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Copyright of Journal of Harbin Institute of Technology. Social Sciences Edition / Haerbin Gongye Daxue Xuebao. Shehui Kexue Ban is the property of Harbin Institute of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Use waste tire glue powder, G-type high adhesive, and matrix asphalt to prepare a high-viscosity modified asphalt. The dynamic shear rheometer DSR was used to test the high temperature rheological properties and fatigue performance of asphalt, and the low temperature bending beam rheometer BBR was used to test the low temperature creep strength and creep rate of asphalt. The results show that:G-type high viscosity agent can effectively adjust the proportion of each component of rubber asphalt, improve its elastic proportion of components, and form a network structure in the rubber asphalt, to improve its colloidal stability, and gready enhance the high temperature deformation resistance, low temperature ductility, elastic recovery, stress sensitivity, fatigue and other properties of the rubber asphalt, and G-type high viscosity agent appropriate dosage in rubber asphalt is 8%. Compared with rubber asphalt, the viscosity, high temperature stability, low temperature flexibility, and anti-fatigue properties of rubber high viscosity asphalt have increased significantly, which can effectively protect the road performance and service life of drainage asphalt pavements. [ABSTRACT FROM AUTHOR]

In order to explore the performance of bright color asphalt pavement, different amounts of silicone-polypropionate (SMP) were selected to modify the bright color asphalt, and carries out three indexes and Brookfield viscosity test. The performance of different graded asphalt mixture is analyzed by rutting test wheel tracking test, low temperature beam bending test, immersion Marshall test and freeze-thaw splitting test. The results show that SMP modifier can improve the viscosity of the modified bright colored asphalt with the increase of the SMP content. In addition in AC (SK70), AC (SBS), CSMA, COGFC four graded types of asphalt mixture, COGFC bright color asphalt mixture has the best rut resistance, and SMP modifier has a certain improvement on the low temperature performance of colored asphalt mixture, but SMP modifier will have adverse effects on the water stability of colored asphalt mixture. [ABSTRACT FROM AUTHOR]

In China, a substantial portion of highway asphalt pavements are no longer capable of accommodating increasing traffic volumes and necessitate renovation and expansion. Prior to commencing such activities, it is crucial to evaluate the performance of the existing asphalt pavements. This study developed a novel normal cloud framework integrating a comprehensive weighted indicator system for existing asphalt pavement. Five key performance indicators including riding quality index (RQI), rutting area ratio (Rr), cracking area ratio (Cr), patching area ratio (Pr), and pavement structural strength index (PSSI) were selected to holistically represent the pavement condition in highway renovation and expansion projects. Subsequently, a method was proposed to determine the weights of these indicators by integrating the analytic hierarchy process (AHP) and entropy. A normal cloud model was constructed to address data characteristics and representation of indicator fuzziness/randomness through digital cloud modeling. The model was applied to 12 sections of the Jingjintang Expressway (Tianjin section). The results revealed only one section where the normal cloud model differed from the pavement maintenance quality assessment (PQI) model. The 3D ground-penetrating radar detection results of this different section indicated that the normal cloud model more closely aligned with the road structure condition. Compared to absolute pass/fail criteria of the traditional PQI model, the cloud model offered enhanced sensitivity to define graded condition assessments essential for reconstruction planning and decision analysis. Therefore, the normal cloud model is more suitable for assessing the performance of existing asphalt pavements in highway reconstruction and extension projects compared to the PQI model. [ABSTRACT FROM AUTHOR]

This paper aims to reveal the interaction relationship between microcracks and macrocracks and the influence of the interaction on the crack propagation behavior. A theoretical model of asphalt concrete was established for the interaction between microcracks with different crack densities and a macrocrack. And a meso-structure model of AC-13 dense-graded asphalt concrete was established by combining the Talyor medium method and the DEM (discrete element method). Macro and micro parameters, such as the stress–strain characteristics, crack evolution parameters, and crack tip stress field, were obtained through a semi-circular bend virtual test and used to study the characteristics of crack propagation under the interaction between microcracks and the macrocrack. The results indicate that the interaction has an effect throughout the process of asphalt concrete damage, and shows shielding and acceleration effects as the microcrack density changes. When the microcrack density is low (f3 ≤ 0.8), the crack propagation process, which is affected by the interaction effect, exhibits significant differences, and the interaction effect shows the shielding effect. When the microcrack density is high (f3 > 0.8), the fracture stage is mainly affected by the interaction effect, which shows the acceleration effect. The results provide a predictive theoretical and numerical model for low-temperature cracking of asphalt pavement, and theoretical support for the design, maintenance, and upkeep of long-life pavement. [ABSTRACT FROM AUTHOR]

In order to study the improvement of the mechanical properties of basalt fiber geogrids on semi-rigid base asphalt pavement and the prevention and control effect of reflection cracks, this paper laid the basalt fiber geogrid and test sensor in the different positions of the semi-rigid base of Yanchong Expressway experimental Sect. (625 m long) are divided into three working conditions: I, II, and III according to different reinforcement levels. Through the test, the temperature and strain at the corresponding positions of the top and bottom of the semi-rigid base course change with time, and the crack performance of the basalt fiber geogrid-reinforced semi-rigid base course is analyzed under the action of temperature and the linear regression equations between the temperature and the strain of the base course. Atmospheric temperature between substrate strain and substrate temperature is obtained. The field test results show that adding basalt fiber geogrid to the semi-rigid base can prevent reflection cracks and improve the anti-crack performance of the semi-rigid asphalt pavement, the best anti-crack effect in the middle position of the semi-rigid base. [ABSTRACT FROM AUTHOR]

Digital image processing is commonly used in civil engineering to measure aggregate morphologies. However, it has limitations due to laying style and acquisition method, restricting analysis to two-dimensional geometric features. To overcome this, a new laser scanning-based method is proposed to reconstruct three-dimensional features of coarse aggregates. Three-dimensional morphology indexes are developed, with promising results. This method effectively captures complete surface information and the ratios between axes, surface area rate, and volume rate describe shape, texture, and angularity well. The proposed methodology accurately characterizes coarse aggregate morphologies, aiding asphalt mixture design. Incorporating the developed indexes enables effective quality control of asphalt pavements. [ABSTRACT FROM AUTHOR]

Conventional human-involved maintenance methods for asphalt pavement pose significant challenges when applied to high-traffic road sections, often leading to congestion and safety risks, as well as reduced maintenance efficiency. In recent years, explorations into unmanned construction technology for newly constructed expressways have yielded beneficial and encouraging results. However, its application in road maintenance in more complex environments still needs to be expanded. In this study, an intelligent unmanned maintenance technology for asphalt pavement was applied to the Lilong Highway in Zhejiang Province, China, and the compactability, thickness, surface smoothness, permeability coefficient, and constructure depth of maintenance road sections were measured. Then, based on fuzzy comprehensive mathematics and the analytic hierarchy process, a comprehensive evaluation was performed on the intelligent unmanned maintenance technology, considering the aspects of road quality, safety, application, and socio-economic benefits. The results show that the road quality of intelligent unmanned maintenance technology can meet the road specification requirements. In addition, the membership degree of unmanned maintenance technology in the excellent grade is the highest, reaching 0.805, and the quantified value for the overall evaluation of the application effectiveness of unmanned maintenance technology is 92.10. This means that the final comprehensive evaluation result of unmanned maintenance technology is rated as excellent. The research findings provide decision-makers with valuable insights into the unmanned automation maintenance challenges faced by asphalt pavement, enabling them to implement appropriate measures to elevate the maintenance standards of road transportation. [ABSTRACT FROM AUTHOR]

To increase the content of reclaimed asphalt pavement (RAP) in asphalt pavement and address the issue of excessive mixing temperature in hot recycling mixtures, a special warm-mix recycling agent was developed for high-content warm-mix recycling technology, and the performance of warm-mix recycled asphalt was analyzed. Based on the principle of consistency with workability, a temperature control process design for high-content warm-mix recycling was proposed, the mix proportion design of high-content warm-mix recycled mixtures was completed, and comprehensive road performance analysis of warm-mix recycled mixtures was conducted. The results show that the developed high-content warm-mix recycling agent exhibits good recycling effect and can achieve mixing and compaction with a lowering temperature of 20 °C. The changes in high and low temperature performance, water stability, and dynamic modulus of warm-mix recycled mixtures can all achieve the same road performance effects as ordinary hot-mix asphalt mixtures. The proposed warm-mix recycling agent and high-content warm-mix recycling mixture design method provide effective references for engineering application with utilization of road solid waste resources. [ABSTRACT FROM AUTHOR]

To establish the rutting prediction model of asphalt pavement under layered variable modulus, the deviation of permanent deformation prediction of asphalt pavement caused by dynamic modulus change was corrected. Based on the asphalt mixture dynamic modulus test and laboratory triaxial dynamic creep test, the correlation between the asphalt mixture dynamic modulus ( | E ∗ | ) and its high-temperature deformation resistance was verified. Abaqus finite element software was used to analyze the dynamic modulus and vertical compressive stress of asphalt pavement with depth and temperature at different times, and the correction factor (m) of vertical compressive stress of each sub layer under different dynamic modulus was proposed. According to the idea of `sub layer deformation superposition', a rutting prediction model of layered variable modulus asphalt pavement was established by using SPSS software regression analysis, which included temperature, asphalt layer thickness, vertical compressive stress, correction factor, load action times and other factors. The results showed that the established rutting prediction model can more accurately predict the permanent deformation of asphalt pavement, improve the rutting prediction accuracy of middle and lower layers by 6. 03% and 10. 34%, respectively, and improve the overall asphalt layer by 5. 19%. [ABSTRACT FROM AUTHOR]

The bonding performance between a thin overlay and the pavement is an important basis for good performance of asphalt pavement. To research the effect of interlayer bonding on the fatigue life of thin overlays, three-point bending fatigue test was carried out on the double-layer beams with interlayer (DLBI). The equivalent fatigue life obtained by the Weibull distribution function was used to analyze the influence of stress ratio, loading frequency, immersion times, and freeze–thaw cycles on the fatigue life. The results suggest that the fatigue performance of DLBI was affected significantly by stress ratio, loading frequency, immersion times, and freeze–thaw cycles. The higher the loading frequency, the greater the effect of the stress ratio on the fatigue performance of the DLBI. The lower the stress ratio, the greater the effect of the loading frequency on fatigue performance of the DLBI. The fatigue life of the DLBI declined by 31.4% and 24.7% after 6 immersion days and five freeze–thaw cycles, respectively. The damage to DLBI caused by one freeze–thaw cycle was equivalent to that caused by 4 days of immersion. Models that take into account four kinds of environment factors to equivalent fatigue life prediction based on 50% failure probability and 5% failure probability, respectively, are proposed, with the equivalent fatigue life method. Taking the equivalent fatigue life as the indicator, the DLBI crack length expansion model is obtained, and the axle load conversion coefficients considering the influence of dynamic loads and adverse seasons factors are calculated. A method is proposed to judge the fracture of double-layer beams. [ABSTRACT FROM AUTHOR]

The maximum permissible content of reclaimed asphalt pavement (RAP) is restricted due to its negative effect on the stability of hot mix asphalt with RAP (HMA-RAP) performance. To address this problem, characteristics of materials, including aggregate gradation, aged asphalt content, and aged asphalt properties, were quantified by testing RAP obtained from different sources. Additionally, the changing law and variability of the indexes are also analyzed. In accordance with the quality requirements of hot mixture asphalt stipulated by the Chinese standard, a control model of the maximum RAP content embraced in recycled asphalt mixture for hot central plant recycling is established. Furthermore, the distribution characteristic of asphalt content with respect to particle size is analyzed. Eventually, a fluctuation range model of blended asphalt penetration is established. The results indicate that (1) the variabilities of aggregate gradation, asphalt content, and aged asphalt properties of RAP are nonnegligible; (2) a control model regarding maximum permissible RAP content in HMA-RAP is proposed based on aggregate gradation and asphalt content; (3) the asphalt content and particle size of RAP are exponentially distributed, and the particle size elevates with the decrease of asphalt content; and (4) the fluctuation range of blended asphalt penetration is related to the asphalt content and penetration of aged asphalt, and the fluctuation range extends with the increasing of RAP content. This paper suggests that, to characterize the variability of RAP with its aggregate gradation and asphalt content, for RAP without pretreatment, the maximum permissible RAP content in HMA-RAP is recommended to be controlled under 30%. [ABSTRACT FROM AUTHOR]

Currently, the research on the mechanical properties of rubber-modified asphalt mixtures primarily focuses on small-scale investigations, with insufficient exploration into the performance of rubber particles and their relationship with the mechanism and properties of modified asphalt mixtures. Limited studies have been conducted on large-scale rubber modification in asphalt mixtures. Due to frequent use and subsequent high damage to existing asphalt pavements, incorporating rubber-modified asphalt mixtures can partially alleviate premature deterioration. Dynamic modulus tests were conducted using MTS equipment under unconfined conditions to investigate the viscoelastic behavior of rubber-modified asphalt mixtures with high rubber content and elucidate the influence of rubber particle content on the elastic deformation and recovery capability. The dynamic mechanical properties of the mixtures were determined at different loading rates, temperatures, and types of rubber-modified asphalt mixtures. Based on the test data, variations in the dynamic modulus, phase angle, storage modulus, loss modulus, loss factor, and rut factor of the rubber-modified asphalt mixtures under different loading frequencies, temperatures, and types were analyzed. The results demonstrate the pronounced viscoelastic behavior of rubber-modified asphalt mixtures. The mixtures exhibit enhanced elasticity at low temperatures and high frequencies, while their viscosity becomes more prominent at high temperatures and low frequencies. Under constant test temperatures, an increase in load loading frequency leads to a higher dynamic modulus; conversely, a decrease in dynamic modulus is observed with increasing test temperatures. The dynamic modulus of ARHM-25 at a frequency of 10 Hz is found to be 12.99 times higher at 15 °C compared to that at 60 °C, while at 30 °C, the dynamic modulus at 25 Hz is observed to be 2.72 times greater than that at 0.1 Hz. Furthermore, the rutting resistance factors of the asphalt mixtures increase with loading frequency but decrease with temperature. The rutting factor for ARHM-13 at a frequency of 10 Hz is found to be 22.98 times higher at 15 °C compared to that at 60 °C, while at a temperature of 30 °C, the rutting factor for this material is observed to be 3.09 times greater at a frequency of 25 Hz than at 0.1 Hz. These findings suggest that rutting is most likely when vehicles drive at low speeds in hot weather conditions. [ABSTRACT FROM AUTHOR]

Microwave maintenance technology, as a new development trend, can realize the environmentally noninvasive and rapid repair of asphalt pavement and gradually replace traditional maintenance methods. Iron tailings were used as a self-healing material in this study to investigate the temperature response matching of microwave maintenance technology. Firstly, the physical properties and the mechanism of iron tailings were elaborated through macroscopic physical index testing and microscopic X-ray diffraction (XRD) analysis. Secondly, the applicability of aggregates to microwave heating was demonstrated by analyzing the temperature rise characteristics of the granules using infrared imaging. Then, the temperature field variation rules of the iron tailing asphalt mixture were summarized by microwave heating Marshall specimens. Finally, the road performance was assessed by conducting high-temperature dynamic stability, low-temperature tensile, water immersion Marshall, and freeze-thaw splitting tests. The experimental results showed that the iron tailings can be used as an aggregate for high-grade asphalt pavement and as the preferred aggregate for microwave maintenance technology. The iron tailings temperature field was radial from the inside out to provide different temperature response states for different pavement diseases, so the asphalt was dissolved and precipitated in a short time. The particle size of iron tailings was inversely proportional to the wave-absorbing heating rate, and the heating efficiency of the small particle size (0–4.75 mm) was the highest. The specimens doped with 4.75–13.2 mm iron tailings showed the best heating performance and road performance, with the average surface temperature of the specimens reaching 126.0 °C within 2 min. In summary, according to different disease types and construction needs, iron tailings can be used as an aggregate for asphalt pavement, providing an appropriate temperature field and improving the efficiency of the microwave maintenance of asphalt pavements. [ABSTRACT FROM AUTHOR]

In order to improve the service quality of roads and resolve the problem of defects in the conventional asphalt pavement in service, this paper uses a 5.3% aluminate coupling agent to modify the surface of nano-ZnO and prepares a composite-modified asphalt with nano-ZnO and basalt fiber (BF) as modifiers. First, the basic performance of different types of asphalt was investigated by means of a rotary film oven experiment. Then, a dynamic shear rheology experiment was carried out to analyze the high-temperature anti-rutting performance of the composite-modified asphalt at different temperatures and frequencies. Then, using a bending creep stiffness test, the low-temperature properties of the composite-modified asphalt were investigated. Finally, the microstructure and modification mechanisms of the composite-modified asphalt were analyzed with scanning electron microscopy and infrared spectroscopy. The results indicate that the anti-aging performance of the nano-ZnO/BF composite-modified asphalt is significantly improved after adding fibers to the modified asphalt. The average mass loss ratio is only 0.192%. At 46 °C, the rutting coefficient of the composite-modified asphalt was increased by 62.3%. The frequency master curve is always at the highest position and continues to rise, indicating a significant improvement in the high-temperature anti-rutting performance of the composite-modified asphalt. At 24 °C, the creep stiffness modulus S value of the composite-modified asphalt increased by 24.9%; moreover, there is no obvious effect of improving low temperature, but the variation range of creep tangent slope m of the modified asphalt after aging is decreased, which further shows that the addition of a modifier can decrease the influence of aging on asphalt. Nanoparticles are uniformly dispersed in the asphalt and form a three-dimensional interconnected structure with BF, which effectively improves the overall performance of the asphalt. Nano-ZnO and fibers have weak chemical reactions in matrix asphalt, but they are physically dispersed and compatible. [ABSTRACT FROM AUTHOR]

For achieving the better modifying effect of polyurethane on asphalt pavement materials, the PUA powder modifier was prepared with fine grinding at the glass transition temperature, and polyurethane-modified asphalt (PUA-MA) with different dosages of modifier was prepared. The impact of the PUA on the physical properties of asphalt binder was studied. The modifying mechanism of PUA on asphalt was explored by investigating the thermal performance and chemical composition of asphalt (thermogravimetric analysis, differential scanning calorimetry test, and Fourier transform infrared spectroscopy). The micrograph of the interactive interface was characterized by scanning an electron microscope. Furthermore, the rheological properties of PUA-MA were also investigated and analyzed. The results indicated that the PUA had a dense structure with few pores on the surface. After mixing with asphalt, it altered the asphalt's internal structure via physical fusion and chemical reaction (carbamate formation). PUA improved the thermal stability of asphalt, enhanced the asphalt's thermal decomposition temperature, and further reduced the thermal mass loss while decreasing the glass transition temperature. The addition and dosage increase in the PUA modifier significantly improved the softening point, viscosity, complex shear modulus, and rutting factor of asphalt. Also, the PUA could improve the elastic recovery ability of asphalt and enhance the rutting resistance of asphalt at high temperatures. However, the crack resistance at low temperatures was not effectively improved (ductility and penetration decreased). When the dosage was 6–9%, PUA-MA had the best high-temperature performance, but asphalt showed poor low-temperature performance at this dosage. This study provides a theoretical reference for popularizing and applying polyurethane as an asphalt modifier in road engineering. [ABSTRACT FROM AUTHOR]

This study aims to predict the mechanical response of crumb rubber-modified (CRM) asphalt pavements under traffic loads using three-dimensional (3D) discrete element method (DEM). First, irregular-shaped aggregates were generated in Python language, and discrete element models of six different asphalt layers, which considered the temperature gradient and fatigue damage, were established using 3D DEM. Then, model parameters were obtained through the uniaxial creep test for asphalt mastics at different temperatures. The fatigue damage was implemented by introducing a damage factor into the Burgers model. Finally, three mechanical response parameters (namely, permanent deformation, shear stress and transverse strain) of the six asphalt layers under traffic loads were analysed and compared. Results show that the mechanical response of CRM asphalt layers under traffic loads is significantly influenced by number of repeated loads, temperature, and asphalt layer materials. The shear stress and transverse strain at the wheel centre vary along the depth of asphalt layers, and the middle layer is the principal area of shear stresses in asphalt pavements. [ABSTRACT FROM AUTHOR]

With the growth of service time, semirigid base asphalt pavements have gradually entered the maintenance and reconstruction period. Therefore, the treatment of waste semirigid bases has become an important issue. In this paper, based on the analysis of the properties of cement-stabilized gravel milling material, the waste semirigid base material is cold recycled using foam asphalt. The mechanical properties of the cold recycled mixture of foamed asphalt formed by 100% cement-stabilized gravel milling material (FACRM-CM) were evaluated by splitting strength test, compressive modulus of resilience test, and dynamic modulus test. The softening mechanism of the semirigid base milling material was investigated from a microscopic point of view with the aid of scanning electron microscopy (SEM). The results indicate that FACRM-CM exhibits adequate mechanical strength for use in road base layers. When semirigid base milling materials are cold recycled using foam asphalt, the stiffness of the resulting mixture decreases, whereas its flexibility increases. The results of this research can be applied to the regeneration of semirigid bases, realizing the transformation of the base from rigidity to flexibility and reducing pavement diseases. [ABSTRACT FROM AUTHOR]

Synthetic fibres have been reported to provide substantial improvements to the mechanical properties of asphalt mixture. This study investigates the impact of aging on the cracking of aramid fibre-reinforced asphalt mixes (AFM) using the simplified viscoelastic continuum damage (S-VECD) theory. Loose asphalt mixtures with 0.05% fibre and control loose asphalt mixes were placed in an oven for 0, 1, 2, 4, and 7 days, respectively. Then, the viscoelastic properties and cracking behaviour of hot mix asphalt (HMA) and AFM were evaluated and compared using the dynamic modulus test and fatigue tests. The test results showed that the difference in the AMR (aging modulus ratio) values increased as the decrease in frequencies and temperatures increased. The aging sensitivity of the AFM was lower than the HMA after the 7d aging condition. The AMR is negatively correlated with the Sapp value which indicates fatigue cracking deterioration and modulus damage are correlated negatively during aging durations. The reductions in fatigue cracking performance of the AFM were 5%, 8%, 20%, and 23% subjected to 1d, 2d, 4d, and 7d aging conditions, which demonstrates the 4d aging condition is the key cracking stage during the aging durations. This study provides a reference for evaluating the anti-cracking performance of AFM under different aging conditions, which can be beneficial to aramid fibre asphalt pavement design and maintenance. [ABSTRACT FROM AUTHOR]

To examine the three-dimensional texture structure of SMA-13 asphalt pavement and assess its anti-skid performance, a light gradient-boosting machine evaluation model was developed using non-contact three-dimensional laser-scanning technology. The study focused on collecting three-dimensional texture data from newly laid SMA-13 asphalt pavement. Subsequently, wavelet transform was employed to reconstruct the pavement's three-dimensional texture, and discrete Fourier transform was utilized to separate macro- and microtextures, enabling the calculation of their characteristics. The macro- and micro-characteristics of the three-dimensional texture and friction coefficient were input into the model. A comparative analysis with linear regression and a random forest model revealed superior accuracy and efficiency in the model. The training set R2 is 0.948, and the testing set R2 is 0.842, effectively enabling the evaluation of pavement anti-skid performance. An analysis of parameter importance indicated that Rku and MPD are still effective indicators for evaluating skid resistance. Furthermore, diverse texture indexes exhibited varying effects on the anti-skid performance. The established asphalt pavement anti-skid evaluation model serves as a theoretical foundation for understanding the actual influence on pavement anti-skid performance. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Beijing University of Technology is the property of Journal of Beijing University of Technology, Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

With the application of machine learning rapidly gaining popularity in computer science and other fields, neural network techniques have successfully simulated the performance of in-service pavements as they are efficient in predicting and solving nonlinear relationships and in dealing with uncertain large-area pavement problems. In this paper, we address the problem of the optimal timing of preventive maintenance of asphalt pavements to accurately predict the condition index (pavement condition index, PCI) of highway asphalt pavements and develop a highly accurate, long-period, multifactor prediction model with the suitability of preventive maintenance at its core. The prediction model is called differential evolution particle swarm optimization back propagation (DEPSO-BP) neural network, and the input dimension of the prediction model is determined by gray correlation analysis (GCA), and DEPSO is used to improve the search efficiency of BP neural network and the asphalt pavement usage performance with parameter continuity prediction model. Finally, the Qinglan Highway (G22) PCI of Gansu Province, China, is selected for example validation, and the prediction results are compared with those of the four models. The results show that the multifactor prediction model based on DEPSO-BP neural network has good generalization ability. This model is important for improving the economic efficiency of road maintenance, and can be used in the long-cycle process to provide model reference and scientific basis for the subsequent road maintenance budget application and decision-making scheme. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Chongqing University of Technology (Natural Science) is the property of Chongqing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The properties and service life of asphalt pavement are to a large extent dependent on pavement structure. Most pavement structural designs at home and abroad commonly follow the typical structural design method; however, considering that the geographical span from east to west in Inner Mongolia is large, a single pavement structure cannot be optimal for all environments, and low-temperature fracturing may easily occur during the road service life. Ten kinds of pavement structures are analyzed in this paper. The pavement structure mechanical indices are analyzed using different soil base modulus values, different axle loads, and different internal contact conditions. A low-temperature return period was introduced to establish a Gumbel extreme temperature model. The low-temperature protection index and calculation method based on the return period for asphalt pavement is proposed, which takes Arxan City as a benchmark for calculating low-temperature protection values in Eastern Inner Mongolia. The low-temperature fracturing formula is improved to calculate low-temperature indexes for different pavement structures. Using a life cycle cost model, the economy of different pavement structures is evaluated from the aspects of initial cost, maintenance cost, and pavement residual value. By establishing a combined weight-fuzzy pavement evaluation model and combining the mechanical response, low-temperature fractures during the return period, and economy of the life cycle, a comprehensive property ranking for different pavement structures was obtained. Finally, the typical structural combination for the asphalt pavement in the Eastern Inner Mongolia is recommended to be three layers of asphalt surface + semi-rigid base or three layers of asphalt surface + asphalt treated base (ATB) + semi-rigid base. [ABSTRACT FROM AUTHOR]

Copyright of DYNA - Ingeniería e Industria is the property of Publicaciones Dyna SL and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study aims to provide a comprehensive review of the research status of flame retardant and smoke suppressive asphalt mixture. The related process of asphalt pyrolysis and smoke generation is dis- cussed. Secondly, the existing test methods of flame retardant and smoke suppression are summarized, and the test methods of asphalt flue gas emission are divided into mass loss method and adsorption method. The flame-retardant technology of flame-retardant asphalt pavement, flame-retardant fiber pavement, and porous flame-retardant pavement are introduced, and the characteristics of two smoke suppression methods, reducing the mixing temperature and adding smoke suppression components are analyzed. The re- search hotspot of flame retardant and smoke suppression on asphalt pavement is analyzed, and the key points and directions for subsequent research on flame retardant and smoke suppression on asphalt pavement are proposed. [ABSTRACT FROM AUTHOR]

The automated detection of distress such as cracks or potholes is a key basis for assessing the condition of pavements and deciding on their maintenance. A fine-grained pavement distress-detection algorithm based on integrated data using a digital twin is proposed to solve the challenges of the insufficiency of high-quality negative samples in specific scenarios An asphalt pavement background model is created based on UAV-captured images, and a lightweight physical engine is used to randomly render 5 types of distress and 3 specific scenarios to the background model, generating a digital twin model that can provide virtual distress data. The virtual data are combined with real data in different virtual-to-real ratios (0:1 to 5:1) to form an integrated dataset and used to fully train deep object detection networks for fine-grained detection. The results show that the YOLOv5 network with the virtual-to-real ratio of 3:1 achieves the best average precision for 5 types of distress (asphalt pavement MAP: 75.40%), with a 2-fold and 1.5-fold improvement compared to models developed without virtual data and with traditional data augmentation, respectively, and achieves over 40% recall in shadow, occlusion and blur. The proposed approach could provide a more reliable and refined automated method for pavement analysis in complex scenarios. [ABSTRACT FROM AUTHOR]

Copyright of China Sciencepaper is the property of China Sciencepaper and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In the maintenance engineering of asphalt pavement, it is often encountered that both the surface and middle layers are damaged and need to be maintained. The cold in-place recycling technology can be used to simultaneously treat multi-layer diseases and reduce the waste of pavement materials. The cold in-place recycling mixture is rarely used for high layer of pavement structure in high-grade highway. In the supporting practical engineering, the emulsified asphalt cold in-place recycling mixtures were paved as the middle layer of pavement structure by the laying of an overlay. In order to comprehensively evaluate the material performances, coring samples were drilled after cold recycling pavement opening to traffic, and different performance tests were carried out based on the coring samples. The newly paved SMA mixtures were set as the control group. The high temperature stability of cold recycling mixture was analyzed by dynamic creep test and MMLS3 accelerated loading test. Then, the cracking resistance of cold recycling mixture was studied by semi-circular bending test. Finally, the effect of curing time on splitting strength of cold recycling mixture was measured, and the moisture susceptibility was analyzed by dry–wet splitting test and freeze–thaw splitting test. The test results showed that the high temperature stability of cold recycling mixture was worse than SMA mixture. For the cold recycling mixture, the deformation value at the early stage and deformation rate at the stable stage were larger than SMA mixture in the accelerated loading process, and shear failure at high temperature occurred earlier. The cracking resistance of cold recycling mixture was worse than SMA mixture because of the aging effect of the old asphalt and adverse influence of the added cement binder. The effect of curing time on splitting strength of cold recycling mixture was significant, and two stable periods of early strength were, respectively, reached after curing 3 days and 7 days. The indexes of moisture susceptibility, including dry–wet splitting strength ratio and freeze–thaw splitting strength ratio, were obviously lower than that of SMA mixture, and the test values not up to the standard requirement existed. For the emulsified asphalt cold in-place recycling mixture, the improvement of material performances should be focused on, especially the moisture susceptibility. In the research, the emulsified asphalt cold in-place recycling mixtures were acceptably used as the middle layer of maintenance pavement structure. The reliable discussions were summarized based on coring samples collected from real-life road sections. The case can provide guidance and reference for similar engineering applications. [ABSTRACT FROM AUTHOR]

Copyright of Transportation Science & Technolgy is the property of Transportation Science & Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To confirm the feasibility of waste incineration fly ash applied in asphalt pavement materials, the waste fly ash from the waste incineration station in Dongguan (DG-FA) and Guangzhou (GZ-FA) were selected as mineral filler replacing limestone powder (LF) to prepare asphalt mortar. The physical properties, chemical composition, and thermal characteristics of FA were analyzed. The effect of FA on the physical properties and rheological properties of asphalt binder was investigated systematically. The micromorphology of FA asphalt mortar was characterized. Finally, the blocking effect of asphalt binder on the leaching of toxic elements from FA was evaluated through XRF test. The results showed that the granular composition of FA particles was similar to that of LF. Furthermore, compared to LF, the specific surface area and the pore structure of FA were more developed, and the high active amorphous material was higher. Adding FA to asphalt mortar and increasing replacing amount improved its high-temperature rutting resistance as well as its ability to adhere to asphalt, while the low-temperature crack resistance was decreased. Further, the asphalt binder provided the good shielding effect against the migration of heavy metals in FA. While the leaching concentration of Pb element slightly exceeded the hazardous waste leaching standard (GB5085.3–2007), the remaining elements met the standard requirements. Overall, FA improved asphalt mortar performance, and the asphalt had a good curing and stabilizing effect on the toxic elements in fly ash, indicating that FA could be used as a filler in asphalt pavements. [ABSTRACT FROM AUTHOR]

At present, the single-point observation method is not able to effectively monitor the overall settlement of the target surface of an embankment. The 3D laser scanning technology was, therefore, introduced to help solve this problem. In this study, the overall settlement of the Shi'an highway extended embankments were dynamically monitored and a series of point cloud data were obtained by 3D laser scanning. Due to the characteristics of point cloud data, the grid analysis and interpolation method in MATLAB were proposed for the analysis, so as to obtain the overall settlement displacements of the extension embankment. Furthermore, the reliability and accuracy of the 3D laser scanning were verified through comparison with the single-point observation, and the results are as follows: during the embankment extension construction process, the monitoring accuracy was improved by 25.8% at least when compared to the single-point observation method; during the asphalt pavement construction, the maximum settlement of single-point monitoring and the 3D laser scanning method recorded similar values of 1.6 mm and less than 2 mm, respectively; throughout the course of the 3-year post-construction settlement observation, the monthly settlement rate was maintained at an insignificant 0.01-0.09 mm/month for the single-point monitoring, and a similar rate of less than 0.05 mm for the 3D laser scanning method. These results show that the 3D laser scanning could reflect the overall settlement dynamics much better, and that combined with its advantages of fast and accurate observation, could be used to evaluate the settlements of new and old embankments in extension projects. [ABSTRACT FROM AUTHOR]

Based on the multiple stress repeated creep recovery test, the high -temperature creep properties of lignin modified asphalt w让h different mass ratios before and after short-term thermal oxygen aging were studied, and the evaluation indexes of creep recovery capability under the influence of temperature and stress were analyzed・ The results show that the specific molecular intermolecular forces of lignimodified asphalt significantly decrease in the high temperature environment, which leads to the weakening of viscoelasticity of asphalt. In the process of temperature and stress loading, the unrecoverable elastic deformation property of asphalt increases, and gradually transitions from elastoplastic damage to creep damage・ The resistance to permanent deformation begins to decline, and the asphalt gradually evolves into nonlinear rheology, showing that some creep failure occurs inside the structure. In view of the linear/nonlinear rheological behavior of asphalt, the traffic grade and nonlinear rheological range of the samples before and after short・term aging are obtained by referring to the criterion of stress sensitivity index of the non-recoverable creep modulus, which is of theoretical and practical value for the construction of asphalt pavement in road engineering. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Dalian University of Technology / Dalian Ligong Daxue Xuebao is the property of Journal of Dalian University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The design parameters are one of the important factors to ensure the quality of asphalt pavement design. In "Highway Asphalt Pavement Design Specification" (JTGD50-2017), the stander of China, used the asphalt mixture anti-pressure resilience modulus at a single temperature of 20 °C as the design metrics. However, asphalt mixture, as a sticky-bullet plastic material, shows different mechanical properties at different temperatures. China is a vast territory, and there are great differences between the high and low temperature value (m and n) of each region. Therefore, it is unreasonable to design asphalt pavement only with the asphalt mixture anti-pressure resilience modulus value at 20 °C. Studies show that the design parameters using PG technology can improve the high temperature anti-rutting and low temperature cracking performance of asphalt pavement. [ABSTRACT FROM AUTHOR]

Water damage is one of the main forms of early damage of highway asphalt pavement, which seriously affects the service performance of asphalt pavement. To address the problem of early water damage of asphalt pavement, the addition of anti-stripping agents in asphalt is an effective technical means. To further analyze the influence of anti-stripping agents on asphalt performance, Qingchuan rock asphalt, acylamine anti-stripping agent, fatty amine anti-stripping agent, rock asphalt + acylamine anti-stripping agent and rock asphalt + fatty amine anti-stripping agent were selected to modify the base asphalt. The rheological properties of modified asphalt were tested using a dynamic shear rheometer and bending beam rheometer. Combined with the mathematical-model-fitting test results of Sigmoidal, Burgers, viscoelastic continuum damage model (VECD), etc., the effects of different anti-stripping agents on the rheological properties of asphalt were evaluated through model parameters. The results showed that the Qingchuan rock asphalt could improve the high-temperature resistance to deformation of asphalt and improved the resistance to deformation of asphalt in a wide frequency domain but increased the risk of low-temperature cracking of asphalt. Acylamine anti-stripping agents and aliphatic amine anti-stripping agents reduced the elastic recovery ability and deformation resistance under a wide frequency domain of asphalt at high temperatures but enhanced the flexible deformation and ductility of asphalt at low temperatures. The compound anti-stripping agent not only improved the high-temperature deformation resistance of asphalt, but also improved the deficiency of rock asphalt's low-temperature performance and effectively enhanced its performance. [ABSTRACT FROM AUTHOR]

To investigate the cooperative influence of waste engine oil (WEO) and Buton rock asphalt (BRA) on asphalt characteristics, the WEO/BRA composite modified asphalt and its mixture with varied dosages were prepared. The high-, moderate-, and low-temperature assessments of WEO/BRA composite modified asphalt were conducted through temperature sweep tests, multiple stress creep and recovery (MSCR), and bending beam rheometer (BBR) tests. The softening point difference was used to analyze the storage stability of composite modified asphalt. Based on the Fourier transform infrared spectroscopy (FTIR) and fluorescence microscope (FM) test, the microscopic feature and chemical constitution of WEO/BRA composite modified asphalt were analyzed. Rutting test, low-temperature bending test, immersed Marshall test, freeze-thaw splitting test, and four-point fatigue bending test were carried out to verify the pavement properties of the WEO/BRA composite modified asphalt mixture. The results indicated that WEO improved the capability in low-temperature conditions and fatigue properties of asphalt modified with BRA. BRA enhanced the high-temperature property of asphalt modified with WEO. The synergistic effect of WEO, BRA, and neat asphalt was a physical reaction, and these modifiers were uniformly distributed in the asphalt. Meanwhile, WEO/BRA composite modified asphalt had excellent storage stability for the single modified asphalt. The test results of the asphalt mixture verified the results, indicating that WEO/BRA composite modified asphalt can be considered a new green and durable asphalt pavement material. [Display omitted] • WEO enhances low-temperature and fatigue properties, while BRA improves high-temperature stability. • WEO/BRA composite asphalt demonstrates potential as a new green pavement material. • The WEO/BRA composite asphalt mixture exhibits excellent fatigue performance. [ABSTRACT FROM AUTHOR]

In order to further study the mechanical properties of new asphalt steel plastic (ASP) pavement and explore optimal ASP pavement structures, this study analyzed the bottom tensile strain of asphalt mixture layer, the bottom tensile stress of steel plate layer, the bottom tensile stress of acrylonitrile butadiene styrene (ABS) layer, the top vertical compressive strain of subgrade and deflection. The results show that when the pavement structure adopts an 8 cm thick SMA layer, a 0.5 cm thick insulation layer, a 20 cm thick ABS layer, and 0.6 cm, 1.0 cm and 1.2 cm thick steel plate layers respectively, the mechanical properties of the ASP pavement are relatively good. The variation in the thickness of the steel plate layer has a greater impact on the bottom stress of steel plate layer. For the same pavement structure, when the dynamic load increases from 0.5 MPa to 0.9 MPa, the maximum values of the design indexes are linearly related to the dynamic load values. Under the static load, the shear stress generated in the steel plate layer is significantly lower than that in asphalt and ABS layers. The new asphalt steel plastic pavement has good mechanical properties and great application potential. • We select three ASP pavement structures with better mechanical properties. • Steel plate thickness has a great impact on the bottom stress of steel plate layer. • The shear stress in steel plate layer is lower than in asphalt and ABS layers. [ABSTRACT FROM AUTHOR]

Asphalt pavements at high altitudes are susceptible to aging and disease under prolonged action of UV light. To improve their anti-ultraviolet aging performance, UV-531/SBS-modified asphalts with UV-531 dopings of 0.4%, 0.7%, and 1.0% were prepared by the high-speed shear method, and the effect of UV-531 on the conventional performance of SBS-modified asphalt before aging was studied by needle penetration, softening point and 5 °C ductility tests. The high- and low-temperature rheological properties of UV-531/SBS-modified asphalt before and after aging were also analyzed by high temperature dynamic shear rheology test and low-temperature glass transition temperature test. Finally, the effect of UV-531 on the anti-aging performance of SBS-modified asphalt was evaluated by three methods, including rutting factor ratio, viscosity aging index, and infrared spectroscopy. The results show that with the increase of UV-531 doping, the needle penetration and 5 °C ductility show an increasing trend, but the effect on the softening point is small. The high temperature stability of SBS-modified asphalt is not much affected by the addition of UV-531, and the low-temperature stability is improved, and when 0.7% UV absorber is added, SBS-modified asphalt shows better low-temperature performance. The results of all three evaluation methods show that the addition of UV-531 significantly improved the anti-UV aging performance of SBS-modified asphalt, with the amount of 0.7% providing the asphalt with the best anti-UV aging performance. The results of the study can provide an important reference for improving the anti-ultraviolet aging performance of SBS-modified asphalt. [ABSTRACT FROM AUTHOR]

The phenomenon of structural destabilization damage to asphalt pavement is becoming increasingly serious as a result of high temperatures and heavy traffic. Considering the advantages of Qingchuan rock asphalt (QRA) in its durability, high-temperature rutting resistance, and good compatibility with asphalt, it was proposed to compound rock asphalt with SBS to ameliorate the high-temperature performance of asphalt. In this study, DSR and BBR were used to determine the rheological properties of Qingchuan rock-modified asphalt (QRMA) and Qingchuan rock–SBS-modified asphalt (QRA-SBSMA), and the optimum blending amount of rock asphalt was determined based on the PG classification results. Secondly, four different structures of '30 mm AC-10 upper layer (70-A, QRMA, SBSMA, QRA-SBSMA) + 50 mm AC-16 lower layer (70-A)' double-layer composite specimens were prepared. Multiple high-temperature performance evaluation indexes (G*/sinδ, Ds, rutting depth, micro-strain, Fn, modulus) were used to assess the improvement effect of QRA. Finally, using a 1/3 scale accelerated loading testing machine, we simulated high-temperature, water, and high-temperature coupled environments to assess the impact of high temperature and water on the performance of QRMA and QRA-SBSMA, respectively. The findings demonstrated that QRA can increase the PG classification of 70-A and SBSMA as well as its resistance to high-temperature deformation. Multi-index comprehensive evaluation methods were used to consummate the asphalt high-temperature evaluation system. The QRA-SBSMA had the smallest rutting depth and creep rate and the largest dynamic modulus, characterizing its ability to optimally resist high-temperature rutting and deformation. [ABSTRACT FROM AUTHOR]

In order to obtain the optimal electrode layout and ice melting effect of cast conductive asphalt concrete steel bridge deck pavement, firstly, pouring conductive asphalt concrete was prepared; secondly, different electrode materials and layout methods were selected to test the heating rate of the specimen from start to 120 min, and the electrode materials and layout methods were optimized. Then, the finite element analysis software ANSYS was used to build the model for heating and ice melting simulation, and the indoor test was used to further verify the ice melting effect of the cast conductive asphalt coagulation with or without the insulation layer. Finally, the thermal-structural coupling analysis of cast conductive asphalt concrete steel bridge deck pavement was carried out using ANSYS finite element software. The results showed that the stainless steel electrode material had the best heating effect, and the electrode thickness in the range of 0.1~3mm had no effect on the heating effect. The intermediate heating rate of the upper surface of the stainless steel sheet electrode cast conductive asphalt concrete in the left and right external electrodes was 8 °C/h, while the intermediate heating rate of the upper surface of the stainless steel mesh electrode cast conductive asphalt concrete was 12.9 °C/h. The layout of the left and right buried stainless steel metal mesh was able to effectively improve the snow melting efficiency; ANSYS finite element ice melting simulation was used to obtain the variation law of ice melting efficiency and a temperature field of cast conductive asphalt concrete. The indoor ice melting test showed that when melting the same thickness ice layer at 50 V voltage, it took 240 min with an insulation layer and 720 min without an insulation layer, which was three times that of the ice with an insulation layer, which further verifies the superiority of its ice melting effect. The most unfavorable load position of pavement under load and temperature field was determined. The maximum tensile stress and compressive stress of the pavement surface were transverse, and the maximum shear stress of the pavement bottom was transverse. [ABSTRACT FROM AUTHOR]

The traditional method of removing ice and snow on roads carries the risk of damaging roads and the environment. In this circumstance, the technology of salt-storage asphalt pavement has gradually attracted attention. However, snow-melting salts may also have an impact on asphalt mixture performance. To explore the effect of snow-melting salts on the mechanical and surface properties of salt-storage asphalt mixtures (SSAM), SSAMs were prepared with styrene–butadiene–styrene (SBS)-modified asphalt and high-elastic asphalt (HEA) as binders and snow-melting salts as fillers. The influence of the type of asphalt binder and the content of snow-melting salt on the performance of the SSAM was preliminarily investigated through laboratory tests. The results show that the high-temperature, low-temperature, and moisture resistance performance of the SBS group SSAM decreased by 9.8–15.1%, 1.6–12.3%, and 6.3–19.4%, respectively, compared with SBS00. The higher the amount of snow-melting salt, the greater the performance drop. The three mechanical properties of the HEA group containing high-elastic agent TPS are 11.3–19.7%, 4.2–12.3%, and 4.8–13.3% higher than that of the SBS group. Even when the content of snow-melting salt is 50% or 75%, the mechanical properties of the HEA group are better than that of SBS00 without snow-melting salt. Snow-melting salt has clear advantages in improving the anti-skid performance but decreases the anti-spalling performance. The surface properties of the HEA group were also better than that of the SBS group. Considering the mechanical properties and surface properties, the comprehensive performance of the HEA group is better than that of the SBS group, and HEA50 has the best comprehensive performance. In addition, the construction performance of the SSAM has also been verified, and the production of SSAM according to the hot mix asphalt can meet the specification requirements. [ABSTRACT FROM AUTHOR]

The performance of the recycled asphalt pavement is directly influenced by the content of the used regenerant (i.e., rejuvenator and/or unaged asphalt binder). The goal of this study is to optimize regenerant content of aged styrene-butadiene-styrene (SBS) modified asphalt binder based on high-temperature creep and low-temperature relaxation performance tests. Initially, penetration, ductility, softening point, multiple stress creep recovery (MSCR), and bending beam rheometer (BBR) tests were carried out to investigate the rheological behavior of the aged SBS modified binder (AMB) regenerated with different contents of the rejuvenator and unaged SBS modified binder (UMB). A method is proposed, based on the rheological behavior of the regenerated AMB, to determine the optimum contents of the regenerants (i.e., rejuvenator and UMB). To reach a successful trade-off between low- and high-temperature properties of the regenerated AMB, the relaxation rate VR and nonrecoverable creep compliance J3.2 (at 3.2 kPa) were selected as the evaluation indices to settle the optimum contents of the rejuvenator and UMB. The results showed that the ductility of regenerated AMB is on par with the UMB when the contents of rejuvenator and UMB are 4% and 70%, respectively. The nonrecoverable creep compliance and relaxation rate of the regenerated AMB tended to increase with the increase in the content of the rejuvenator and UMB, whereas the recovery rate and relaxation modulus decreased. It indicated that the low-temperature performance increased while the high-temperature performance was adversely affected by the increase in the content of the regenerants. The VR and J3.2 of the regenerated AMB were comparable to those of unaged state, when the contents of the rejuvenator and UMB in the aged binder were 5% and 70%, respectively. It indicated that the high-temperature creep and low-temperature relaxation performance of the AMB reach a balance. [ABSTRACT FROM AUTHOR]

Pavement surface texture evaluation is mainly analyzed based on elevation data in previous research, and attention also need to be paid to wavelength information. Furthermore, a well-established relationship model between surface texture and skid resistance for real road sections still needs further investigation to help provide useful information on appropriate maintenance time considering skid resistance attenuation. In this research, the macro-texture of asphalt pavement was evaluated from different aspects, including elevation, wavelength information, and geometry, and the relationship models between the macro-texture and skid resistance (at both low and high speeds) were established and compared using the multiple linear regression (MLR) and back propagation (BP) neural network to recommend a suitable one. In order to achieve this, this study monitored anti-skidding performance and the macro-texture of six road sections for 18 months. Firstly, the Dynamic Friction Coefficient (DFC) test and core drilling were conducted on site at three different service times. Additionally, a laboratory accelerated loading test was carried out on specimens prepared by similar material composition to one of the road sections, and the British Pendulum Number (BPN) was tested after different passes of loading. Secondly, 3D laser scanning was carried out on core samples from road sections and laboratory specimens after different passes of loading. The correlation degree between macro-texture indexes and anti-skidding performance was analyzed with the grey correlation entropy analysis method. Finally, the relationship models between the anti-skidding performance at high and low speeds and macro-texture were established based on the MLR and BP neural network. The results indicate that the macro-texture indexes calculated based on elevation data to characterize vertical irregularities have a good correlation with the skid resistance despite the different service times and pavement types. Compared with the BP neural network model, the MLR model has low correlation and noticeable error. The relationship model between F60 (DFC at the speed of 60 km/h) and macro-texture could be well established by the BP neural network. In addition, the relationship between F20, BPN, and pavement surface macro-texture is poor, making it impossible to establish a model with good correlation. Generally, it is recommended to use the BP neural network to establish the relationship model between macro-texture and skid resistance. [ABSTRACT FROM AUTHOR]

Sprinkled snow melting salt (SMS) exerts a snow melting effect and also has a negative impact on the asphalt pavement and the environment. Salt storage pavement technology can alleviate these two problems. However, non-alkaline SMSs may have the risk of affecting asphalt mastic properties and further affecting the mechanical properties of asphalt pavements. Therefore, the general properties and rheological properties of two styrene-butadiene-styrene-modified asphalts with and without high elastic polymer were studied after adding SMS. The asphalt mastic without a high elastic agent is defined as the SBS group, and the other group is the HEA group. Our results show that the HEA group shows a lower penetration and a higher softening point, ductility, and viscosity than the SBS group. The more the SMS, the more the reduction effect of the general performance. The elastic recovery of asphalt mastic decreases with the content of SMS. SMS has no obvious effect on the ratio of the viscous and elastic composition of asphalt mastic. The creep of asphalt mastic increases with the content of SMS. The high elastic polymer can significantly reduce the creep, and even the strain of HEA100 is smaller than that of SBS00. SMS increases the creep stiffness and reduces the creep rate at low temperature. Although SMS increases the potential of asphalt pavement to melt ice and snow, it also reduces the high-temperature rutting resistance and low-temperature crack resistance of asphalt mastic. Salt storage pavement materials can be used in combination with high elastic polymers to reduce the negative effects brought by SMSs. [ABSTRACT FROM AUTHOR]

In this study, a 3D finite element model was established for the asphalt pavement with cement-stabilized magnesium slag-aeolian sand base to explore the difference between the performance of cement-stabilized magnesium slag-aeolian sand base under the actual operation state and that under the design operation state. The model was also used to provide a theoretical basis for determining their construction technologies and the causes of pavement damage. Moreover, it was used to simulate the three-layer continuous, layered continuous, and layered discontinuous construction technologies through the interlayer contact state between bases (upper base, lower base, and subbase). Next, under the action of traffic load, the mechanical response of this model under the completely continuous state and three construction technologies was calculated. On this basis, the influence of the interlayer contact state between bases on the mechanical response of structural layers in the asphalt pavement was analyzed. Results demonstrate that in case of the change in the interlayer contact state between bases, the vertical displacement on the surface of each structural layer basically keeps an unchanged distribution, and the horizontal compressive stress at the bottom of the upper base is turned into tensile stress, and the maximum shear stress at the bottom of the lower base is changed from a smooth bimodal distribution into a unimodal distribution. The index values are influenced to different degrees, among which the horizontal tensile stress at the bottom of the upper and lower bases is influenced to the greatest extent, followed by the maximum shear stress at the bottom of the upper base, lower base, and subbase and the vertical displacement of the pavement. When the layered continuous and discontinuous construction technologies are adopted, the pavement performance index decrease by 3.0% and 6.5%, respectively, in comparison with that in the event of layered continuous construction technology. The layered continuous construction technology is recommended, and pertinent measures should be taken during the construction stage. [ABSTRACT FROM AUTHOR]

Salt storage asphalt pavement has been considered as a functional pavement that could effectively and actively melt snow on the road. Based on the previous studies, the macro melting snow and ice mechanism on the salt storage road is studied, high performance salt storage materials have been developed, as well as to analyze pavement and anti-freezing performance of salt storage asphalt mixture. Although some studies have evaluated salt storage asphalt mixtures and salt storage materials, there still remains many issues related to the slow-release effect of salt storage materials and road performance. Therefore, the article tries to review the key contents: mechanism for ice-snow melting of salt storage asphalt pavement, salt-storage materials design, salt-storage asphalt mixture-mix design. Additionally, key points concerning the road and anti-freezing performance of salt storage asphalt pavement were assessed. Finally, a series of important proposes for further investigations in this field have been presented. [ABSTRACT FROM AUTHOR]

It is significant to make full use of solar energy to reduce the deterioration of asphalt pavements and the negative impact on the environment due to temperature changes. Using phase change materials (PCMs) in asphalt mixture could increase temperature regulation and reduce thermal degradation due to temperature cycling. In order to study the effect of a new solid–solid PCM called PPGC-PCM on the performance of asphalt mixture, a series of tests were carried out. The control group and six different contents of PPGC-PCM were added into AC-13 asphalt mixtures. The effects of PPGC-PCM on the mechanical, moisture resistance, high-temperature, and low-temperature cracking resistance properties of asphalt mixture was analyzed. The influence of PPGC-PCM on the thermal properties in asphalt mixture was analyzed by thermal conductivity test. Results showed that the addition of PPGC-PCM could improve the moisture resistance and low-temperature cracking resistance of asphalt mixtures, as well as greatly reduce the thermal conductivity of the asphalt mixture. The optimal application could be achieved by using the PPGC-PCM with 7.5% addition ratio. In addition, the cooling test proved that the addition of PPGC-PCM could significantly improve the heat preservation capacity of the asphalt mixture. The temperature difference between PPGC-PCM and control testing groups was up to 3.8°C, and the mixture was cooled from 21°C to 0°C with a delay of 18–21 min.

Research on the aging process of styrene-butadiene-styrene block copolymers (SBS) block copolymers modifier has practical significance in guiding the recycling of SBS-modified asphalt pavement. The objective of this study is to investigate the aging process of SBS modifier under various oxygen and thermal conditions to address the variations of physical properties and chemical reaction during the service life of recycled asphalt pavement (RAP). In the proposed testing process, SBS modifier was thermal oxidative and vacuum thermal aged at different temperatures and time prior to blending with base asphalt to prepare SBS-modified asphalt. SBS modifier was first dissolved by carbon tetrachloride (CCl4) and then tested through infrared (IR), gel permeation chromatography (GPC), and thermogravimetric (TGA) tests to investigate the variations on microstructure and chemical compositions of aged SBS modifier. The effect of aged SBS modifier on performance of SBS-modified asphalt was evaluated by comparing the mechanical and chemical properties of base and SBS-modified asphalts. Based on the results of the experimental program, appearance variation, modifying effects, and chemical reaction of SBS modifier under oxygen condition were obviously different from that of vacuum condition. The chemical reaction of SBS modifier was not significant at vacuum and high temperature condition, instead, a small amount of degradation was observed. Degradation of mechanical performance of SBS-modified asphalt was mainly caused by aging of base asphalt. Therefore, the SBS modifier in the RAP was suggested to be considered in the mixture design. [ABSTRACT FROM AUTHOR]

Smartphones have integrated various sensors (e.g. GPS, acceleration sensor) and can be used to evaluate roads roughness. In this study the theoretical algorithm, in which the vehicle suspension parameters were included, would be established to calculate International Roughness Index (IRI) from acceleration using smartphones. Firstly, based on Android Studio 2.0, a client application installed on smartphones was developed. Next, the physical parameters of a quarter actual vehicle model (QAVM) were identified utilizing the front wheel drop test in accordance with complex modal theory. Then, the relationships among acceleration, IRI and the profile elevation were established through the derivation of theoretical formula. Finally, a validation analysis was implemented to evaluate the feasibility and reliability of this methodology. The validation experimental results on three asphalt pavement segments indicated that the collected acceleration data utilizing smartphone were basically consistent with that by accelerometers. Meanwhile, IRI calculated by the proposed theoretical methodology was close to that obtained by digital survey vehicle (DSV) and the maximum relative error between them was below 10%. Overall, due to the consideration of vehicle dynamic characteristics, the proposed method could improve the measurement accuracy and enable various vehicles to be used for road roughness evaluation. [ABSTRACT FROM AUTHOR]