High-temperature Performance Of Asphalt Mixture Research Articles

Influence of direct coal liquefaction residue (DCLR) on the rutting behavior of asphalt mixture with the discrete element method

The research explores the influence of direct coal liquefaction residue (DCLR) as a fine aggregate on the rutting behavior of asphalt mixtures (AMs). Four AMs were prepared and modeled, namely AM (AM-0), AM with 2.36 mm DCLR (AM-2.36), AM with 1.18 mm DCLR (AM-1.18), and AM with 0.6 mm DCLR (AM-0.6). Firstly, the rutting depth and uplift height of AMs were analyzed. Results indicated that the rutting depth and uplift height of AMs increased with rising temperatures and loads. The order of rutting depth and uplift height of AMs at different temperatures and loads was: AM-0＞AM-2.36＞AM-1.18＞AM-0.6. This suggests that DCLR replacing fine aggregates improved the high-temperature performance of AMs, and DCLR replacing 0.6 mm fine aggregate was the best alternative. Moreover, the influence mechanism of DCLR on the rutting behavior was investigated by the force chain distribution and particle movement. The results showed that the rutting deformation was caused by the movement of 0.6–2.36 mm particles. Compared with AM-0, the chain distribution of AM-2.36 was uniform and sparse, and the movement of 0.6–2.36 mm particles in AM-2.36 was small. This was due to the composite modification effect of DCLR within the AM, which increased the bonding degree of asphalt mastics. This enhancement improved connectivity between aggregates, strengthened their load transfer capacity, and raised the AM's overall self-organizing adaptability. Finally, it was also found that DCLR as fine aggregates served dual roles within the AM, acting both as a skeleton and a filler.

The influence of Multi-Layer Plastic Packaging (MPP) on the high-temperature performance of asphalt binders and mixtures using wet and dry mixing methods

ABSTRACT High temperatures, combined with heavy traffic loads, increase the risk of permanent deformation and reduce the useful lifespan of pavements, leading to a greater need for maintenance and rehabilitation activities throughout the pavement's service life. This study aims to evaluate the effectiveness of recycled thermoplastic additives, specifically Multi-Layer Plastic Packaging (MPP) materials, in enhancing the high-temperature performance of asphalt mixtures. MPP materials, including types such as Polyester, Polyethylene, Nylon, and Metalized Polyester, were used for binder modification in asphalt mixtures. The modification was conducted using both wet and dry methods. The physical and rheological properties of the modified binders were assessed at high temperatures to determine their impact on stiffness and resistance to permanent deformation. The results indicate that MPP materials significantly improve the high-temperature performance of asphalt mixtures by enhancing binder stiffness and resistance to permanent deformation, with the wet method proving more effective than the dry method. These findings highlight the need for developing practical guidelines for incorporating MPP materials in asphalt production in the future and underscore the importance of comprehensive studies on maintenance, rehabilitation, and overall pavement lifecycle costs.

Research on the Road Performance of Ring Diamond Resin Modified Asphalt Mixture

In order to solve the problems of ineffective modification and high cost of most asphalt modifiers, a new type of high viscosity and high elasticity asphalt modifier - ring diamond resin is introduced, and this modifier is injected into 70 # base asphalt. Through high-temperature rutting, low-temperature bending, immersion Marshall and freeze-thaw splitting tests, the road performance of 70 # base asphalt and ring diamond resin modified asphalt mixture is compared and analyzed. Intended to improve the quality of asphalt pavement while reducing economic costs, thereby extending the service life of the road. The research results indicate that the ring diamond resin modifier can greatly improve the high-temperature performance of asphalt mixtures, and to a certain extent improve their low-temperature crack resistance and water stability. It is a resin modified material with great potential and high advantages. It is recommended to use a dosage of 1% in practical road engineering applications.

Study on the shear strength of asphalt mixture by discrete element modeling with coarse aggregate morphology

High shear strength is crucial for asphalt pavements to resist permanent deformation at high temperatures, which is largely determined by the skeletal structure of coarse aggregates. In this study, four size ranges of polyhedral coarse aggregate clumps were built to simulate the morphology and dimensional characteristics of coarse aggregate. Subsequently, virtual triaxial shear tests were simulated using discrete element models. Three gradation types were analyzed to study the effects of aggregate structure, granularity composition, and coarse aggregate modulus on the shear strength of asphalt mixtures. The results show that it is feasible to obtain accurate morphological features of coarse aggregates by controlling the minimum diameter of the filled spheres in a polyhedral coarse aggregate box when constructing a discrete element model. The virtual triaxial shear test model developed in this study can be effectively utilized to simulate the shear mechanical properties of asphalt mixtures under various confining pressures. The numerical simulation results indicate that the cohesion of asphalt mixture AC-13 is the best, while the internal friction angle and shear strength of SMA-13 are the highest. The ranking of factors that affect the cohesion and internal friction can be summarized as: aggregate structure ≫ coarse aggregate modulus > granularity composition, while the order of factors that affect the shear strength is: aggregate structure ≫ granularity composition > coarse aggregate modulus. This indicates that the aggregate structure is crucial for the high-temperature performance of asphalt mixtures. This study addressed the issue of high variability in laboratory test results for macroscopic properties of asphalt mixtures and analyzed the skeleton role of coarse aggregate in asphalt mixtures from a mesoscopic perspective. The findings parameters for explaining the strength mechanism. The discrete element models also facilitate the optimization of asphalt mix design with reduced labor and time consumption on laboratory testing.

Effect of Basalt Fiber Diameter on the Properties of Asphalt Mastic and Asphalt Mixture.

In this study, basalt fiber having two types of diameters (16 μm and 25 μm) was selected and added to asphalt mastic and asphalt mixtures using different fiber proportions. The influences of fiber diameters and proportions on the properties of asphalt mastic and mixtures were studied. The adhesion behavior of the fiber-asphalt mastic (FAM) interface was evaluated by a monofilament pullout test, and the rheological properties of FAM were evaluated by temperature sweep, linear amplitude sweep, and bending beam rheological tests. In addition, the high-temperature stability, intermediate and low-temperature cracking resistance, and water stability of fiber-modified mixtures were studied by wheel tracking, ideal cracking, a low-temperature bending beam, and a water-immersed Marshall test. The results showed that the interface adhesion behavior between 16 μm fiber and asphalt mastic was more likely in the fiber failure mode at both -12 °C and 25 °C. Adding basalt fiber can significantly improve the high-temperature and fatigue properties of asphalt mastics. Moreover, 16 μm fiber had a better modifying effect on asphalt mastic than 25 μm fiber. The same enhancement trend can be observed in asphalt mixtures. Basalt fibers with 16 μm diameters can improve the high-temperature performance of asphalt mixtures more significantly. In addition, 16 μm fiber could sharply enhance the cracking performance of the mixtures at intermediate and low temperatures, while the enhancing effect of 25 μm fiber on the mixture is insignificant, though both diameters of the fibers have a minor effect on the water stability.

Study of shear strength and gradation optimization of asphalt mixture based on uniaxial penetration numerical test

Improving the shear strength is an effective way to improve the high-temperature performance of asphalt mixtures. In this study, we conducted numerical tests of uniaxial penetration of asphalt mixture to analyze the influencing factors of shear strength and shear cracking mechanism of asphalt mixture. Moreover, the stress transfer paths during cracking and the effect of voids on shear cracking behavior were also explored. Finally, a strong interlock skeleton-dense gradation with high temperature resistance of AC-20 mixture was proposed based on the shear strength. The results show that an appropriate increase in asphalt content, an increase in aggregate roughness, and a decrease in the void ratio improve the shear strength of the asphalt mixture. The shear cracking process is influenced by the combination of shear stress, tensile stress, and microcracks. Shear cracks are spread around and below the specimen in a “V” shape. The expansion and penetration of micro cracks are caused by the stress concentration phenomena brought on by the existence of voids, which also reduces the shear strength of the structure. The high-temperature performance of the AC-20 mix with strong interlock skeleton-dense gradation was improved by about 27%.

Correlation between the Rheological Properties of Asphalt Mortar and the High-Temperature Performance of Asphalt Mixture

The performance of an asphalt mixture is significantly affected by the properties of its asphalt mortar, which consists of an asphalt binder, mineral fillers, fine aggregates and air voids. The aim of this work was to evaluate the correlations between the high-temperature performance of an asphalt mixture and the rheological properties of its corresponding asphalt mortar. The multisequence repeated loading (MSRL) test was used to estimate the high-temperature performance of the asphalt mixture. Six different gradations, AC-13, SMA-13, SUP-13, AC-20, SUP-20 and AC-25, and two styrene–butadiene–styrene (SBS)-modified asphalt binders were considered and used to prepare the asphalt mixture specimens. The gradations and asphalt types of asphalt mortars were consistent with their asphalt mixtures. A modified multiple-stress creep–recovery (MSCR) test was proposed for evaluating the rheological properties of asphalt mortar with a dynamic shear rheometer (DSR). Based on the basic form of the Hirsh model, a multiple regression model was established, and its coefficient of determination (R-square) was 0.96. The rheological response of the asphalt mortar presented great correlation with the high-temperature behaviour of the asphalt mixture. In addition, the MSCR indicators (nonrecoverable compliance and percent recovery) obtained at 12.8 kPa creep stress represented the rheological status of asphalt mortar in asphalt mixture well. Therefore, the mechanical behaviours of asphalt mixture at high temperature could be accurately predicted by the MSCR indicators of asphalt mortar and its coarse aggregate parameters.

Fine aggregate sizes effects on the creep behavior of asphalt mortar

Asphalt mortar consists of fine aggregates dispersed in an asphalt mastic (a matrix of asphalt binder and filler) and can have a significant influence on the high-temperature performance of asphalt mixtures. However, the fine aggregate sizes (FAS) governing the creep performance of asphalt mortar is not well understood. The effect of different FAS on the creep properties of asphalt mortar was investigated through experimental and numerical methods. A static compressive yield test and a dynamic triaxial creep test were performed on various asphalt mortar samples to determine their creep response under different conditions of temperature and stress level. It was found that the maximum strain in the asphalt mortar gradually reduces with an increase in FAS under the conditions of constant temperature – constant stress level, different temperature – constant stress level, and constant temperature – different stress level. Further, the modified Burgers model was proposed as a viscoelastic prediction model of asphalt mortar. A viscoelastic fitting analysis was carried out to validate the proposed model and the results indicated its adequacy for predicting the asphalt mortar’s creep response. At the end of the study, a grey relation entropy (GRE) analysis was done to quantify the degree of influence of the various FAS on the viscoelastic behavior of asphalt mortar. From the GRE analysis, FAS between 0.15 mm and 0.3 mm was found to be the most crucial. Below 0.15 mm FAS, asphalt mortar is mostly viscous. It begins to show elastic properties when the maximum FAS is between 0.15 mm and 0.3 mm, while above 0.3 mm and towards 2.36 mm the asphalt mortar increasingly becomes more elastic. The findings from this study can be useful to pavement engineers and other pertinent stakeholders seeking to optimize the aggregate gradation design of asphalt mixtures through the fine aggregate portion in order to enhance rutting resistance performance.

Research on the Preparation of Graphene Quantum Dots/SBS Composite-Modified Asphalt and Its Application Performance

This study aims to prepare a graphene quantum dots (GQDs)/styrene-butadiene segmented copolymer composite (GQDs/SBS) as an asphalt modifier using the Pickering emulsion polymerization method. The physicochemical properties of the GQDs/SBS modifier and their effects on asphalt modification were investigated. In addition, the GQDs/SBS modifier was compared with the pure SBS modifier. Research results demonstrated that GQDs could be evenly dispersed into the SBS phase to form a uniform composite. Adding GQDs brings more oxygen-containing functional groups into the GQDs/SBS modifier, thus strengthening the polarity and making it disperse into the asphalt better. Compared with the SBS modifier, the GQDs/SBS modifier presents better thermostability. Moreover, GQDs/SBS composite-modified asphalt achieves better high-temperature performance than SBS-modified asphalt, which is manifested by the increased softening points, complex shear modulus and rutting factors. However, the low-temperature performance decreases, which is manifested by reductions in cone penetration, viscosity and ductility as well as the increased ratio between creep stiffness (S) and creep rate (m), that is, S/m. Furthermore, adding GQDs can improve the high-temperature performance of asphalt mixture, but it influences low-temperature and water stability slightly. GQDs/SBS also have the advantages of simple preparation techniques, low cost and are environmentally friendly. Therefore, they have become a beneficial choice as asphalt cementing material modifiers.

Study on the Performance and Adhesion Behavior of Ultrathin Wearing Course Using Calcined Bauxite as Aggregate

An ultrathin wearing course is an effective maintenance treatment for prolonging the service life of asphalt pavements, which have been widely used in the field of pavement construction and road maintenance. However, the repeated vehicle load and wear results in a decreased durability of ultrathin wear course cover pavement. Hence, the gradation of ultrathin wear course was designed using calcined bauxite in this study, and the water stability, low-temperature properties, resistance to permanent deformation, and salt erosion were investigated through a laboratory test. Results indicated that the addition of a nonammonia antistripping agent significantly improves the water stability of the asphalt mixture with calcined bauxite and its ability to resist salt erosion as well as improve its low-temperature deformation ability. At the same time, polyphosphoric acid improves the adhesion between asphalt and calcined bauxite aggregate and the high-temperature performance of asphalt mixture but has limited improvement in water stability and resistance to salt erosion. This research is conducive to the widespread use of calcined bauxite aggregates in road pavements and is of great significance for improving the durability of ultrathin wear course asphalt pavements.

Establishment of Rutting Model of Wheel-Tracking Test for Real-Time Prediction of Rut Depth of Asphalt Layers

The construction process control of asphalt layers directly affects the road service life and quality. The objective of this study was to establish a rutting model of the wheel-tracking test used for the real-time prediction of the rut depth of asphalt layers in the construction process. The gradation of asphalt mixture, asphalt content, and molding temperature were considered in the development of the new rutting model of the wheel-tracking test. The effects of these three factors on the high-temperature performance of asphalt mixture were analyzed. The order of importance of the factors affecting the high-temperature performance of asphalt mixture is the gradation of asphalt mixture, asphalt-aggregate ratio, and molding temperature. Overall, the predicted values of the rut depth of the wheel-tracking test are very close to the measured values. Furthermore, the difference between the rut depths of asphalt layers of the test group and the control group is small. These comparison results indicate that the new rutting model of the wheel-tracking test has high accuracy and good applicability for the test road.

Study on the influence of aggregate strength and shape on the performance of asphalt mixture

The strength and shape of aggregates significantly affect the internal skeleton structure (ISS) of the asphalt mixtures, which affects the service life of asphalt pavement. ISS is a critical factor that decides the load transfer path in the asphalt mixture. To improve the performance of the asphalt mixture, three aggregates Granite, Diabase, and Limestone with different strengths and shapes were used. Two-dimensional image processing was used to acquire the ISS including contact properties, distribution and orientation of aggregates. Marshall, wheel tracking and three-point bending beam tests were carried out to evaluate the relationship between skeleton indexes with mechanical properties. Results indicated that the coarse aggregate voids filling method could obtain mineral gradations with the same volume combinations for the three aggregates. The crushing value, loss-angles value, roundness, and flakiness index have an excellent relationship with contact characteristics, showing that strength and shape significantly affect the ISS of the asphalt mixture. The results of Marshall, rutting, and bending stiffness modulus are consistent with the internal structural index, proving that low-temperature and high-temperature performance of asphalt mixture are directly affected by aggregate contact properties. There is a weak linear relationship of strength parameters with mechanical properties because Diabase is three times stronger than Granite but has a lower performance demonstrating that the strength of aggregate has a minimal effect on the performance and stability of the asphalt mixture. The results obtained in this study could be used to improve the utilization efficiency of aggregate.

Investigation of the Performance of Ceramic Fiber Modified Asphalt Mixture

Ceramic fiber (CF) is a novel thermally resistant material with the potential to improve the high-temperature performance of asphalt mixture. In this study, asphalt mixtures with 0%, 0.1%, 0.2%, 0.3%, 0.4%, and 0.5% CFs were prepared. The Marshall test, wheel tracking test, Marshall immersion test, freeze-thaw splitting test, and low-temperature bending test were conducted to evaluate the performance of the CF-modified asphalt mixture. The morphologies of these asphalt mixtures were observed using scanning electron microscopy to analyze the modification mechanism. The results showed that the CFs could improve the mechanical properties, high-temperature stability, moisture susceptibility, and low-temperature cracking resistance of asphalt mixture, with the optimum CF content being 0.4%. Further microscopic analysis showed that the CFs improved the performances of asphalt mixture through forming three-dimensional network structure, asphalt absorption, bridging cracks, and pulling-out effect.

Evaluating the Performance of Reclaimed Asphalt Pavement Incorporating PelletRAP as a Rejuvenator

In the recent years, the use of reclaimed asphalt pavement (RAP) in the pavement has become inevitable for economic and environmental reasons. However, the brittleness property of aged asphalt in the RAP restrict its usage in a high percentage. Nevertheless, the rejuvenators are introduced into the mixtures to reverse the effect of ageing processes, decrease the stiffness and increase the workability of RAP mixture. In the present research, various percentages of PelletRAP rejuvenator were added to 100% of RAP mixtures. The performance characteristics of rejuvenated mixtures were investigated via resilient modulus (MR), dynamic creep, and wheel tracking tests. The results showed that when the PelletRAP was included into the mixture, the MR values and the creep stiffness modulus (CSM) decreased, while the permanent creep, the creep strain slope (CSS) and the rutting depth increased. However, all the rejuvenated mixtures exhibited better results than that of virgin mixture. Such a trend of findings suggested that PelletRAP can be used as a rejuvenator without a negative effect on the high-temperature performance of asphalt mixtures.

Evaluation of High-Temperature Performance of Asphalt Mixtures Based on Climatic Conditions

The dynamic stability of a rutting test does not optimally reflect the high-temperature stability of asphalt mixtures. In this study, a rutting test was performed over a long duration (4 h) at different temperatures (40, 50, 60, 70 °C) for three asphalt mixtures, namely, matrix AC-16, SMA-16, and modified AC-16 asphalt mixtures. Subsequently, the temperature rutting rate was obtained after considering the annual temperature conditions of Guangdong and Beijing in China. Because the conditions of the rutting test were different from that of the actual pavement, the rut depth was calculated using a modified temperature rutting rate. This modification considered four factors: wheel trace distribution, temperature, pavement thickness, and loading rate. The calculation of the temperature rutting rate considered the climatic conditions and utilized the rutting deformation data from hour 1–4 of the rutting tests, during which the asphalt mixture was in a stable creep period. Thus, the high-temperature stability of the asphalt mixture was reflected more scientifically by the temperature rutting rate than the dynamic stability. The high-temperature rut-resistance of the asphalt mixture was found to improve significantly after the introduction of two additives (anti-rutting agent and lignin fiber). The modified formula for rut depth can realistically predict the annual rutting depth for three asphalt mixtures in a one-way driving pavement.

Laboratory research on road performances of unsaturated polyester concrete at medium-high temperature

Unsaturated polyester resin (UP) and aggregate can synthesize unsaturated polyester resin concrete (UPC) with high performance, which was often used to fill materials and wear layers. However, the UP contained in UPC was usually high, resulting in high engineering cost. At the same time, there is less researches on the direct use of UPC as a paving material. In this paper, the Marshall mix design procedure was used to design UPC, and the road performance of UPC at medium-high temperature were studied. The aging test, Marshall test, the water immersion Marshall test, and the rutting test were performed to observe the road indicators of the UPC. At the same time, the uniaxial creep test and the indirect tensile test at different temperatures were carried out to observe the performances change of UPC with temperature. Results showed that UPC had a better water-resistance ability than that of asphalt mixture (AC) under the coupling effects of high temperature and water. Besides, the dynamic stability (DS) values of UPC were higher than that of asphalt mixture. However, UPC had a lower residual strain rate and creep rate relative to the asphalt mixture. The bonding effect of the UPC was better than that of the asphalt mixture at high temperature from the indirect tensile test results. High-temperature aging had a visible deteriorating impact on the high-temperature performance of asphalt mixture. As the UP is a thermosetting resin, UPC had excellent high-temperature durability. With the aging time increasing, the mechanical properties of UPC gradually decreased, but its mechanical properties were still superior to asphalt mixtures under the same aging conditions.

Performance Evaluation of Bone Glue-Modified Asphalt

Asphalt is one of the primary materials that are extensively used by the pavement industry throughout the world. Its behaviour is highly dependent on the amount of loading and the level of temperature it is exposed to. Asphalt has been modified in the past with different additives to improve its high- or low-temperature properties. In Pakistan, temperature remains high for most of the time of the year; hence, asphalt binders with less susceptibility to higher temperatures are preferred for flexible pavements. Acids, polymers, fibers, and extenders have been used by the researchers to improve high-temperature performance of asphalt mixture. In the present study, a bio material derived from the animal waste, named as bone glue (BG), has been used with the 60/70 penetration grade binder in dosages of 3%, 6%, 9%, and 12% by weight of asphalt binder. The bone glue is produced from a sustainable source. It is a cost-effective and eco-friendly material. Moreover, it produces a durable and nonhazardous asphalt composite. The influence of addition of bone glue on asphalt binder was evaluated using different testing techniques which include consistency tests, rheological analysis, and adhesion tests. Furthermore, different performance tests were conducted on bone glue-modified asphalt mixtures. Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) analysis were carried out to ensure the homogeneity and proper mixing of bone glue in asphalt binder. The results from the tests reveal that bone glue stiffens the asphalt binder hence enhancing its high temperature performance. Bone glue dosage of 9% by weight of the binder was found to be the optimum dosage based on the rheological and performance analysis.

Evaluation of Susceptibility of High-Temperature Performance of Asphalt Mixture to Morphological Feature of Aggregates by Fractal Theory

AbstractMorphological characteristics of aggregates have been regarded as a significant factor related to the high-temperature performance of asphalt mixtures. Fractal theory was used to calculate ...

Developing an optional multiple repeated load test to evaluate permanent deformation of asphalt mixtures based on axle load spectrum

An optional multiple repeated load (OMRL) test, capable of simulating the axial load spectrum in real pavement, was developed to evaluate the rutting susceptibility of asphalt mixture. This new test was conducted at the temperature of 60°C under multiple stresses determined by a simplified axle load spectrum considering the pavement management system (PMS). A pre-stage dynamic creep test was employed to determine the loading cycles of the first increment. Two kinds of asphalt mixtures were compared in the OMRL test with varying orders of multiple stresses and they were also tested in dynamic creep test under five different loading levels. As the test results show, loading sequences have a significant impact on the high-temperature performance of asphalt mixtures. The curve of permanent strain rate versus stress level could fit well with a power-law model in the dynamic creep test, and a similar result can be obtained by the OMRL test. However, the OMRL test shows higher efficiency than the traditional dynamic creep test. Besides, the secondary stage of the OMRL test fits a broken-line model since various stress levels are conducted on the specimen. The newly proposed lowest average strain rate (LASR) and multiple flow number (MFN) could evaluate the rutting resistance of asphalt mixtures under a more realistic loading condition. Overall, this OMRL test provides a better understanding of the rutting behavior of asphalt mixtures to improve the mix design and field performance.

The Effect of Morphological Characteristic of Coarse Aggregates Measured with Fractal Dimension on Asphalt Mixture’s High-Temperature Performance

The morphological properties of coarse aggregates, such as shape, angularity, and surface texture, have a great influence on the mechanical performance of asphalt mixtures. This study aims to investigate the effect of coarse aggregate morphological properties on the high-temperature performance of asphalt mixtures. A modified Los Angeles (LA) abrasion test was employed to produce aggregates with various morphological properties by applying abrasion cycles of 0, 200, 400, 600, 800, 1000, and 1200 on crushed angular aggregates. Based on a laboratory-developed Morphology Analysis System for Coarse Aggregates (MASCA), the morphological properties of the coarse aggregate particles were quantified using the index of fractal dimension. The high-temperature performances of the dense-graded asphalt mixture (AC-16), gap-graded stone asphalt mixture (SAC-16), and stone mastic asphalt (SMA-16) mixtures containing aggregates with different fractal dimensions were evaluated through the dynamic stability (DS) test and the penetration shear test in laboratory. Good linear correlations between the fractal dimension and high-temperature indexes were obtained for all three types of mixtures. Moreover, the results also indicated that higher coarse aggregate angularity leads to stronger high-temperature shear resistance of asphalt mixtures.