Amplitude Sweep Test Research Articles

Exploring the interplay between thermo-oxidative degradation and asphalt aging in thermoplastic polyurethane-modified asphalt: Mechanisms, properties, and performance evolution

The aging behavior of thermoplastic polyurethane-modified asphalt (TPUMA) is intricate and the mechanisms of its thermal degradation are not well understood. This study examines the viscoelastic, chemical and morphological characteristics of thermoplastic polyurethane modified asphalt (TPUMA) under different aging conditions (RTFOT/PAV). The rheological master curve model of the S parameter was used to analyze the fitting effect on TPUMA, with SBS (styrene–butadiene–styrene) modified asphalt serving as the control group. The relationship between the phase angle plateau area and polymer aging degradation was elucidated. This study investigates the impact of polymer degradation on the high-temperature rheological behavior and medium-temperature fatigue properties of asphalt through temperature sweep, multiple stress creep recovery (MSCR), and linear amplitude sweep (LAS) tests. Fourier transform infrared spectrometer (FTIR) and confocal laser scanning microscopy (CLSM) are used to qualitatively and quantitatively analyze the chemical composition and morphological evolution of TPUMA during thermal-oxidative degradation. The findings suggest that TPUMA's performance changes in the aging environment is result from the dual coupling effect of polymer degradation and asphalt oxidative hardening. The closely arranged isocyanate (-NCO) and polar component molecular chains in asphalt slow down its oxidation speed, which enhances the aging and deformation resistance of TPUMA. The successful blending of TPU and asphalt was confirmed, and the degradation degree of the polymer was quantitatively characterized by the percentage of the degraded area. The results provide insights to better understand the interplay between TPU degradation and asphalt oxidation.

Mechanical and rheological properties of polyurethane-polyurea (PU-PUa) modified asphalt binder

Polyurethane (PU) is one of the common polymer modifiers used for asphalt, and the PU modified asphalt currently plays a fundamental role in road constructions. However, most of the PU as the modification could bring about an increasement in viscosity and rigidity to asphalt binders, thus leading to insufficient ductility and deformation compatibility for the materials to some extent. In the present study, a composite polymer material synthesized with polyurethane and polyurea (PU-PUa) was introduced as a modifier to the asphalt binder in an attempt to integrate their individual advantages into the asphaltic material. The curing time, tensile strength, and Fourier Transform infrared spectroscopy (FTIR) tests were conducted to determine the optimal proportion of the PU and PUa in the compound polymer, and its formation mechanism was also discussed. The fundamental properties of the asphalt binders modified with various contents of PU-PUa (5%, 10%, and 15% by weight), such as the storage stability, rheological properties, creep recovery capacity, and fatigue resistance, were investigated through the thermal storage, dynamic rheological, stress creep recovery (MSCR), and linear amplitude sweep (LAS) tests. Furthermore, in order to understand the adhesion property of the PU-PUa modified asphalt on aggregates, the pull-off tests considering both dry and water immersion conditions were performed. The test results showed that the PU-PUa could be effectively used to modify asphalt binders, and 7:3 was found to be the best proportion of the PU and PUa. The addition of PU-PUa could promote the high temperature performance, enhance the recovery ability for creep, and extend the fatigue life of the asphalt binders (for both 70# and SBS asphalt). The optimal content of PU-PUa for the modification was found to be 10% based on the storage stability and mechanical performance of the modified asphalt binders.

Performance evaluation of rapeseed oil-based derivatives modified hard asphalt binders: Towards greener and more sustainable asphalt additives

Hard asphalt binder is regarded as a favorable option in comparison to polymer-modified asphalt for rutting due to the benefits of cost-effectiveness and extreme stiffness behavior. However, its inherent poor ability to withstand fatigue damage and thermal cracking restricts its applications as a pavement material. This study aimed at enhancing the low-temperature and fatigue performance of hard asphalt binders with newly-developed rapeseed oil (RO)-based derivatives. Two rapeseed oil -based derivatives of epoxidized rapeseed oil (ERO) and acrylated epoxidized rapeseed oil (AERO) were laboratory synthesized through oxidation and ring-opening grafting reactions, respectively. Fourier transform infrared spectroscopy (FTIR) and Hydrogen nuclear magnetic resonance (1were conducted to confirm the successful synthesis of derivatives. Mass loss, aging index, performance grading, temperature-frequency sweep, linear amplitude sweep and bending beam rheometer test were employed to assess the modified effects of rapeseed oil-based derivatives on two types of hard asphalt binders. To further explore the differences between RO and derivatives, the properties of modified hard asphalt binders using two derivatives were compared against the performance of RO-modified hard asphalt binders. With the additional RO, ERO, and AERO, the modified hard asphalt binders had significantly improved the resistance to thermal cracking and fatigue damage at low and intermediate temperatures, respectively. RO was found to have the most positive effect on the stress relaxation and the most adverse effect on the stiffness of hard asphalt binders. While, ERO- and AERO-modified hard asphalt binders had shown better antioxidative and anti-aging performance than that of RO-modified hard asphalt binders. Additionally, AERO-modified hard asphalt binders were noticed to have improved the elasticity of hard asphalt binders owing to the formation of a polymer elastic network. According to the study, two rapeseed oil-based derivatives had shown great potential as green and sustainable asphalt modifiers on the improvement of thermal and fatigue cracking resistance with the minimal adverse effect on anti-rutting performance of the hard asphalt binders. The test results revealed that the rapeseed oil-based derivatives modified hard asphalt binders could be employed in various pavement applications with great economic and sustainable benefits.

The effect of incorporating magnetic fly ash in asphalt binders with respect to permanent deformation and fatigue

The search for efficient and environmentally viable materials to improve the quality and durability of asphalt binders used in roadways has been growing in recent years. This is especially true giving the increase in the volume and magnitude of traffic loads, as well as the changes in the earth's temperature that cause frequent pavement distresses, such as permanent deformation and fatigue. In this context, the objective of this work is to evaluate the potential of magnetic particles from fly ash, as a residual resource with high added value and low-cost raw material for modifying asphalt binders. Magnetic particles were incorporated into the asphalt binder at 2%, 4%, 6% and 8%, content by weight. The materials were characterized by chemical, empirical and rheological tests, specifically the Multiple Stress Creep and Recovery and the Linear Amplitude Sweep test. X-ray Fluorescence data revealed silicon, aluminum and iron as the main elements present in the fly ash, as well as the increase in iron concentration after magnetic separation in the magnetic particle sample. A homogeneous dispersion of magnetic particles in the asphalt binder observed by Scanning Electron Microscopy and shifts in infrared bands characteristic of iron (ca. 450 cm-1) and of asphalt binder (ca. 1456 cm-1) clearly indicated a significative interaction between the magnetic particles and the asphalt binder. The rheological results indicated that the incorporation of particles provide better performance to the binder in terms of both permanent deformation and fatigue. The modified binders were less susceptible to permanent deformation than the neat binder, and this is reflected in the increase in adequate traffic levels, moving from standard traffic to heavy traffic at a temperature of 64 °C. This economical, easy, and sustainable approach to using magnetic particles in hot asphalt binders can contribute to producing asphalts that are more efficient with changes in temperature and traffic.

Development of a “Green” Emulsion with a Milk Protein Hydrolysate: An Evaluation of Rheology, Texture, In Vitro Bioactivity, and Safety

Bioactive peptides are promising cosmetic active ingredients that can improve skin health and appearance. They exhibit a broad spectrum of activity, including anti-aging, antioxidant, antimicrobial, and anti-inflammatory effects. The aim of this study was to develop a safe, stable, and efficacious environmentally friendly (“green”) emulsion using a milk protein hydrolysate as a model active ingredient. Potential emulsions were formulated with biodegradable emollients, stabilized with naturally derived mixed emulsifier, and prepared by cold process. They were evaluated for rheological behavior (continuous rotation and oscillation tests), physical stability (dynamic mechanical thermal analysis—DMTA test), and texture profiles, as well as cytotoxic, antioxidant, and antimicrobial effects. Rheological characterization revealed shear-thinning flow behavior with yield point from continuous rotation tests and predominantly elastic character from oscillation (amplitude and frequency sweep) tests, with small structural change detected in the DMTA test. These results implied satisfactory rheological properties and good stability. Texture analysis revealed acceptable spreadability and substantivity of the emulsions. The protein hydrolysate showed antioxidant activity. The developed emulsions showed low antibacterial activity against selected microorganisms, but this was due to the action of preservatives, not peptides. All potential emulsions showed a desirable safety profile. The results obtained provide the basis for the next stage of formulation development, i.e., in vivo efficacy tests.

Cell-Laden 3D Printed GelMA/HAp and THA Hydrogel Bioinks: Development of Osteochondral Tissue-like Bioinks.

Osteochondral (OC) disorders such as osteoarthritis (OA) damage joint cartilage and subchondral bone tissue. To understand the disease, facilitate drug screening, and advance therapeutic development, in vitro models of OC tissue are essential. This study aims to create a bioprinted OC miniature construct that replicates the cartilage and bone compartments. For this purpose, two hydrogels were selected: one composed of gelatin methacrylate (GelMA) blended with nanosized hydroxyapatite (nHAp) and the other consisting of tyramine-modified hyaluronic acid (THA) to mimic bone and cartilage tissue, respectively. We characterized these hydrogels using rheological testing and assessed their cytotoxicity with live-dead assays. Subsequently, human osteoblasts (hOBs) were encapsulated in GelMA-nHAp, while micropellet chondrocytes were incorporated into THA hydrogels for bioprinting the osteochondral construct. After one week of culture, successful OC tissue generation was confirmed through RT-PCR and histology. Notably, GelMA/nHAp hydrogels exhibited a significantly higher storage modulus (G') compared to GelMA alone. Rheological temperature sweeps and printing tests determined an optimal printing temperature of 20 °C, which remained unaffected by the addition of nHAp. Cell encapsulation did not alter the storage modulus, as demonstrated by amplitude sweep tests, in either GelMA/nHAp or THA hydrogels. Cell viability assays using Ca-AM and EthD-1 staining revealed high cell viability in both GelMA/nHAp and THA hydrogels. Furthermore, RT-PCR and histological analysis confirmed the maintenance of osteogenic and chondrogenic properties in GelMA/nHAp and THA hydrogels, respectively. In conclusion, we have developed GelMA-nHAp and THA hydrogels to simulate bone and cartilage components, optimized 3D printing parameters, and ensured cell viability for bioprinting OC constructs.

Influence of Modified Stalk Fibers on the Fatigue Performance of Asphalt Binder

The type and content of modified stalk fibers significantly influence the fatigue properties of asphalt binder. In this study, different concentrations of NaOH solution were used to modify stalk fibers, and scanning electron microscopy (SEM) was used to observe the effect of the modified concentration on the fiber morphology. A dynamic shear rheology (DSR) test and a linear amplitude sweep (LAS) test were conducted to analyze the effects of the fiber type and content on various factors such as the complex shear modulus G*, phase angle δ, and fatigue parameters (A35 and B). Consequently, the fatigue life Nf of the fiber asphalt binder was calculated using a viscoelastic continuum damage model. The results show that stalk fibers modified using a 5% alkali solution exhibited the best oil absorption and heat resistance, the asphalt binder with a 1.5%–2% fiber content exhibited the best resistance to fatigue, and the fatigue performance of the asphalt binder with different types of fibers was superior when fiber doping was at 1.5%. Additionally, the fatigue parameter A35 of the modified cotton and corn stover fibers increased by 40.5% and 57.6%, respectively, and the fatigue parameter B decreased by 5.8% and 4.8%, respectively, compared with that of the unmodified stover fibers. Finally, the modified corn stalk fiber asphalt binder with a 1.5% fiber content demonstrated the best fatigue resistance.

Rheology of cellulose nanocrystal and nanofibril suspensions

Nanocellulose is a sustainable nanomaterial and a versatile green platform that has attracted increasing attention. Although the wide applications of its aqueous suspensions are closely related to rheology, comprehensive studies of their rheological behavior, especially the yielding behavior, are still limited. Herein, to investigate the relationship between structure and rheological properties, the viscoelasticity, thixotropy and yielding behavior of two commonly used nanocelluloses, rod-shaped cellulose nanocrystals (CNCs) and filamentous cellulose nanofibrils (CNFs), were systematically investigated. The viscosity, viscoelasticity and thixotropic behavior of the suspensions were analyzed by steady-state shear, frequency sweep, creep-recovery, hysteresis loop, and three-interval thixotropic recovery tests. The yielding behaviors were evaluated through creep, steady-state shear, step shear rate, stress ramps, amplitude sweep, and large amplitude oscillatory shear tests. The rheological properties of the two typical suspensions showed a strong dependence on concentration and time. However, compared to CNC suspensions, CNF suspensions exhibited stronger thixotropy and higher yield stress due to the higher aspect ratio of CNF and the stronger structural skeleton of the suspensions as supported by Simha's equation and micromorphology analysis. This work provides a theoretical rheology basis for the practical applications of nanocellulose suspensions in various fields.

Research on low-temperature and fatigue properties of recycled asphalt based on the stability of the micelle structure

The research is focused on the asphalt colloid system and provides a detailed analysis of why the effective recovery of low-temperature performance and fatigue performance is challenging during the regeneration of aged asphalt. This study initially examined the alterations in the stability of colloidal structures and micelle structures while rejuvenating aged asphalt. These were performed through four-component analytical tests and asphaltene-resin (A-R) adsorption experiments, respectively. Subsequently, the impact of the regeneration process on the low-temperature performance and fatigue performance of aged asphalt was assessed using bending beam rheometer (BBR) tests and linear amplitude sweep (LAS) tests, respectively. In addition, linear regression analysis was employed to determine the relationship between the stability of colloidal and micelle structures and the performance of recycled asphalt in terms of low-temperature and fatigue resistance. The results show that regeneration of aged asphalt results in 100% recovery of colloidal structural stability, while the maximum recovery of micelle structural stability is only 68.2%. The stability of the micelle structure in recycled asphalt is primarily influenced by the proportion of aged asphalt to virgin asphalt. When the mass ratio of aged asphalt to virgin asphalt is 2:8, the stability of the micelle structure can be restored to 58.1%. However, when the mass ratio is reversed to 8:2, the stability of the micelle structure can only be restored to 21.6%. The impact of the regeneration agent on the recovery of micelle structure stability is minimal. Out of all the samples that underwent regeneration, the highest level of enhancement in the stability of the micelle structure achieved by the rejuvenators was approximately 15%. Linear regression analysis showed that the low-temperature performance of recycled asphalt was significantly affected by the stability of the colloid and micelle structure. The fatigue performance of recycled asphalt was only significantly affected by the stability of the micelle structure. Therefore, enhancing the stability of the micelle structure in recycled asphalt can effectively improve its low-temperature and fatigue performance. This study provides valuable insights into the underlying factors contributing to the subpar low-temperature and fatigue performance of recycled asphalt. Moreover, it contributes to the development of more effective rejuvenators for aged asphalt recycling.

Effect of different rejuvenation methods on the fatigue behavior of aged SBS modified asphalt

Reclaimed bituminous mixture can be used in new pavement after rejuvenation. Common rejuvenation method and reactive rejuvenation method can be used to restore the properties of aged SBS modified asphalt(ASMB). This work focused on the recovery effect of fatigue resistance for ASMB by different rejuvenation methods. The effect of common and reactive rejuvenation on the fatigue behavior of ASMB was investigated by multi-stress creep and recovery test, linear amplitude sweep test and fatigue-healing-fatigue test. The results show that, as compared with common rejuvenation method, reactive rejuvenation method is more conducive to restoring the creep recovery rate and the non-recovered creep compliance of ASMB. Linear amplitude sweep test indicates that reactive rejuvenated ASMB shows the good fatigue stress cracking resistance, the fatigue life of which at 2.5% and 5.0% strain levels is increased by 30% and 71% as compared with that of common rejuvenated binder. Meanwhile, the self-healing index of reactive rejuvenated ASMB is also enhanced by 28.7%, which indicates its better self-healing potential and fatigue damage resistance. Furthermore, the fatigue life of SMB is reduced by 77.7% after aging, while that of ASMB is extended by 93.5% after common rejuvenation, and the fatigue life of reactive rejuvenated ASMB is almost twice than that of common rejuvenated binder. It means that reducing the adverse effects of aged asphalt and reconstructing the broken SBS cross-linking structure during rejuvenation process of ASMB are all crucial for restoring its fatigue resistance.

The role of plasma in the yield stress of blood.

Yielding and shear elasticity of blood are merely discussed within the context of hematocrit and erythrocyte aggregation. However, plasma might play a substantial role due its own viscoelasticity. If only erythrocyte aggregation and hematocrit would determine yielding, blood of different species with comparable values would present comparable yield stresses. rheometry (SAOS: amplitude and frequency sweep tests; flow curves) of hematocrit-matched samples at 37°C. Brillouin Light Scattering Spectroscopy at 38°C. Yield stress for pig: 20mPa, rat: 18mPa, and human blood: 9mPa. Cow and sheep blood were not in quasi-stationary state supporting the role of erythrocyte aggregation for the development of elasticity and yielding. However, pig and human erythrocytes feature similar aggregability, but yield stress of porcine blood was double. Murine and ruminant erythrocytes both rarely aggregate, but their blood behavior was fundamentally different. Pig plasma was shear-thinning and murine plasma was platelet-enriched, supporting the role of plasma for triggering collective effects and gel-like properties. Blood behavior near zero shear flow is not based solely on erythrocyte aggregation and hematocrit, but includes the hydrodynamic interaction with plasma. The shear stress required to break down elasticity is not the critical shear stress for dispersing erythrocyte aggregates, but the shear stress required to fracture the entire assembly of blood cells within their intimate embedding.

Rheological properties of SBS-modified asphalt containing aluminum hydroxide and organic montmorillonite

The composite flame retardant composed of aluminum hydroxide (ATH) and organic montmorillonite (OMMT) is of potential application value in the tunnel asphalt pavement. To investigate the effect of ATH and OMMT on the rheological properties of SBS modified asphalt at high and low temperatures. In this study, the composite ATH/OMMT/SBS modified asphalt was subjected to multiple stress creep recovery (MSCR), linear amplitude sweep test (LAS), and Bending beam rheometer (BBR) experiments. Analysis of high and low temperature rheological properties and fatigue properties of composite ATH/OMMT/SBS modified asphalt under the conditions of single incorporation and composite modification. The findings of the tests suggest that ATH can significantly improve the fatigue life but has adverse impact on the creep recovery property of asphalt materials, OMMT has a significant improvement effect on the low-temperature performance, however, the detrimental effect of OMMT on fatigue performance is greater than the improvement of ATH. The research results provide a reference for the practical application of flame retardants.

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.

Linear viscoelastic properties and fatigue S-VECD based evaluation of polymer-modified asphalt mixtures

Direct tensile fatigue tests associated with the simplified continuous damage viscoelastic model (S-VECD) have proven to be an effective tool for evaluating fatigue in asphalt materials. Thus, this study evaluated the fatigue damage of asphalt mixtures modified by the addition of polymer based on the results of the direct tensile fatigue test using the S-VECD model. Three asphalt mixtures were produced: a control asphalt binder with 50/70 penetration, a polymer-modified styrene-butadiene-styrene (SBS) asphalt binder, and a mixture produced with a modified asphalt binder (composed of 98.38% control + 1.26% Ethylene Methyl Acrylate and Glycidyl Methacrylate (EMA-GMA) + 0.21% High-Density Polyethylene (HDPE) + 0.15% Polyphosphoric Acid (PPA116%)). The binders were evaluated for physical and rheological properties, and fatigue using the Linear Amplitude Sweep (LAS) test, applying the S-VECD model. Asphalt mixtures were evaluated for stiffness using tensile strength, resilient modulus and flow number tests. The viscoelastic linear behaviour (LVE) was characterized based on the dynamic modulus test and the fatigue performance was evaluated from the uniaxial direct traction test with the application of the S-VECD viscoelastic damage model. The results of the LAS test indicated that the modified binder presented the best fatigue performance, being classified according to the binder fatigue factor (FFB) as excellent. Mixtures with binders modified by polymers showed the highest values in mechanical performance tests. As for the LVE behaviour, the mixture with the modified binder showed the expected behaviour, with higher dynamic modulus values at high temperatures (low reduced frequencies), and the lowest modulus values at lower temperatures (high reduced frequencies). In addition, for the entire spectrum of frequencies and temperatures, the modified mixture presented the lowest values of phase angle, indicating more elastic and less viscous behaviour. From the direct tensile test, based on the GR failure criterion, the modified mixture showed better fatigue performance, with a higher value of the Fatigue Factor of the Mixture (FFM). Based on the DR failure criterion, from the Sapp damage capacity, mixtures with polymers were classified with the best performances concerning fatigue. Therefore, the use of polymer-modified binders promoted asphalt mixtures with better fatigue damage performance.

Mechanical Resistance of Hot-Mix Asphalt Using Phosphorite as Filler

Phosphorites (PF) have small particle sizes and interesting chemical compositions to be used as filler in asphalt mixtures. The present study assessed the performance that a hot-mix asphalt (HMA) displays when the natural filler (NF) is completely replaced by PF. X-ray diffractometry (XRD), X-ray fluorescence (XRF), and scanning electron microscope (SEM) tests were carried out on NF and PF particles. Asphalt mastic was manufactured using a weight ratio of filler (NF and PF) to asphalt binder of 1∶1.2. Penetration, softening point, viscosity, and linear amplitude sweep test were performed on the asphalt mastic. The following tests were carried out on mixes manufactured with NF (control) and PF (HMA-PF): Marshall, indirect tensile strength, Cantabro, resilient modulus, permanent deformation, and fatigue under stress-controlled mode. Additionally, moisture damage resistance was assessed through the tensile strength ratio (TSR) parameter. The HMA-PF mix displayed a better performance in all the evaluated properties, without increasing the optimum asphalt binder content. PF as fillers could be an interesting alternative in the manufacture of HMA mixtures subjected to high temperature climates.

Viscoelastic fracture mechanics-based fatigue life model in asphalt-filler composite system

Asphalt-based composites gradually reach the end of their life as the service time increases, which directly leads to fatigue failure of the pavement structure. However, there is currently a lack of a fatigue life model for asphalt-based composites that has a clear physical interpretation. To address this issue, a viscoelastic fracture mechanics-based (VEFM) fatigue life model is proposed to predict the fatigue failure life for asphalt-based composites in this study. The VEFM fatigue life model was established within a viscoelastic fracture mechanics framework and was applied to two types of asphalt-filler composite systems (AFCS). To obtain the model parameters and verify the proposed model, various tests including linear amplitude sweep tests, time sweep tests at low-stress levels and high-stress levels, as well as surface energy tests were conducted on AFCS. The results indicate that the established VEFM fatigue life model can be expressed as a function of the loading level, viscoelastic fracture parameters, initial shear modulus, and surface energy. The initial edge flow of AFCS increases with the temperature and has minimal effect on the fatigue life throughout the fatigue process. A critical fatigue failure point is defined by the curve of damage rate and damage density. The fatigue life of AFCS increases with the temperature while decreasing with the loading level.

Combining bran-enrichment with sugar replacement in biscuits enables the flexible use of a sustainable and fibre-rich by-product

Fibre-rich by-products like wheat bran are a sustainable source of health promoting components. However, substantial enrichment in bran of popular and convenient food like biscuits negatively impacts dough rheology and baked product properties. In this study, we suggest that alterations in dough rheology and biscuit properties resulting from bran enrichment can be compensated for by steering the properties of the water-sugar mixture as obtained by concomitant sugar replacement. In particular, the plasticizing properties of the water-sugar mixtures and the hygroscopicity of the sugar mixture were used as quantitative parameters in combination with the ratio between bran and flour. These three parameters were varied independently and tested against dough rheology (amplitude sweep tests and dynamic mechanical thermal analysis) and biscuit properties. The results indicated that the three parameters could well describe all the relevant physical properties related to dough rheology after mixing and during heating and to biscuit properties. The increase in dough elastic behavior induced by bran addition could be compensated for by reducing the plasticizing and hygroscopic properties of the sugar (replacers) mixture. Increased mechanical strength and reduced biscuit spread of bran enriched biscuits could be compensated in a similar manner. Overall, the formulation strategy presented in this study suggests the possibility to decouple texture from nutritional composition of bakery products like biscuits, allowing a more flexible use of fibre-rich and nutrient-dense by-products like bran.

Rheological measurements and normal compression tests on shear thickening fluids below room temperature

This work concentrated on the rheological measurements and normal compression tests of a shear thickening fluid (STF) below room temperature from −20 to 20 °C. The STF was made of 20% of fumed silica and 80% ethylene glycol in weight fraction. Experimental measurements were conducted with a parallel plate MCR301 rheometer. Temperature dependency, steady-state tests, oscillatory fRequency sweep tests, oscillatory shear strain amplitude sweep tests, and normal compression tests were applied on STF, and the testing results were analysed and discussed. The temperature played an important role in the performance of STF. The low temperature increased the STF’s viscosity and shear thickening effect but decreased the STF’s critical shear rate. Frequency was found to contribute to the STF’s phase change from the liquid state to the solid state. The normal compression tests were conducted to determine the equivalent stiffness of STF under different temperatures and various shear rates. The results showed that the STF’s equivalent normal stiffness could be increased by either lowering the applied temperature or increasing the shear rate. A mathematical model was adopted to represent the viscosity of STF in the temperature range from −20 to 20 °C.

Evaluation of Fume Suppression, Viscosity-Retarding, and Rheological Properties of Eco-Friendly High-Viscosity Modified Asphalt

In order to address the issues of high viscosity and excessive fume exhaust associated with high-viscosity modified asphalt (HVMA), the objective of this study was to develop an eco-friendly HVMA by incorporating fume suppressants and viscosity-retarding agents (VRAs). To begin with, desulfurization rubber powder (DRP) was utilized as a modifier, and fume suppressants, including activated carbon, a chemical reaction fume suppressant, and a composite fume suppressant combining activated carbon and chemical reaction fume suppressant were added to the HVMA separately. The fume suppression effect and odor level were observed to determine the optimal fume suppressant composition for this study. Based on these observations, an area integration method was proposed, utilizing rotational viscosity testing and temperature sweeping experiments, evaluating the viscosity-retarding effect and mixing temperature when different amounts of Sasobit VRA, Evotherm3G VRA, and a composite VRA of Sasobit and Evotherm3G were added to the HVMA. This approach aimed to identify the eco-friendly HVMA with the most effective fume suppression and viscosity-retarding abilities. Furthermore, the morphology and rheological properties of the eco-friendly HVMA were examined through fluorescence microscopy, zero shear viscosity test, multiple stress creep recovery analysis, liner amplitude sweep test, and frequency sweep test. The results demonstrated that the HVMA formulation consisting of 15% DRP and 1% composite fume suppressant exhibited a satisfactory fume suppression effect and odor level. Based on this, the HVMA formulation containing 0.6% Evotherm3G and 3% Sasobit VRAs displayed the best viscosity-retarding effect while reducing the mixing temperature. Moreover, when compared to common HVMA, the eco-friendly HVMA exhibited excellent high-temperature resistance, successfully accomplishing the dual objectives of ecological friendliness and superior performance.

Study of fatigue performance of fiber reinforced high-viscosity asphalt mastic based on rheology

Open-graded asphalt mixture pavement, with its functional benefits of drainage and noise reduction, holds promising engineering application potential. The high-viscosity asphalt mastic significantly influences the performance of this open-graded asphalt mixture. In this study, the fatigue performance of fiber reinforced high-viscosity asphalt mastic was investigated based on rheology. Shear rheometer was used to perform temperature sweep tests, time sweep tests, and linear amplitude sweep tests on the fiber reinforced high-viscosity asphalt mastic. The influences of filler/binder ratio, filler properties, fiber type, and content on the fatigue performance of the mastic were analyzed. Time sweep test data was used to establish a prediction equation for temperature-stress fatigue life of the mastic. The interconnectivity and differences between various fatigue life indicators were studied based on phenomenology and energy dissipation theory. The fatigue characteristics and damage mechanism of the mastic were investigated using a viscoelastic damage model, and the fatigue lives at different strain levels were observed. The research results indicate that fatigue damage of high-viscosity asphalt mastic mainly occurs at low temperatures. An increase in filler/binder ratio at the same temperature reduces the anti-fatigue performance of the mastic. Compared with dust, mineral powder has a larger specific surface area and better fatigue resistance performance. The established temperature-stress equation can accurately predict the fatigue life of mastic under different temperatures and stresses. The fatigue indicators Np20 and Nfm, based on energy dissipation theory, show a favorable linear relation with the fatigue indicator Nf50 based on phenomenology, and these three indicators are consistent in evaluating the fatigue performance and life of the mastic. Np20 and Nfm are found to be more applicable for evaluating the fatigue performance of fiber reinforced high-viscosity asphalt mastic. The fatigue life of the mastic decreases with increasing strain levels, and high-viscosity asphalt mastic containing basalt fiber shows better adaptability to complex traffic conditions.