinal direction. It may cause property variance between longitudinal and transverse directions. Portable Seismic Pavement Analyzer for Soils (D-PSPA) was used to evaluate the effect of rolling direction on unbound material modulus. A series of D-PSPA tests were conducted on subgrade, subbase and base materials at the National Airport Pavement Test Facility (NAPTF) in both longitudinal and transverse directions. Single factor analysis of variance (ANOVA) was performed on test results to investigate whether there is a significant difference between two directions. The preliminary data analysis indicates that the seismic modulus measured in longitudinal direction is higher than transverse direction for subbase. Higher seismic modulus was obtained in transverse direction for base. Subgrade, on the other hand, appears to be not affected by the rolling direction.

The dynamic cone penetrometer (DCP) has been studied extensively since its early development in the 1960’s to expand its use for evaluating in situ engineering properties of pavement base courses, subbases, and subgrade layers. The DCP penetration rate (PR) has been correlated to common soil strength parameters such as California Bearing Ratio (CBR) and modulus with an emphasis on using the DCP in lieu of traditional CBR and falling weight deflectometer (FWD) or heavy weight deflectometer (HWD) testing. This paper evaluates the use of the DCP for assessment of material strength for pavement applications. Focus is placed on the use of the DCP for estimating soil strength, compaction quality control, and detecting pavement sublayer strength variability. A database containing 185 test points at 24 sites where DCP, FWD, and/or CBR tests were conducted was populated and used to perform regression analyses. Relationships between PR, CBR, and backcalculated modulus were developed and compared to existing correlations. The application of DCP in soil strength determination, compaction quality control, and pavement variability detection was established.

With recent focus on sustainable construction practices and the ever-increasing transportation cost and scarcity of natural resources, use of unconventional aggregate materials, such as primary crusher run and concrete demolition waste, have become viable for the construction of pavement working platforms over very weak and often wet subgrade soils. To this end, a research study was undertaken at the Illinois Center for Transportation to evaluate the adequacy and field performances of such large-sized aggregate materials and validate new material specifications. A state-of-the-art image analysis technique was utilized to characterize the size and morphological properties, e.g. shape, texture and angularity of two large-sized aggregates, referred to herein as primary crusher run and crushed concrete. For the field evaluation, full-scale test sections were constructed with these large-sized aggregate materials over a very weak engineered subgrade and subjected to accelerated pavement testing. Construction quality control was achieved through in-place density and modulus measurements on conventional aggregate capping surface layers using nuclear gauge, lightweight deflectometer and soil stiffness gauge type devices. Periodic rut measurements were carried out on the pavement surface throughout the accelerated loading process using an Accelerated Transportation Loading Assembly (ATLAS). Contributions of the underlying pavement layers to the total rut accumulation was evaluated through innovative applications of ground penetrating radar (GPR), a light weight penetrometer device, known as the French Panda, as well as a geo-endoscopy probe. Layer intermixing and material migration at the aggregate subgrade and subgrade interface was found to improve the layer stiffness and pavement performance results significantly.

A new approach is proposed in this paper for estimating the resilient modulus (M_R) of pavement subgrade soils taking account of the influence of the soil suction (ψ). This approach includes two steps: step (i) estimating the soil-water characteristic curve (SWCC) using one-point method, and step (ii) predicting the M_R - ψ relationships using a simple model and the estimated SWCC from step (i). Estimations of the SWCC and the M_R for two different subgrade soils using (i) the proposed approach, and (ii) the widely used mechanistic-empirical pavement design guide (MEPDG) approach are compared with the experimental measurements. The comparison results suggest that the proposed new approach provides reliable estimations of both the SWCC and the M_R - ψ relationships. The proposed approach in this paper is relatively simple and is promising for use in the design of pavements.

An innovative technique is presented to control frost heave that is rapid to perform, is easy to control and is safer than other procedures during remediation. A two part structural polymer is injected below the highway subbase to create a permanent layer of expanded structural foam that acts as an insulation layer to limit heat loss from below. Because the heat loss is less, the temperature of the subgrade remains higher which makes it less likely to freeze and heave. The results of a successful two-year study are presented. Frost heave is caused by water freezing into ice lenses in the pore space of silty soils. As the water freezes, it accumulates into ice lenses that can lift the frozen base course aggregates above it. The heave is highly variable because small variations in soil properties can make the surface of a flexible pavement irregular and dangerous on which to drive. This paper describes the application process of an expanding structural polymer and its success in mitigating the problem. Heaves in a 100 foot (30 m) long section of flexible pavement were reduced from 3 inches (75 mm) to less than one-half inch (12.5 mm) over most of the road to a level undetectable to the motorist. In-situ temperatures were measured using thermistors above and below the polymer layer and the effect of the freezing front on the measured surface heave are compared in both treated and non-treated areas.

Moisture variation in a pavement structure due to the environment has a large impact on the moduli of unbounded layers. The moisture variation can affect the performance of the pavement as documented in a number of laboratory and field studies. As such, it is desirable to account for this behavior in the design or evaluation of a pavement. In this study, the effects of moisture variation and compaction effort were investigated through a series of well-controlled laboratory tests on different fine-grained geomaterials. Different sources of fine-grained materials were selected to prepare the laboratory specimens for both resilient and seismic modulus tests. The existing modulus-moisture models were evaluated during the moisture conditioning cycles for the specimens prepared and compacted at different moisture levels. Furthermore, the normalized difference of moisture content at the time of compaction and optimum moisture content was used to explain the trends. A model is proposed to improve the prediction of changes in resilient modulus based upon moisture content. The proposed model showed reasonable agreement with the experimental data.