Pavement Test Research Articles

Asphalt pavement structural competency during staged airfield runway construction strategy

ABSTRACT This paper reports the results from a full-scale evaluation of asphalt pavement structural competency during a multi-stage construction strategy. The staged pavement construction included three stages: (1) new conventional asphalt pavement, (2) unpaved full depth reclaimed (FDR) pavement, and (3) thin surface asphalt paved FDR layer. The full-scale pavement sections consisted of a standard and substandard pavement structural design. The accelerated pavement testing (APT) experiments were executed by simulating the loading conditions of an aircraft with a critical combination of relatively high wheel load and high tire inflation pressure. The structural capacity of the pavement test items was monitored using a falling weight deflectometer. From this study, the staged pavement construction concept was found to be a potential approach to extend the service life of asphalt pavements. Unpaved FDR layers are structurally competent to support a low volume of aircraft operations. These findings support the transition to the use of asphalt pavements containing an FDR layer from an experimental to routine rehabilitation practice for airfield asphalt pavements.

Machine Learning Approach to Rapidly Evaluate Curling of Concrete Pavement

This paper focuses on the methodology for evaluating the degree of total curling in concrete pavement using machine learning. Deflection induced by falling weight deflectometer (FWD) testing is known as a direct correlation to total curling including built-in and daily curling. However, deflection measurement in the in-service road is also affected by others, such as environmental conditions, pavement geometry, subgrade stiffness, and mixture design. Thus, it is challenging to determine the level of curling from FWD data due to the complexity of influencing parameters. To navigate this complexity, prominent machine learning models are exploited to identify a non-linear relationship between curling and FWD deflections. A finite-element simulation of FWD is conducted to generate a vast data set, and a robust regression model is trained to estimate the total effective temperature difference (TETD) to quantify the effects of curling. Since input parameters for testing pavements can be measurable in the field, curling from TETD can be readily obtained using the proposed methodology. Comparative simulations highlight that the proposed models, with an MAE less than 0.5 °C significantly outperform the multiple regression performance, which registers an MAE of 3.45 °C in TETD, particularly in offering cost-effective and noise-tolerant prediction.

Comparison of surface layers responses under heavy truck loadings on new and rehabilitated pavement with different interface bond conditions

The integrity and functionality of road pavements are vital for ensuring safe and efficient transportation networks. However, surface layers are prone to various forms of deterioration. This study investigates the responses of two pavement structures-one newly constructed and one rehabilitated-under traffic loading, through experimental tests conducted on an accelerated pavement testing facility (APT) and numerical simulations using the Viscoroute©2.0 software. Focus is placed on surface layer behavior, with an emphasis on understanding the behavior of interfaces between the asphalt layers. The findings show that the new pavement structure exhibits good bonding and continuous strain distribution, while the reinforced pavement structure exhibits partial sliding at the interface and strain discontinuity. For the new pavement structure, the strains are well predicted using a bonded interface, while for the rehabilitated pavement structure, the strains are predicted using a thin elastic interface layer with a low elastic modulus.

Evaluation of carbon nanotube (CNT) cement-based traffic sensor incorporating steel slag based on Accelerated Pavement Test (APT)

ABSTRACT In this study, a carbon nanotube (CNT) cement composite containing CNT and steel slag was developed and its application in traffic information sensing was studied. The mix ratio of steel slag cement mortar matrix and CNT cement composite was determined by mechanical properties and electrical conductivity tests. Then the CNT cement composite intelligent sensing device was prepared and an Accelerated Pavement Test equipment was used to test its piezoresistive response curve. The test results show that steel slag and CNT enhance mechanical properties and electrical conductivity. The vehicle speed and wheelbase were calculated based on the piezoresistive response results, and the calculation errors of the wheel speed (0.375 and 0.844 km/h) were less than 10% and 20%, respectively. The wheelbase estimate has a maximum error of approximately 12% and 15% for wheel speeds of 0.375 and 0.844 km/h, respectively. Therefore, the CNT cement composite containing steel slag developed in this study has the potential to serve as a traffic sensor.

Evaluation of the effect of binder type and layer thickness on the performnce of open graded friction courses

To improve the long-term durability and functionality of open graded friction courses (OGFC), the Florida Department of Transportation (FDOT) investigated the use of a highly modified asphalt binder and increased thickness using Accelerated Pavement Testing (APT). A total of six test sections with combinations of two modified binder types (PG 76–22 and PG 82–22) and three lift thicknesses of 0.75 (19.05 mm), 1.25 (31.75 mm) and 2 (50.8) inches were constructed at FDOT’s APT facility. Accelerated loading was performed using a Heavy Vehicle Simulator (HVS) to evaluate the relative rutting performance of the test sections. Supplementary field and laboratory tests to evaluate tensile strength, Cantabro loss, field permeability, surface characteristics, and asphalt binder properties were also conducted. Test results indicated that the use of PG 82–22 polymer modified asphalt (PMA) binder may be beneficial to improve long-term durability of the OGFC. Thicker layers of OGFC were found to have considerably lower durability. It is recommended that the use of a highly modified PMA asphalt binder in OGFC layers be considered when raveling and other durability issues are of concern.

Laboratory and Field Performance Evaluation of NMAS 9.5, 8.0, and 5.6 mm SMA Mixtures for Sustainable Pavement

This study evaluates the laboratory and field performance of stone mastic asphalt (SMA) mixtures with nominal maximum aggregate sizes (NMAS) of 9.5, 8.0, and 5.6 mm. Aggregates and fine aggregates of these sizes were produced using an impact crusher and a polyurethane screen. Mix designs for SMA overlays on aged concrete pavement were developed. Laboratory tests assessed rutting performance using full-scale accelerated pavement testing (APT) equipment and reflective cracking resistance using an asphalt mixture performance tester (AMPT). Field evaluations included noise reduction using CPX equipment, skid resistance using SN equipment, and bond strength using field cores. Results showed that for 8.0 mm SMA mixtures to achieve the same rutting performance as 9.5 mm SMA, PG76-22 grade binder was required, whereas 5.6 mm SMA required PG82-22. The 8.0 and 5.6 mm SMA mixtures showed 22.2% and 25% reduced crack progression, respectively, compared with the 9.5 mm SMA mixtures. Field evaluations indicated that 8.0 mm and 5.6 mm SMA pavements reduced tire–pavement noise by 1.7 and 0.8 dB, increased skid resistance by 8.5% and 2.0%, and enhanced shear bond strength by 150%, compared with 9.5 mm SMA. Overall, the 8.0 mm SMA mixture on aged concrete pavement demonstrated superior durability and functionality toward sustainable pavement systems.

Comparative Evaluation of Falling Weight Deflectometer, Traffic Speed Deflectometer and Rapid Pavement Tester in Deflection Measurement

This study intends to compare deflections obtained from traffic speed deflection devices (TSDDs) with the deflections of the falling weight deflectometer (FWD). For this purpose, deflections were measured on five sections of three roads in the Norwegian road network using traffic speed deflectometer (TSD) and rapid pavement tester (Raptor). Deflections were also measured using FWD at three different temperatures and the curves of FWD deflections versus temperature (FWD temperature-dependent deflection curves) were obtained. These curves were used to correct the effect of temperature difference. It was shown that both TSD and Raptor have the potential to detect structural deficiencies; however, TSD had better consistency with FWD with regard to deflection values and deflection basin parameters. A refinement was then made to make the Raptor data more consistent with FWD data. Calculating bearing capacity before and after refinement revealed that refining Raptor data can substantially increase the consistency between Raptor and FWD.

Dynamic response and sound radiation of cracked asphalt pavements under moving loads and variable thermal profiles

ABSTRACT This study investigates the acoustic performance and dynamic response of cracked, viscoelastic porous asphalt pavements under moving loads and variable thermal conditions. Realistic pavement cracks are modelled using an advanced line spring model with fracture compliance coefficients. The novelty lies in the synergistic integration of a heterogeneous triple-porosity media model, a non-uniform depth-dependent temperature profile, and an advanced fracture mechanics-based line spring model with arbitrary crack orientation. Variations in temperature that are uniform, linear, and nonlinear with respect to the thickness layer axis are taken into account. The governing equations are derived by Hamilton’s principle and solved analytically via Fourier-Laplace transforms. The acoustic pressure is first-time predicted through Rayleigh integral analysis. Durbin’s numerical inversion validates the model’s accuracy versus sophisticated finite element simulations. Parametric analysis offers new insights into the effects of crack length, pore size distribution, loading frequency, and thermal gradients on noise pollution and fatigue cracking. The integrated chemo-thermo-mechanical modelling enables optimal structural design and accelerated pavement testing to limit acoustic radiation and premature failure in porous asphalt pavements. It allows for the development of noise-reducing porous asphalt mixtures by modifying aggregate gradation, binder content, and air void distribution.

Fatigue cracking prediction of RIOHTrack full-scale test track based on variable-order fractional Burgers model

We propose a modified thermal cracking (MTC) model in this paper, which utilizes the evolution of crack propagation to predict the number and density of cracks that will form on the RIOHTrack full-scale test track. We incorporate the variable-order fractional Burgers model as an important component of the thermal cracking (TC) model, for calculating the creep compliance. Furthermore, we apply the Levenberg–Marquardt (LM) algorithm as a data-driven approach, for parameter fitting. The MTC model is constructed technically through creep compliance approximation compute and parameter fitting as follows. First, we employ the variable-order fractional Burgers model to calculate the asymptotic creep compliance of each pavement segment within the RIOHTrack full-scale test track. More precisely, we derive the explicit asymptotic expansion of creep compliance based on the variable-order fractional Burgers model. Such an asymptotic expansion represented by the Gamma function is a simplified representation of the creep compliance, and it ensures that the fitting accuracy R2 is greater than 0.87. Parameter fitting of the creep compliance is based on the RIOHTrack full-scale pavement test data, using the LM algorithm. Then, the creep compliance in the original TC model is mathematically upgraded to the above variable-order fractional approximation form, and parameters in the MTC model are numerically estimated using the LM algorithm based on prior knowledge from the RIOHTrack test data. Our prediction analyses based on the RIOHTrack data demonstrate the superior performance of the proposed MTC model.

Assessment of mechanical performance of electrically conductive asphalt pavements using accelerated pavement testing

ABSTRACT Electrically Conductive Asphalt (ECA) pavements are a promising technology for preventing snow and ice accumulation on roadways. This study assesses the mechanical performance of ECA pavements using Accelerated Pavement Testing (APT). Three pavement test strips were constructed in New Jersey: a traditional asphalt layer as test strip-I, an ECA mastic prepared using a combination of asphalt binder and conductive fibres (strip-II), and an ECA-HPTO (high performance thin overlay mixture) layer containing graphite and carbon fibres (strip-III). Each test strip was instrumented with asphalt strain gauges (ASGs), pressure cells, and thermocouples to evaluate the structural responses. A Heavy Vehicle Simulator (HVS) was used to apply 300,000 passes on each test strip using a 40-kN truck tire. The structural integrity of the test strips was evaluated by conducting Heavy Weight Deflectometer (HWD) testing before and after HVS loading. Data from the ASGs revealed that strip III exhibited the highest cracking resistance (nearly 2 times less tensile strain). The rut depths in all test strips were negligible (less than 2 mm). ECA mastic and steel electrodes in the ECA layer impact the structural integrity of test strips, with variations in HWD deflection behaviour indicating the role of electrode spacing in maintaining pavement stability.

Preparation and thermal performance testing of diatomite-modified asphalt pavements

In this study, the efficacy of diatomite as a modifier in asphalt pavements is thoroughly examined. The research primarily focuses on evaluating the thermal performance of asphalt mixtures modified with varying diatomite contents. Key findings indicate significant improvements in the rutting resistance, with the dynamic stability of the 15% diatomite mixture being 3.4 times higher than the control mixture. Additionally, the 10% diatomite mixture shows a 20% increase in bending strain energy density, enhancing low-temperature performance. However, a diatomite content beyond 10% tends to diminish these benefits. Fatigue life at 10% diatomite content is improved by 18%–24%, demonstrating the material’s potential in extending pavement longevity. Water stability tests also reveal notable improvements, with the 15% diatomite mixture exhibiting a 15% increase in tensile strength ratio post-water conditioning. These results collectively establish diatomite as a cost-effective and efficient modifier for asphalt pavements, promoting enhanced durability and performance.

Validating a finite element model for rigid aircraft pavement load transfer against full scale testing

ABSTRACT Rigid aircraft pavements are generally comprised of unreinforced concrete slabs constructed on a bound or granular sub-base layer, over the natural or constructed subgrade or fill. Important to any rigid aircraft pavement design and construction are the joints between the concrete slabs. The joints control shrinkage cracks during curing, allow for thermal expansion and contraction during temperature cycles, they isolate concrete slabs from structural penetrations and importantly, provide load transfer between adjacent slabs. Load transfer is commonly modelled using finite element methods; however, any new model should be validated against observed physical events. Recently, full-scale testing was performed at the Federal Aviation Authority National Airport Pavement Testing Facility as part of Construction Cycle 8 (CC8), which investigated load transfer characteristics for a range of joint types. The results from CC8 tests provide up-to-date stress and strain values to validate any new finite element model. This paper presents the development of a finite element model to predict load transfer of a doweled construction joint, and its validation against CC8 test results. The model showed good agreement with CC8 test results, and now that it is validated, will be used to investigate innovative joint solutions for rigid aircraft pavements.

Tracking particle displacements in unbound aggregate layers of roadways

ABSTRACT Accelerated pavement tests were conducted on reduced-scale pavement sections under controlled environmental conditions using the model Mobile Load Simulator (MLS11). A unique monitoring system was developed as part of this study to evaluate the response of the pavement sections under rolling wheel loads. The performance of the sections with an increasing number of wheel passes was evaluated by measuring the surface rutting as well as the subsurface displacement of particles within the base layer. The sections were built in modular frames constructed above grade to facilitate access to the particles within the base layer from the sides of the frame. Surface rutting was measured intermittently using an in-house developed laser profilometer. A unique, cost-effective assembly of 30 linear position transducers was designed to continuously track the displacements of artificial particles within the base layer. The displacements, measured with the new system, were found to be particularly suitable to generate horizontal permanent displacement fields and strain fields. Overall, the new developments allowed comprehensive monitoring of the internal response of pavements subjected to wheel loading.

Colour pervious concrete pavements applied to bikeway track: mechanical, hydraulic and functional performances

ABSTRACT Pervious concrete pavement test sections employing coloured permeable concrete were constructed as an experimental bicycle lane. For two of the sections, coloured concrete was used with pigment addition consisting of Fe2O3 (red) and Cr2O2 (green). The impacts on the resistance and stiffness of the concretes when using these pigments were analysed in relation to the reference concrete (grey). Alterations in plasticiser dosage during mixing were readily observed with the red concrete. The flexural strength increased substantially in the case of the red coloured concrete, as well as the modulus of elasticity of the material. Initial infiltration rates decreased with the use of coloured pigments, especially for red concrete, with expressive drops in permeability. Simultaneously, the resistance to friction given by the British Pendulum Number was reduced due to the use of red or green pigments. The consequences of using red pigment with a very high grains specific surface are discussed, since they are advantageous in the case of mechanical responses eventually inferior in terms of hydraulic and functional aspects.

Reimagining unbound road pavement technology: Integrating testing, design, construction and performance in the post-digital era

The Industry 4.0 revolution signifies a pivotal transition in pavement technology, emphasising the integration of digital and physical systems to revamp traditional, empirical-based pavement design, construction, and maintenance practices. This shift promises enhanced efficiency, sustainability, and a move towards integrated practices, highlighted by adopting “Digital Twin” technology. Unlike traditional Building Information Modeling (BIM), Digital Twin technology offers a real-time, dynamic representation of physical infrastructure, enabling improved asset management through distributed sensing and predictive performance analytics. Leveraging findings from the Australian Research Council (ARC)’s Industry Transformation Research Hub for Smart Next Generation Transport Pavements (SPARC Hub), this paper focuses on the integration of pavement testing, design, construction, condition assessment and asset management into the lifecycle of unbound road pavements. The paper outlines how such technological integration streamlines decision-making processes and significantly boosts the functionality and longevity of pavement infrastructures. Despite facing challenges like cost, data security, and the need for specialised skills, the potential for digital technologies to improve pavement durability, efficiency, and sustainability is significant. Future research directions are identified to overcome implementation barriers, explore untapped technological potentials, and assess the sustainability benefits of digital approaches in pavement engineering, aiming to forge more resilient, efficient, and sustainable road networks for future generations.

Integrating Tensometer Measurements, Elastic Half-Space Modeling, and Long-Term Pavement Performance Data into a Mechanistic–Empirical Pavement Performance Model

Pavement performance models (PPMs) are utilized to predict pavement network conditions which is an essential part of any sustainable pavement management system (PMS). The reliability of a PMS and its outputs is proportional to the reliability of the PPM used. This article describes a mechanistic–empirical pavement performance model based on pavement response parameters—strains calculated in the pavement layers measured by tensometers embedded in the pavement surface and verified by calculations in the elastic half-space model and supplemented by empirical data from long-term pavement performance monitoring and accelerated pavement testing. Hence, the herein described PPM combines pavement serviceability evaluation, pavement bearing capacity, and the physico-mechanistic properties of paving materials. The analytical methods which were used to ascertain the physico-mechanistic characteristics, the material fatigue degradation model, and the surface degradation, unevenness in particular, are described. A comparison of the empirical PPM created in the last century used by the national road administrator to this day and the newly created PPM is presented. The comparison shows the difference in the calculated socio-economic benefits and subsequent cost–benefit analysis results. The comparison shows that the use of the old PPM may have produced false economic evaluation results that have led to poor decision making, partially explaining the unsustainable trend of road network management in our country.

Laboratory and Field Performance Evaluation of Cracking of Airfield Warm Mix Asphalt with Reclaimed Asphalt Pavement at the National Airport Pavement and Materials Research Center

The U.S. Federal Aviation Administration is exploring initiatives to decrease transportation greenhouse gas emissions by developing carbon reduction strategies, including using low-embodied carbon materials, such as reclaimed asphalt pavement (RAP), in airport pavement construction. However, verifying RAP’s viability for airfield pavements with laboratory and field performance measures is essential. This study compared the cracking susceptibility of a P-401 hot mix asphalt and warm mix asphalt (WMA)+RAP airfield mixes using laboratory performance tests and conducted a preliminary evaluation of pavement responses from accelerated pavement testing (APT) fatigue tests. The observations and outcomes presented in this paper found that adding 20% of recycled materials with WMA additives had a decreasing impact in mix performance but did not overly affect the asphalt mix properties, as cracking properties from the different test procedures were found with comparable outcomes. Additional observations from strain gauges and temperature probes in the National Airport Pavement and Materials Research Center test cycle 2 APT fatigue test sections showed that the maximum tensile strains in the WMA surface lane 5 south section were consistently higher than those in the WMA+RAP lane 6 south section, which may be because of the higher load level that it was exposed. Additionally, the hardened or aged RAP binder in the entire lane 6 south section may have increased its stiffness, resulting in lower strain levels than in the lane 5 south section. Notably, both sections showed an increase in tensile strains with an increase in asphalt concrete temperature, which confirmed the temperature dependency behavior of asphalt concrete.

Design, Placement, and Laboratory and Field Evaluation of Rejuvenated Cold Recycled Asphalt Mixtures

Cold recycled (CR) pavements, the combination of reclaimed asphalt pavement and a recycling agent (foamed or emulsified asphalt) at ambient temperatures, can provide a sustainable method to rehabilitate, reconstruct, and construct roadways. However, CR pavement is not a one-for-one replacement of typical asphalt base mixtures. To utilize CR pavements as an alternative to a typical asphalt base mixture or surface course, additional materials such as rejuvenating agents may be needed. This research focuses on the formulation, plant production, and placement on the National Center for Asphalt Technology pavement test track off-ramp, and laboratory evaluation of three rejuvenated CR mixtures, one foamed asphalt CR mixture, and an engineered emulsion CR mixture. These mixtures were subjected to strength and moisture susceptibility testing, along with the indirect tensile asphalt cracking test (IDEAL-CT) and high-temperature indirect tensile test (HT-IDT). The influence of laboratory production versus plant production and the impact of rejuvenators on mixture performance and density were investigated. International roughness index and rut depth data for the off-ramp sections indicate adequate performance, except for the anionic emulsion with bio-based rejuvenator section. Laboratory test results indicate that the addition of rejuvenators into two of the three CR mixtures increased density and decreased moisture susceptibility and increased the CTIndex by at least 35% compared to non-rejuvenated CR mixtures. HT-IDT strengths revealed that two of the three rejuvenated mixtures performed slightly below the non-rejuvenated mixtures.

Accelerated Pavement Testing of Re-Recycled Cold Central Plant Recycled Asphalt Mixtures

Cold central plant recycled asphalt mixtures (CCPR) have been shown to provide a high-quality, economical, and environmentally conscious asphalt base mixture. Existing literature, however, does not indicate what would be an appropriate future rehabilitation method for a pavement that includes CCPR. Given the previously cited benefits of CCPR, it is logical to ask whether a CCPR can be re-recycled and, if so, how will it perform? This paper presents a study of a test section containing a re-recycled CCPR placed at the National Center for Asphalt Technology Test Track. CCPR from a Virginia Department of Transport study on the Test Track was recovered, re-recycled, and placed at 5-in. thick with a 2-in. asphalt concrete (AC) overlay. In preparing for a re-recycled CCPR layer, milling an existing CCPR layer resulted in a coarser gradation and lower indirect tensile strength values. Initially, the re-recycled CCPR test section did not perform well owing to moisture in the aggregate base present during construction of the re-recycled CCPR layer. It is suspected that this moisture negatively affected the curing of the re-recycled CCPR layer. Thus, the re-recycled CCPR layer was milled and re-recycled again (3rd generation re-recycled CCPR) and placed at 5-in. thick with a 2-in. AC overlay. The 3rd generation re-recycled CCPR performed well through 3 million equivalent single axle loads (ESALs), the same number of ESALs that resulted in fatigue cracking and rutting failures in the initial re-recycled CCPR.

Service performance evaluation of light-transmitting concrete lane markings on highways based on accelerated pavement testing

Applying light-transmitting concrete (LTC) to highway lane markings is a novel idea to increase the visual recognition distance and promote traffic safety. However, compared to its excellent visual recognition performance, its service performance has received little attention in the current research. This paper conducted an accelerated pavement test to investigate the behaviour of rutting depth, British Pendulum Number (BPN) and water permeability coefficient of the LTC lane markings. The results show that rutting depth of LTC is lower than that of asphalt pavement. As a result, small height steps appeared at the seam of the two parts. For the anti-sliding performance represented by the BPN, the BPN of LTC gradually exceeds asphalt pavement and maintains a slightly higher value. For the water permeability coefficient, the LTC is almost un-permeable, avoiding water damage during service. According to these findings, the LTC lane markings meet the requirements of highway service performance. .