Service Life Of Asphalt Pavement Research Articles

Experimental Study on Anti-Aging Effect of Asphalt Binder Liquid Anti-Aging Agent

During its service life, asphalt pavement is affected by environmental factors such as heat, light, oxygen and moisture. The asphalt binder ages, resulting in a decrease in the performance of the asphalt pavement. Therefore, the development and application of an asphalt anti-aging agent is of great significance. In this paper, the road performance of the developed asphalt binder liquid anti-aging agent was verified in the two scales of asphalt binder and asphalt mixture, respectively. Firstly, a simple aging test method was proposed using needle penetration as the evaluation index. The aging time of the simple aging method was determined to be 20 h. Secondly, the addition of anti-aging agents improved the low-temperature performance of the asphalt binder and had a less adverse effect on the high-temperature performance. The test values of needle penetration and the ductility of the asphalt binder increased and the values of the softening point decreased. And the road performance of the anti-aging asphalt mixture basically met the specification requirements. The addition of the anti-aging agent improved the low-temperature performance of the aged asphalt mixture by 16%, which is of great significance for improving the service life of asphalt pavement.

Fire-Retarding Asphalt Pavement for Urban Road Tunnels: A State-of-the-Art Review and Beyond

AbstractWith the rapid urbanization and development of metropolises, urban road tunnels have been constructed at an increasing rate, significantly alleviating urban traffic pressure, and improving urban resilience. Fire hazards have become a major threat to modern road tunnels due to the growing popularity of electric vehicles and high-density transportation of goods, particularly flammable materials. Asphalt pavements, as an essential component of road tunnels, may release harmful effluences and smoke under high temperatures, exacerbating the fire and adding risk to life safety. It is hence critical to investigate fire-retarding asphalt materials and their potential use in urban road tunnels pavements. This paper provides a comprehensive review of fire-retarding asphalt pavements for urban road tunnel pavements. The review covers tunnel fire generation mechanisms, evaluation methods, flame retardants for asphalt pavements, and recent developments in flame retardant technologies. By investigating these aspects, this paper aims to better understand the flammability of asphalt mixtures and asphalt pavements in urban road tunnels, promote the research of flame-retardant technology, and ultimately reduce the damage and loss caused by asphalt road tunnel fire accidents. Additionally, this study identifies the limitations of current research and provides an outlook for future research to contribute to the resilience of urban road tunnel structures and the longer service life of asphalt pavement in semi-closed road tunnels.

Self-healing performance and rheological properties of styrene-butadiene-styrene block copolymer modified asphalt promoted by polyurea elastomers containing disulfide bonds

Self-healing asphalt is considered as one of the desirable methods to extend the service life of asphalt pavement. This research prepared a polyurea elastomer containing dynamic disulfide bonds (PUA)/styrene butadiene styrene block copolymer (SBS) composite modified asphalt. Moreover, a new asphalt self-healing performance evaluation method based on the damage process and results has been proposed. Subsequently, the self-healing ability of PUA, the distribution of modifier, the functional group and molecular weight of composite modified asphalt were characterized by fluorescence microscope, Fourier transform infrared spectroscopy (FTIR) and Gel permeation chromatography (GPC). The self-healing potential and limits of PUA/SBS composite modified asphalt was investigated through the proposed healing linear amplitude scanning (HLAS) test. Results show that the SBS content and fatigue load level are the main factors affecting the self-healing promotion effect of PUA. The critical point of healing fatigue strain (HFS) can indirectly characterize the threshold at which healing promoters exert their effects. Next, the addition of fillers will reduce the self-healing performance of PUA/SBS composite modified asphalt, but it still improves by at least 61.318% compared with SBS modified asphalt. Finally, the addition of self-healing elastomers (PUA) improves the permanent deformation resistance at high temperature and low-temperature crack resistance of SBS modified asphalt. The dynamic recombination of disulfide bonds can increase the fatigue cycle number of 4%SBS modified asphalt by 93.52% at a 5% load strain level.

Modeling damage caused by combined thermal and traffic loading using viscoelastic continuum damage theory

Various engineering models have been proposed to mitigate fatigue cracking associated with thermal and traffic loadings, which are the two primary fatigue cracking mechanisms that negatively affect the service life of asphalt pavement. Thermal fatigue cracking is induced by cycles of temperature changes with relatively long time periods, which can be regarded as slow frequency sinusoidal loading. Traffic fatigue cracking is induced by numerous vehicle load repetitions and is often characterized using fast frequency sinusoidal loading. These two loading types occur simultaneously in the field. In order to investigate how to properly model the damage due to these two loading types, a set of tests that vary the load, frequency, and mode of testing was designed to mimic the scenarios that asphalt pavements experience under thermal loading and traffic loading separately and under the combined and simultaneous effects of both thermal and traffic loading. The viscoelastic continuum damage (VECD) model was applied to simulate the changes in material integrity under each condition. After determining the appropriate configuration for the proposed prediction model, the material integrity predictions were found to be accurate for the fast frequency tests but less accurate for the slow frequency tests. This difference is attributable to plasticity being a much more significant factor under slow frequency conditions than under fast frequency conditions. For the tests combining both fast and slow frequency conditions, the material integrity results oscillated continuously. It was postulated that these oscillations were due to the recovery mechanisms of asphalt concrete such as nonlinearity and healing. When the simplified viscoelastic continuum damage (S-VECD) model was applied, which does not consider the material’s recovery characteristics, the predicted material integrity was able to match the overall trend observed in the tests. Ultimately, a new way to model combined damage simultaneously under two cracking mechanisms (thermal fatigue cracking and traffic fatigue cracking) is introduced in this paper.

Study on Rheological Properties and Modification Mechanism of Budun Rock Asphalt/Nano-Silica Composite Modified Asphalt

To enhance the high and low-temperature performance of asphalt materials and extend the service life of asphalt pavement, two types of external admixtures, Butonite rock asphalt, and nano-silica are added to the asphalt. By conducting dynamic shear rheological tests and bending creep stiffness tests, the high and low-temperature rheological properties of Budun rock asphalt/nano-silica composite-modified asphalt were evaluated. The distribution of Budun rock asphalt and nano-silica in asphalt was studied using scanning electron microscopy and infrared spectroscopy tests, revealing the synergistic modification mechanism of Budun rock asphalt and nano-silica. The results show that the optimal dosage of Butonite rock asphalt and nano-silica composite-modified asphalt is 25% and 5%, respectively. At this dosage, the rutting factor G*/sinδ of composite-modified asphalt at 82 °C Compared with the matrix asphalt, the frequency main curve of Budun rock asphalt/nano-silica composite-modified asphalt is higher than that of the matrix asphalt and nano-silica-modified asphalt by 4 kPa. The creep modulus S at −18 °C decreases by 117.2 MPa, indicating that the high-temperature performance, low-temperature performance, and temperature sensitivity of Budun rock asphalt/nano-silica composite-modified asphalt are significantly improved compared to the matrix asphalt; The distribution of nano-silica particles in Budun rock asphalt/nano-silica composite-modified asphalt is uniform, and together with Budun rock asphalt, it forms a stable three-dimensional network skeleton structure; Budun rock asphalt/nano-silica composite-modified asphalt has generated new functional groups, and the blending process is mainly based on physical reactions, supplemented by weak chemical reactions.

Mechanistic investigation of grid-reinforced asphalt pavements with measured interface properties

The bond properties at layer interfaces are a required input in mechanistic asphalt pavement models. For design and analysis procedures, involving the calculation of key responses that are commonly linked to performance, perfect bond conditions are regularly assumed between layers. One emerging approach for prolonging the service life of asphalt pavements, either new or rehabilitated, is installing asphalt grid reinforcement (AGR) products between paving lifts. In these cases, the perfect bond assumption may not hold – undermining the reinforcement potential. Accordingly, the objective of this study was to investigate the effects of layer interface properties on key responses in pavements with AGR. The investigation was carried out by combining results from a full-scale construction, laboratory tests on asphalt concrete (AC) cores, and synthetic simulations. The latter were performed with a recently developed semi-analytic mechanistic code that can accept AGR products. This code can handle time- and temperature-dependent layer and interface properties, as well as moving loads. From the laboratory tests, it was found that the bond between AC lifts, with and without an AGR, is time- and temperature-dependent – best characterised by a relaxation interface stiffness function. This relaxation function was measured to be consistently larger without an AGR than with an AGR. Nonetheless, pavement simulations showed that including an AGR has no pronounced effect on strain magnitudes under high-speed/low-temperature conditions, can lessen horizontal strain magnitudes at the reinforced interface and at the AC bottom (mainly under slow-speed/high-temperature conditions, and depending on the installation depth of the AGR), and has no pronounced effect on deflections regardless of the loading speed and temperature level. It is concluded that even if laboratory measurements display a reduced interface stiffness when including an AGR, the reduction may not have any practical implication on key pavement responses, and the reinforcement potential is not necessarily undermined. The modelling and experimental approaches outlined and utilised in this study offer a rational tool for analysing this matter/question on a case-by-case basis.

Rheological properties and aging resistance of self‐healing polyurea elastomer modified asphalt

AbstractPolymer modified asphalt containing dynamic chemical bonds has the potential to increase the service life of asphalt pavement due to its excellent self‐healing ability. The effect of this self‐healing accelerator with dynamic chemical bond on the rheological properties and aging resistance of asphalt binder is still unclear. In this study, a self‐healing polyurea elastomer (PUA) modified asphalt containing dynamic disulfide bonds was prepared. The high‐ and low‐temperature performance and fatigue resistance of PUA modified asphalt were studied through multiple stress creep, low‐temperature bending beam rheometer, mechanical glass transition temperature, and linear amplitude scanning tests. Moreover, considering the service environment of asphalt over a wide temperature range (−30–70°C), three rheological aging indices (RAI) were proposed. At the same time, the aging resistance of PUA modified asphalt was evaluated by chemical aging index (CAI) based on carbonyl and sulfoxide groups. Finally, a linear relationship is established between RAI and CAI over a wide temperature range. The experimental results show that self‐healing accelerators can increase the resistance to permanent deformation of asphalt by 47.41% and the fatigue resistance by 88.54%. The S value of PUA modified asphalt decreased by at most 33.21% and the m value increased by at most 35.23% compared with BA at −18°C. Moreover, PUA can improve the long‐term thermal oxygen aging resistance of asphalt binders by at least 38.33% over a wide temperature range.Highlights Rheological properties of self‐healing polyurea elastomer modified asphalt. Aging resistance of self‐healing polyurea elastomer modified asphalt. Proposed rheological aging indices for different temperature ranges. Clarified the correlation between chemical–rheological aging indices.

Effect of Fibers on Extending the Service Life of Asphalt Concrete Pavements

Fiber stabilizers can significantly extend the road’s service lifeIn the research below, six different types of fibers are selected to research extending the service life of asphalt pavements by improving raw materials in the early stage from the perspective of asphalt concrete material selection based on the renovation of the municipal service road (G321) in Neijiang City, Sichuan ProvinceThe effect and economical efficiency of different materials on extending the service life of asphalt concrete pavements were compared by analyzing the properties of different materials such as high-temperature stability, low-temperature crack resistance, water stability, freeze-thaw splitting, etc., and their respective economic benefitsThe results of the research can provide a reference for similar engineering projects.

Enhanced stability of a three-dimensional graphene nanosheets networks modified asphalt mixture

To date, several concepts have been developed to enhance the mechanical and service life of asphalt pavements. Additives such as graphene, carbon nanotubes, carbon fibers and carbon black are used in the hot mix asphalt (HMA) or the asphalt binder (i.e., bitumen) for higher resistance to permanent deformations such as rutting, and transverse thermal cracking due to increased traffic volumes, vehicle mass and axle loads. In this study, graphene nanosheets (GNs) were used as potential modifier of bitumen binder in the HMA. The objective of this work is to investigate the impact of GNs modified bitumen on the Marshall stability and flow of the asphalt mixture using laboratory-compacted samples. The X-ray diffraction (XRD) study revealed a diffraction peak of GNs (002) at 2θ =26.5° along the bitumen’s γ-band and 10-band, which confirm a successful dispersion of GNs into bitumen binder. Furthermore, morphological analysis showed formation of a three dimensional (3d) interconnected networks of GNs between the bitumen micro-structures which could act as bridges for increased flexural strength of the binder. The Marshall stability and flow test results indicate that the mechanical properties of asphalt mixture were influenced by the addition of GNs to the bitumen binder. At 5% by weight of GNs modified bitumen (GNs-B), the compacted hot-mix Asphalt sample showed a higher Marshall stability of 11.7 kN recording 13.6% enhancement in comparison with the asphalt mixture with pure bitumen (P-B). In addition, when GNs-B was used, a lower flow of 1.4 mm was recorded which is desirable to prevent rutting and other forms of failure in asphalt pavements. This study underlines that adding GNs into asphalt binders such as bitumen could play a key role in enhancing the performance of asphalt pavements, which in turn extends their service life and saves maintenance expenses.

Impact of Rejuvenator-Modified Mastic on Asphalt Mixture Stiffness: Meso-Scale Discrete Element Method Approach

Encapsulated rejuvenators embedded in asphalt mixtures are a promising technology to extend the service life of asphalt pavements. However, their effects on the asphalt mixture’s performance still need to be properly understood. A recently developed three-dimensional discrete element method framework enables the evaluation of non-homogeneous distributions of the rejuvenator, closely resembling real conditions. This includes different scenarios involving capsule content and release efficiency. The presented numerical results show that the rejuvenator-to-mastic ratio and the number of rejuvenator-modified contacts influence the stiffness properties of asphalt mixtures. In cases where a homogeneous rejuvenator distribution is assumed, the three-dimensional DEM model predicts a significant reduction in the asphalt mixture’s stiffness that compromises the pavement’s performance. Simulations show that the diffusion effect needs to be considered for predicting the post-healed behavior of asphalt mixtures. For cases considering more suitable modified mastic amounts (less than 1.20 wt%), the effect on the asphalt mixture’s stiffness modulus is less pronounced, and the phase angle is not significantly affected. Additionally, the presented simulations suggest that the capsule content can be increased up to 0.75 wt%, and capsules with a release rate higher than 48% can be used without compromising the rheological performance of asphalt mixtures, possibly improving their self-healing properties. These numerical insights should be considered in future designs to achieve optimal post-healed behavior.

Low temperature failure behavior analysis of fiber reinforced asphalt concrete under indirect tension test using acoustic emission and digital image correlation

Failure behavior is the key property needed to be characterized in asphalt concrete at low temperature, which is one of the major influence factors for service life of asphalt pavement. In this study, the reinforcing effect of glass fiber on failure process of asphalt concrete under indirect tension (IDT) test at − 10 ℃ was investigated using acoustic emission (AE) and digital image correlation (DIC) techniques. Control asphalt concrete (CAC) with no fibers was also carried out for comparison. The evolutions of AE parameters including amplitude, count, duration, rise time and corresponding cumulative ones were obtained and analyzed to characterize the failure processes of fiber reinforced asphalt concretes (FRACs) and control one, which were compared with the results from static displacement and strain data obtained through DIC. The effect of fiber length was also investigated to better understand the reinforcing mechanism and determine the proper reinforcing fibers. The test results revealed that low temperature failure processes of CAC and FRAC could be effectively classified according to the variations of AE parameters and corresponding cumulative ones. Three and five failure stages were identified for CAC and FRACs, respectively, which could clearly reflect the reinforcing effect of glass fiber. Cumulative AE parameters presented better identification effect on fiber reinforcement than displacement or strain, while stain data exhibited favorable performance for microcrack initiation. As for the fiber length effect on damage failure process of FRAC, evolutions of cumulative AE parameters before final failure of specimen became more stable with the increase of fiber length within 6–20 mm. AE technique presented great potential for failure behavior analysis and explanation of fiber reinforcing mechanism in asphalt concrete, which also provided promising method for real-time monitoring of cracking in asphalt pavement.

Evaluating the Short-term Performance of Spray-on Rejuvenators using a Modified Bending Beam Rheometer Test Methodology

Spray-on rejuvenation is a preventive maintenance strategy that highway agencies use to prolong the service life of asphalt pavements. This process involves applying rejuvenators on the surface of asphalt pavement to reverse the stiffening caused by aging. However, with several rejuvenators available on the market, it can be challenging to select specific products without understanding their effects at the mixture level. In this study, 12 different spray-on rejuvenators were applied on two different test sections (each with multiple test cells) at the Minnesota Road Research Facility. To assess the short-term (1–2 months) performance of rejuvenators, bending beam rheometer (BBR) test beams were prepared from the surface of the field-extracted cores, and a creep stiffness test was performed. The creep stiffness was measured at three different temperatures to evaluate the effectiveness of rejuvenators at these temperatures. The BBR test was not used to assess the low-temperature cracking resistance; instead, it was simply used to measure the beams’ linear viscoelastic property (i.e., the creep stiffness). Results indicated that the effect of rejuvenation is more evident at higher temperatures (20°C in this case). Besides, specific unexpected effects of rejuvenator products were observed. One of the test sections included extensive microcracks visible on the surface (presumably because of construction-related issues). Some of the rejuvenators closed these microcracks, leading to a “bridging” effect and increasing the stiffness of the BBR beams. This study provides a reference for evaluating the effect of spray-on treatments at the asphalt mixture level, which can assist roadway agencies in decision-making.

Adhesion failure mechanism of asphalt-aggregate interface under an extreme saline environment: A molecular dynamics study

The extreme saline environment seriously threatens the service life of asphalt pavement. The interface adhesion failure between asphalt and aggregate is fundamental to pavement diseases. Therefore, the interface of asphalt-NaCl solution-mineral was simulated by molecular dynamics to investigate the adhesion failure mechanism between asphalt and aggregate in an extremely saline environment. The results show that the polarization-inducing effects of sodium and chloride ions promote the cross-sectional diffusion of the NaCl solution at the interfaces and contribute to the redistribution and rediffusion of asphalt components, and the formation of hydrogen bonds between water and asphalt components. The NaCl solution prevents the accumulation of saturates, resins, and asphaltenes on the SiO2 surface, and strips aromatics from the SiO2 surface due to the interaction. Sodium ions can be attracted to the oxygen atoms on CO32– to occupy active sites on the CaCO3 than asphalt, which makes it easier for chloride ions to penetrate the asphalt molecule and asphalt components to detach from CaCO3. These behaviors effectively impair the adhesion at the asphalt-mineral interface. The 3 wt% and 20 wt% NaCl solutions have the greatest effect on the adhesion work of the asphalt-SiO2 and asphalt-CaCO3, reducing them by 55.93 % and 66.03 %, respectively.

Performance evaluation of asphalt mixture reinforced by lignin and ceramic fiber

A single-adding fiber technology only plays a role in improving one performance of asphalt mixture such as high temperature or low temperature or water damage performance. Although double-adding fiber-reinforced asphalt mixtures are expected to improve overall road performance, existing research still only focuses on the analysis of a single performance. In this study, two representative fibers including lignin fiber (LF) and ceramic fiber (CF) were selected including to investigate the role of double-adding fibers in asphalt mixtures. The effect of different fiber proportions on the overall road performance of stone matrix asphalt (SMA-13) mixtures was analyzed via wheel tracking tests, low temperature bending test, moisture susceptibility test and fatigue test, etc. The results revealed that the combined addition of LF and CF exhibited superior improvements in mechanical strength, anti-rutting performance, moisture susceptibility, and fatigue life as compared to that of using either fiber alone. Specifically, compared to that of SMA mixtures using LF, the SMA mixtures using both two fibers improved in 11% dynamic stability, 8.6 % low-temperature bending stress, 2.1 % moisture susceptibility and 20 % fatigue life, respectively. And compared to that of SMA mixtures using CF, the mixtures using both two fibers increased in 11 % low-temperature bending strain and 8 % fatigue life, while improving slightly in dynamic stability, low-temperature bending stress, and moisture susceptibility respectively. Based on the results of efficiency coefficient method, the recommended ratio of LF to CF in the asphalt mixture is 1:2, providing a more balanced and comprehensive enhancement of road performances. This study provides a theoretical reference for the engineering application of improving the road performance of asphalt mixture through composite fiber blending, which can effectively enhance the service life of asphalt pavement.

Thermal and structural response of a pavement solar collector prototype

Thermal and structural response of a pavement solar collector prototype

Performance study on anti-weather aging combinations for high-content polymer modified asphalt and comparison by improved multi-scale mathematical TOPSIS method

Novel materials with anti-aging functionality play a crucial role in delaying the aging process and extending the service life of asphalt pavement. The objective of this study is to employ an improved mathematical TOPSIS method to optimize the best anti-weather aging combination for high-content polymer modified asphalt (SHCPMA). Firstly, the selection of light-absorbing materials, light-shielding materials, and antioxidants was conducted based on UV–vis spectroscopy test, resulting in eight unique anti-aging combination schemes. Then, an accelerated weather aging test was performed on SHCPMA to simulate its long-term outdoor aging process. Subsequently, a comprehensive investigation of the macro-rheological properties and micro-chemical properties of SHCPMA was carried out using rheological tests, Fourier transform infrared spectroscopy test, and gel permeation chromatography test. Finally, a comprehensive analysis was conducted using TOPSIS method to determine the optimal anti-weather aging combination. The results showed that UV531, NanoTiO2, Irganox1010 + Irgafos168 were the preferred light-absorbing, light-shielding, and antioxidant materials, respectively. These three types of anti-aging materials can effectively absorb solar radiation, shield solar radiation, and neutralize free radicals, thereby inhibiting the formation of polar oxygen-containing functional groups, and the degradation of polymer molecules during weather aging. The improved TOPSIS method indicated the combined use of three types of anti-aging materials can maximize SHCPMA's resistance to weather aging, and the synergistic effect of light-absorbing material and light-shielding material was also ideal in terms of anti-aging performance. The optimization of anti-aging materials contributes to prolonging the road service life, thereby promoting sustainable development in pavement engineering.

Preparation and characterization of polyurethane-modified asphalt containing dynamic covalent bonds

Self-healing behavior of binder has important potential for promoting low-carbon service and extending service life of asphalt pavement. A novel self-healing polyurethane modified asphalt with dynamic covalent bonds was prepared in this work. The chemical structure, thermal-oxygen stability, rheological properties, fatigue properties and self-healing capability of polyurethane modified asphalt with dynamic covalent bonds were systemically investigated through Fourier infrared spectrum test, thermal gravimetric test, dynamic shear rheology test, linear amplitude sweep(LAS) test and multiple fatigue-healing-fatigue test. The result indicates disulfide dynamic covalent bond and oxime urethane dynamic covalent bond were successfully introduced into polyurethane cross-linking structure in asphalt, and the thermal-oxygen stability of asphalt has a significant increase after modification under the environmental conditions of construction and service. Rheological properties analysis suggests the introduction of dynamic covalent bonds is beneficial to improve the low-temperature toughness of polyurethane modified asphalt, and enhances its low-temperature cracking resistance. LAS analysis indicates the fatigue life of polyurethane modified asphalt can also be lengthened by over 70% at different strain levels(1.5%, 2.5% and 5%) with the introduction of dynamic covalent bonds, which is attributed to the excellent conformation adjustment ability and stress dissipation ability of dynamic cross-linking structure in asphalt. The multiple fatigue-healing-fatigue test shows the self-healing capability of polyurethane modified asphalt has an improvement with the introduction of dynamic covalent bonds, especially at the later stage with serious fatigue damage, and oxime urethane dynamic covalent bond shows the better contribution effect as compared with disulfide bond. This is due to the reversible fracture-rearrangement characteristics of dynamic covalent bonds. This work provides a new idea for improving the self-healing capacity and rheological properties of binder, reducing the frequency of pavement maintenance and extending the pavement service life.

Performance of Oil-Absorbing organogel Polystyrene-Stearyl methacrylate as a fume suppressant of asphalt binder

Hazardous fumes can be generated during the high-temperature construction of asphalt pavement. Various fume suppressants have been developed, but many may compromise the performance of asphalt binder, which shortens the service life of asphalt pavement. This study aims to investigate the performance of a novel fume suppressant, namely oil-absorbing organogel polystyrene-stearyl methacrylate (P(S-SMA)), which can reduce the construction fumes of asphalt binder while maintaining good rheological performance. The results of the Fourier Transform Infrared Spectroscopy (FT-IR), Fluorescence Microscopy (FM) and asphalt fume mass tests showed that adding P(S-SMA) can improve the aging resistance of asphalt binder and reduce the particles (≥1 μm) and volatile organic compounds (VOCs) released up to 19.6 % and 30.4 % within 1 h, respectively. The rheological test results indicated that P(S-SMA) could effectively improve the viscoelastic properties, high-temperature performance and fatigue resistance of asphalt binder due to the combination of “supporting” and “hardening” effects after adding P(S-SMA). With 5% P(S-SMA) added, elastic and viscosity properties were increased by 90.6 % and 25.3 % and fatigue life was increased by 38.9 % and 26.4 % at the strain levels of 2.5% and 5%, respectively. This study proved the feasibility of using P(S-SMA) as a novel performance-enhancing fume suppressant of asphalt binder.

Investigation of factors affecting modified asphalt binder development and performance using the poker chip test

With the surge in the use of modified asphalt binders throughout the world, it is important to examine these materials for performance outside of their linear viscoelastic (LVE) range. Modified asphalt binders, which are usually costlier, are expected to increase the service life of asphalt pavements. The current paper utilizes two approaches to evaluate the nonlinear viscoelastic and failure performance of eight binders including six novel modified asphalt binders. First, the poker chip test for cracking performance evaluation was conducted at different loading rates and aging levels. The results conclude the efficacy of the poker chip test to differentiate and rank the best performing modified asphalt binders. Furthermore, the impact of varying the loading rates, aging levels, modifications, and performance grades was also studied. These results indicated that loading rates ranging from 1 to 4 N/s can be used to differentiate modified binder performance with similar ranking, which allows a wider range of machines to be used to do this test. In addition, the impacts of aging were studied to introduce differentiation between modifiers which are sensitive to aging. Apart from this, the Multiple Stress Creep Recovery (MSCR) test was conducted to evaluate the rutting performance. MSCR results further augmented the confidence in initial rankings as polymer-modified binders showed superior performance to other modifier types. It was observed that the top two binders in terms of poker chip results also had the best MSCR performance. Hence, instead of balancing the performance, like is done for mixtures, between rutting and cracking, an optimum binder can be synthesized which has excellent performance against load-related cracking and permanent deformation. This sets the stage for a balanced binder selection and design process to be implemented into future specifications and research efforts.

Study on compaction characteristics and mechanical performance deterioration of large stone porous asphalt mixes

Large stone porous asphalt mixes (LSPM) have advantages in promoting pavement performance, including cracking resistance, rutting resistance, and moisture susceptibility. Engineering practice demonstrates that performance degradation is crucial and has an impact on the durability and service life of asphalt pavement. Therefore, this paper aims at investigating the damage characteristics of LSPM as well as proposing the corresponding control methods. Firstly, a simulation device is designed to carry out the temperature cooling testing of LSPM in the laboratory. Then, the variation of air void contents in LSPM was analyzed with different testing temperatures, loading times, and freeze–thaw cycles. LSPM macro-mechanical strengths and cracking resistance were measured during freeze–thaw cycles. The outcome demonstrates that different sections cool at various rates and for varying lengths of time. The effective compaction time and compactness are directly related to the ambient temperature. Paving at medium and high temperatures is an efficient way to increase the compactness of LSPM. The testing temperature, loading time, and freeze–thaw cycles have significant influences on the change of air void contents, while the influence of load strength is low. The penetration shear strength decreases as the number of freeze–thaw cycles increases, and the change trend gradually decreases. Freeze-thaw cycles will lessen the anti-cracking performance of LSPM. Strictly regulating construction parameters, air void content, and drainage conditions could increase the LSPM asphalt pavement's durability and service life. The change in pore structure composition is the primary factor influencing the damage performance of LSPM.