Airfield and Highway Pavements 2017: Pavement Innovation and Sustainability

This study investigates the effects of the type and configuration of embedded electrodes on resistive heating performance of an electrically conductive concrete (ECON) heated-pavement system (HPS). Three ECON slabs—an ECON slab with perforated galvanized steel angle electrodes, an ECON slab with steel rebar electrodes, and an ECON slab with perforated galvanized steel angle electrodes with an isolation layer—were designed and constructed. The resistive heating performance of the slabs was evaluated by measuring the electric current and ECON slab surface temperature at specific points during the application of voltage. The results revealed that the performance of the ECON slab with perforated galvanized steel angle electrodes was marginally changed when an isolation layer was used, so with respect to construction practice and cost considerations, an isolation layer is not deemed to be necessary for constructing large-scale ECON heated pavements. Electrical current measurements can be used for evaluating the conductivity and the heating capability of the ECON slabs.

This paper presents preliminary results of the evaluation of several prototype systems for harvesting energy from the action of traffic on roadways. These systems utilize piezoelectric elements that respond to traffic-induced compressive stresses, and are referred to as HiSEC (highway sensing and energy conversion) modules. The evaluation of the HiSEC prototypes involves laboratory testing of their power output as a function of stress, finite element (FE) simulation of their mechanical behavior and economic analysis of the value of the power being generated. The results available to date suggest that this technology shows promise in powering equipment independently of the power grid.

With a view towards sustainability and eco-friendliness, the paving industry is now more interested in incorporating better pavement materials and pursuing strategies that will result in greener and longer lasting highways. Temperature plays a crucial role in the long-term performance of pavements. High temperature in pavements contribute to the urban heat island (UHI) effect and reduction of pavement life. In concrete pavements, the development of large temperature and moisture differentials during both daily and on a seasonal basis can produce warping and curling stresses. If these stresses exceed the flexural limits of the rigid pavement they may lead to the formation of structural cracks. In asphalt pavement, higher temperatures may deteriorate the viscoelastic property of asphalt binders and may lead to reduced stiffness and rutting. This study evaluated three surface treatment methods as cool pavement strategies to reduce temperature in concrete pavements. Geosynthetic reinforced chip seals (GRCS) with high albedo aggregate and lightweight aggregate impregnated with phase change material (PCM), and thin hot mix asphalt (HMA) layers were investigated. Temperature data were collected under simulated conditions in the laboratory. The results of these various surface treatment methods were compared to those from a control cement mortar sample. The results show that the GRCS with high albedo can be used as an effective strategy for reducing temperature in concrete pavements.

In a bid to reduce the cost of pavement construction and the environmental impact of using cement as a conventional stabilizer, there is a need for a green alternative. The use of mucilage of Optuntia ficus indica cladodes (MOFIC) which contains several amino acids and sugars was used in improving the strength properties of cement stabilized lateritic soil. The parameters tested were atterberg limits, compaction characteristics (optimum moisture content and maximum dry density), California bearing ratio (CBR) and the UCS. The addition of (cement + MOFIC) to the cement stabilized sample reduced the plasticity index which improved from a subgrade to a subbase material. Furthermore, the CBR value of 76 and 58% was obtained for the addition of (cement + MOFIC) for both the soaked and unsoaked samples. The unconfined compressive strength (UCS) improved from 140 to 720 kN/m² as a result of the connectivity of the polysaccharide component in the pectin of the mucilage. In a bid to reduce the cost of cement as a conventional stabilizer and espouse green construction, the use of (cement + MOFIC) is a sustainable and cost effective alternative in improving the strength properties of pavement interlayer material.

Enormous quantities of domestic, industrial, agricultural and mining waste are generated annually. A large quantity of waste material is dumped at land filling site, which if investigated properly can be utilized in road construction sector. The utilization of these waste materials can be an economical and eco-friendly alternative in nearby areas for road construction. The results, to date, indicate that there is a wide scope for the use of such materials. However, in developing countries, only a few materials have been used and that too on experimental basis. The main objectives of the present investigation is to assess the usefulness of industrial waste as a soil admixture, and focused to improve the engineering properties of soil to make it capable of lower layer of road construction. Present investigation describes the behavioral aspect of soils mixed with industrial waste materials viz. Fly ash (FA) and bagasse ash (BA) to improve the load bearing capacity of the soil. Clayey soil has been considered using two different types of stabilizer viz. FA and BA ranging from 5 to 35% by weight of soil. The physical and chemical properties of these stabilizers were ascertained and compared. Admixing of all these stabilizers improve soaked CBR and unconfined compressive strength (UCS) values substantially and dramatic reduction in dry density was observed. Stress-strain characteristics of these ashes admixed with clayey soil is similar and showed mark influence of compacted density on angle of internal friction and cohesion. Microstructural investigation by using SEM technique, morphological properties of soil-FA and soil-BA mixtures was studied. From the SEM image analysis, presence of enormous quantities of amorphous compounds is also confirmed.

Polyethylene terephthalate (PET) is among the most widely used plastic resins around the world with increased recycling rates every year. However, still most of the PET waste gets incinerated or buried in the land. If PET particles can be incorporated into concrete, a large proportion of PET could be reused and the resulting environmental pollution could be mitigated. Prior research results on mechanical properties of the PET concrete, demonstrate that the strength of concrete decreases with increasing the PET replacement ratio. However, the toughness of PET concrete is higher than the normal concrete which may extend its use in transportation and pavement engineering applications where impact and dynamic loads govern the design.

The use of recycled pavement layers in highway rehabilitation is becoming increasingly popular; however, the in-place properties of recycled materials can be significantly different from those of traditional unbound granular materials, and can differentially change with variations in temperature and moisture conditions. To effectively design pavements using recycled materials, a better understanding of their in-place properties is needed. The objectives of the study reported in this paper were to determine the in-place properties of recycled materials common to the New England region and to evaluate the changes in these properties with changes in temperature and moisture. Five instrumented pavement sections with base layers containing recycled materials were evaluated over the course of the study. Falling weight deflectometer (FWD) testing was conducted throughout the year and at frequent intervals during the spring to capture thaw weakening and recovery behavior of the materials. Modulus values for the layers were initially backcalculated from the FWD data using the BAKFAA software program, and were further refined using a forward calculation procedure. The final recommended values for the sites evaluated in this study are presented. Results of this study show that the in-place modulus values of base layers containing recycled materials can vary significantly depending upon the material type and the recycling method. The results also show that materials that are classified similarly can have very different modulus values. Furthermore, the relative sensitivity of the different materials to changes in temperature and moisture also varied. The results of this study provide useful information regarding the behavior of base layers containing recycled materials common to the New England region, and the response of those materials during spring thaw weakening and recovery periods. The reported values can be used to conduct Monte Carlo analysis to conduct a probabilistic evaluation of the designed sections, and develop confidence limits regarding the change in structural strength over different seasons.

Cold-recycling of asphalt is an effective method enabling agencies to conserve valuable resources during rehabilitation of distressed roads. The objectives of this study are to improve the understanding regarding cold-recycled asphalt performance, investigate the impact of the recycled asphalt pavement (RAP) gradation and RAP binder content on properties of the cold-recycled asphalt at given recycling agent and water content level, and evaluate the effect of recycling agent content and water content levels on the performance of Cold-Recycled asphalt. Various RAP sources with controlled gradations and five different asphalt content levels were mixed with emulsion at two different dosages and tested for performance properties; including Marshall stability and moisture susceptibility. The results show that at the early stages of curing the effect of gradation of the RAP is more important than the aged RAP binder content. Moreover, at this stage, increasing emulsion content improves wet stability and moisture susceptibility of the samples regardless of the RAP binder content and gradation of the cold-recycled mix.

In some regions of northwestern Pennsylvania, high-quality aggregate for use in hot mix asphalt (HMA) has been significantly depleted and is not readily available. This shortage has triggered removing high-quality coarse aggregate from reclaimed asphalt pavement (RAP) for use in HMA construction, leaving the fine millings behind. Research was conducted to seek alternatives for use of the remaining fine portion of the RAP. The suitability of using fine millings in construction of cold mix thin overlays, the binder course of new pavements and the main course in low-volume highways was evaluated through a set of laboratory experiments. A range of moisture and emulsion contents were used to prepare cold mix specimens, which were fabricated to represent thin overlays and new pavements. Indirect tensile strength was selected as the principal measure of suitability for the proposed applications. Results suggest that the cold mix thin overlays made with the fine portion of RAP, as well as thicker layers made with a blend of the fine portion of RAP and virgin coarse aggregates, can be effectively used for rehabilitation or new construction. Raveling tests were also conducted, and it was found that the cold mixes with RAP can perform satisfactorily under repetitive traffic loading. Field studies are required to verify the findings from this research.

The enhancement of the performance of flexible pavements by reinforcing asphalt mixtures is considered valuable because of the negative environmental conditions and heavy loads pavements endure resulting in the unsatisfactory performance of conventional mixtures. This research investigates the mechanical properties of cold mix asphalt (CMA) mixtures reinforced by natural (coir) and synthetic (glass) fibers, the main aim being to develop and optimise a high performing CMA mixture for use as a surface course, incorporating natural and synthetic fibers, which could be used in place of hot mix asphalt (HMA) in any situation. Laboratory investigations were performed to measure and evaluate the mechanical properties of reinforced and unreinforced mixtures with different fiber types, contents and lengths. These investigations included the indirect tensile stiffness modulus test, uniaxial creep test, wheel tracking tests and water sensitivity in terms of indirect tensile strength. The results revealed a considerable improvement in the mechanical properties of CMA specifically because of the high stiffness and tensile strength properties of the fibers used. Due to these improvements, rutting resistance and structural resistance to distress occurring in asphalt pavements and pavements service life, may be enhanced.

By design, airports have vast areas of paved surfaces, most of which consist of impermeable pavement. As has long been recognized, impermeable pavements have the ability to increase both stormwater runoff and the heat island effect. Although many sustainability and low-impact development (LID) manuals include permeable pavement as an alternative to impermeable surfaces, available documentation indicates its use is still very limited at airports, particularly in aircraft movement areas.

Fully permeable pavements capture stormwater and infiltrate it into the ground and/or hold it until discharging into stormwater conveyance. In either case, they offer benefits in terms of reducing or eliminating the need for stormwater conveyance infrastructure, capturing pollutants, and potentially reducing air temperatures around them. This paper reviews recent advances in structural design, materials and hydraulic design that have filled many of the gaps in permeable pavement technology. The paper then presents the results of a recent survey in California, with some additional out of state responders, regarding awareness of permeable pavements and obstacles to their implementation. Finally, the paper presents recommendations for filling remaining gaps and overcoming obstacles to implementation.

Open graded friction course (OGFC) is a thin surface layer on pavements constructed with an open gradation asphalt mixture comprising of mostly coarse aggregate with very little fines to ensure a higher air voids content. This layer improves road users’ safety in wet conditions. The University of Tennessee conducted a survey to states Departments of Transportation (DOT’s) to gain knowledge on the usage, benefits, and challenges of OGFC. This paper presents the results of the survey that was sent to 52 states including District of Columbia and Puerto-Rico. Forty states (77%) responded to the survey. The responses indicate that 45% of the respondents still use OGFC, 42% used in the past they are no longer using it and 13% never used OGFC. The use is more concentrated in the Southern states than the Northern states of the U.S.

A project named COOEE, financed by the Danish Innovation Fund, was commenced in 2012. This project dealt with reduction of CO₂ emissions by exploitation of rolling resistance modelling of pavements. The challenge was to establish a scientific background for the development of pavements with low rolling resistance that satisfy safety standards and provide at least 15 years durability. Stone mastic asphalt (SMA) is the most common surface layer adopted on the Danish road network and the COOEE project aimed at optimizing the mix design with the goal of reducing rolling resistance. The optimization procedure has led to mixes fulfil the project objectives but at the same time exhibited deficiency in texture stability and durability. An extensive laboratory investigation has been completed in order to identify the deficiency sources and suggest appropriate solutions. In this connection, a study of workability and mechanical properties of COOEE mixtures, supported by a rheological characterization of the adopted binder, was conducted and compared to those measured on a conventional SMA. The investigation results highlight the importance of providing a proper compaction degree—as a fundamental requirement for achieving desired mix performance. It is also found that investigating binder properties with a dynamic shear rheometer is essential for gaining better understanding of mixture response.

In 2009, the U.S. cement and concrete industries established the Concrete Sustainability Hub at the Massachusetts Institute of Technology (MIT) in order to develop more sustainable and durable pavement infrastructure and buildings. With regards to pavements, a primary thrust of MIT’s activities has been improving the Life Cycle Assessment practices to better quantify the environmental impacts over the life of a pavement. In doing their research, MIT determined that the environmental impact from the “use phase” almost always plays a substantial role and can often surpass the materials, construction and maintenance phases combined. Furthermore, they found that most of a pavement’s use-phase impacts come from emissions by vehicles using the pavement due to excess rolling resistance between the pavement and the vehicle. The study of assessing how much excess fuel or energy is used by vehicles due to pavement affects is called pavement-vehicle interaction or PVI. This paper summarizes the PVI research findings to date and shows how incorporating PVI-related impacts into the decision-making process can lead to meaningful reductions in vehicle emissions.

Pavement distress mechanisms become more prevalent in recent years such as surface rutting and surface initiated wheel path cracking. The main objective of this study is to evaluate tire-pavement contact stress distribution of pavement response using finite element analysis. It also assesses some of the effects of tire related factors on tire contact pressures and its response on flexible pavement. Tire-pavement contact stress is simulated using 3-D finite element method in ABAQUS for five layers of flexible pavement at various loads. 40 kN wheel load to represent a set of dual tires were assumed to be uniformly distributed over the contact area between tire-pavement surface. Four different tire-inflation pressures (350, 490, 630, and 700 kPa) were used to investigate some of the effects of tire-pavement structure. The finite element (FE) model analyses were verified with experiment results. Results have shown that contact stresses vary significantly for the different types of tire-pavement contact that were investigated. The tire’s finite element was validated using measured contact area and deflection.

Intelligent compaction (IC) technology has been emerging during the past decade to evaluate the stiffness of compacted pavement layers. The application of IC technology to compacted unbound geomaterial layers have been combined with nondestructive testing (NDT) devices to better characterize the stiffness parameters. The areas identified as less-compacted are common candidates for performing the NDT spot tests. The relationships among the accelerometer-based stiffness values from rollers and the NDT results can significantly impact the interpretation of the collected IC data. A section of a construction site was selected to evaluate the correlation between the results of two NDT spot tests, plate load test (PLT) and light weight deflectometer (LWD) test, with the IC data. The overall trends of PLT and LWD data were similar over the test section. However, the correlation of the IC results with the selected spot tests depended on several factors including the accuracy of the global positioning system and the data reduction approach. The LWD device seems to be a proper accompanying device for verifying the less-stiff areas detected from the IC data.

Pavement surface characteristics affect highway safety, comfort, and durability. Over decades the most widely used surface evaluation method depends on human observations, while automation has become possible in recent years on collecting data and producing results for certain aspects of pavement performance. This paper presents the application of the newly developed 1mm 3D laser imaging technology for long-term performance monitoring of pavement surface characteristics. Six long term pavement performance (LTPP) warm mix asphalt (WMA) overlay experiment (SPS-10) sections and six high friction surface treatment (HFST) sites in Oklahoma are tested. The 3D surface data are used for comprehensive evaluation of pavement surface distress, transverse profiling for rutting, longitudinal profiling for roughness and macrotexture for safety analysis. In addition, pavement friction data are continuously collected at highway speed using a Grip Tester to monitor the variation of pavement surface skid resistance. Data collection is performed every three months and the performance of surface characteristics is evaluated. Results from this study can be used for the evaluation of long-term pavement performance and the effectiveness of various maintenance treatments.

Unmanned aircraft systems (UAS) offer unparalleled and unprecedented opportunities for performing cost-effective and efficient health monitoring and management of transportation infrastructure systems. This paper introduces a network of UAS that can be utilized to perform an array of tasks such as surveillance, 3-D rendering, high definition (HD) visual monitoring, light detection and ranging (LiDAR) tests, infrared thermography, and non-destructive evaluation (NDE). These methods can be used for monitoring infrastructure defects to accomplish detailed inventory, survey, and condition assessment of transportation infrastructure systems. The modular and multi-purpose nature of UAS wherein UAS can be equipped with a variety of application-specific payloads such as LiDAR and infrared thermal imaging camera resulting in a range of civil and transportation applications is highlighted. Overall, the paper delivers a vision for next-generation, autonomous health monitoring of transportation infrastructure systems using UAS.

Sustainable super water/ice-repellent pavements are gaining attention as a smart solution for mitigating problems associated with winter pavement maintenance of roadways and airfields. Such smart pavements can facilitate surface drainage and prevent or curb ice formation or snow accumulation. While a conventional method for melting ice and snow is the use of deicing chemicals, such materials can transfer to the surface of nanotechnology-based pavements and influence their water/ice-repellency by changing the chemistry of water or ice. This study focused on characterizing the degree of hydrophobicity of Portland cement concrete (PCC) nano-coated with polytetrafluoroethylene/polyetheretherketone (PTFE/PEEK). A layer-by-layer (LBL) spray deposition technique was used for spraying the binding agent and water-repellent materials. The liquid-repellency was characterized by measuring the static liquid contact angles (LCAs) and calculating the works of adhesion (WA). The liquid types used included distilled water and two types of deicing chemicals prepared by dissolving salts in distilled water. Data analysis results revealed that salt contamination improves the water-repellency of nano-coated surfaces.