Impact of starch amylose and amylopectin on the rheological and 3D printing properties of corn starch.

This study evaluated the influence of the amylose and amylopectin on the physicochemical properties and printing performance of corn starch gels. Amylose in starch-based gels enhances their storage modulus and the support performance of printed products by promoting the formation of cross-linked gel structures and crystalline structures. However, the higher amylose content in starch gels makes extrusion difficult, resulting in intermittent extrusion in 3D printing. Despite the increased shear-thinning ability of high-amylose starch, its low water retention capacity leads to water loss and rough printed morphology. Additionally, starch with 72 % amylose content exhibits insufficient adhesive properties for effective layer bonding, negatively impacting structural integrity. While gels with 72 % and 56 % amylose content demonstrate higher viscosity and enhanced mechanical properties, their poor adhesion limits the quality of printed layers. Conversely, waxy starch gel demonstrates continuous extrusion and adhesion but lacks adequate support. The 27 % corn starch gel achieves the highest 3D printing accuracy at 88.12 %, suggesting an optimal amylose-amylopectin ratio for desired ink material performance. These findings enhance our understanding of the relationship between amylose content in starch and 3D printing performance, providing a theoretical basis for the development of starch-based printing products.

Ultrasonication: An Efficient Alternative for the Physical Modification of Starches, Flours and Grains.

Ultrasonic (USC) treatments have been applied to starches, flours and grains to modify their physicochemical properties and improve their industrial applicability. The extent of the modification caused by USC treatment depends on the treatment conditions and the natural characteristics of the treated matter. Cavitation leads to structural damage and fragmentation and partial depolymerization of starch components. The amorphous regions are more susceptible to being disrupted by ultrasonication, while the crystalline regions require extended USC exposure to be affected. The increased surface area in USC-treated samples has a higher interaction with water, resulting in modification of the swelling power, solubility, apparent viscosity, pasting properties and gel rheological and textural properties. Starch digestibility has been reported to be modified by ultrasonication to different extents depending on the power applied. The most important treatment variables leading to more pronounced modifications in USC treatments are the botanical origin of the treated matter, USC power, time, concentration and temperature. The interaction between these factors also has a significant impact on the damage caused by the treatment. The molecular rearrangement and destruction of starch structures occur simultaneously during the USC treatment and the final properties of the modified matrix will depend on the array of treatment parameters. This review summarizes the known effects of ultrasonic treatments in modifying starches, flours and grains.

Effect of Rice Bran Protein on the Foaming Properties and Foaming Characteristics of Rice Bran Protein-Sodium Caseinate and Rice Bran Protein Nanoparticles-Sodium Caseinate.

Rice bran, a byproduct of rice milling, comprises 12-14% protein. The foaming properties and associated mechanisms of the composite rice bran protein system were not well studied. In this study, a composite protein system composed of rice bran protein (RBP)-sodium caseinate (NaCas) and rice bran protein nanoparticles (RBPNs)-sodium caseinate (NaCas) was investigated. The results showed that the synergistic effect of RBP and NaCas increased the foaming stability of the composite solution up to 83.77 ± 2.75%. Moreover, the foaming capacity and foaming stability of the RBPNs-NaCas composite solution were up to 177.50 ± 3.53% and 80.28 ± 0.39%, respectively. The physicochemical properties results revealed that the particle size volume peaks of RBP-NaCas and RBPNs-NaCas were mainly concentrated at 55.7 nm and 197.1 nm, and RBPNs-NaCas showed a wider single peak particle size distribution. The ζ-potential values of RBP-NaCas and RBPNs-NaCas were changed to -35.5 ± 0.07 mV and -27.2 ± 0.28 mV after complexation. The apparent viscosity and consistency factor of RBP-NaCas decreased by 31.1% compared to RBP, while RBPNs-NaCas displayed similar parameters to the single proteins. The interfacial rheological test showed that RBP and RBPNs can significantly improve the interfacial properties of NaCas by enhancing the interfacial interaction and the interfacial viscoelastic modulus of composite proteins, which is conducive to the stability of the foam system. The outcome of the study provided a theoretical basis for RBP and RBPNs to partially replace NaCas in the processing of foamed food.

Nutrient Composition, Physical Characteristics and Sensory Quality of Spinach-Enriched Wheat Bread.

Food innovation that utilises agricultural waste while enhancing nutritional value is important for waste valorisation and consumer health. This study investigated incorporating spinach (Spinacia oleracea), as a model leafy agricultural waste, into wheat bread. We analysed the nutrient content, colour, texture, sensory attributes and purchase/consume intention ratings. Adding 10-40% spinach (w/w) yielded loaves with similar heights but significantly different colour and texture (p < 0.05) from white bread. Increasing spinach decreased total carbohydrates (including starch) while significantly increasing other nutrients (protein, fibre, iron, magnesium, potassium, zinc, calcium, vitamins A, C, E, folate, niacin, pyridoxine, nitrate/nitrite and polyphenols) (p < 0.05). Spinach addition increased bread porosity, linked to higher pasting parameters (peak, trough, breakdown, final and setback viscosity) with reduced pasting time and temperature. Texture analysis resulted in decreased hardness, chewiness, gumminess and firmness while increasing cohesiveness, with maximum resilience at 20% spinach enrichment. Sensory analysis with 21 untrained panellists revealed decreased visual appeal, less preferred taste, odour and overall liking (p < 0.05) with increasing spinach, with no significant difference in texture acceptance, but the 20% enrichment had comparable acceptance to white bread. Enriching staple foods like bread with leafy vegetable waste offers a promising approach for increasing daily vegetable intake.

Influence of EGCG (Epigallocatechin Gallate) on Physicochemical-Rheological Properties of Surimi Gel and Mechanism Based on Molecular Docking.

The influence of epigallocatechin gallate (EGCG) on the physicochemical-rheological properties of silver carp surimi gel was investigated. The gel strength, texture, water-holding capacity (WHC), dynamic distribution of water, and rheological properties of surimi gels added with different levels (0, 0.02, 0.04, 0.06, 0.08, and 0.1%) of EGCG were measured. The results showed that with the increase of EGCG content, the gel strength, hardness, WHC, and immobilized water contents of surimi gels showed a trend of first increasing and then decreasing, and EGCG 0.02% and EGCG 0.04% showed better gel performance as compared with the control. EGCG 0.02% had the highest gel strength (406.62 g·cm), hardness (356.67 g), WHC (64.37%), and immobilized water contents (98.958%). The gel performance decreased significantly when the amounts of EGCG were higher than 0.06%. The viscosity, G', and G″ of the rheological properties also showed the same trends. The chemical interaction of surimi gels, secondary structure of myofibrillar protein (MP), and molecular docking results of EGCG and silver carp myosin showed that EGCG mainly affected the structure and aggregation behavior of silver carp myosin through non-covalent interactions such as those of hydrogen bonds, hydrophobic interactions, and electrostatic interactions. The microstructures of EGCG 0.02% and EGCG 0.04% were compact and homogeneous, and had better gel formation ability. The lower concentrations of EGCG formed a large number of chemical interactions such as those of disulfide bonds and hydrophobic interactions inside the surimi gels by proper cross-linking with MP, and also increased the ordered ß-sheet structure of MP, which facilitated the formation of the compact three-dimensional network gel.

Fermentation of Rice, Oat, and Wheat Flour by Pure Cultures of Common Starter Lactic Acid Bacteria: Growth Dynamics, Sensory Evaluation, and Functional Properties.

Recent consumer demand for non-dairy alternatives has forced many manufacturers to turn their attention to cereal-based non-alcoholic fermented products. In contrast to fermented dairy products, there is no defined and standardized starter culture for manufacturing cereal-based products. Since spontaneous fermentation is rarely suitable for large-scale commercial production, it is not surprising that manufacturers have started to adopt centuries-known dairy starters based on lactic acid bacteria (LABs) for the fermentation of cereals. However, little is known about the fermentation processes of cereals with these starters. In this study, we combined various analytical tools in order to understand how the most common starter cultures of LABs affect the most common types of cereals during fermentation. Specifically, 3% suspensions of rice, oat, and wheat flour were fermented by the pure cultures of 16 LAB strains belonging to five LAB species-Lacticaseibacillus paracasei, Lactobacillus delbrueckii, Lactobacillus helveticus, Streptococcus thermophilus, and Lactococcus lactis. The fermentation process was described in terms of culture growth and changes in the pH, reducing sugars, starch, free proteins, and free phenolic compounds. The organoleptic and rheological features of the obtained fermented products were characterized, and their functional properties, such as their antioxidant capacity and angiotensin-converting enzyme inhibitory activity, were determined.

Effect of plasticizers on the rheological properties of xanthan gum - starch biodegradable films.

The effect of plasticizers, namely glycerol, sorbitol, and citric acid, on the structural and mechanical properties of biodegradable films obtained from xanthan gum (XG) and starch was studied. The plasticizing effect of glycerol, sorbitol, and citric acid on XG-starch films is justified by the destruction of intermolecular contacts between starch and XG macromolecules and the redistribution of hydrogen bonds in the system as a result of the hydrotropic action of plasticizer molecules. The use of glycerol proved to be the most effective for regulating the deformation of films, while the use of sorbitol to preserve strength. The dependence of the film roughness on the type and concentration of plasticizers was characterized. The smallest values of protrusions on the surface of XG-starch films were found in the presence of sorbitol. Considering the effect of the concentration of plasticizers on the stickiness of the surface of XG-starch films and their structural and mechanical properties, 1.5 % concentration of glycerol, sorbitol and citric acid was determined as optimal.

Rheological Changes in Bio-Based Filaments Induced by Extrusion-Based 3D Printing Process.

In this work, the authors investigated the impact of extrusion-based printing process on the structural characteristics of bio-based resins through rheological measurements. Two commercially available filaments made from unfilled and wood-filled polylactide (PLA) polymers were considered. Three-dimensional specimens were prepared by printing these filaments under various operating conditions, i.e., changing the extruder temperature and printing rate, and examined using time sweep tests. Specific cycle rheological testing was conducted on pelletized filaments to simulate temperature changes in the printing process. The rheological characteristics of unprocessed materials, in terms of storage (G') and loss (G″) moduli, were found to be slightly affected by temperature changes. For a pure polymer, the G' slope at a low frequency decreased over time, showing that the polymer chains evolved from a higher to a lower molecular weight. For wood-filled materials, the G' slope rose over the testing time, emphasizing the formation of a percolated network of structured filler within the matrix. On the other side, the rheological parameters of both materials were strongly impacted by the printing extrusion and the related conditions. At lower nozzle temperatures (200 °C), by decreasing the printing speed, the G' and G″ curves became increasingly different with respect to unprocessed resin; whereas at higher nozzle temperatures (220 °C), the influence of the printing speed was insignificant, and all curves (albeit distant from those of unprocessed matrix) mainly overlapped. Considerations on degradation kinetics of both materials during the printing process were also provided by fitting experimental data of complex viscosity with linear correlation over time.

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.

New Derivatives of Modified Starch for Food Technology.

The food industry extensively uses chemically modified starches and their hydrolysates, which is mainly due to their emulsification ability. Therefore, it becomes inevitable to develop new starch derivatives, including modified starch hydrolysates, and effective preparation methods to meet the increasing demands of producers, consumers, and technology. This study comprehensively researches the physical, chemical, and functional properties (such as the water-binding capacity, swelling power, solubility, and fat absorption capacity) of chemically modified biopolymers and their enzymatic hydrolysis products. We utilized oxidized and acetylated potato and waxy-corn starches with varying degrees of substitution by carboxyl and acetyl groups in our research. The process of enzymatic hydrolysis was performed in a recirculated membrane reactor (CRMR). Our findings indicated that the physicochemical properties of starch derivatives and their hydrolysates depended on the biological origin of the biopolymer and the type and degree of modification. However, the presence of carboxyl groups in the modified starch molecules is critical and affects the rheological properties and water-binding capacity of the starch preparations. For example, in the case of waxy-corn starch preparations with a lower content of carboxyl groups (i.e., derivatives with a low degree of oxidation), the water-binding capacity (WBC) increases when compared to native starch. The highest WBC value of 206.3% was noted for the doubly modified waxy-corn starch with an oxidation degree of 0.2% and an acetylation degree of 2.5%, while native waxy-corn starch shows a WBC of 161.4%. In contrast, it was observed that preparations with a higher content of carboxyl groups, i.e., derivatives with an oxidation degree of 2.5%, show a lower swelling power compared to native waxy starch.

Preparation of an Antibacterial Branched Polyamide 6 via Hydrolytic Ring-Opening Co-Polymerization of ε-Caprolactam and Lysine Derivative.

In this study, we successfully realized the hydrolytic ring-opening co-polymerization of ε-caprolactam (CPL) and lysine derivative. A novel antibacterial modified polyamide 6 with a branched structure was obtained after the quaternization of the co-polymers. The co-polymers exhibited a significant increase in zero shear viscosity, melt index and storage modulus at the low frequency region. The quaternized co-polymers displayed thermal properties different from pure PA6 and good mechanical (tensile) properties. The antibacterial activity of the quaternized co-polymers depends on the quaternary ammonium groups' incorporated content. At 6.2 mol% incorporation of quaternary ammonium groups, the strong antibacterial activity has been introduced to the co-polymers. As the quaternary ammonium groups approached 10.1 mol%, the antibacterial polymers demonstrated nearly complete killing of Staphylococcus aureus (Gram positive) and Escherichia coli (Gram negative). The above research results provided a new approach for the study of high-performance nylon.

Investigating the physicochemical, rheological, and sensory properties of low-fat mayonnaise prepared with amaranth protein as an egg yolk replacer.

This study investigated the possibility of using amaranth protein isolate (API) as a plant-based substitute for egg yolk (EY) in the preparation of low-fat mayonnaise (LFM). The alkali extraction/acidic precipitation method was used to isolate amaranth protein; its functional properties were then studied. The results showed that besides its great water and oil absorption capacities, API had better emulsifying capacity and significantly higher (p < .05) emulsion stability at pH 2.0 than alkali pH values. Five mayonnaise samples with different API/EY combination ratios (%) (i.e., 0/0.75, 0.25/0.5, 0.375/0.375, 0.5/0.25, and 0.75/0) were prepared. The color, emulsion stability (ES), freeze-thaw stability (FTS), droplet size, structure, rheology, and sensory properties of samples were examined. API replacement showed no adverse effects on the L* value, ES, and sensory attributes (p > .05). Low API concentrations (0.25% and 0.375%) significantly (p < .05) increased the droplet size and decreased the FTS of LFM emulsion. High API concentrations (0.5% and 0.75%) had no significant effect (p > .05) on droplet size and formed emulsions with more tightly packed oil droplets. The Cross model was chosen best to describe the flow behavior of LFM samples (R 2 = 0.99). The sample with 0.75% API had significantly (p < .05) the highest values of η o (zero-shear viscosity) and λ (relaxation time), indicating greater interaction between the emulsion particles. All samples showed a weak gel structure (G' > G"). In conclusion, API can be considered an appropriate substitute for EY in LFM production, which can benefit human health and offer a new strategy for preparing vegan products.

Ultrasonic-assisted preparation of SBS modified asphalt: Cavitation bubble numerical simulation and rheological properties.

SBS (styrene-butadiene-styrene block copolymer) is currently the most widely used asphalt modifier, and SBS modified asphalt is usually prepared by high-speed shearing. This paper combines the cavitation effect of ultrasonic to assist in the preparation of SBS modified asphalt, and conducts numerical simulation and rheological properties research on the cavitation bubbles in the molten SBS modified asphalt fluid. The cavitation bubbles in the modified asphalt fluid will expand and contract as the pressure changes inside and outside the bubbles. When the cavitation bubble is compressed to the minimum and the pressure inside the bubble reaches 1.94 × 105Pa, the direction of the velocity vector near the cavitation bubble will change with the expansion and compression of the bubble. The expansion-contraction process of a single cavitation bubble can release 6.41 × 10-7J of energy, thus breaking the long bonds in asphalt and generating a large number of free radicals react with the unsaturated C = C bonds in the SBS molecules. According to the preparation process of modified asphalt, the influence of ultrasonic wave on rheological property of modified asphalt was studied through experiments. The results show that ultrasonic treatment can enhance the elasticity of asphalt and improve the temperature sensitivity of asphalt. With the increase of ultrasonic treatment time, the anti-rutting deformation ability of SBS modified asphalt is greatly improved. At the same temperature, the recovery rate of asphalt also increases with the increase of ultrasonic treatment time, and the non-recoverable compliance (Jnr) decreases Combined with the numerical simulation of cavitation bubbles, the ultrasonic process is added to asphalt production, which is of great significance for the green production of modified asphalt and the improvement of the rheological properties of modified asphalt.

Ultrasound-assisted plasma-activated water thawing of porcine longissimus dorsi: Effects on physicochemical, thermal stability, rheological, and structural properties of myofibrillar protein.

This study evaluated the effects of five thawing methods (air thawing (AT), water thawing (WT), plasma-activated water thawing (PT), ultrasound-assisted water thawing (UWT) and ultrasound-assisted plasma-activated water thawing (UPT)) on the physicochemical, thermal stability, rheological, and structural properties of porcine longissimus dorsi myofibrillar protein (MP). UPT treatment significantly improved protein solubility (73.10%) and reduced protein turbidity (0.123) compared with AT, WT, and PT treatments (P < 0.05). UPT treatment reduced the MP particle size (635.50 nm) and zeta potential (-6.38 mV) compared with AT and WT treatments (P < 0.05), which was closer to that of the fresh sample. UPT treatment also maintained the MP surface hydrophobicity and thermal stability. UPT treatment improved the MP rheological properties of the sample. In addition, UPT treatment effectively protected the MP secondary and tertiary structures. In conclusion, UPT treatment better maintained the MP physicochemical, thermal stability, rheological, and structural properties of thawed porcine longissimus dorsi. Therefore, UPT treatment can be considered as an effective thawing method.

3D Printing Properties of Heat-Induced Sodium Alginate-Whey Protein Isolate Edible Gel.

The objective of this study was to develop a food 3D printing gel and investigate the effects of whey protein isolate (WPI), sodium alginate (SA), and water-bath heating time on the 3D printing performance of the gel. Initially, the influence of these three factors on the rheological properties of the gel was examined to determine the suitable formulation ranges for 3D printing. Subsequently, the formulation was optimized using response surface methodology, and texture analysis, scanning electron microscopy (SEM), and Fourier-transform infrared (FTIR) spectroscopy were conducted. The rheological results indicated that gels with WPI concentrations of 6-7 g, SA concentrations of 0.8-1.2 g, and water-bath heating times of 10-12 min exhibited lower yield stress and better self-supporting properties. The optimized formulation, determined through response surface methodology, consisted of 1.2 g SA, 6.5 g WPI, and a heating time of 12 min. This optimized formulation demonstrated enhanced extrusion capability and superior printing performance. SEM analysis revealed that the optimized gel possessed good mechanical strength, and FTIR spectroscopy confirmed the successful composite formation of the gel. Overall, the results indicate that the optimized gel formulation can be successfully printed and exhibits excellent 3D printing performance.

Functional Nanostructured Lipid Carrier-Enriched Hydrogels Tailored to Repair Damaged Epidermal Barrier.

In this study, a functional nanostructured lipid carriers (NLCs)-based hydrogel was developed to repair the damaged epidermal skin barrier. NLCs were prepared via a high-energy approach, using argan oil and beeswax as liquid and solid lipids, respectively, and were loaded with ceramides and cholesterol at a physiologically relevant ratio, acting as structural and functional compounds. Employing a series of surfactants and optimizing the preparation conditions, NLCs of 215.5 ± 0.9 nm in size and a negative zeta potential of -42.7 ± 0.9 were obtained, showing acceptable physical and microbial stability. Solid state characterization by differential scanning calorimetry and X-ray powder diffraction revealed the formation of imperfect crystal NLC-type. The optimized NLC dispersion was loaded into the gel based on sodium hyaluronate and xanthan gum. The gels obtained presented a shear thinning and thixotropic behavior, which is suitable for dermal application. Incorporating NLCs enhanced the rheological, viscoelastic, and textural properties of the gel formed while retaining the suitable spreadability required for comfortable application and patient compliance. The NLC-loaded gel presented a noticeable occlusion effect in vitro. It provided 2.8-fold higher skin hydration levels on the ex vivo porcine ear model than the NLC-free gel, showing a potential to repair the damaged epidermal barrier and nourish the skin actively.

Fabrication of high internal phase emulsions (HIPEs) using pea protein isolate-hyaluronic acid-tannic acid complexes: Application of curcumin-loaded HIPEs as edible inks for 3D food printing.

Pea protein isolate (PPI)-hyaluronic acid (HA)-tannic acid (TA) ternary complexes were assembled using non-covalent interactions, their potential application in 3D printing and delivery of curcumin were investigated. As the HA-to-TA ratio in the complexes changed from 1:0 to 0:1, the oil-water interfacial tension first decreased and then increased, and the secondary structure of the proteins changed. The composition of the complexes (HA-to-TA ratio) was optimized to produce high internal phase emulsions (HIPEs) containing small uniform oil droplets with good storage and thermal stability. When the HA to TA ratio is 7:1 (P-H7-T1), HIPEs exhibited better viscosity, viscoelasticity, and thixotropy, which contributed to its preferable 3D printing. Moreover, curcumin-loaded HIPEs stabilized by P-H7-T1 showed a high lipid digestibility (≈101%) and curcumin bioaccessibility (≈79%). In summary, the PPI-HA-TA-stabilized HIPEs have good potential to be 3D-printable materials that could be loaded with bioactive components.

Cure State Sensing of Polymethylmethacrylate Using a Vibrating Axial Probe.

A new axially vibrating sensor based on an audio voice coil transducer and a lead zirconate titanate (PZT) piezoelectric disc microphone was developed as a probe for the measurement of in vitro rheological fluid properties, including curing progress for polymethylmethacrylate (PMMA) mixtures with important uses as bone cement in the field of orthopedics. The measurement of the vibrating axial sensor's acoustic spectra in PMMA undergoing curing can be described by a damped harmonic oscillator formalism and resonant frequency (ca. 180 Hz) shift can be used as an indicator of curing progress, with shifts to the blue by as much as 14 Hz. The resonant frequency peak was measured in 19 different 4.0 g PMMA samples to have a rate of shift of 0.0462 ± 0.00624 Hz·s-1 over a period of 400 s while the PMMA was in a dough state and before the PMMA transitioned to a hard-setting phase. This transition is unambiguously indicated by this sensor technology through the generation of a distinct circa 5 kHz high-Q under-damped ring-down response.

Development of Negative-Temperature Cement Emulsified Asphalt Spraying Materials Based on Spraying Performance and Rheological Parameters.

To develop a cement emulsified asphalt composite (CEAC) that can be sprayed under a plateau negative temperature environment, the effects of the water-solid ratio, calcium aluminate cement substitution rate, emulsified asphalt content, sand-binder ratio, and polyvinyl alcohol (PVA) fiber content on the spraying performance and rheological parameters of CEAC were explored through the controlled variable method. Additionally, the correlation between the spraying performance and rheological parameters of CEAC was established, and the optimal proportion of CEAC was determined. Then, the difference in frost resistance and pore structure between the cement slurry (CS) without emulsified asphalt and CEAC at the optimum proportion was analyzed. The results showed that the optimum proportions for sprayed CEAC were 0.14 water-solid ratio, 0.5 sand-binder ratio, 25% substitution of calcium aluminate cement, 5% emulsified asphalt content, and 1.5% PVA fiber volume mixing. The yield stress and plastic viscosity of CEAC were positively correlated with the build-up thickness, whereas the rebound rate and the latter showed a negative correlation. The spraying performance may be described by the rheological parameters; the ranges of yield stress and plastic viscosity of 2.37-3.95 Pa·s and 77.42-108.58 Pa, respectively, produced the best spray ability. After undergoing an equivalent number of freeze-thaw cycles, CEAC exhibited lower mass and strength loss rates compared to CS, thereby demonstrating superior frost resistance. In addition, the pore structure analysis showed that the difference in capillary and macropore contents was the main reason for the variability in frost resistance between CS and CEAC.

Enhancing Pavement Durability: Comparative Rheological Evaluation of Conventional and Rejuvenated Reclaimed Binders under Aging Conditions.

A drawback of recycled mixtures containing reclaimed asphalt is their increased stiffness, further worsened by the accelerated aging of binders in extreme weather conditions. Previous studies have shown that while rejuvenating agents can mitigate some of these issues by improving flexibility and reducing brittleness, they often present challenges, such as performance variability and the potential for rutting. This study aims to develop an optimal blend of reclaimed bitumen, a rejuvenating agent, and pure bitumen to achieve rheological properties similar to a control 35/50 pen-grade bitumen for road paving. Hence, the rejuvenated binders comprised 30:70 blends of reclaimed asphalt bitumen and 50/70 pen-grade bitumen, adding 0.2% to 0.6% of a rejuvenating agent by mass of the reclaimed asphalt. Sample testing included conventional penetration grade, softening point, and viscosity tests, followed by dynamic shear rheometer tests under unaged, short-term, and long-term aging conditions. The results show that the binder blend with 0.4% rejuvenator closely resembles the rheological properties of 35/50 pen-grade bitumen. This blend exhibits a 20% to 55% stiffness reduction for recycled mixtures with 30% reclaimed asphalt. Notably, the rejuvenated binders exhibited a similar level of aging resistance to the control bitumen, with a marginal difference of less than 5% in aging ratios. Meanwhile, large strain amplitude tests showed the importance of defining maximum rejuvenating incorporation rates in recycled mixtures to avoid rutting problems, where binders with 0.4% rejuvenator doubled the rutting potential (Jnr values). This innovative study highlights the potential for enhancing recycled mixtures' performance by evaluating rejuvenated reclaimed binders' rheology subjected to different aging conditions, thus contributing to sustainability in pavement construction.