Long-term Aging Research Articles

Влияние сухого созревания на белки мышечной ткани говядины

Meat is an inherent part of human diet. Its quality develops at different stages of production, storage, and processing. In this respect, the stage of aging is especially important. This technology makes it possible to regulate biochemical processes in meat raw materials. Long-term dry aging is a promising method that presupposes conditions that limit the growth of microorganisms. The transformations in the protein component are an important but understudied aspect of meat quality formation during dry aging.
 The research featured Hereford beef carcasses of Siberian breeding. The samples were isolated from the inner part of bone spinal-lumbar cuts after 21, 35, and 42 days of dry aging under the following conditions: 0–1°C, 74–75% relative humidity, 0.5 m/s air velocity. The samples were subjected to dry aging after 24 h at 4°C. The fractional composition of proteins was controlled by vertical electrophoresis in a Mini-Protean Tetra System chamber. The amino acid composition was defined by high-performance liquid chromatography in a Shimadzu LC-20 Prominence liquid chromatograph with a Shimadzu SPD20MA diode-matrix detector and a Kromasil C-18 separation column. The protein digestibility was measured by sequential exposure to pepsin-trypsin proteinase system under simulated gastric digestion.
 Long-time dry aging triggered proteolysis under the action of endogenous enzymes. The electropherogram analysis showed that the proteolytic changes in high-molecular myofibrillar proteins of high-quality beef became more pronounced after a longer maturation period. The distribution of protein fractions by dry aging stages indicated a different rate of degradation of contractile, regulatory, and cytoskeletal proteins. As a result, the structural integrity of muscle fibers degraded, the meat grew tender, and the proteins became more available to digestive enzymes. The amino acid and protein digestibility analyses in vitro demonstrated an increase in the nutritional value of beef and the availability of proteins to the action of proteinases after 42 days of dry aging.
 Long-term dry aging of high-quality beef increased the digestibility of muscle proteins as a result of proteolysis that accompanied the accumulation of low-molecular fractions. According to the amino acid analysis, the optimal result was most pronounced on day 42 as proven by the moderate oxidative changes in proteins.

A novel aging acceleration rate equation for accelerated weather aging test of high viscosity modified asphalt: Theoretical derivation and experimental correction

Accelerated weather aging test is a novel aging method for evaluating the long-term real aging behavior of large-void asphalt pavement (OGFC) and high viscosity modified asphalt (HVMA). However, uncertainties in aging acceleration rate and inconsistencies in selecting weather parameters are the core issues restricting its widespread application. To address these issues, this study proposes a novel approach to construct aging acceleration rate equation for the accelerated weather aging test, considering aging kinetics theory and experimental data correction. First, three representative weather aging combinations were chosen, and a theoretical model for aging acceleration rate was preliminarily constructed based on thermal aging kinetics theory, photoaging kinetics theory, and humidity peak model. Then, by comparing the aging performance between accelerated weather aged HVMA and natural aged HVMA, the experimental aging acceleration rate range (AF1) was determined, and the theoretical model was parameterized to formulate the aging acceleration rate equation at the binder level. Finally, based on the aging performance comparison between accelerated weather aged HVMA and recycled HVMA from field-aged OGFC, the experimental aging acceleration rate range (AF2) was determined, and the mixture-level aging acceleration rate equation after parameter correction was determined. The results show that after theoretical derivation and experimental correction, the aging acceleration rate equation at the binder level incorporates temperature acceleration rate, solar radiation acceleration rate, humidity acceleration rate, and binder correction coefficient Cα (Cα = 1.214). For the mixture level, it also requires considering mixture correction coefficient Cβ (Cβ = 3.731). Under the three typical weather aging combinations in this study, a one-day accelerated weather aging test can simulate the aging effect of 18, 40 and 81-days natural aging for HVMA or 2, 5, and 10-months field aging for OGFC. The aging acceleration rate equations involve real weather parameters, allowing the determination of aging acceleration rates under any combination of weather parameters. This provides a foundation for weather parameter selection and enables accurate simulation of long-term aging of HVMA and OGFC in the laboratory.

Study on the effect of aging on cracking resistance of virgin asphalt binder and its evolution model

The cracking resistance of asphalt pavement is significantly affected by the aging of asphalt binder. A better understanding of the effect of aging on the cracking resistance of virgin asphalt binders can help to determine the optimum maintenance time. In this study, the rolling thin film oven test (RTFOT) and pressure aging vessel (PAV) test were conducted to simulate short-term aging and long-term aging of asphalt binders, respectively. Frequency sweep tests were conducted on two asphalt binders at different aging conditions. The Glover-Rowe (G-R) parameter, stiffness modulus (S), creep rate (m), continuous grading temperature (Tc), critical temperature difference (ΔTc), relaxation time (λ), dissipation energy ratio (Wd/Ws), low-temperature indicator ratio (m/S), low-temperature comprehensive compliance parameter (Jc) were obtained. Meanwhile, the sensitivities of different indicators to aging were analyzed and the correlations between G-R parameter and various low-temperature indicators were discussed. Subsequently, a nonlinear model of asphalt binder aging was established by a rheological indicator. The results showed that aging had a significant impact on the low-temperature properties of asphalt binder. G-R parameter, Tc, λ increased with the growth of aging severity, whereas m, ΔTc, Wd/Ws were contrary to this trend. S, m/S, Jc had no significant relationship with the degree of aging. Moreover, G-R parameter and ΔTc were very sensitive to aging. The G-R parameter had a good correlation with m, Tc, λ, ΔTc and Wd/Ws, respectively. It indicated that G-R parameter was closely related to the low-temperature properties of asphalt binders. The aging nonlinear model containing G-R parameter could exactly describe the aging evolution of virgin asphalt binder. It is helpful for the prediction of cracking resistance of asphalt binder and determination of maintenance plan.

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.

Properties of recycled facemask fiber modified asphalt binder: Comparative analysis of surface modification and composite modification method

Polymer-modified asphalt binders had been developed as a novel strategy for road and building materials. People generally use disposable facemasks to reduce the risk of respiratory diseases during travel and commuting. These discarded masks will become a serious environmental problem. Recycled facemask has great potential application in the modified asphalt, but its modification effect of modified asphalt needs to be studied. In this work, different kinds of fibers and their modified asphalts had been successfully prepared and comparatively analyzed after the surface of fibers treated by butyl acrylate (BA) and further modified by copper oxalate (CO) nanoparticles. From the test results, the activation energies of polypropylene fiber extracted from recycled facemask (RPF) modified asphalt (RPA), treated RPF (MRP) modified asphalt (MRPA), and MRP further decorated with CO (MRPCO) modified asphalt (MRPCOA) were 64.08 kJ/mol, 59.09 kJ/mol, and 62.32 kJ/mol, respectively. MRP and MRPCO were better dispersed in asphalt than RPF. MRPA performed a lower value of the viscoelastic than RPFA, but MRPCOA performed the higher value of viscoelastic than MRPA. Compared with RPA, the short-term aging factors of MRPA and MRPCOA decreased by 31.73% and 53.18%, while long-term aging factors of MRPA and MRPCOA decreased by 11.34% and 12.31%. From the nanoindentation data, the maximum depth of MRPA increased by 5.23% and the hardness decreased by 2.55% than RPA. The maximum depth of MRPCOA also decreased by 6.68% and its hardness also decreased by 4.45% than MRPA. These results indicated composite modification of RPF performed better than only surface modification based on the viscoelastic and aging properties of modified asphalts. It provided a meaningful study for the potential applications of various recycled polymeric fibers in modified asphalt binder in the future.

Effect of Mo-doping on the stability of D022 superlattice and mechanical properties in the Ni2.1CoCrFeNb0.2 high entropy alloy

High entropy alloys (HEAs) with D022 superlattice have shown excellent yield strength. However, long-time annealing leads to the decrease of strength due to the coarsening of D022 superlattice. Therefore, stabilizing the D022 phase of HEAs is of critical importance. Here, we report that a minor addition of Mo significantly enhances the phase stability of D022 phase and mechanical performance of Ni2.1CoCrFeNb0.2 HEAs. Experimental results show that the Mo-doping slows down the coarsening of D022 phase significantly by decreasing the diffusivity and reducing the lattice misfit between precipitates and matrix. Due to the enhanced coarsening resistance of D022 phase, the Mo-doped Ni2.1CoCrFeNb0.2 HEA shows good strength and ductility after long-term aging. These insights provide some guidelines for the design of precipitation-hardened alloys for high-temperature application.

Long-Term Aging Study on the Solid State Interfacial Reactions of In on Cu Substrate.

Indium is considered a candidate low-temperature solder because of its low melting temperature and excellent mechanical properties. However, the solid-state microstructure evolution of In with different substrates has rarely been studied due to the softness of In. To overcome this difficulty, cryogenic broad Ar+ beam ion polishing was used to produce an artifact-free Cu/In interface for observation. In this study, we accomplished phase identification and microstructure investigation at the Cu/In interface after long-term thermal aging. CuIn2 was observed to grow at the Cu/In interface and proved to be a stable phase in the Cu-In binary system. The peritectoid temperature of the Cu11In9 + In → CuIn2 reaction was confirmed to be between 100 and 120 °C. In addition, the growth rate of CuIn2 was discovered to be dominated by the curvature of the reactant Cu11In9/In phase and the temperature difference with the peritectoid temperature. Finally, a comprehensive microstructural evolution mechanism of the Cu/In solid-state interfacial reaction was proposed.

The Adhesion and Moisture Damage Resistance between Castor Oil-Based Bio-Asphalt and Aggregates under the Action of Thermal-Oxidative Aging

This study aims to investigate the adhesion properties and moisture damage resistance between castor oil-based bio-asphalt (COBA) and aggregates under the action of thermal oxidation. Different dosages of castor oil-based bio-oil (5%, 10%, and 15%) were used to prepare the COBA by mixing it with petroleum asphalt. The short-term and long-term aging of COBA were simulated by the rolling thin-film oven test (RTFOT) over 85 min and 385 min, respectively. The boiling method, photoelectric colorimetry, contact angle test, and contact angle moisture susceptibility test (CAMSI) were used to evaluate the adhesion and exfoliation of the COBA–aggregates before and after thermal oxygen aging. Then, the aging degree of COBA was quantitatively evaluated by Fourier transform infrared (FTIR), and the correlation between aging condition and COBA–aggregates adhesion was analyzed. The results showed that the cohesion in COBA increased by 23.1% on average due to the addition of bio-oil. And the adhesion between COBA and aggregates increased by 5% due to the acidic compounds formed in the process of interaction with silicates on the surface of the aggregates. After short-term thermal oxidation, the adhesion between COBA and its aggregates was further improved as the polar components in the asphalt binder increased when the bio-oil dosage was less than 10%. However, with the continuous increase in the bio-oil amount and thermal oxidation degree, the adhesion decreased by 12.6% when compared to the virgin status; in addition, the adhesion grade decreased. Also, a low dosage of bio-oil was found to also improve COBA’s resistance to moisture damage, and helped to reduce moisture sensitivity during the interaction with asphalt binder. However, the acidic compounds that were generated by the reaction with hydrolyzed aggregates in the presence of asphalt binder reduced the adhesion between COBA and the aggregates. Finally, FTIR revealed a good correlation between IC=O and adhesion between COBA and the aggregates.

Thermal Aging Degradation of High-Viscosity Asphalt Based on Rheological Methods.

With the acceleration of the construction of sponge cities in China, porous asphalt pavement (PA) is has been widely used. High-viscosity asphalt (HVA) is the core material in building PA because it has good rheology properties, which can provide good raveling and rutting resistance. However, due to the open-graded structure of PA, HVA was more susceptible to rapid aging, which significantly affects the durability of PA. To investigate the thermal aging effect on the rheological properties of self-modified HVA (SHVA), five types of asphalts were aged using a rolling thin film oven (RTFO) and pressure aging vessel (PAV). Then, rheological tests were adopted, such as temperature sweep test (TS), repeated creep and recovery test (RCR), and bending beam rheometer test (BBR). The results indicate that during the aging process, the oxidation-induced hardening effect of neat asphalt and the degradation-induced softening effect of the modifier changes the rheology properties of HVA significantly. As the aging progresses, the contribution of the modifiers of HVA to anti-aging performance is greatly reduced. At high temperatures, HVA demonstrates better anti-aging performance than conventional styrene-butadiene-styrene (SBS)-modified asphalt (Guo Chuang, GC). The change of the high-temperature rheological indices of the two HVA types (SHVA and TAFPACK-super HVA (TPS)) showed a smaller activation energy index (EAI), a more considerable viscous component of binder creep stiffness (Gv), and more minor accumulated stain (racc), indicating a more significant anti-short-term and long-term aging performance, which is beneficial to the high-temperature performance of asphalts. However, the changes in low-temperature rheological properties do not align with those in high-temperature rheological properties after long-term aging. The BBR test results reveal that TPS exhibits worse low-temperature performance than GC and SHVA. During the thermal aging process, the contribution rate of the modifiers in SHVA against RTFO and PAV aging is higher than that of the modifiers in TPS, which contributes to the superior anti-aging property. Overall, SHVA demonstrates the best anti-aging performance among the five asphalts tested.

Evaluating the Impact of Long-Term Land Use Change and Age since Disturbance on Soil Faunal Diversity

Soil organisms are the biological drivers of processes and functions that maintain soil properties and ecosystem services. Soil fauna contribute to nutrient turnover, decomposition and other important biogeochemical processes. This investigation assessed the diversity and abundance of soil arthropods (0.1–4 mm) along a chronosequence of land use types covering a relatively small geographical distance but with the same underlying soil type and climatic conditions. The compared habitats and the approximate ages since anthropogenic disturbance were ancient woodland (>200 y), old woodland (<200 y), unimproved semi-natural grassland (>50 y), willow/poplar coppice (>30 y), unimproved permanent pasture (<20 y), improved permanent pasture (<10 y), and recently grazed and reseeded grassland (>2 y), and the soil types of all habitats were the same within a 5 km radius. Land use type and age since anthropogenic disturbance significantly (p < 0.05) influenced the community composition of soil fauna, with richer arthropod communities found in woodlands compared with recently managed grassland. This study has confirmed a significant effect of land use type and age since disturbance on soil faunal diversity and community structure.

Evaluation of Aging and Moisture Damage Potential of Warm Mix Asphalt Incorporating a Synthetic Wax Additive

This paper presents the effects of a warm mix additive on the moisture damage of warm mix asphalt (WMA). Asphalt mixtures were made using different WMA contents (0, 2 and 3%) at different compaction temperatures. Aging properties were studied from the effects of artificial long-term aging on resilient modulus (MR) and indirect tensile strength (ITS) of WMAs. Moisture damage was investigated in term of tensile strength ratio (TSR) of unaged and aged specimens conditioned in one and three cycles of freezing and thawing. The results showed that the aging significant affected the MR and ITS of WMA. The additive content increased with air voids but in contrary with the bulk density. Hence, the use of higher additive content can be more beneficial in terms of resilient modulus. Decreasing compaction temperature could significantly decrease the ITS while the TSR of WMA reduced as compaction temperature decreased. From moisture damage tests, the TSR of aged samples was found to be lower than that of unaged samples

Unravelling Thermal and Enthalpy Evolutions of Commercial Sodium-Ion Cells upon Cycling Ageing via Fiber Optic Sensors

Battery ageing is inevitable for chemistry of any kind and still occupies a central place in battery research and development. However, the operando monitoring of battery ageing under real working conditions remains largely unexplored. Herein, we demonstrate the feasibility of using fiber Bragg grating sensors to operando monitor the thermal (temperature and heat) evolutions of commercial 18650 sodium-ion cells during long-term cycling ageing. With the delicate heat deconvolution, the evolutions of entropy and overpotential heat rates upon the cycling ageing are decoded, while the ageing-driven changes in overpotential components are further analysed. Drawing also on thermodynamics, high-resolution enthalpy profiles are computed from operando heat and voltage profiles, enabling to track and unravel redox variations during the cycling ageing. Collectively, this work shows that fiber optic sensors are essential tools for operando deciphering cell ageing and offer tremendous opportunities for academia and industry alike.

Effects of thermal aging at 873 K on the impact properties of an ODS ferritic steel

This investigation presents the effects of long-term thermal aging on the impact properties of an ODS reduced activation ferritic steel. The ODS ferritic steel, with composition Fe–14Cr–2W–0.4Ti–0.3Y2O3 (wt. %), was manufactured by mechanical alloying, compacted by hot isostatic pressing and hot cross rolled. A 1273 K annealing treatment was applied, followed by thermal aging at 873 K for 2000 h in Ar, to evaluate the thermal stability of the alloy. Charpy impact testing was performed from 77 to 473 K to investigate the mechanical response of the material under dynamic loads. The ductile-to-brittle transition temperature (DBTT) showed a slight increase with values of 255 ± 12 K before aging, and 270 ± 20 K after aging. The aging treatment softened the steep character of the Charpy impact curves inducing a wider transition regime with mixed brittle and ductile fracture mechanisms. This behavior was confirmed by the analysis of Force vs. Displacement Charpy curves and fractographic observations. Hot cross rolling induced a crack divider geometry and secondary cracks formation by delamination. Ductile fracture was less evident after aging due to the redistribution and transformation of Cr-W-rich precipitates along grain boundaries. Electron Backscattered Diffraction highlighted the features of transgranular brittle cracks at temperatures below the DBTT and showed misoriented and deformed regions near the fracture surface at temperatures above the DBTT.

Rationally designed fluorinated aromatic polyamide membrane for stable air dehumidification

Membrane based dehumidification technology has attracted wide attention. The anti-hydrolytic property of the membrane holds a significant role in its long-term operation in a wet environment. Herein, a series of fluorinated aromatic polyamides (FPA) are first proposed for stable air-dehumidification. Amide bond offers superior hydrolytic stability over chemical bond in the present dehumidification membrane. The deliberately introduced bulky fluorinated group (-CF3) increases the water permeability and enhances the anti-hydrolytic property of the FPA membranes. The membrane separation performance and membrane stability are further tuned by adjusting the molar ratio of para- and meta-amide groups to optimize the intermolecular forces and polymer chain arrangement, which is verified by the refractive index data and wide-angle X-ray diffraction results. The obtained co-FPA membranes exhibit tunable gas and water vapor permeation properties. With increasing para-amide group content, the gas and water vapor permeability of copolyamides gradually decreases and the selectivity of H2O/N2 increases. Meanwhile, the hydrolytic stability of the co-FPA membranes increases with the increase of TPC content as verified by 1H NMR, GPC, and mechanical property tests. Among these co-FPA membranes, the co-FPA-70 membrane exhibits the most excellent hydrolytic stability. The membrane shows almost no change in 1H NMR spectra and 97% retention of tensile strength after 5000 h of hydrolysis reaction. In the meanwhile, it shows excellent separation stability with a water vapor permeability retention of 74% during long-term hydrolysis aging operation. This study demonstrates the great potential of polyamide for the fabrication of dehumidification membranes with high hydrolysis resistance.

Evaluation of cracking resistance of asphalt concrete under long-term aging condition

Cracking is one of the primary distresses in asphalt pavements under traffic loading and climate. Asphalt cracking can be caused by aging asphalt binders in production, transportation, construction, and exploitation. Therefore, it is very necessary to study the influence of aging on cracking resistance for asphalt concrete. This paper initially evaluated the cracking resistance of asphalt concrete with a nominal maximum aggregate size of 12.5mm (AC 12.5) under long-term aging conditions. Based on the laboratory experiments, the study evaluated the required technical parameters of 60/70 binder, PMBIII binder, and AC 12.5 considering long-term aging conditions. Test results indicated that the aging of asphalt binder can significantly affect the cracking resistance of asphalt concrete.

Age-Optimal Downlink NOMA Resource Allocation for Satellite-Based IoT Network

The upcoming satellite-based Internet of Things (S-IoT) has the capability to provide timely status updates to massive terrestrial user equipments (UEs) via non-orthogonal multiple access (NOMA), due to the worldwide coverage inherited from satellite. Considering the constrained power and storage resources while keeping the information freshness in S-IoT, we first propose three constraint conditions including average/peak power constraints, network stability and minimum requirement. Then, we formulate a long-term age of information (AoI) minimization problem under the three constraint conditions. To solve this complex long-term problem, we transform the above mentioned constraints into three queue stability problems via the Lyapunov optimization framework, thus converting our long-term multi-slot stochastic optimization problem into a series of single time slot deterministic optimization problems. Moreover, we leverage the ListNet algorithm to derive the weights of the queue backlog and channel conditions to obtain an optimized power allocation order with linear complexity. Finally, we utilize the particle swarm optimization algorithm to derive the NOMA long-term AoI minimization (AM) power allocation problem within a practical complexity, named NOMA-AM scheme. Simulation results show that the proposed NOMA-AM scheme has the lowest expected weighted sum AoI compared to several benchmark schemes.

Golden-Free Robust Age Estimation to Triage Recycled ICs

Non-destructive golden-free detection of recycled/counterfeit integrated circuits (ICs) is the focus of this paper. This is achieved by estimating the functional/operational age of the IC. The age estimation method is based on exploiting short-term aging effects in advanced transistor technologies to induce bit errors at the IC’s output. Gate-level simulations are used to capture the impact of workload on short-term aging. In advanced technology nodes including bulk CMOS at 45 nm or below and FinFET, combining transistor aging with ultra-fast voltage scaling magnifies effects of aging-induced degradation at high voltage when voltage scales to a lower level, causing short-term aging-based timing violations. These timing violations create bit errors at IC outputs. We employ the bit error patterns to build a machine learning (ML) based non-linear regression model to estimate the IC’s age. Our study confirms that short-term aging-induced output bit error patterns can be used to estimate long-term age of an IC. If the IC’s age is beyond a pre-defined threshold, it can be marked as recycled. Although this paper considers FinFET technology, the method applies to bulk CMOS advanced nodes at 45nm or below. We model IC-to-IC variations taking into account voltage scaling. We demonstrate the approach on two cryptographic ICs and the method accurately estimates the long-term age of an IC, facilitating recycled IC detection.

The Properties of Modified Bagasse Fiber/Nano-TiO2 Composite Asphalt in a High-Temperature and High-Humidity Salt Environment.

The southern tropical coastal areas of China are high-temperature and high-humidity salt environments, which hinder the durability and service life of ordinary asphalt pavement. To enhance the durability of asphalt pavement in these areas, modified bagasse fiber combined with nano-TiO2 was used to improve the corrosion resistance of asphalt pavement in high-temperature and high-humidity salt environments. The micro-morphology, high-temperature oil absorption, high-temperature heat resistance, and hygroscopicity of bagasse fiber modified using three silane coupling agents combined with NaOH were compared, and the best silane coupling agent/NaOH modification scheme for bagasse fiber was found. Based on conventional physical tests (penetration, softening point, ductility), rheological property tests (rotational viscosity, dynamic shear rheological test, multi-stress creep recovery test, linear amplitude scanning test), and a four-point bending fatigue test of the asphalt mixture, the properties of modified bagasse fiber asphalt binder and mixture after cyclic dry-wet erosion under pure water and salt solution (NaCl, Na2SO4) were determined, and the effects of the erosion environment and fiber ratio on the basic physical and rheological properties of the asphalt were clarified. Compared with the silane coupling agents KH550 and KH590, the bagasse fiber modified with KH570/NaOH had a better high-temperature oil absorption capacity, heat stability capacity, and matrix asphalt compatibility. The worst erosion environment was Na2SO4, but the increase in test temperature and fiber content weakened the sensitivity of the asphalt binder performance in different erosion environments. The erosion capacity order was as follows: Na2SO4 > NaCl > pure water. In the worst erosion environment, 0.5% modified bagasse fiber/Nano-TiO2 asphalt binder (Bn-570-0.5) had the best corrosion resistance in a high-temperature and high-humidity salt environment. The penetration, softening point, creep recovery rate R3.2, non-recoverable creep compliance Jnr3.2, and fatigue life after long-term aging (with 5% strain) of Bn-570-0.5 were, respectively, increased by -16.9%, 37.5%, 37.95%, -27.86%, and 38.30% compared with unblended base asphalt binder (B). In addition, the four-point flexural fatigue life of Bn-570-0.5 was 169.2% higher than that of the unblended base mixture.

Analysis of SBS content quantitative determination and rheological properties of aged modified asphalt binder

The content of styrene–butadiene–styrene (SBS) modifier has a significant influence on the physical and chemical characteristics of asphalt. However, determining the SBS content in SBS modified asphalt (SBS MA) after aging remains a challenge. To facilitate the understanding of the relationship between physical properties and SBS content, the Fourier transform infrared (FTIR) and potentiometric titration test were utilized to detect SBS content of aged binders. In this paper, radial and linear SBS were incorporated into asphalt binders at three levels, and their rheological properties were investigated after thin film oven aging (TFOT) and long-term aging. Furthermore, the actual SBS content versus the rheological index at different aging stages was investigated. The results showed that both IC=C and Na2S2O3 titration volume highly correlated with SBS content (R2 > 0.99), and there was only a slight difference between the actual content of SBS determined by the two methods. The fatigue resistance, high-temperature elastic, and low-temperature cracking characteristics of asphalt were weakened after aging, due to SBS degradation, especially in the early stage. In addition, the resistance to deformation, elastic recovery, anti-fatigue properties of radial SBS MA were superior to that of linear SBS MA at the same SBS content, while the low-temperature cracking performance demonstrated an opposite trend. The actual SBS content versus the rheological indexes after aging can be well-fitted by a nonlinear equation. Therefore, FTIR and potentiometric titration tests can effectively predict SBS content and analyze the aging degree of SBS MA.

Fe-14Ni-14Cr-2.5Al steel showing excellent corrosion-resistance in flowing LBE at 550 °C and high temperature strength

We investigated the corrosion behavior, microstructural evolutions, and mechanical properties in an alumina forming austenitic (AFA) Fe-14Ni-14Cr-2.5Al steel after exposure in the flowing lead-bismuth eutectic (LBE) at 550 °C for 4008 h and aging in air for 5000 h. The results showed that the AFA steel exhibited not only excellent corrosion-resistance in the flowing LBE but also a strong stability of austenite and high yield strength (589 MPa) at 550 °C. The excellent corrosion-resistance was ascribed to the rapid formation of a thin Al2O3 scale. For the first time, the precipitation of γ'-Ni3Al phase was observed in the AFA steel after long-term aging at 550 °C.