•A novel methodological framework analyzing critical property of asphalt mastic was developed.•A novel method to calculate filler critical volume fraction was established.•Transformation from ...volume-based into number-based distribution functions for filler particles was conducted.•Nearest surface distance of filler particles in asphalt mastic was estimated through nearest surface functions.•Filler critical volume fraction of asphalt mastic under different temperatures was computed.
This study aims to provide a new insight into the reinforcement effect of filler on stiffness of asphalt mastic through the probability theory, nearest surface function and micromechanics. To implement the consideration of microphysical mechanisms in the stiffening behavior of asphalt mastic composite, a general methodological framework was developed. A new method to calculate the filler’s critical volume fraction (CVF) in asphalt mastic was constructed through the volume fraction of penetrable transition zone (PTZ) acting as a link. Particle size distribution (PSD) of filler was tested by a laser particle size analyzer. Asphalt mastics were fabricated with different filler concentrations. Distributions of filler particles in these mastics were tested by a scanning electron microscope. Complex stiffness moduli of asphalt binder and mastics were tested by a dynamic shear rheometer. Nearest surface distance (NSD) of filler particles in asphalt mastics was analyzed by nearest surface functions. Filler’s CVF in asphalt mastics was calculated through the constructed method. Results show that the shifted Rosin-Rammler distribution function allows to describe the PSD of filler with a high accuracy. Void nearest-surface exclusion probability of filler particles allows to represent the volume fraction of free asphalt in asphalt mastic. The larger the filler volume fraction, the higher the proportion of NSD making particles intercontact. A filler particle with larger radius has more likely to contact with other filler particles, and thus large particles tend to dominate the interparticle interaction in asphalt mastic. The mean NSD of filler particles decreases with increasing the filler volume fraction. The volume fraction of PTZ has an increased first and decreased afterwards trend with the filler volume fraction. The filler’s CVF decreases with the temperature increases. The constructed method is capable of determining the filler’s CVF in asphalt mastic.
•The aging resistance of WTR/APAO modified asphalt and asphalt mixture were investigated.•The evaluation indexes of the effect of long-term aging on performance was proposed.•The incorporation of WTR ...and APAO improves the resistance of asphalt to long-term aging.•The high and low temperature performance of 15%WTR + 4%APAO asphalt mixture after long-term aging are better than SBS asphalt mixture.
The aging resistance of asphalt mixture has an important impact on the long-term quality and service life of asphalt pavements. This research aims at studying the effects of long-term aging on waste tire rubber (WTR) and amorphous poly alpha olefin (APAO) modified asphalt binder and mixtures. The prepared compounds included, 12%WTR + 4%APAO and 15%WTR + 4%APAO modified asphalts, were used as experimental objects. Base asphalt binder (70 penetration grade), 15%WTR modified asphalt and styrene–butadiene-styrene (SBS) modified asphalt were the reference objects. First, pressure aging vessel (PAV) and long-term oven aging (LTOA) were used to simulate the long-term aging of asphalt binder and mixture, respectively. Secondly, the performance tests of asphalt binder and mixture were carried out, and the evaluation indexes of the effects of long-term aging on performance were proposed. For the asphalt binder, the results show that the incorporation of WTR and APAO significantly improves the post-aging conventional properties, rheological properties and fatigue properties. The Fourier transform infrared spectroscopy (FTIR) results were found to correlate to the physical tests results. In the asphalt mixture part, the results show that 15%WTR + 4%APAO modified mixture has better high temperature and fatigue performance after aging, among the rubber-based asphalt mixtures. The low-temperature performance of WTR/APAO asphalt mixture was not compromised after aging. Compared with the SBS modified asphalt mixture, the high and low-temperature performance of 15%WTR + 4%APAO asphalt mixture after aging are better. Overall, 15%WTR+4% APAO asphalt mixture has better advantages to counteract the influence of oxidative aging.
This paper evaluates the influences of variations in asphalt mixture parameters during construction on the variations of pavement performance using back-propagation (BP) neural networks. The ...variations of gradation (VG) and asphalt-aggregate ratio (VRa) were assessed through a variability analysis. The influences of VG and VRa propagation were analyzed via BP neural networks and a sensitivity analysis. A reliability assessment was conducted to evaluate the joint effects of VG and VRa. Results illustrate that the VG and VRa during transportation are more severe than those during other processes. BP neural networks can precisely and robustly trace the influences of the VG and VRa. Pavement performance exhibits greater sensitivity to VRa and VG at sieve sizes of 0.075 mm and 2.36 mm. The joint effects of VG and VRa significantly degrade permanent deformation more than fatigue life. High-quality paving effectively mitigates the negative impacts of segregation during transportation.
Display omitted
•Variations of gradation (VG) and asphalt-aggregate ratio (VRa) are more severe during transportation.•BP neural networks effectively trace the fluences of VG and VRa on pavement performance.•The joint effects of VG and VRa degrade permanent deformation more than fatigue life.•High-quality paving mitigates segregation impacts during transportation.
Variability of gradation for asphalt mixture is always the difficulty faced by the control of pavement construction, involving the pavement performance. The main purpose of this study is to improve ...the efficiency of detection for gradation variation and clarify the relationship between gradation variation and construction process. The variability of gradation for superpave asphalt mixtures was investigated with nominal maximum aggregate size (NMAS) of 13 mm, 20 mm, and 25 mm in construction. The correlation between the passing percentages at each sieve size and performance of asphalt mixture was first established by coupling grey relational analysis and entropy weight method. A digital image processing technology with multi-thresholds segmentation (DIP-MTS) was developed and verified through the experiment comparison. An approach to reversely calculate the gradation of cold aggregate was established. The mixture gradations during various construction stages were compared. Results illustrate that the passing percentages of sieves with NMAS, 4.75 mm, and 0.075 mm have a significant influence on the pavement performance and should be paid more attention during construction. The detection results of DIP-MTS are closer to the experimental value, and this technology is capable of detecting gradation for moving aggregate. The reverse calculation approach is proved feasible. Gradation variation in transportation is more severe than other construction processes.
Display omitted
•The critical passing percentages of gradation were determined.•A DIP-MTS technology was developed and verified.•An approach to reversely calculate the grading of cold aggregate was established.•Transportation process is the most sensitive process to the gradation variation.
Display omitted
•Multiple aggregate shape classification methods were compared and analyzed.•Multi-view features were constructed by combining multiple single-view features.•Multi-view images were ...constructed by fusing morphologies from different views.•SVM and Resnet18 were adopted for aggregate shape classification.•Both multi-view features and multi-view images have significant 3D shape characterization ability.
The content of elongated and flat aggregates is a critical detection index in road engineering. In this study, using image sequences of falling aggregates, two multi-view morphological methods were proposed for aggregate shape classification. The multi-view features of the aggregates were constructed by combining multiple single-view features from different views. Furthermore, a joint-view normalization method was proposed to improve the three-dimensional shape characterization capability of the multi-view features. Based on the multi-view features, a support vector machine was adopted to achieve aggregate shape classification. In addition, multiple two-dimensional aggregate morphologies from different views were directionally guided and fused to construct a multi-view image, which could reflect the three-dimensional shape of the aggregates. The multi-view images were then fed into ResNet18 for aggregate-shape classification. Notably, compared with single-view morphological methods based on the aggregate morphology in the vertical and random views, the two multi-view morphological methods developed herein significantly improved the classification accuracy. Moreover, it was found experimentally that increasing the height of the field of view improved the classification accuracy of the multi-view morphological methods. The proposed multi-view morphological methods demonstrate significant potential for application in the automatic identification of elongated and flat aggregates in road construction.
•A new perspective considering filler distribution was provided in micromechanical modeling of asphalt mastic.•Three viscoelastic micromechanical models of asphalt mastic were improved.•The effects ...of various parameters on the distribution of the shear modulus ratio were investigated.•The improved models can determine the spatial distribution characteristic of effective properties for asphalt mastic.•A key dimensionless diameter that has a significant effect on effective shear modulus of asphalt mastic exists.
This study aims to provide a new perspective into the consideration of filler distribution characteristic in micromechanical modeling of asphalt mastic through combining fractal microstructure. To do this, three viscoelastic micromechanical models were improved by the preliminarily combination between micromechanical equivalence and fractal statistic principles. Particle size distribution (PSD) of filler was tested by a laser particle size analyzer. Asphalt mastics with different filler concentrations were fabricated. Dynamic shear moduli of asphalt and asphalt mastics was tested by a dynamic shear rheometer. The PSD of the circles intercepted by the plane and dimensionless area of the intercepted asphalt matrix were analyzed. The dynamic shear modulus ratio of asphalt mastic to binder were calculated based on the improved models. The effects of various parameters on the distribution of the ratio were investigated. Results show that the shifted R-R distribution function is capable of capturing the PSD of filler. The dimensionless area increases with increasing dimensionless diameter, but decreases with increasing filler volume fraction. The shear modulus ratio shows a three-stage reduction trend with dimensionless diameter, replying that the shear modulus of asphalt mastic appears as a random distribution in space. Meanwhile, the spatial distribution is influenced by filler volume fraction and thus there has difference between the stiffening effects of filler on various local regions in asphalt mastic. Poisson’s ratio of binder plays an enhanced role in the stiffening effect of filler, which is affected by the spatial locations within asphalt mastic. Modulus and Poisson’s ratio of limestone filler and modulus of binder have little effect on the distribution of the shear modulus ratio. The combination of micromechanical modeling and fractal characteristic is capable of determining the spatial distribution characteristic of effective properties for asphalt mastic. The local homogenization of asphalt mastic in terms of the modulus and its influence on properties of asphalt mixture should be focused on and conducted in future.
•A novel framework was developed to implement an accurate description on TPS of rutting.•A new dimensionality reduction method was constructed to avoid the repetition of indexes.•The categorization ...and time-dependent evolution of TPS were conducted.•Different types of TPS correspond to different index systems.
This study aims to characterize the transverse profile shapes (TPSs) of rutting on asphalt pavement and to produce useful information to the highway administration in what concerns rutting. A novel framework was developed to implement an accurate description on rutting, which integrates four steps (data acquisition, TPS adjustment, TPS categorization and indicator analysis). Various indexes were analyzed and used to characterize these profiles. A new dimensionality reduction method was constructed based on correlation coefficient matrix (CCM) to avoid the repetition of indexes. These data from the Long-Term Pavement Performance (LTPP) program were collected and screened in the study. The categorization and time-dependent evolution of TPS were conducted based on the developed framework. The statistical analysis and dimensionality reduction of these indexes were carried out. Results show that the established framework allows to categorize and accurately describe the TPS of rutting. The TPSs are divided into five typical shapes and an irregular shape, and the type 5 and the irregular shape are not very valuable. There are different time-dependent evolutions for various types of TPS, which may be associated with trajectory of vehicles. The obtained critical value of these indexes should be attracted an attention from road administrations. The constructed dimensionality reduction method is capable of eliminating the redundancy of indexes, and thus optimizing the characterization effects. Different types of TPS correspond to different index systems. Extensive work on the application of information proposed in this study is still need in predicting pavement performance and conducting maintenance decision-making in further.
•A new modified adhesion test by considering cyclic temperature effect is proposed.•The cyclic temperature effect is simulated through 3 hot-cold cycles.•The total dissipated energy is proposed to ...evaluate the effect of aging on sealant adhesion.
Due to the influences of installation and field environment, the adhesion failure usually occurs during the actual application of sealants. But current specification methods do not adequately consider the installation aging and field cyclic temperature effect on the adhesion of sealants. Hence, a new modified adhesion test method was proposed to quantitatively evaluate the effect of aging on the adhesion of three types of sealants. The cyclic temperature effect was simulated through 3 hot-cold cycles and the aging during installation was modelled through the short-term thermal aging. Based on the modified adhesion test, an evaluation method and 3 evaluation indexes were proposed to quantitatively evaluate the adhesion of sealants. Further, based on energy method, total dissipated energy (Et) was proposed and used to quantitatively evaluate the effect of aging on sealant adhesion. Then the aging indexes of several evaluation indexes were proposed to analyze the effect of aging on the adhesion of sealants. Finally, a comparison was made between current specification bond test and the modified adhesion test and the advantages of modified adhesion test were demonstrated. The results show that short-term aging had a significant weakening effect on the maximum tensile stress (σn) and made the tensile separation stiffness (Kn) of different sealants change irregularly. The conventional adhesion evaluation index, growth rate of tensile separation stiffness (Gs), is not suitable for evaluating the effect of aging on sealant adhesion. Compared to Gs, the Et index reflects the accumulation of dissipated energy during the whole test process, and improves the stability of the overall evaluation. The evaluation index Et and the corresponding aging index AIE were recommend to quantitatively evaluate the effect of aging on sealant adhesion. Due to the effect of short-term aging, the adhesion of three types of sealants under the cyclic temperature effect decreases by 15%∼35%. One recommend that the effect of short-term aging should be considered in the adhesion evaluation of sealants.
•A general framework of degradation-based reliability was developed.•A degradation model to describe the evolution of degradation index was established and validated.•A new approach to calculate ...reliability was established using Monte Carlo simulation.•The developed approach can capture a real-degradation behavior of stabilized base course materials.
The dynamic elastic modulus of stabilized base course materials is crucial to the design and evaluation of pavement, which has a great effect on the life-cycle performance of pavement. In this study, the fatigue performance of commonly used stabilized base course materials was investigated. A general framework of degradation-based reliability was developed. To accurately characterize the degradation process of dynamic elastic modulus, a degradation index was proposed and its failure threshold values were defined. A degradation model to describe the evolution of degradation index was established and validated. A new approach to calculate reliability was established using Monte Carlo simulation. The corresponding degradation-based reliability was conducted on the fatigue test data. Results show that the value of critical degradation index is significantly influenced by the properties. The proposed degradation model is capable of predicting the degradation index with high degree of accuracy. The developed degradation-based reliability approach is able to capture the more real-degradation behavior of stabilized base course materials. The degradation-based reliability includes three phases, which correspond to different degree of cracking. The mean value of fatigue life corresponds to reliability decreasing phase.
•A simplified pavement analysis model was designed to analyze the loading conditions of pavement structures.•The traditional loading modes can only reflect two kinds of critical loading ...conditions.•The energy-controlled mode is more suitable to evaluate the fatigue performance of asphalt mixtures.
Loading mode plays a key role in the fatigue performance evaluation of asphalt mixtures. However, the stress-controlled mode and strain-controlled mode cannot reflect the pavement structure loading conditions. In this paper, a simplified pavement analysis model was designed to analyze the loading conditions of pavement structure, and the energy-controlled mode was put forward. The improved 4PB beam fatigue test procedures were proposed to achieve the energy-controlled mode. And the traditional 4PB beam fatigue tests were also conducted under stress-controlled mode and strain-controlled mode for comparative analysis, respectively. Results show that stress-controlled mode and strain-controlled mode can only reflect two kinds of critical loading conditions in the pavement structures, and do not have universal applicability. An intermediate loading condition that the stored energy approximately remains constant is found. The energy-controlled mode can be achieved well by improved test procedures. And the fatigue life Nf of asphalt mixtures measured under energy-controlled mode falls in between fatigue life Nf that is measured based on the stress-controlled mode and strain-controlled mode. The test results coincide with the theoretical analysis of simplified pavement analysis model. Therefore, the energy-controlled mode is more suitable to evaluate the fatigue performance of asphalt mixtures.
