Asphalt Pavement Analyzer Research Articles

Gradation characteristics-based interlayer mixture design method for enhanced rutting resistance of asphalt pavements

The major role of interlayer mixtures is to mitigate reflective cracking by absorbing or dissipating concentrated stress, and relatively low-stiffness materials are typically used. However, there is a concern that interlayer mixtures may increase the risk of rutting because of these low-stiffness materials. The dominant aggregate size range (DASR) porosity has been successfully applied for structural mixtures to ensure enhanced rutting performance. This study mainly focused on developing new DASR porosity requirements for interlayer mixtures that ensures acceptable rutting performance in the mix design phase. Ten interlayer mixtures with a broad range of DASR porosities were evaluated using the asphalt pavement analyzer test. Our results indicated that the gradation characteristics of interlayer mixtures played an important role in rutting performance. Also, a relationship between DASR porosity and the rutting potential of interlayer mixtures was identified that resulted in the establishment of the preliminary DASR porosity requirements.

Mechanical analysis of asphalt pavement based on bimodulus elasticity theory

The bimodulus elasticity theory was introduced into pavement mechanical analysis for the first time in this study. By developing an efficient finite element method of bimodulus structural calculation for asphalt pavement, the mechanical analysis of typical asphalt pavement structure in China was carried out. The results indicated that the mechanical properties of asphalt pavement based on the bimodulus theory are nonlinear and anisotropy. Besides, the deviation between the mechanical response calculation based on bimodulus elasticity theory and the traditional linear case was more than 50%. Moreover, a great deviation on the normal stress and strain was reported, but in the case of the shear stress and shear strain, a small error was found. Especially the mechanical response of the key points in pavement design was greatly affected by the difference in tensile and compressive moduli of surface layer and base cemented mixture, which had its maximum deviation is up to 280%. Due to the significant and inevitable difference in the tensile and compression modulus of pavement materials, the bimodulus elasticity theory is suggested to be used in the mechanical calculation of asphalt pavement design.

Environmental Benefit Analysis of Hot Central Plant Recycling Asphalt Pavement Based on LCA

In order to determine the energy-saving and emission-reduction effects of the application of hot central plant recycling in the highway asphalt pavement maintenance project, this study selects a road section of overhaul project in Tongren as the analysis object, and adopt the environmental benefit analysis method based on life cycle assessment to analyze the energy consumption and environmental emissions of hot central plant recycling and hot mix asphalt. The comparison shows that the application of hot central plant recycling in highway asphalt pavement maintenance project has good energy saving and emission reduction benefits, and the aggregate and asphalt production stage are the main components. Moreover, under the condition of ensuring the road performance of recycled pavement, with the increasing proportion of reclaimed asphalt pavement, the environmental benefit of recycled pavement is higher. While with the increase of reclaimed asphalt pavement transportation distance, the environmental benefit presents a downward trend.

Analytical solution for the mechanical responses of transversely isotropic viscoelastic multi-layered asphalt pavement subjected to moving harmonic load

This work aims to develop a wave propagation-based analytical solution that can be effectively used for calculating the mechanical responses of transversely isotropic viscoelastic multi-layered asphalt pavement subjected to moving harmonic load. The material property can be considered transversely isotropic viscoelastic during the analytical solving. The interlayer conditions with different bonding levels are described by the Goodman model. The moving harmonic load is exerted on the surface of the multi-layered medium. The detailed implementation of the mathematical derivation (i.e., integral transforms, formulation of up-coming and down-going wave vectors) and the numerical program for the mechanical responses are presented. The proposed analytical solution is verified by finite element simulation and exhibits computational efficiency and accuracy. In addition, the effects of the load and material parameters on the mechanical responses of the multi-layered medium are investigated. Furthermore, the proposed analytical solution is extended to the study of tire–pavement interaction under random unevenness, and the random mechanical responses of the pavement under moving load with random amplitudes are obtained. In conclusion, the proposed analytical solution can be used as an effective tool for asphalt pavement design and analysis with consideration of the realistic load and material parameters.

Characterisation of Colloidal Nanosilica Modified Asphalt binder

Nanosilica (NS) has been used in this study as an asphalt binder modifier to improve the binder properties. Penetration grade 60/70 (PEN 60/70) asphalt binder was modified with NS in colloidal form with an average size of 10 to 15 nanometer (nm). The nanosilica modified asphalt binders (NSMB) were tested for different tests such as physical properties, atomic force microscopy (AFM), dynamic shear rheometer (DSR), multiples stress creep and recovery (MSCR) and asphalt pavement analyser (APA). The result obtained from physical properties shows that the additions of NS significantly improve the properties of base asphalt binder in terms of penetration, softening point and viscosity. It was also found that NSMB is stable during the high temperature storage period. SEM images showed that NS particles dispersed well in base asphalt binder and AFM images showed that the addition of nanosilica in asphalt binder improved its surface stiffness. In addition, NSMB significantly increases the G*/sinδ value, failure temperature, and percentage creep recovery while, decreased the non-recoverable creep compliance, which indicated higher elasticity and beneficial in increasing the rutting resistance as compared to the base asphalt. On the other hand, from APA test, it was found that NSMB reduced the rutting depth of asphalt mixture. It can be concluded from the analysis that a maximum of 2% NS be added into the base asphalt for optimum binder modification.

Mechanical responses analysis and modulus inverse calculation of permeable asphalt pavement under dynamic load

Permeable pavements play an important role in the mitigation of stormwater runoff and urban heat island effect. However, due to low strength and clogging, permeable pavements are always applied in light traffic areas. Therefore, it is necessary to understand the structural performance of permeable pavements under different conditions. In this paper, the performance of two permeable pavement structures (fully-permeable (FP) pavement and semi-permeable (SP) pavement) under dry and wet conditions is analyzed with the finite element method (FEM) modeling and one-third scaled MMLS3 test. A preliminary FEM model was established and empirical values of modulus are used. To make the model more closely simulate the actual conditions of the pavement, the modulus was calibrated according to the MMLS3 test results. The results of resilient strain and calibrated modulus of two structures under dry and wet conditions were analyzed, and the SP structure appears better cracking and moisture damage resistances. The modulus increases firstly and then decreases with the change of loading repetitions, which is considered to be caused by the combined action of further compaction of load and temperature. Since the change rate of surface layer modulus of the SP structure with loading repetitions is higher than that of FP structure, and only the base material of the two structures is different. It can be considered that the base layer modulus will affect the bottom strain of the surface layer, thus affecting the surface layer modulus. Furthermore, by calculating the difference between the base layer and the surface layer, it is found that the smaller the modulus gap between them, the smaller the change rate of the surface layer modulus.

Abrasion Resistance and Rutting Resistance of Micro-Surfacing with Crumb Rubber of Dry Process

In order to improve the common micro-surfacing is easy to loose and fall off, and improve the wear-resistance and anti-rutting performance of pavement, this paper uses waste rubber powder as the filler of micro-surfacing mixture, and adopts the method of dry adding. The test of micro-surfacing with crumb rubber of dry process based on APA test was carried out at 40 °C without water. Asphalt pavement analyzer shows that the micro-surfacing with crumb rubber of dry process has better wear-resisting and anti- rutting performance.

Urban rainfall characteristics and permeable pavement structure optimization for sponge road in North China

Permeable asphalt pavement types are generally selected according to local traffic volume and rainfall intensity. This study focuses on the design of the pavement drainage asphalt pavement combination scheme by analyzing the rainfall characteristics of five representative cities in North China. Furthermore, nine kinds of drainage pavement scheme applicable to Beijing are proposed. To this end, the permeable function design analysis, as well as the bearing capacity design analysis of permeable asphalt pavement, was carried out with the help of storm runoff simulation software SWMM5.1 and pavement structure analysis software BISAR3.0, respectively. The results indicate that the minimum total design thickness of permeable surface layer and permeable basic layer meeting the requirements of road drainage in this region is 170 mm, and the nine drainage pavement schemes meet the specification requirements.

Mechanical response analysis of asphalt pavement on curved concrete bridge deck using a mesostructure-based multi-scale method

Curved concrete bridges are an important infrastructure form, which meet the needs of modern transportation. Due to their relatively sophisticated geometries, asphalt pavements on the bridge decks are typically subjected to more severe loadings. This study investigated multi-scale mechanical responses of asphalt pavement on a curved bridge deck by using a macro-mesoscale coupling algorithm that can rationally considered the mesostructure of asphalt concrete. The influence of driving speeds, curvature radii, and temperatures on the mechanical responses of different scales was analyzed. The results showed that with the increase of the curvature radius and the decrease of the driving speed, both unevenness of tire loads on the asphalt pavement and stress concentrations in the mesostructure of the asphalt pavement were reduced. Under low temperature, asphalt concrete pavement on the deck encountered stress concentration and mesoscopic damage more easily. Increasing temperature can reduce these effects; however, due to the decrease of its asphalt mortar modulus, plastic deformation may occur in the pavement.

Energy Consumption and Environment Performance Analysis of Induction-Healed Asphalt Pavement by Life Cycle Assessment (LCA).

In this paper, the sustainability of induced healing asphalt pavement is demonstrated by comparing the impact of asphalt pavement maintained by induced healing asphalt pavement technology and traditional maintenance methods (such as milling and overlaying). The functional unit selected is a 1-km lane with an analysis period of 20 years. The stages to be considered are material manufacturing, paving, maintenance, milling and demolition. Two case studies were analyzed to assess the impact of different technologies on the energy consumption and environmental performance of each maintenance alternative. By comparing the energy consumption and environmental emissions of the whole life cycle of pavement under the two technical conditions, the results show that the total energy consumption of traditional asphalt pavement is about 2.5 times that of induction-healed asphalt pavement, and the total greenhouse gas (GHG) emissions of the former are twice as much as that of the latter.

Laboratory Evaluation of Modified Asphalt Mixes Using Nanomaterial

Abstract More demands on pavement—including increasing temperature variability and precipitation and higher loading conditions, along with an increase in the rate of load applications—result in decreased pavement performance and reduce its service life. Three major distresses identified with asphalt pavements are rutting, fatigue cracking, and thermal cracking. Polymers have been frequently used for modification of asphalt binders to improve pavement performance and reduce pavement distress. However, there are problems associated with incompatibility between the modifier (polymer) and the binder as well as a reduction in the aging resistance of the asphalt. Furthermore, asphalt modification with polymers can result in operational difficulties as well as a significant increase in cost. This paper investigates the application of several nanomaterials, including nanoclays (halloysite and bentonite) and cellulose nanocrystals, as promising alternatives to improve asphalt performance and increase the service life of asphalt pavements. Using the Superior Performing Asphalt Pavement (SuperPave) asphalt mixture design and analysis system, the rheological properties of nanomodified asphalt binder and mechanical properties of the resulting asphalt mixes were evaluated at low and high temperatures. Results showed a noticeable improvement in the high-temperature properties of the modified asphalt mixes, with no significant effect on the low-temperature properties of the asphalt mixes or rheological properties of the modified asphalt binder. Considering the cost of the nanomaterials, it was concluded that they may provide a cost-effective alternative for asphalt modification.

Laboratory Evaluation of Electrically Conductive Asphalt Mixtures for Snow and Ice Removal Applications

The study evaluates the electrical conductivity and mechanical performance of graphite modified asphalt mixtures. The effects of air voids, carbon fiber, and binder performance grade (PG) on the electrical resistivity of graphite modified asphalt mixtures are also assessed. Three graphite grades, two asphalt binders (polymer-modified PG 76-22 and neat PG 64-22), one aggregate type, and one carbon fiber were used to produce graphite modified asphalt mixtures. The mixtures were produced without graphite (control mix, PG 76-22), with only graphite (three grades and PG 76-22), with both graphite and 1% carbon fiber (three grades and PG 76-22), and with graphite (all three grades) and PG 64-22. The electrical conductivity, resistance to rutting, resistance to cracking, and durability of these mixes were evaluated using electrical resistivity (using a multi-meter), asphalt pavement analyzer, Hamburg wheel tracking device, semi-circular bend, indirect tension cracking, and Cantabro loss tests. Test results showed that graphite improves the electrical conductivity of asphalt mixtures when added at dosages of 10% to 15% or higher by volume of binder. Graphite grades with larger particle sizes helped improve the conductivity of asphalt mixtures better than graphite grades with smaller particle sizes. Air voids (higher air voids increased resistivity), carbon fiber dosage (decreased resistivity), and binder performance grade (neat binders had lower resistivity) affected the electrical resistivity of graphite modified asphalt mixtures. Furthermore, graphite modified mixes had better rutting resistance but higher susceptibility to breakdown and cracking when compared with unmodified mixtures.

Multi-scale analysis of asphalt pavement on curved concrete bridge deck considering effect of mesoscopic structure characteristics

• A two-dimensional (2D) random aggregate generation method was adopted to develop mesoscale models with different mesostructure characteristics. • A three-dimensional (3D) macroscopic model of the bridge deck pavement including two structural layers was established. • A multiscale coupling algorithm was used to establish the relationship between models at different scales. • Damage density is used to evaluate the damage possibility of asphalt mixture. • The influence factors of mesostructure damage are graded. Mesostructure characteristics of asphalt mixture, as essential factors, affect the mechanical response and mesoscopic damage of bridge deck pavement. This study explored the effect of different mesostructure characteristics on the mechanical properties and damage behavior of asphalt pavement on a curved concrete deck using a mesostructure-based multiscale method. A two-dimensional (2D) random aggregate generation method was adopted to develop mesoscale models with different aggregate volume fractions (30%, 40% and 50%), aggregate size ranges (4.75mm-2.36mm, 9.5mm-2.36mm, 13mm-2.36mm and 16mm-2.36mm) and aggregate shapes (quadrangle, hexagon, octagon and random). A three-dimensional (3D) macroscopic model of the bridge deck pavement including two structural layers was established. A multiscale algorithm was used to establish the relationship between models at different scales. In addition, the angle index (AI) was used as an evaluation index of coarse aggregates in irregular shapes, and the damage density was used to evaluate the damage possibility of mesostructure. The results showed that the damage density of asphalt mixture mesostructure had a linear relationship with AI, and the damage density became bigger as the AI decreased. Besides, increasing the range of aggregate size and the volume fraction of aggregate could reduce the damage density of asphalt mixture mesostructure, and ultimately improve the comprehensive performance of bridge deck pavement. For the damage density of bridge deck pavement, the angle index of aggregate was the most important factor, followed by the volume fraction and size range of aggregate.

SAPAVE: an improved semi-analytical FE program for dynamic viscoelastic analysis of asphalt pavement

ABSTRACT Analyzing dynamic viscoelastic responses induced by moving loads is a significant issue for pavement design and performance evaluation. Developing three-dimensional FE models in commercial software is an effective method, but the time-consuming disadvantage prevents it from extensive engineering applications. In this paper, an improved semi-analytical FE model was proposed to overcome this drawback. Besides, modified artificial boundaries were applied to minimise the interference of reflected waves generated by model edges. Further, a program named SAPAVE has been developed in MATLAB to achieve the modeling procedure, of which accuracy and efficiency were verified by comparing with the three-dimensional FE model in ABAQUS. The computing cost of SAPAVE was only one-sixth of ABAQUS, while SAPAVE can roughly achieve the function of ABAQUS for simple pavement modeling. The response considering the asphalt layer as viscoelastic was quite different from the linear elastic in the comparative study. The viscoelastic analysis seems to be closer to the field situation. Besides, the impact of vehicle speed was studied to examine the application ability of SAPAVE, and the results were generally consistent with existing researches. Overall, this study indicates that SAPAVE is an efficient and accurate tool for mechanical analysis of asphalt pavement.

Effect of Gradation Variability on Volume Parameter and Key Performances of HMA

The graded mineral aggregate composed of coarse aggregate, fine aggregate, and mineral powder is the main component of hot asphalt mixture (HMA), and it occupies a mass ratio of more than 95% in HMA. The gradation variability of mineral aggregate is frequently an unavoidable problem in the construction of asphalt pavement engineering. In order to investigate the effect of gradation variability on the volume parameters and key performances of HMA, the asphalt concrete with a nominal maximum particle size of 20 mm (AC20) was selected as the research carrier. Firstly, a benchmark mineral aggregate gradation (BMAG) was designed based on the theory of dense skeleton gradation presented in the paper. Secondly, six types of HMA (that is, AC20) with variable gradations were also determined and all the specimens were prepared by rotary compaction process with the same optimum asphalt content (gradation varies but asphalt content remains the same), and finally based on asphalt pavement analyzer, the performances of all the specimens of each gradation were tested. The results show that, compared with the BMAG-HMA, the volume parameters such as air voids, voids in mineral aggregate, and voids filled with asphalt of the variable-graded HMA change in different directions, but the water stability and high-temperature performance both degrade greatly. The experimental results also show the feasibility and effectiveness of the dense skeleton gradation design theory adopted in this study.

Mechanical response analysis of asphalt pavement on concrete curved slope bridge deck based on complex mechanical system and temperature field

Curved concrete bridges with small radii and large longitudinal slopes are important parts of viaduct ramp, on which the asphalt pavement plays an important role in resisting and dispersing traffic loads. Due to the complexity of curved concrete bridge structures with small radii and large longitudinal slopes, the asphalt pavement is subjected to complex mechanical action under loading. This study investigated the mechanical response of the asphalt pavement on a concrete deck under complex load conditions through a three-dimensional finite element model.The effects of different curvature radii, inside and outside wheel groups, driving speeds and temperature fields on the mechanical response of asphalt pavement were analyzed. The results show that in the process of driving on curved bridge deck, the inside and outside wheels of a vehicle produce different normal forces and longitudinal shear forces due to the influence of centrifugal force and radial force moment. With the decrease of the curvature radius and the increase of the driving speed, nonuniform loads are produced on the bridge deck pavement, which would eventually contribute to nonuniform damages. Under different temperature fields, the bridge deck pavement can undergo different failure modes. Besides, temperature fields have the greatest impact on the damage of bridge deck pavement, followed by driving speeds and curvature radii.

Rutting Performance of Semi-Rigid Base Pavement in RIOHTrack and Laboratory Evaluation

Through a simple performance dynamic modulus test (SPT), standard rutting test, Hamburg rutting test, French rutting test and asphalt pavement analyzer rutting test, the rutting resistance of asphalt mixtures in the middle and lower courses of three semi-rigid base asphalt pavement of Beijing full-scale test track road in China was evaluated. The test results show that the rutting resistance of asphalt mixtures of the middle and lower courses can be greatly improved by using low-grade asphalt, especially 30# asphalt. The rutting resistance of SBS modified asphalt mixtures is also better. The SPT dynamic modulus test can indirectly characterize the rutting performance of the asphalt mixture. The rutting test results of a laser road detection vehicle and 3 m ruler show that the asphalt grade has a significant impact on the rutting performance of semi-rigid base asphalt pavement. Compared with 70# asphalt used in the middle and lower courses, the rutting resistance of the pavement structure can be improved by more than 20%. The result also show that the APA rutting test results can closely characterize the full-scale test track results, which is an optimal test method for evaluating the rutting performance of semi-rigid base asphalt pavement. The research results can provide a theoretical basis and reference for the rational design and rutting evaluation of semi-rigid base asphalt pavement.

Response Characteristics Analysis and Fatigue Life Assessment of Asphalt Pavement around the Manhole

In view of the damage of the pavement around manholes, this paper proposes an effective way to analyse the stress characteristics of the road under vehicle load and evaluate the fatigue life of the pavement around manholes. A half vehicle-road-manhole cover coupling dynamic model is established to calculate the dynamic load coefficient. According to the finite element analysis (FEA) model in ABQUS, the dynamic response characteristics of the pavement around the manhole are analysed, and the stresses under different braking force and different vehicle type are compared. In addition, the fatigue life of the pavement surface layer under different loading conditions is calculated, and three different fatigue life models are selected to analyse the influence of different factors on the fatigue life of the pavement base structure around the manhole. The results show that the fatigue life of the pavement base layer decreases with the increase of manhole subsidence value, and the fatigue life increases with the increase in thickness of the surface layer, and the change of elastic modulus of the subgrade has no obvious influence on the fatigue life of road base. Finally, a fatigue life evaluation index based on high root energy is proposed to compare the three models more intuitively. Consequently, the analysis results can provide a basis for manhole surrounding pavement design and maintenance, and the analysis method is worthy of further application in the research of pavement fatigue life under more influencing factors.

A Study on the Reduction of Urban Heat Island Phenomenon by Analysis of a Porous Asphalt Pavement

A Study on the Reduction of Urban Heat Island Phenomenon by Analysis of a Porous Asphalt Pavement

Application of Balanced Mix Design Methodology to Optimize Surface Mixes with High-RAP Content

The most common use of reclaimed asphalt pavement (RAP) is in the lower layers of a pavement structure, where it has been proven as a valid substitute for virgin materials. The use of RAP in surface mixes is more limited, since a major concern is that the high-RAP mixes may not perform as well as traditional mixes. To reduce risks or compromised performance, the use of RAP has commonly been controlled by specifications that limit the allowed amount of recycled material in the mixes. However, the ability to include greater quantities of RAP in the surface mix while maintaining a satisfying field performance would result in potential cost savings for the agencies and environmental savings for the public. The main purpose of this research was to produce highly recycled surface mixes capable of performing well in the field, verify the performance-based design procedure, and analyze the results. To produce the mixes, a balanced mix design (BMD) methodology was used and a comparison with traditional mixes, prepared in accordance with the requirements of the Virginia Department of Transportation’s volumetric mix design, was performed. Through the BMD procedure, which featured the indirect tensile cracking test for evaluating cracking resistance and the Asphalt Pavement Analyzer (APA) for evaluating rutting resistance, it was possible to obtain a highly recycled mix (45% RAP) capable of achieving a better overall laboratory performance than traditional mixes designed using volumetric constraints while resulting in a reduction in production cost.