Asphalt Pavement Structure Research Articles

A model for variation with time of flexiblepavement temperature

Abstract The bituminous material performance is affected basically by the prevailing temperatures. The mechanical properties of these materials can vary significantly with the changes in the temperature magnitude. Hot mix asphalt (HMA) is a visco-elastoplastic material, so the pavement structural capacity is affected by the temperature variations. To determine the characteristics of the strength of the flexible pavement rationally, the prediction of the distribution of temperature in HMA pavement layers is a must. Heavy loadings subjected to highways and roads can cause serious deterioration to the HMA pavements. In this research, the temperature for three thicknesses of asphalt pavement structure was measured, and the air temperature to predict a model explains the relationship between the temperature and the depth of the pavement structure. The suggested model was successfully validated utilizing the data from three depths of asphalt pavement structure and the temperature on the surface of the asphalt pavement. The developed model consists of two independent variables, which are the depth within the pavement and ambient air temperature. The predicted model will be useful for the pavement designers those in need to predict the temperature of the profile of pavement to determine the engineering characteristics of field pavement.

Study of the Durability of a Fully Permeable Asphalt Pavement Structure Based on the Accelerated Pavement Test Method under Saturated Conditions

Study of the Durability of a Fully Permeable Asphalt Pavement Structure Based on the Accelerated Pavement Test Method under Saturated Conditions

Assessment of Modulus Attenuation of Cement and Lime-Fly Ash Semi-Rigid Road Base Materials

For asphalt pavement structures, semi-rigid road base course has to sustain repeated high-axle load during its service life and the performance of semi-rigid road base materials directly influences the durability of pavement structures. The dynamic compressive resilience modulus of two commonly used semi-rigid road base materials, cement stabilized aggregates (CSG) and lime-fly ash stabilized aggregates (LFSG) were evaluated at different frequencies using a Universal Testing Machine (UTM). The results showed that LFSG had higher dynamic modulus than that of CSG and the load frequency had less influence on the dynamic modulus of these two semi-rigid road base materials. The four-point bending test was applied to measure the flexural-bending strength and the fatigue life of these two semi-rigid materials. A higher flexural-bending strength of LFSG indicated its better bearing capacity than that of CSG. The fatigue life of LFSG and CSG decreased with the increase of stress–strength ratio and the LFSG performed better in terms of fatigue resistance. The fatigue damage models of CSG and LFSG based on Stress-Life (S-N) curve are established. As per incremental-recursive mechanics, a general modulus degradation model was established and verified by the results of full-scale accelerate loading test. This model cannot only be used to predict the fatigue deterioration of semi-rigid road base materials under different stress levels, but is also able to calculate the current bending elastic modulus based on its initial modulus value.

The Innovative Self-Sensing Strain Sensor for Asphalt Pavement Structure: Substitutability and Synergy Effects of Graphene Platelets With Carbon Nanotubes in Epoxy Composites

Situ sensors with high accuracy, long durability, and high survival rate are crucial for the health monitoring of asphalt pavement. Due to the harsh environment during the construction period and service life, the monitoring components which can be buried synchronously with the construction period of the road surface become a difficult problem to be solved urgently. The development of functional composites sheds a new insight for pavement strain detection with remarkable self-sensing behavior. In this paper, the substitutability and synergy effect of graphene platelets with carbon nanotubes (CNTs), the effect of CNT types with different specific surface areas in epoxy composites to the morphological, electrical, and mechanical properties, and the strain-electrical resistance response peculiarity of composites were evaluated. The performance of developed composite sensors with epoxy encapsulation was investigated through laboratory experiments. The morphologies showed that CNT-GNP hybrids in composites present a better dispersion state because of the size effect and synergetic effect whereas the pure CNTs are prone to entangle with each other. Composites with CNT(SSA500) display the most amounts of conductive units in same dosage. CNTs and GNP can strengthen the elastic modulus of the epoxy matrix to basically the same as that of asphalt mixture within the range of 1100–1500 MPa. At last, Laboratory experiments have proved the promising prospect for CNTs-GNP/epoxy composites serving as the strain sensor. The developed composites-based strain sensor can provide a new prospect for asphalt pavement monitoring.

An improved computation method for asphalt pavement texture depth based on multiocular vision 3D reconstruction technology

The depth of an asphalt pavement structure is an important index used to reflect the anti-skid performance of the pavement, which directly affects the driving safety of vehicles. In the current specifications (e.g., China, European and American standards), the mean texture depth (MTD) of an asphalt pavement is generally measured by the sand-patch method (SPM). However, SPM is easily affected by the operator’s subjective experience and experimental environment, resulting in low accuracy and high scatter in the data. In view of such shortcomings, a fast and accurate method to obtain the texture depth of asphalt pavement was proposed by designing a new test tool and a computer-aided calculation method. The multiocular vision theory was adopted to reconstruct a three-dimensional (3D) point cloud model of pavement texture. To reflect the concavity and convexity of pavement texture and eliminate the influence of pavement slope, the iterative closest point (ICP) algorithm was employed to obtain the datum reference plane (DRP). On this basis, the pentahedral volume calculation method suitable for evaluating the texture depth of an asphalt pavement was proposed. Laboratory experiment results using SPM were inverted by equal volume calculation to obtain the texture reference plane (TRP) and MTD'. Meanwhile, a 3D average maximum elevation (Avg.EL) algorithm was obtained by the evolution of two-dimensional mean profile depth (MPD). Furthermore, three parameters, namely MTD, MTD', and Avg.EL, were used to measure the texture depth of two field pavement sections in service. The experimental results showed that the correlation between MTD' and MTD was better than that between Avg.EL and MTD, and the degree of scatter was smaller. MTD' could be used directly as a reference value for MTD. In the present work, the 3D volume calculation method of asphalt pavement texture depth was proposed, which integrates the technical flow of image acquisition, model reconstruction, and algorithm analysis. The developed method provides a technical reference for the application of computer vision technology in the analysis of pavement texture depth.

Performance of a UHPFRC overlay in the rehabilitation of a typical asphalt pavement structure

This study determine the mechanical performance of a 40 mm thick overlay using UHPFRC (Ultra High-Performance Concrete) as the outer surface for restoring a flexible pavement structure. A 30 m long test section was built, divided into two 15 m sections. Section 1 was restored with a 60 mm overlay of Hot Mix Asphalt -HMA- and Section 2 was restored with a 40 mm overlay of UHPFRC without intermediate transverse joins. The two sections were instrumented with pressure cells in order to evaluate the vertical load in the inner fiber of each restoration layer. The mechanical properties of the materials were evaluated, the structural modeling was carried out with the falling weight deflectometer (FWD) and the Bisar 3.0 software. The structural modeling showed an 82% increase in the lifecycle for the section restored with UHPFRC. The functional evaluation of the rehabilitated structures was carried out considering parameters as: friction, percentage of cracking, rutting, international roughness index -IRI- and smoothness.

A data-driven approach to the evaluation of asphalt pavement structures using falling weight deflectometer

<p style='text-indent:20px;'>The evaluation of asphalt pavement structures has been a critical challenge in the field due to the practical limitations in methodology. In this paper, we propose a data-driven framework to evaluate structural performance of nineteen widely used asphalt structures in the Research Institute of Highway Ministry of Transport track (RIOHTrack). Specifically, we utilize the unsupervised machine learning method to delineate the similar and disparate performance among tested structures based on four years of falling weight deflectometer (FWD) experiments. Next, the structural performance is investigated on the temporal scale and the dynamic performance variations are captured over the course of the testing. Finally, experimental results are discussed and we provide essential evidence to aid future asphalt pavement design and construction.</p>

Multiple Reflective Cracks in Semirigid Base Asphalt Pavement under Traffic Load Using XFEM

This paper built a three‐dimensional layered structure model of semirigid base asphalt pavement with single and double transverse reflective cracks based on the Extended Finite Element Method and fatigue fracture theory. The effects of the number of cracks, crack spacing, and crack length on the stress intensity factors (KI, KII, and Keff) under moving vehicle loads were studied. The fracture life of the asphalt pavement structure was calculated based on the Pairs formula. The results demonstrate that reflective cracks in semirigid asphalt pavement are composite cracks of type I and type II under moving vehicle loads, and shear fracture is the main reason for the failure of the base. The damage to the pavement base will be accelerated with the increase in the number of cracks and the length of the cracks. As the distance between the two reflection fractures is closer, the interaction between the cracks has a superimposed enhancement effect on the crack propagation. Compared with the single nonpenetrating crack model, the fatigue life of the nonpenetrating reflective crack in the double crack pavement structure with a crack spacing of 30 cm is reduced by 46.87%. The research on the propagation mechanism of reflective cracks in this paper provides the essential theoretical and numerical basis for the design, construction, working condition evaluation, and maintenance of pavement structures.

Response of Asphalt Pavement Structure Layer and Particle Movement Velocity Based on Particle Flow Theory

AbstractAn asphalt mixture is a heterogeneous material composed of coarse/fine aggregate, asphalt, and admixtures. The damage of asphalt mixtures under vehicle load is closely related to the moveme...

Equivalent Resilient Modulus Inversion and Calculation of Different Asphalt Pavement Structures

Based on the modulus inversion theory and the equivalent principle of deflection basin, by analyzing the deflection basin data of each structure layer measured by the FWD, the obtained equivalent resilient moduli of different structural layers in three different structures (a semirigid type Asphalt pavement and two inverted asphalt pavements) were compared. At the same time, the calculated equivalent resilient modulus of the top surface of the structural layer based on the inversion method was used to modify the existing theory formula. The results show that, with the inversion method and the theoretical calculation method, the calculated equivalent resilient modulus of the top surface of the cushion layer has a small error, but the theoretical calculation method overestimates the equivalent resilient modulus of the top surface of the cement stabilized crushed stone layer and the top surface of the graded crushed stone transition layer, especially for the inverted asphalt pavement; by contrast, the corresponding result of the inversion method is closer to the value in actual engineering. While determining the equivalent resilient modulus of the cushion layer, the influence of the thickness of the cement stabilized crushed stone layer needs to be considered, and the inverted asphalt pavement structure should adopt a thicker asphalt layer to reduce the modulus deviation; at the same time, the more the structural layers and the larger the difference in the interlayer modulus ratio, the larger the deviation of equivalent resilient modulus of the top surface of the base layer; for the inverted asphalt pavement and semirigid asphalt pavement, the correction coefficients of the calculation formula of the equivalent resilient modulus of the top surface of cement stabilized gravel layer are 0.35∼0.55 and 0.65∼0.75, respectively. The inversion method can be used to determine the equivalent resilient modulus of each structural layer of the inverted asphalt pavement and semirigid asphalt pavement, and its results can provide a basis for the design of the structure reconstruction of asphalt pavement.

Mechanics of multilayered or functionally graded material pressed onto an imperfect rigid base with a circular opening by localized surface loading

Loaded materials constrained by imperfect boundary can be found in many engineering scenarios, including blanking process, contact pressure sensor and soil/rock foundation subjected to underground mining. This paper examines the surface loading problem of a multilayered or functionally graded material (FGM) resting on an imperfect rigid smooth base weakened by a circular opening. The surface loading is axisymmetric and coaxial with the circular opening. This mixed boundary value problem is analogous to a Mode-I penny-shaped crack in multilayered elastic medium. With the aid of the GKS-based method for N-layered elasticity, the problem is formulated as a system of dual integral equations and then reduced to a Fredholm integral equation of the second kind. Solutions of the SIF, COD and full elastic field are expressed in terms of the solution of the integral equation. Numerical results obtained from the present solutions are compared with the those from finite element method. Using the new solutions, numerical studies are also conducted for four examples, including a homogenous layer, a multilayered material, a material with FGM coating and an asphalt pavement structure with FGM properties. These numerical results demonstrate that (1) a small size of surface loading can result in high SIF value at the crack tip; (2) placing the hard layer as the top surface is most effective for reducing ground settlement; (3) the gradation in Poisson’s ratio can have non-negligible effect on the SIF for thin FGM coating; (4) effect of the circular opening to the ground settlement can be significant if its radius is comparable to the total thickness of the upper layers.

Analysis on Mechanical Behavior of Typical Asphalt Pavement Structure based on the Tire Load Effect

Further development of modern science and technology has made more science and technology technologies used in the modern social and life practice, and much more is this with the road construction. National development cannot be separate from the convenient traffic facilities, and in the current stage, the asphalt pavement design specification in China requires the road construction by simulating the force of the vehicle on the pavement structure with the round uniformly distributed load under the supposition of continuous interlayer pavement structure. However, as time goes on, the disadvantages of such design specification have gradually exposed, in which different materials, construction schedule and weather conditions will result in the significant difference in the asphalt pavement construction, thus resulting in weak interlayer viscous structure of the pavement, and finally causing the road subsidence and cracking. For this reason, this article has analyzed the mechanical behavior of typical asphalt pavement structure on the basis of explaining the influencing factors of the tire on typical asphalt pavement pressure under the tire load effect, with the expectation that there will be more professional construction of the asphalt pavement.

Determining the Environmental Potentials of Urban Pavements by Applying the Cradle-to-Cradle LCA Approach for a Road Network of a Midscale German City

This study used a cradle-to-cradle Life Cycle Assessment (LCA) approach to evaluate the environmental potentials of urban pavements. For this purpose, the urban road network of the City of Münster (Germany) was selected as the case study, and comprehensive data for several phases were collected. The entire road network is composed of flexible pavements designed according to specific traffic loads and consists of main roads (MRs), main access roads (MARs), and residential roads (RSDTs). Asphalt materials, pavement structures, and maintenance strategies are predefined for each type of road and are referred to as “traditional” herein. Some pavement structures have two possible maintenance strategies, denoted by “A” and “B”, with distinguished periods of intervention. To evaluate the impact of using recycled materials, we considered alternative pavement structures composed of asphalt materials containing a greater amount of reclaimed asphalt pavement (RAP). The study was carried out considering analysis periods of 20, 50, 80, and 100 years and using two indicators: non-renewable cumulative energy demand (nr-CED) and global warming potential (GWP). The results show that the use of higher amounts of RAP can mitigate negative environmental impacts and that certain structures and maintenance strategies potentially enhance the environmental performance of road pavements. This article suggests initiatives that will facilitate the decision-making process of city administrators to achieve more sustainable road pavement constructions and provides an essential dataset inventory to support future environmental assessment studies, particularly for European cities.

Characteristics and analysis of dynamic strain response on typical asphalt pavement using Fiber Bragg Grating sensing technology

The purpose of this research was to reveal the dynamic strain response characteristics and variation law of asphalt pavement structure with different base types under traffic load, and provide reliable measured data for the development of a pavement structure design method combined with China's national conditions and highway construction characteristics. Four types of base pavement were designed, cement treatment base, cement treatment base + graded gravel base, asphalt treatment base + cement treatment base, and asphalt treatment base + graded gravel base asphalt pavement. The dynamic responses of four kinds of asphalt pavements at different transverse positions, depths, and speeds under 100 kN loading conditions were tested using fiber Bragg grating sensors. The results show that the longitudinal strain at the bottom of the surface courses under dynamic load reveals the compressive-tensile-compressive alternating law. The longitudinal strain at the bottom of the base courses is mainly tensile strain. The maximum peak value of the surface courses appears at the corresponding single wheel load center. The maximum peak value of the base courses appears at the corresponding dual-wheel gap center. The faster the traveling speed is, the shorter the loading time of each structural layer of asphalt pavement, and the higher the loading frequency is. The loading position has a significant influence on the peak value of dynamic strain response. Reducing the cement-treated base course's strength and stiffness appropriately and ensuring the continuity of each layer's modulus to the greatest extent will benefit each structural layer's dynamic strain response distribution and improve the bearing capacity and durability of each layer of asphalt pavement against a heavy load.

Fatigue resistance design of rubberized asphalt mixture pavement under three-dimensional stress state

With the promotion of sustainable development globally, it is a positive and feasible measure to put waste tires into road engineering, such as rubber asphalt pavement. Therefore, it is very significant to improve the accuracy of fatigue resistance design of rubber asphalt pavement structures. This work aims to truly characterize the fatigue resistance of rubberized asphalt pavement structure, and provides favorable conditions for the efficient utilization of waste rubber powder in asphalt pavement engineering. First, the strength tests under different stress status and loading rates were carried out, which set up the strength yield surface on account of the Miller yield criterion. The fatigue tests of rubberized asphalt mixture in various stress levels and stress state were carried out. Von mises stress was taken as the characteristic parameter of the fatigue equation, and a unified fatigue characteristic equation of rubberized asphalt mixture affected by individual stress states was developed through the routine fatigue test. Finally, combined with Miller yield criterion and fatigue unified equation, the fatigue resistance model of rubberized asphalt pavement structure under the three-dimensional stress state was conducted. The results indicate that: the established Miller strength yield surface can reasonably describe the three-dimensional failure characteristics of rubberized asphalt mixture. Besides, the unified model of fatigue properties of rubberized asphalt mixture only needs to be characterized by single parameter, which is a power function coefficient in the new fatigue equation, and the value is −6.021. Moreover, the fatigue resistance model of the rubberized asphalt pavement structure sufficiently considers the difference between the tension–compression strength and fatigue characteristics of rubberized asphalt mixture and the stress state correlation. This study improves the scientificity and reliability of structural resistance design, and provides help for predicting the fatigue life of rubberized asphalt pavement.

Rutting prediction models for asphalt pavements with different base types based on RIOHTrack full-scale track

Asphalt mixture is a typical viscoelastic-plastic material and rutting deformation is very common in asphalt pavement. Considerable empirical and mechanistic-empirical (M−E) rutting prediction models are established to evaluate rutting performance. However, these models lack reliable database, and the mode applicability to different asphalt pavement structures is still not clear. Based on the field data from RIOHTrack full-scale track, this paper aims to establish more accurate and suitable empirical or M−E models for different asphalt pavement structures. Firstly, main influence factors were analyzed and the field database was determined; then, model frameworks and parameters were constructed; next, prediction models using empirical and M−E methods were established respectively; lastly, the model applicability was clarified, and the mechanism of base type influence on rutting performance was also analyzed. Results show that the proposed M−E model is suitable for semi-rigid or rigid base asphalt pavement (SBAP or RBAP), while the exponential-empirical (E-E) model is appropriate for flexible base asphalt pavement (FBAP). The base type has great influence on rutting performance and deformation mechanism. The model development and selection process could be used to find a suitable rutting prediction model for different asphalt pavement structures in other area. These findings also contribute to clarifying the rutting deformation mechanism and pavement maintenance.

Effect of Shear Stresses on Asphalt Pavement Performance and Evaluating Debonding Potential under Repeated Loading: Numerical Study

The primary of this paper is to evaluate the potential of shear failure in asphalt pavement with the primary focus on the layer interface debonding. To fulfill this objective, a three-dimensional (3D) finite-element (FE) model is developed to calculate the stress state within the asphalt pavement structure. Five different cases of vehicle maneuvering where shear forces acting on the surface layer were selected, and pavement responses were obtained and analyzed under 100 loading cycles at three different temperatures. Results show that maximum shear stress occurred on top of the surface layer, and with receding from the surface, the stresses reduced significantly along the pavement depth. The case where the vehicle moves along the curved road section induced the highest transverse shear stress, whereas braking action caused the highest longitudinal shear stress both within the pavement layer and at the layer interface. Moreover, the maximum shear stress in both directions and all studied cases took place in somewhere within the tire imprint area. With increasing temperature, the pavement responses increased in all cases accordingly. In addition, pavement responses at the bottom of the binder course were significantly lower than those of at the bottom of the surface layer. In general, pavement responses in pavement layers were larger than their counterparts at the layer interface. Finally, the concept of interface shear ratio (ISR) is presented to evaluate the potential of debonding at the layer interface under repeated loading. According to initial results, the ISR could be considered as a promising criterion for assessing shear failure potential at layer interface.

Wave Propagation Approach for Elastic Transient Responses of Transversely Isotropic Asphalt Pavement under an Impact Load: A Semianalytical Solution

The conventional transfer matrix method, adopted formerly in a semianalytical solution for layered elastic or viscoelastic asphalt pavement structures, has inherent deficiencies, such as ill-condition matrix, numerical overflow, and error accumulation, due to exponential items. This phenomenon is more evident in multilayered dynamic analysis with imperfect interfaces. Moreover, several studies revealed that pavement materials exhibit transverse isotropy in service. Consequently, a novel semianalytical solution methodology, wave propagation approach, was proposed herein to calculate the dynamic responses of asphalt pavement under an impact load considering the transversely isotropic material model and the imperfect interfaces. First, the transfer matrix was established based on matrix theory and wave propagation approach, while the relation between the state vector and wave vector in the transformed domain was constructed simultaneously. Then, combined with the boundary conditions and interface contact conditions, the solution of the wave vector in the transformed domain was derived. Finally, based on Laplace–Hankel inverse transform, the state vector in the time domain was obtained, followed by numerical computation with programming. The accuracy and efficiency of the proposed semianalytical solution, together with the influence regularities of several variables, were discussed. Results showed that due to the absence of positive exponential functions and a large-dimensional matrix, accuracy and efficiency requirements were satisfied during calculation. Moreover, the variation induced by the transversely isotropic properties and interface conditions, presented in the dynamic responses, reiterated that these factors should be considered during the design and analysis of asphalt pavement structures.

Performance Evaluation of Fatigue and Fracture Resistance of WMA Containing High Percentages of RAP

Sustainability and durability are the key requirements of pavement structure. Sustainability of asphalt pavement structure involves utilization of Warm Mix Asphalt (WMA) technologies with the addition of Reclaimed Asphalt Pavement (RAP), where durability of asphalt involves performance parameters like fatigue and fracture resistance properties etc. Utilizing the RAP content in asphalt mix increases the mixing and compaction temperature which may degrade the performance of asphalt. Hence, numerous studies have recommended different WMA technologies to decrease mixing and compaction temperature of asphalt mix containing RAP. The present research work evaluates the fatigue and fracture performance of WMA and Hot Mix Asphalt (HMA) with varying percentages of RAP and Sasobit. Different mixes of WMA and HMA were designed with varying percentages of RAP (0, 20, 40 and 60%) through Marshall Mix design. Sasobit (organic/wax-based additive) was used as WMA technology to prepare WMA at varying percentages (0, 2, 4 and 6%). The fatigue behavior of asphalt was evaluated using four-point bending test, where fracture resistance of asphalt was determined using Semi Circular Bending (SCB) test in the laboratory. Fatigue and fracture resistance of WMA were improved with the increase in percentages of Sasobit and RAP content, while the addition of RAP in HMA showed a decreasing trend of fatigue and fracture resistance due to the stiffer nature of RAP. Furthermore, WMA was identified as economical for construction besides other benefits like improved properties and environment friendly asphalt mix. Doi: 10.28991/cej-2021-03091741 Full Text: PDF

Dielectric properties of asphalt pavement materials based on the temperature field

Nondestructive testing equipment evaluates the quality of asphalt pavements and identifies different distresses based on the difference in the relative permittivity of asphalt pavement materials at different positions of the asphalt pavement structural layers. Thus, the accurate determination of the relative permittivity of asphalt pavement materials is essential for the quality evaluation of asphalt pavements. However, the dynamic temperature field inside the asphalt pavement will affect the performance and dielectric properties of each layer mixture and therefore affect the detection accuracy of nondestructive testing equipment.In order to analyze the influence of the temperature field on dielectric properties of asphalt pavement materials, the relative permittivity of each structural layer of the actual core specimen was measured at different temperatures by using the Dielectric Constant Test Platform, and a temperature-based dielectric composite model was developed. Meantime, the temperature field simulation of the typical asphalt pavement structures and distresses were carried out based on COMSOL finite element simulation, and the heat radiation, heat conduction, and heat convection were theoretically analyzed. On this basis, the relative permittivity and the relative permittivity correction rate of each structural layer was calculated to quantify the influence of the temperature field on the dielectric properties of asphalt pavement materials.This study confirmed that a crucial correlation exists between the temperature and relative permittivity of asphalt pavement mixtures. The temperature field distribution of distresses, namely, top-down cracks, reflective cracks, and road cavity, were simulated, and then the measured dielectric permittivity of each asphalt pavement structural layer was corrected. These findings can provide a theoretical basis for the temperature correction of detection data of nondestructive testing equipment and lay the foundation for the accurate identification of typical distresses in asphalt pavement.