Long-term Aging Research Articles

Evolutions on Microstructure and Impact Toughness of G115 Steel after Long-Term Aging at 700 °C

The microstructure and impact toughness evolution of G115 steel after long-term (ranging from 500 h to 10,000 h) aging at 700 °C were investigated in this study. The results showed that the microstructure of the G115 steel evolved from a finer-grained matrix with minor precipitates to a coarse-grained matrix with more precipitate with aging time, presenting a decrease in the local deformation degree in the matrix. The impact toughness of the steel decreased with aging time, presenting the largest decline at the initial aging times. The decrease in impact toughness was attributed to the coarsening of precipitates (M23C6 and Laves phase) in the steel matrix. The stable impact toughness during the whole aging process (from 500 h to 10,000 h) should be related to the comprehensive effects, including the precipitation of the Laves phase, the increase in high-angle grain boundaries, and the softening of the metal matrix.

Effect of microwave and deodorant treatments on long-term aging characteristics of crumb rubber modified asphalt

This research examined and compared the effect of microwave and deodorant treatments on the rheological and microscopic characteristics of crumb rubber modified asphalt (CRMA) after long-term aging. Although the emissions from the asphalt modified by microwave treatment of crumb rubber (CR-micr) or high-alkane alcohol deodorant treatment of crumb rubber (CR-de) are reduced significantly compared with the ordinary CRMA, the research on their rheological and microscopic properties after aging is insufficient (especially for the CRMA with CR-de), which may pose a potential risk to their application in road engineering. To address this issue, this paper first used the rolling thin film oven and pressure aging vessel test to imitate the long-term aging of CRMAs. Then, the rheological properties of aged CRMA samples were evaluated using a dynamic shear rheometer and a bending beam rheometer. Meanwhile, the surface micromorphology, micromechanical characteristics and the chemical functional groups of CRMA samples before and after long-term aging were characterized by atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR). The results demonstrated that the microwave treatment can enhance the fatigue life of the long-term aged CRMA by approximately 29 % under 8 % CR content and 3 % strain level, while effectively improve the resistance to low-temperature cracking. Meanwhile, after long-term aging, the carbonyl index of CRMA with CR-micr is 36 % lower than that of CRMA with CR-de and 50 % lower than that of ordinary CRMA. The micromechanical modulus of CRMA with CR-micr is also lower than that of CRMA with CR-de and ordinary CRMA. These findings manifest that the microwave treatment can improve the ability of CRMA to resist long-term aging, and the deodorant treatment does not have an adverse effect on this ability.

Long-Term Calendar Aging across Commercial Lithium-Ion Cell Chemistries - Part II: Modeling and Early Prediction

Lithium-ion (Li-ion) batteries are widely used in applications such as mobility, stationary grid systems, and various consumer and commercial systems. In electric vehicles (EVs), batteries often remain idle, with only about 10% utilization. Moreover, in stationary battery energy storage systems (BESS) designed for peak shaving, resting periods tend to cause more aging effects than the operational cycles. Consequently, quantifying the effect of calendar aging is crucial. However, current calendar aging models are inadequate for accurately modeling and predicting the diverse aging behaviors of commercial Li-ion batteries. In this study, we analyze a new, long-term Li-ion battery calendar aging dataset, which includes eight different commercial battery types. We compare and validate three calendar aging models—semi-empirical, symbolic regression, and Long Short-Term Memory Network (LSTM). We examine the transferability of these models across various commercial cell types, offering insights into their generalizability. Additionally, we introduce a novel trajectory-to-trajectory approach for early prediction of calendar aging lifetime. For the first time, we investigate the model's ability to interpolate and extrapolate aging behavior under different storage temperatures. This research provides practical insights for optimizing battery management strategies in conditions dominated by calendar aging.

Long-Term Calendar Aging across Commercial Lithium-Ion Cell Chemistries- Part I – Exploratory Data Analysis

In this study, calendar aging is investigated across different cell chemistries, temperatures, and state of charges in a dataset spanning over 10 years. By tracking the capacity and resistance over the course of degradation, we analyze the similarities and difference in calendar aging seen across chemistries and testing conditions. We parameterize degradation curves using standard semi-empirical models to assess Arrhenius dependence, t^x fitting, and time dependent non-linearity of calendar aging across different chemistries, testing conditions, and cell to cell variability. Through this process we demonstrate the complexity of calendar aging and the difficulty of its modeling, calling for the need for more robust prediction models.

Investigation on rheological properties and aging mechanism of asphalt under multiple environmental conditions

Under climatic conditions such as high temperature plus ultraviolet radiation and water, the mechanical properties of asphalt pavement will be significantly attenuated. Present research mainly focused on thermal oxidation and ultraviolet radiation aging, and there were many controversies about the effect of water on the aging performance of asphalt. In addition, the relationship between the aging behavior of asphalt under complex environments and the standard PAV test needs to be further clarified. This research comprehensively evaluated the rheological properties, microscopy, and functional group of matrix asphalt, SBS, and high viscosity modified asphalt under different climatic conditions. Compared with thermal oxidation aging, daily exposure to UV radiation can increase the aging degree of matrix and modified asphalt by about 5 % and 1.5 %, respectively. Compared with thermal oxidation aging, the presence of water and the coupling effect of UV and water can reduce the aging degree of asphalt by 3.5 % and 2.6 %, respectively. After 5 days of thermal oxidation and UV coupling, the aging degree was close to or even greater than that of the PAV experiment. Asphalt aging caused an upward shift in the complex modulus master curve, and a downward shift in the phase angle master curve of matrix asphalt and high viscosity modified asphalt. Due to the synergistic effects of hardening and polymer degradation, the phase angle master curve of SBS modified asphalt showed an upward trend in the low frequency range. Under the influence of climatic conditions, the polymer of asphalt would degrade, the particle size of the polymer phase decreased, and the brightness of fluorescent image became darker. The rich polymer phase structure of high viscosity modified asphalt enabled it to maintain excellent mechanical properties even after long-term aging.

Effect of Phosphate-Bridged Monomer on Thermal Oxidative Behavior of Phthalonitrile Thermosets.

Phthalonitrile thermosets are known for their excellent mechanical, physico-chemical, and fire-retardant properties, making them attractive for aerospace and mechanical engineering applications. When producing and applying phthalonitrile-based structural parts, it is essential to consider aspects such as processability and the long-term stability of the material's properties at high temperatures. In our previous studies, we demonstrated that resins containing phosphate-bridged bisphthalonitrile monomers are easily processable due to their low melting temperature and wide processing window. In this study, we investigated the impact of bis(3-(3,4-dicyanophenoxy)phenyl)phenyl phosphate (PPhPN) monomer content on physico-chemical and mechanical properties, thermal stability, and thermal oxidative stability. This research highlights the importance of conducting long-term thermal oxidative aging studies in addition to thermogravimetric analysis to properly assess the stability of thermosets. The findings indicate that adding less than 15% of PPhPN results in the formation of a crystalline phase, which impairs the resin's processability. Conversely, a high PPhPN content reduces the material's thermal oxidative stability. Therefore, based on mechanical and physico-chemical tests after thermal oxidative aging, it can be concluded that a 10-15% concentration of the phosphate-containing monomer enables easy processability of the phthalonitrile resin and provides excellent long-term thermal oxidative stability at temperatures up to 300 °C, while maintaining a flexural strength exceeding 120 MPa and an elasticity modulus of 4.3 GPa.

Modeling and Laboratory Investigation of Tack Coats as Bituminous Pavement Interlayer

The adhesive properties of tack coats between asphalt pavement layers are crucial for the pavement’s structural behavior. This study first involved numerical analyses to compare stress patterns, deformations, and displacements in the pavement structure under various geometric and mechanical conditions. A rational calculation method based on the theory of elastic multilayer systems was used to quantify the impact of layer properties such as thickness, stiffness modulus, and Poisson’s ratio on interlayer bonding. Three bonding conditions—Full Friction, Partial Bonding, and Full Debonding—were analyzed to understand the tack coat’s effect between the top two layers. The second phase involved characterizing the mechanical behavior of the interface through shear strength tests (Leutner shear test) on both laboratory-prepared specimens and samples from a 10-year-old highway. Specimens were prepared using a Roller Compactor and tested under different interface conditions: hot-on-hot (H/H), residual bitumen 200 g/m2 (RB 200), and residual bitumen 400 g/m2 (RB 400). The tests examined the bonding effects in terms of tangential force and shear displacement at failure, as well as the impact of vehicular traffic on rutting and fatigue failure. Finally, this study investigated the long-term aging effects of the binder on interlayer bonding and sought to correlate the results of numerical calculations with those of the laboratory tests.

Long-term aging behavior and mechanism of CMSX-4 nickel-based single crystal superalloy at 950 ℃ and 1050 ℃

Nickel-based single crystal superalloys CMSX-4 have been widely used to manufacture aeroengine turbine blades because of their excellent high-temperature comprehensive properties. The microstructure evolution behavior, mechanism, and influence on micromechanical behavior of the second-generation nickel-based single crystal superalloy during long-term aging at 950°C and 1050°C for 10–2000 h were investigated. The results show that, with the extension of aging time, the average size of γ' phase increased, whose morphology changed from square block to strip and L shape and rafting phenomenon was observed. The coarsening of γ' conforms to Lifshitz–Slyozov–Wagner (LSW) theory and the coarsening rates are 4.241×10−5 and 9.954×10−5μm3/h at 950°C and 1050°C, respectively. After aging at 950°C and 1050°C for 1000 h, segregation of refractory elements was formed in the samples. There are hard topological close-packed (TCP) phases surrounded by γ' envelope precipitates, which destroyed the continuous structure of γ'. The precipitation of TCP caused the depletion of refractory element Re in the γ' envelope phases, resulting in softening effect. It was also found that high temperature can not only accelerate the coarsening of γ' phase but also promote the precipitation and growth of TCP phases.

Laboratory Study of Aging Characteristics of Binder Warm Mix Asphalt Chemical Additive: Rutting, Fatigue Resistance, and Chemical Composition

The research aims to comprehensively assess the impact of anti-stripping agents ZycoTherm (Zyc) and Evotherm M1 (EM1) on Warm Mix Asphalt (WMA). The study employs a range of laboratory tests to investigate the rheological and chemical properties of modified asphalt. Conventional tests such as penetration and softening points are employed alongside advanced techniques including Dynamic Shear Rheometer (DSR), and Linear Amplitude Sweep (LAS) analyses to delve into the rheological properties. Chemical properties (SARA) were analyzed using thin-layer chromatography. Both short-term aging (STA) using The Rolling Thin-Film Oven (RTFO) and long-term aging (LTA) based on the Universal Simple Aging Test are simulated under controlled laboratory conditions. It was found in conventional tests that the value changed, but not significantly. In terms of rutting and fatigue performance, Zyc 0.05% showed positive results. Fatigue behavior shows Zyc has better resistance. The asphalt fractional composition test showed changes in each age condition.

Assessment of chemical degradation of epoxy resin binder used in the service of the Qin terracotta warriors

Since the Qin terracotta warriors were unearthed, polyamide 650 cross-linked E-44 epoxy resin binder has been employed to bond and restore them. In this paper, the chemical aging of the binders service in indoor natural environment during the past 30 years in the terracotta warriors was studied by means of infrared spectroscopy, X-ray photoelectron spectroscopy and thermogravimetric analysis. The results indicated that the binders did not emerge the characteristic peak of carbonyl stretching vibration at 1700 cm−1 in the IR spectra of all determined binders, and their thermal decomposition curves did not emerge any abnormal changes, and the thermal decomposition mainly occurred above 300 °C. There are evident ceramic grains attached to the surface of the binders being peeled off for sampling. These results that the binders service in the Qin terracotta warriors did not exhibit an observable chemical aging and still has strong adhesion. Generally, discrepancies were observed between natural aging and accelerated artificial aging due to the ineffectiveness of the latter to reproduce the effects of complex weather conditions. Compared to artificially accelerated aging, the evaluation results in a long-term natural aging of the binder which is used for restoration of the life-size Qin terracotta warriors, providing in the present investigation, are more reliable in terms of predicting the safety of restored terracotta warriors.

Understanding the differential precipitation behavior of friction stir welded Al-Zn-Mg-Fe alloy during long-term natural aging

Al-Zn-Mg-Fe (HE700) is a new generation cast alloy based on dilute Al-Fe hypoeutectic system. Being a new member, the precipitation behavior of the HE700 alloy is not fully understood unlike its conventional 7xxx series counterparts. Moreover, presence of Fe and friction stir welding (FSW) used to join such alloys add to the complexity of the precipitation phenomenon. The present study captured the microstructural features with atomic-scale resolution that provided new insights into the nature, distribution, and evolution of precipitates in this alloy. The stir zone (SZ) and heat-affected zone (HAZ) exhibited significantly different natural aging behavior. Finer precipitates identified as GPI and GPII (Guinier Preston zones) were found to coexist with very fine zinc-rich solute clusters in the SZ. The GP zones evolved gradually and transitioned into strengthening precipitates. The HAZ, on other hand, exhibited heterogeneous distribution of coarse pre-existed particles and fine MgZn2 precipitates that were heterogeneously nucleated by localized solute supersaturation and thermally induced dislocations. Hardness variations can be correlated to precipitates evolution thereby helping design a suitable post-weld heat treatment (PWHT) process.

Unraveling the potential of Cu addition and cluster hardening in Al-Mg-Si alloys

With the aim of further exploiting the trade-off between formability and strength in Al alloys, this study addresses the influence of Cu in Al-Mg-Si alloys that achieve simultaneously high strength and high ductility via cluster hardening. The study carefully examines the mechanical properties and strain hardening behavior of various Mg/Si ratios with and without Cu and compares the effects of pre-aging and atypical long-term low-temperature aging treatments at 100°C to conventional heat treatments. Interestingly, in all cases adding Cu improved ductility. In the extremal case cluster hardening plus the addition of Cu quadruples elongation, while keeping yield strength similar to the classical T6 state. The results of the study are discussed with a focus on the dense distribution of clusters and partial hardening phases based on atom probe tomography data. Most importantly, the cluster-hardened alloys exhibit pronounced strain-hardening properties, which we evaluate using a Kocks-Mecking approach in combination with a microstructural analysis in the pre-aging and long-term aging condition. The key finding of the study involves the role of Cu in refining clusters/precipitates, where it causes a substantial increase in number density and volume fraction. This refinement, in combination with strain-induced clustering, contributes significantly to improving the alloys’ overall mechanical performance and underlines the central role of Cu in tailoring microstructural features, especially in alloys primarily strengthened by clusters.

Laboratory evaluation of performances and thermo-oxidative aging characteristics of high-viscosity modified asphalt

High construction temperatures and complex application conditions make the high-viscosity modified asphalt (HVMA) susceptible to aging. This work presents a comprehensive investigation of the performances and thermo-oxidative aging characteristics of HVMA. Fistly, an instant high-viscosity modifier (HVM) was synthesized and then optimized by entropy weight method. The modification mechanism and high- and low-temperature performances of HVMAs were investigated by the Fourier transform infrared spectroscopy (FTIR), temperature sweep, and low temperature creep tests. Besides, thermo-oxidative aging characteristics were evaluated by the frequency sweep, multiple stress creep recovery (MSCR) and fluorescence microscopy (FM) tests. Results shows that the recommended formulation of instant HVMA (HVMA-I) was 12 % instant HVM and 0.2 % stabilizer. Grafting and cross-linking reactions involved in HVMA-I, thus ensuring the excellent high- and low-temperature performances. The thermo-oxidative aging of HVMA consisted of the modifier degradation and the binder oxidation. Short-term aging produced a marginal effect as a fluctuating change direction for complex modulus. Long-term aging had pronounced effects on the performances of HVMA. At the macroscopic level, the complex modulus was increased and the nonrecoverable creep compliance was decreased; at the microscopic level, the fluorescence area was reduced and phase network was degraded.

Long-term thermal aging of austenitic stainless-steel weld: Microstructure evolution in δ-ferrite and δ / γ phase boundary and apparent recovery of mechanical properties

This study aimed at investigation of thermal aging effects on evolution of microstructure and mechanical properties of ER316L austenitic stainless-steel weld (ASSW). The ASSW was subjected to thermal aging at 400 °C for up to 30,000 h. Initially, thermal aging triggered spinodal decomposition of δ-ferrite and clustering of Ni. Thermal aging up to 20,000 h further enhanced spinodal decomposition and G-phase formation. After 30,000 h of aging, precipitation of Mo-rich χ-phase occurred adjacent to the G-phase. Concurrently, thermal aging induced segregation of different elements and formation of nickel depletion zone was observed at the ferrite/austenite (δ/γ) phase boundary. The consequence of these microstructure changes was the hardening of δ-ferrite and loss of fracture toughness of ASSW. However, after 30,000 h of aging at 400 °C, degraded fracture toughness and tensile properties were partially recovered. This recovery in fracture toughness was attributed to the evolution of microchemistry and the formation of a softer shell in the δ/γ phase boundary region.

Fatigue-Healing Performance Analysis of Warm-Mix Rubber Asphalt Mastic Using the Simplified Viscoelastic Continuum Damage Theory

As a green and low-carbon road material, warm-mix rubber asphalt (WMRA) has received extensive attention from scholars for its road performance. In the in-depth study of its properties, the fatigue characteristics of WMRA are particularly critical. However, in current studies on asphalt fatigue performance, its self-healing ability is often underestimated or neglected. Furthermore, the simplified viscoelastic continuum damage theory (S-VECD), with its accuracy, speed, and convenience, provides a powerful tool for analyzing asphalt fatigue performance. Therefore, to analyze the fatigue and self-healing performances of WMRA in practical applications, four sample materials were selected in this study: virgin asphalt mastic (VAM), rubber asphalt mastic (RAM), Sasobit rubber asphalt mastic (SRAM), and Evotherm rubber asphalt mastic (ERAM). Subsequently, the samples were subjected to a comprehensive experimental design with frequency sweep tests, linear amplitude sweep tests, and multiple intermittent loading time sweep tests under different aging conditions. The fatigue and self-healing performances of different aging degrees and different types of WMRA were evaluated based on the S-VECD theory. The results show that aging reduces the fatigue and self-healing performances of asphalt mastic to a certain extent, and at a 7% strain, the fatigue life of SRAM after long-term aging is only 30.7% of the life of the unaged sample. The greater the aging degree, the more pronounced the effect. Under different aging levels, the warm-mix agent can significantly improve the fatigue and self-healing performances of rubber asphalt mastic. After undergoing ten fatigue intermittent loading tests, the recovery rate of the complex shear modulus for the long-term aged VAM was 0.65, which is lower than that of SRAM under the same conditions, and the warm mix can further extend the fatigue life of rubber asphalt by improving the self-healing properties of the asphalt. The role of Sasobit in enhancing the fatigue and self-healing performances of rubber asphalt mastic is more significant. This study can provide a theoretical basis for the promotion and application of WMRA pavements and contribute to the sustainable development of road construction.

Resurface of rubber modified asphalt mixture with stress absorbing membrane interlayer: From laboratory to field application

The increasing concern over tire pollution, exacerbated by the improper disposal of waste tires, serves as the backdrop for this research, which aims to explore the efficacy of incorporating ground tire rubber (GTR) into asphalt mixtures enhanced with a stress-absorbing membrane interlayer (SAMI). In this study, three variations of Hot Mix Asphalt (HMA) were evaluated: a conventional mix, a rubber-modified asphalt mixture (RMA), and a trans-polyoctenamer rubber (TOR) modified asphalt mixture in the laboratory. The assessment focused on the high and low-temperature performance of the asphalt mix and binder. Key findings from the laboratory tests indicate that the integration of a SAMI layer and GTR as additives markedly boosts the crack resistance of the asphalt mixture. Despite a reduction in fracture energy across all three HMA types following long-term aging, the GTR-modified HMA maintained superior fracture energy relative to the conventional mix. Initially, the inclusion of GTR adversely affected the mixture's rutting resistance. However, after undergoing long-term aging, both the conventional and GTR-modified HMAs exhibited exceptional rutting and moisture damage resistance. Field noise assessments further demonstrated that GTR-enhanced pavements produced noise levels approximately 2 dB lower than those of standard asphalt pavements. Additionally, pavements lacking a SAMI layer manifested low-severity cracking, with an average cracking frequency occurring every 2 ∼ 6 m, whereas pavements equipped with a SAMI layer exhibited no cracking following two winter seasons. The rubber asphalt overlay may increase the leaching of 6PPD-quinone, but the SAMI layer helps reduce tire wear particle generation by preventing road cracking. Rubber asphalt overlay leaching tests resulted in 6PPD-quinone concentrations lower than currently available toxicity data (LC50 for Coho Salmon, 0.095 ug/L). In conclusion, the utilization of dry-processed rubber asphalt mixes alongside a SAMI layer in pavement construction not only has the potential to extend the service life of pavements but also contributes to the production of quieter road surfaces. This study underscores the environmental and functional benefits of incorporating rubber modifications into asphalt pavements, presenting a viable strategy for mitigating tire pollution through the reuse of waste tires in infrastructure.

Adverse outcome pathway-based approach to reveal the mechanisms of skin sensitization and long-term aging effects of chlorothalonil

Chlorothalonil (CHT) is a widely used antifungal agent and is reported to be a sensitizer that can cause allergic contact dermatitis (ACD). ACD initiation is associated with various innate immune cell contributions and is usually accompanied by persistent inflammation, which is a potential contributing factor to skin damage. However, detailed information on the mechanisms by which CHT induces skin sensitization and damage is still insufficient. This study focused on investigating the possible sensitization process and mechanism of CHT and the adverse effects of repeated CHT exposure. CHT activates dendritic cells and promotes the proliferation of lymph cells in the skin sensitization phase, causing severe inflammation. Keratinocytes activate the NLRP3 inflammasome pathway to cause inflammation during CHT treatment, and macrophages also secrete inflammatory cytokines. In addition, CHT-induced inflammation triggered skin wrinkles, decreased epidermal thickness and decreased collagen. Cell experiments also showed that repeated exposure to CHT led to cell proliferation inhibition and senescence, and CHT-induced autophagy dysfunction was not only the reason for inflammation but also for senescence. This study defined the possible process through which CHT is involved in the skin sensitization phase and elucidated the mechanism of CHT-induced inflammation in innate immune responses. We also determined that repeated CHT exposure caused persistent inflammation, ultimately leading to skin aging.

Effect of W and Mo contents on the microstructural evolution and properties in the 9% Cr martensitic rotor steel during long-term aging at 630 °C

The evolution of tensile properties and microstructure in three 9% Cr martensitic rotor steel with varying contents of W and Mo elements is investigated after aging at 630 °C for different durations, with a primary focus on the characteristics of martensite laths and blocks, grain boundaries, dislocations, and precipitates. The results indicate that the presence of W and Mo elements not only influences the precipitation and coarsening behavior of Laves phases but also that of M23C6 carbides, which differs from conventional beliefs. The elevated content of Mo and reduced content of W in the steel leads to a reduction in the equilibrium Cr concentration, promoting enhanced precipitation of Cr atoms and increases nucleation sites of M23C6 carbides. During the aging treatment, the M23C6 carbides in the 2.0W0.5Mo steel exhibits the highest content and the lowest coarsening rate. The strength of 9% Cr martensitic rotor steel is primarily enhanced through dislocation strengthening and grain boundary strengthening. The presence of fine M23C6 carbides effectively immobilizes dislocations and interfaces, resulting in the exceptional stability of the microstructure in the 2.0W0.5Mo steel and a minimal reduction in yield strength.

Binary eutectic phase change materials application in cooling asphalt: An assessment for thermal stability and durability

Organic eutectic phase change materials (PCM) show great promise as thermal storage agents for regulating the temperature of asphalt pavements. Assessing their aging characteristics and durability when integrated into asphalt is crucial and necessitates further in-depth research. This study evaluates the impact of aging on binders with acid/palmitic acid binary eutectic PCM (SA/PA-PCM). Aging was simulated using the rolling thin film oven (RTFO) and pressure aging vessel (PAV) devices. The current study leads to the conclusion that the use of SA/PA-PCM is promising. Specifically, the incorporation of SA/PA-PCM significantly improves the aging resistance, showcasing notable enhancements in thermal stability, fatigue performance, anti-cracking ability, and thermal regulation of asphalt. Only a 5 % decrease occurred in the melting enthalpy of the binder with 15 % SA/PA-PCM after 60 h of long-term aging (from 32.17 to 25.87 J/g), showing a stable thermal storage ability. The maximum temperature difference and lag is 9.3 °C and 46 min. respectively. To sum up, Asphalt with 15 % SA/PA-PCM surpasses other binders, displaying higher melting latent heat, reduced sulfoxide index, increased long-term aging resistance, and superior stress relaxation capabilities. This research confirms the potential of SA/PA-PCM in asphalt applications, providing a new path for durable and environmentally friendly road infrastructure.

Effects of Impurities and Ageing on the Functional and Rheological Properties of Asphalts with Additives from Recovered and Pyrolysis-Processed Plastics.

This article is a continuation of work on the use of plastic waste (such as PP, PS, LDPE, HDPE, and their mixtures) processed in the proprietary pyrolysis process as asphalt additives. The article carried out detailed tests of the mixes of selected additives with pen-graded bitumen 50/70, taking into account, among others, the influence of impurities and the ratio of PE to PP in the additives as well as short- (RTFOT) and long-term (RTFOT + PAV) ageing. An extensive research program was carried out, including functional and rheological tests in a wide range of temperatures. First, tests of stability and adhesion to various types of aggregates were carried out, demonstrating the usefulness of the proposed additives. Then, the elastic recovery and the impact of technological ageing on penetration, Fraass breaking temperature, and plasticity range were assessed. The same binder mixes were subjected to rheological tests in a wide range of technological and operational temperatures, assessing, among others, viscosity, the norm of the complex shear modulus, elastic recovery and compliance in the MSCR test, and stiffness in the bending beam rheometer. This entire class of tests was carried out for clean samples and those containing impurities, indicating their impact on individual material parameters.