Pavement Layers Research Articles

Finite Element Analysis of PCCP Curling and Roughness

Smoothness specifications for newly built Portland Cement Concrete Pavements (PCCP) in Kansas have evolved over the last two decades through applications and a number of revisions. However, some PCCP sections built under current specifications in the smoothness bonus range experience rapid loss of smoothness with time. Sometimes this happens even before the sections are opened to traffic. It is believed that this loss results from curling due to the temperature differential between the pavement top and bottom surfaces. In this study, threedimensional simulation of curling of PCCP has been presented using a finite element (FE) software, ANSYS. A number of FE models were built to simulate several newly built PCCP sections in Kansas. The sections were modeled as three-layer systems with cement-treated base and lime-treated subgrade. Layer materials were modeled as linear elastic and the properties were obtained from the tests conducted during construction. Pavement layers and steel dowel bars were modeled using 3- dimensional solid (brick) elements. The complex interaction of the slab with the dowel bars was modeled as a contact problem. Regression models were developed for the curling deflection and International Roughness Index (IRI), a roughness statistics resulting from the curled profiles, based on different simulation parameters. The results obtained from the simulations show that the curling deflection and IRI calculated from the deflected slab profiles are affected by the slab thickness, compressive strengths of the concrete slab and base layers, and the temperature differential between the pavement top and bottom surfaces. Both curling deflection and IRI increase with an increase in temperature differential and compressive strength of the stabilized base layer. Higher slab thickness and concrete compressive strength would result in lower curling deflection and IRI values.

A Pilot Study of Instrumented Unbonded Concrete Overlay in Toronto

Unbonded concrete overlays provide structural rehabilitation and can be cost effective when the existing pavements are highly distressed and/or removal of existing pavement layers is not desirable. This paper describes a pilot study, which involves a three way partnership between the University of Waterloo, the Cement Association of Canada and the City of Toronto, to evaluate and document the performance of the first instrumented unbonded concrete overlay in Canada. The rehabilitation area is located at a heavily-trafficked intersection on Bloor Street and Aukland Road in the City of Toronto. The large volumes of bus traffic from the nearby subway station caused significant damage to the pavement structure. The rehabilitation design was composed of placing an unbonded concrete overlay on Bloor Street and replacing the section on Aukland Road with full depth exposed concrete. Twelve strain gauges are embedded in the concrete layer and they are strategically located along the wheel paths of the buses. The sensors are being monitored to assess long-term performance of the concrete overlay and the full depth concrete subjected to traffic and climatic loads. This paper outlines the design parameters, site conditions, and material properties of the overlay. The construction and full-scale instrumentation of this project are described, followed by preliminary analyses of up-to-date performance records.

A Numerical Study of the Effect of Geogrid on Road Way Reinforced with Layers of Pavements

A Numerical Study of the Effect of Geogrid on Road Way Reinforced with Layers of Pavements

The high value utilization characteristics of coal gangue powder with emulsified asphalt mastic through rheological and viscoelastic damage theory

In order to solve the problems of rutting and early fatigue cracks in emulsified asphalt cold recycled pavement, and the shortage of natural stone resources and new environmental hazards caused by the use of traditional limestone powder filler. In this study, coal gangue powder was added to prepare Emulsified Asphalt Mastic (EAM) to improve the rheological properties and fatigue performance. A series of tests, including frequency scanning, temperature scanning, Multiple Stress Creep Recovery (MSCR), Linear Amplitude Scanning (LAS), and Fourier Transform Infrared spectroscopy (FTIR) were conducted. Through rheology theory, viscoelastic damage theory, the impact of three fillers: Coal Gangue Powder (CGP), Limestone Powder (LP) and Portland Cement (PC), as well as four kinds of Powder-Binder ratios (P/B) (0.6, 0.9, 1.2, 1.5) on the high temperature rheology and medium temperature fatigue performance of EAM was analyzed. The findings reveal that the filler content has a great influence on the proportion of viscoelastic components of EAM in the low frequency domain. The complex shear modulus (G*) and phase angle (δ) of EAM were suitable for Christensen-Anderson-Marasteanu model (CAM) model in the wide frequency domain. Increasing the filler content and Rotating Thin Film Oven Test (RTFOT) aging can improve the high-temperature stability and stress sensitivity of EAM, but it reduced its fatigue resistance. The high temperature performance of EAM containing PC and CGP exhibit superior high-temperature performance compared to LP fillers. Conversely, LP mastic demonstrate superior anti-fatigue performance under actual strain levels in both thin and thick asphalt pavement layers, surpassing the performance of PC mastic and CGP mastic. Therefore, coal gangue powder can be used as a new type of green filler to replace limestone powder. An appropriate amount of incorporation can improve the high temperature stability of the mortar and does not have a huge impact on the fatigue performance. The most suitable range of P/B is identified as 0.6–1.0 when utilizing LP as the filler, 1.2–1.5 when utilizing PC or CGP as the filler.

Literary Review of Incorporation of Plastic Waste in Pavement Layers

Literary Review of Incorporation of Plastic Waste in Pavement Layers

Soil-aggregate-cement mixtures for base pavement layers: A strength and stiffness characterization

Pavements subjected to high volume load require a robust structure. In Brazil, cemented base layer is usually used instead of asphalt concrete thick layer due to cost issues. Soil-aggregate-cement (SAC) mixture is an alternative in pavement application, but the lack of design and dosage protocols hinders the understanding of the parameters influencing its mechanical behavior. This study presents a mechanical characterization of SAC mixtures in terms of strength (UCS and ITS) and stiffness (Mr), focusing on integrating the needs of pavement design to dosage purposes. For this, different SAC mixtures are produced, varying the soil-aggregate proportion (30:70 and 20:80) and cement content (3, 5 and 7 %). Mechanical properties were measured on cured mixtures at 0, 7 and 28 days and compared to structural responses of hypothetical pavements computed by mechanistic analysis. The results indicate a potential for using SAC mixtures in base layers due to their higher strength and stiffness. Predictive models relating ITS x UCS, Mr x UCS, and Mr x ITS with good statistical fit were proposed to assist researchers and engineers in selecting mixtures more adequate and durable for pavement applications, based on the concept of limiting the tensile stress acting on the cemented base course.

Evaluation and prediction of interface fatigue performance between asphalt pavement layers: application of supervised machine learning techniques

ABSTRACT Assessing interlayer fatigue performance is crucial for the durability and structural integrity of asphalt pavements. This study introduces supervised machine learning techniques to estimate interface fatigue life (IFL) and interface shear stiffness (ISS) between asphalt layers. Using 84 lab-prepared specimens tested under varying conditions-temperature, normal pressure, loading frequency and shear stress, with a constant tack coat type and application rate-predictive models were trained and validated. The influence of each factor on fatigue indices was evaluated before employing genetic expression programming (GEP) and artificial neural networks (ANNs) for prediction. Model efficacy was quantified using statistical metrics, highlighting the robustness of ANN models (R² = 0.980, RMSE = 0.826, MAE = 0.636 for ISS and R² = 0.972, RMSE = 0.498, MAE = 0.383 for IFL) over GEP models (R² = 0.921, RMSE = 1.402, MAE = 1.079 for ISS and R² = 0.913, RMSE = 0.623, MAE = 0.479 for IFL). Sensitivity analysis confirmed alignment with experimental data, identifying temperature as the most critical factor and frequency as the least influential on interface fatigue performance. These findings could lead to more reliable and efficient designs of interlayer bonding in asphalt pavement layers.

Long-term rutting prediction of gussasphalt steel bridge deck pavement based on comprehensive finite element modelling

ABSTRACT Gussasphalt is widely used for steel bridge deck pavements, but it is prone to rutting during the operational stage. This paper proposes a finite element-based method for predicting rutting in gussasphalt steel bridge deck pavements. Based on the Nanjing Yangtze River Fourth Bridge project, asphalt mixture specimens were prepared and tested in the laboratory. The viscoelastic-plastic constitutive model was fitted via dynamic modulus test and uniaxial repeated loading creep test results. Wheel track tests were conducted to validate the numerical model. The temperature gradient was obtained using actual environmental data and validated using actual data from buried thermocouples. Based on the equivalent conversion and simplification of traffic loads, the permanent deformation of the pavement layer was calculated using both the viscoelastic-plastic constitutive model and the time-hardening creep constitutive model. The viscoelastic-plastic constitutive model yields an average relative error of 25% and an absolute error of 0.57 mm, while the time-hardening creep constitutive model shows an average relative error of 40% and an absolute error of 1 mm. The results indicate that the viscoelastic-plastic constitutive model can more accurately predict the long-term rutting of the steel bridge deck pavement.

Effect of Sand Addition on Laterite Soil Stabilization.

Lateritic soils, particularly abundant in tropical regions, have been successfully used in the construction of unbound layers of flexible pavements in Brazil since the 1970s. Despite their potential, these soils are often discarded or only recommended after stabilization processes, based on traditional parameters such as gradation requirements and Atterberg limits. This study investigates the mechanical characteristics of a lateritic soil from Roraima, focusing on its resilient modulus and permanent deformation properties, assessed through repeated load triaxial tests. Specifically, this research examines the effect of adding 20% sand on the mechanical behavior of the material. The results indicate that sand addition did not significantly improve the mechanical performance. The laterite-sand mixture exhibited an average resilient modulus (RM) of 744 MPa, lower than the 790 MPa of pure lateritic soil, suggesting that pure laterite remains suitable for pavement applications. Furthermore, the permanent deformation analysis revealed that the mixture with sand experienced nearly twice the plastic strain compared to pure laterite, which demonstrated superior accommodation under repeated loading. In the shakedown analysis, pure laterite exhibited a more stable performance, indicating greater durability in pavement applications. These findings highlight the importance of understanding the mechanical behavior of lateritic soils beyond conventional testing methods, emphasizing the potential of pure laterite as a viable alternative to enhance the strength and durability of pavement structures.

Backcalculation of asphalt pavement materials’ moduli considering absolute and relative errors

Backcalculation is a procedure used to estimate the material properties of pavement layers from the results of non-destructive tests, such as the Falling Weight Deflectometer (FWD). This procedure is important to assess the quality of a pavement structure during its construction and/or to monitor its condition during its lifespan. The Finite Element Method (FEM) can be used to evaluate the pavement deflections, provided that the loading, geometry, and material properties of each pavement layer are known. Thus, assuming a linear elastic behavior and known Poisson’s ratios and layer thicknesses, the backcalculation procedure consists of the determination of the set of elastic moduli that minimize the differences between the simulated (FEM) and measured (FWD) deflections. Different error measures can be adopted to assess the quality of the model fitting. The resulting Nonlinear Least Squares (NLS) problem can be solved using classical algorithms, such as Gauss-Newton and Levenberg–Marquardt methods. However, these algorithms present convergence problems for NLS with large errors. In this case, it can be necessary to use of hybrid algorithms based on a combination of Gauss-Newton and BFGS methods. The robustness, accuracy, and computational efficiency of classical and hybrid algorithms are compared in the backcalculation of asphalt pavements.

Accelerating Plastic Pollution Mitigation through Sustainable Urban Infrastructure Development

Plastic waste plagues both land and aquatic environments. The surface layer refers to the road pavement layer that comes into direct contact with a vehicle's wheel surface. The surface layer distributes wheel load far more evenly than the layer underneath. The surface layer design incorporates top-notch materials that can be used as additives to enhance the quality of the asphalt mixture. This study evaluates the asphalt mixture's durability using Marshall characteristics and Cantabria tests carried out in a lab setting. An ideal asphalt concentration of 5.25% is obtained. Low Density Polyethylene (LDPE) is added to the asphalt mixture at various contents, 0%, 2%, 4%, 6%, and 8%. The study's findings indicate that adding plastic waste to the asphalt mixture can enhance its performance. The two main mitigating actions are probably plastic prohibition laws and public awareness campaigns. To evaluate the possible environmental effects and resources utilized over the course of a plastic product's life span, researchers stress the importance of its life cycle assessment and circularity. Innovations are necessary to minimize, reuse, recycle, recover, and develop environmentally friendly plastic substitutes. By empowering and educating communities and citizens on how to reduce plastic pollution and use alternative plastic solutions, governments must enforce and promote collective action. This research must prioritize addressing plastic waste as a global issue.

Influence of Sand Gradation on Volumetric Weigh and Compressive Strength of Pavement Foam Mortar

Abstract Foam mortar is a substitute for sub-base layers and base layers in road pavement construction on peat soil, which has the advantages of lightness, strength, and self-compacting. Sand is one of the building blocks of foam mortar. The purpose of the study was to analyze the effect of the gradation of sand on the resulting physical and mechanical properties of foam mortar (foam concrete). In this research, six gradations of sand were made (gradations of 3 sand sources and 3 gradations based on pusjatan standards) and then used in the manufacture of foam mortar and analyzed for volumetric weigh and compressive strength. Foam mortar from the six gradations of sand, it is concluded that gradation no. 6 (lower limit of pusjatan gradation) with a value of volumetric weigh is 0.97 t/m3 does not float perfectly in water, and no. 1 to 5 (gradation of 3 sand sources and 2 gradations of Pusjatan upper limit and middle) with a volumetric weigh is 0.83 t/m3 - 0.93 t/m3 floats in water. The compressive strength values of the 6 gradations are above 2000 kPa and can be used as foundation layers in road pavements.

Diffusive and convective transport properties and pore-network characteristics of recycled, compacted concrete aggregates for use as road pavement materials

Gas transport parameters, such as gas diffusivity (Dp/D0) and air permeability (ka) of materials, and pore-network properties play important roles in the movement of gases and water vapor in road pavement layers and contribute to assessment of the urban heat island effect in urban areas. This study carried out a series of laboratory tests to measure the Dp/D0 and ka of recycled concrete aggregates (RCA) used for road base and subbase materials at variable fines contents and moisture conditions. The results revealed bimodal patterns in both water retention and the derived pore-size distribution curves for tested RCA samples. Both fines and initial moisture contents under compaction affected the characteristics of pore networks and structures, such as the effective pore space and water blockage effects that control the gas transport parameters of porous media in RCA samples. Especially, the increase of fines significantly reduced the pore-network parameters. The structure-dependent water-induced linear reduction (SWLR) model functioned well to predict the Dp/D0 of RCA samples when the air-filled porosity was less than 0.175 cm3 cm−3. The most likely windows for ka of RCA samples were predicted by equations developed from the SWLR model.

Characterization of Wind Turbine Blade Deformation and Wake Flow Field with Different Numbers of Lay-Up Layers

The change in the composite lay-up method affects the blade stiffness, which in turn affects the structural dynamic and aerodynamic characteristics, but the influence law is not yet clear. In this paper, two-way fluid–structure coupling is used to study wind turbine blades with different numbers of lay-up layers. The analysis results show the following: (1) With the increase in the number of pavement layers, the maximum deformation of the blade tip decreases, the magnitude of the decrease also decreases gradually, and the growth trend of deformation along the blade spreading direction is gradually flattened. (2) The maximum stress–strain of the root of the blade gradually decreases, the tip of the blade is the opposite of the blade, the unevenness of the distribution of the stress–strain of the surface of the blade is gradually slowed down, and the concentration area is shifted back. (3) The different numbers of pavement layers affect the turbulence intensity of the blade in the flow field space. Herein, the spatial distribution trend of turbulence intensity in the flow field of wind turbine blades with different numbers of layers is basically the same, and the trend of turbulence intensity changes is gentle when the number of layers is increased. (4) The amount of the tip vortex in the wake stream of the wind turbine decreases, and the decay rate of the center vortex increases. A reasonable lay-up scheme can improve the deformation and stress of the blade, extend the service life of the blade, promote airflow mixing, and enhance the energy conversion efficiency.

Influence of Iron Mining Waste Addition as a Sustainable Alternative on the Resilient and Physical Properties of Soils for Pavement Design

Mining activities generate large volumes of waste, posing environmental and economic challenges, particularly in Brazil’s Quadrilátero Ferrífero region. This study assesses the potential reuse of iron ore waste from Samarco Mineração S.A. in road pavement layers by blending it with phyllite residual soil (PRS) and lateritic clayey soil (LCS). The addition of 50% waste to PRS led to substantial improvements, increasing the resilient modulus (RM) by up to 130% under medium stress and reducing expansibility from 6.1% to 1%, meeting Brazilian standards for sub-base applications. These enhancements make the PRS-waste blend a viable and sustainable option for reinforcing subgrade and sub-base layers. In contrast, the LCS with 20% waste showed moderate RM improvements under high-stress conditions, while higher waste contents reduced stiffness, indicating that higher dosages may adversely affect performance. This study highlights the potential of inert, non-hazardous mining waste as a safe and efficient solution for pavement applications, promoting the sustainable use of discarded materials.

Effects of overloading commercial vehicles on vehicle damage factor for the National Highways in Bihar

Abstract Overloaded vehicles and traffic growth have a significant impact on the pavement’s performance and service life. As a result, pavement construction and rehabilitation costs have drastically increased. The paper presents the results of the research, including analysis of axle-wise commercial vehicles with 24 h axle-load survey data over a one-year period. The information was collected from two sections of National Highway Road using a weigh-in-motion machine. The fourth power rule is used to calculate the VDF value of over-loaded, legal-loaded, and actual-loaded vehicles by converting the all-vehicle load into a standard axle load. This paper presents the axle-wise impacts of overloaded vehicles on the calculated VDF value. The analysis has shown that when only over-loaded traffic is considered, the class-2 VDF value is higher than the other classes of vehicles, and the class-5 VDF value is higher when all types of collected traffic—legal-loaded and over-loaded traffic are considered. The study concluded that 20% overloaded weight of vehicles increases the VDF value by about 3–4 times. The study reveals that the actual loaded VDF value should be considered during the design of new pavement instead of the VDF value of over-loaded and legal-loaded vehicles. This result may assist the pavement designer in calculating the thickness of the pavement layer and the construction cost of the pavement.

Experimental and numerical study on ovalisation test for pavement and HMA layer interface behaviour assessment

Good bonding of interfaces between pavement layers is fundamental to ensure their durability. The ovalisation test constitutes an in-situ way of assessing pavement interface conditions. This test requires setting a device equipped with contact sensors into a circular core hole. During the trafficking of a heavy vehicle nearby, diameter variations of the core hole are measured above and below the considered interface to estimate its bonding condition. Sensitivity analysis was performed to understand how the ovalisation device could help in pavement evaluation. This study shows that an increasing offset leads to a non-linear response on ovalisation test results. Also, the speed of the rolling load highlights the viscoelastic properties of the upper layers. As a result, interface bonding evaluation with the ovalisation test should be made at a small offset and a low speed for the rolling wheel. Numerical simulations are also proposed to confirm the experimental data observed.

FIELD PERFORMANCE OF HOT IN-PLANT PRODUCED ASPHALTIC CONCRETE WEARING COURSE (ACWC) WITH 30% RECLAIMED ASPHALT PAVEMENT (RAP)

Hot in-plant recycling stands as an effective yet underutilized method in Malaysia for reusing pavement milling waste, resulting in insufficient established benchmarks and validated trials. The Utilization of Reclaimed Asphalt Pavement (RAP) can divert a significant amount of waste asphalt millings from landfills, while conserving energy and natural resources. This study focused on the recycled mixture, ACWC-30RAP, which integrated 30% Reclaimed Asphalt Pavement (RAP). In July 2022, a 400 m trial lay was conducted from KM413.90 to KM414.30 Southbound (SB), Section C3, along the PLUS North-South Expressway (NSE). Field tests were systematically conducted on both the ACWC-30RAP and conventional ACWC20 mixtures at different phases including month-6, month-9, and month-12 post-construction. The primary objective was to assess fundamental properties related to the structural stiffness of pavement layers as well as the pavement performance and condition for both trial sections using various field testing including Falling Weight Deflectometer (FWD) and Multi-Laser Profiler (MLP). Following the 12-month trial period, both the ACWC-30RAP and conventional ACWC20 mixtures experienced actual traffic loading and environmental conditions. Remarkably, the ACWC-30RAP demonstrated comparable field performance as the conventional ACWC20. This alignment in performance signified a promising avenue for employing the recycled mixture with high RAP content. Using ACWC-30RAP can also provide economic benefit, reducing the production cost by approximately 25%. In essence, the ACWC-30RAP had achieved an equivalent level of confidence to the conventional ACWC20 mixture, which was exclusively composed of virgin materials. cts.

Calculation of the Number of Roller Passes When Strengthening Roads Using Recycled Asphalt Granulate

Statement of the problem. Work during the repair, overhaul and reconstruction of highways involves the destruction of old asphalt concrete pavement using the cold milling method. The resulting discrete material is used to strengthen roadsides, and if it is regenerated, it is used to construct base layers and lower layers of covering. The compaction of layers of road pavement is carried out with rollers, the efficiency of which depends on the properties of the resulting material, the power parameters of the rollers, and the technology of work, determined by the number of passes of the roller along one track. Analysis of the work showed that there are no substantiated recommendations for determining the number of roller passes taking into account the properties of the material being compacted. Establishing such dependencies makes it possible to clarify the composition of the compaction machine link when installing structural layers of road pavements while ensuring the required quality of work. Results. Analytical dependencies are presented for calculating the deformation modulus and rigidity of a layer of processed asphalt granulate under load, taking into account the thickness of the layer and the size of the fractions. The stresses under the rollers were determined for different types of rollers and their operating modes, taking into account the technical characteristics. The results of a study to determine the number of roller passes when installing a layer of recycled asphalt granulate are presented, taking into account the size of the fractions and the characteristics of the rollers used. Conclusions. It has been established that both the deformation modulus and the rigidity of the compacted layer can be taken as a criterion when choosing the parameters of the rollers and determining the number of passes of the roller along one track. Based on the results obtained, we can conclude that for a given value of the deformation modulus and the stiffness coefficient of the compacted layer of asphalt granulate, it is possible to determine the number of passes, the type of roller and its operating mode to ensure the required characteristics of the layer.

Correlative Study of Light-Weight Deflectometer, Plate Loading, and California Bearing Ratio Tests for Unbound Pavement Layers Using Genetic Algorithm

Correlative Study of Light-Weight Deflectometer, Plate Loading, and California Bearing Ratio Tests for Unbound Pavement Layers Using Genetic Algorithm