Changes In Rheological Properties Research Articles

Effects of ultraviolet and thermal oxygen ageing on the rheological properties of SEBS/MWCNTs composite-modified asphalt

To enhance the anti-ageing properties of asphalt binder, multiwalled carbon nanotubes (MWCNTs) and styrene-ethylene-butylene-styrene (SEBS) were used to create a composite-modified asphalt (CMA). The ageing resistance was assessed through rheological property changes, using a dynamic shear rheometer (DSR) for various tests. FTIR spectroscopy analyzed the ageing mechanism. The results showed that CMA exhibited significantly better rutting resistance than matrix and SBS asphalt. Although the fatigue life of CMA was lower than SBS asphalt, ist was still dramatically higher than matrix asphalt. MWCNTs reduced the low-temperature relaxation performance of unaged asphalt. Notably, CMA showed superior ageing resistance against both thermal oxygen and UV ageing, with decreases of about 30% and 28% in the UV ageing index and long-term ageing index, respectively, compared to matrix asphalt. The carbonyl and sulfoxide indices increased after ageing, with the composite containing 3% SEBS demonstrating optimal ageing resistance and road performance.

Investigation of Improving Stability in Desulfurized-Rubber-Modified Asphalt Using Cerium-Stearate Incorporation

To enhance the compatibility of high-content desulfurized-rubber-modified asphalt (DRMA), the innovative selection of cerium hard acid is employed in this study to investigate its impact on the compatibility of DRMA. The results indicate that when the optimal content of cerium stearate is 1%, the compatibility of the modified asphalt is improved. On the microscopic level, it is observed that the total heat absorption of the modified asphalt decreases and thermal storage stability is enhanced as measured by differential scanning calorimetry. On the macroscopic level, it gives the smallest difference in softening point, optimal storage stability, and best compatibility of the modified asphalt. Additionally, dissolution tests and adhesion tests demonstrate that the inclusion of cerium stearate increases the solubility of desulfurized rubber in asphalt and reduces the stripping rate of desulfurized-rubber particles on the asphalt surface, thereby decreasing phase separation and promoting the compatibility of DRMA. Furthermore, rheological tests indicate that cerium stearate improves both high-temperature and low-temperature performance of the modified asphalt. The addition of cerium stearate increases the dynamic shear modulus of the modified asphalt, maintaining good stability and elasticity under shear loading, with minimal change in low-temperature rheological properties and lower temperature sensitivity, indicating the best compatibility at this point. Finally, molecular-dynamics simulation data indicate that the addition of cerium stearate decreases the parameter difference in the dissolution of modified asphalt and enhances the binding energy of the modified asphalt, demonstrating the feasibility of cerium stearate in promoting the compatibility of modified asphalt.

Influence of Variable Intensity Ultraviolet on the Performance of SBS Modified Asphalt

Previous scholars studied UV aged asphalt performance under constant UV intensity. This study proposed a method of UV aged asphalt based on the time-varying UV intensity, which is more capable of realistically simulating the UV aging of asphalt under natural conditions. The softening point, viscosity, and DSR tests were used to analyze changes in conventional and rheological properties of UV aged asphalt and compared them with RTFO (Rolling Thin-Film Oven) aged asphalt. Fourier transform infrared (FTIR) spectroscopy and scanning electron microscope (SEM) tests were analyzed for the microscopic characteristics. The aging index was also used to evaluate the percentage of asphalt aging attributable to each UV aging cycle. The results show that the softening point is more susceptible to UV radiation, with UV-6 cycles exceeding the softening point increment of RTFO. On the contrary, the viscosity is more susceptible to thermo-oxidative aging, and the viscosity increment of RTFO is 39.3% higher than that of UV-12 cycles. Based on DSR's test results, the rutting factor magnitude of RTFO was between 9-12 UV aging cycles The phase angle results indicate that thermo-oxidative aging is more likely to convert asphalt to elastomer than RTFO asphalt. UV aging process of asphalt produced sulfinyl and, carbonyl and other polar functional groups, asphalt intermolecular forced to enhance the production of a harder oxidation layer, the asphalt surface began to appear cracks. As aging time increases, the cracks become longer and deeper. Practical image recognition technology can identify the areas of the cracks. The crack area follows a linear pattern during cycles 3 to 9, while the growth rate slows down during cycles 9 to 12.

Exploration of changes in rheological and spectral properties of rice protein inks before and after 3D printing

The aim of this work was to understand the effect of the printing process on food inks by applying the chemometric approach to analyze the rheological and spectral properties of rice protein. Rice protein was printed under two conditions (speed: 35 and 50 mm/s, layer height: 1.5 and 1.2 mm, and nozzle diameter: 1.7 and 1.2 mm). Infrared spectroscopy and oscillatory tests at 1 Pa between 0.1 and 10 Hz were performed before and after printing. PCA and k-means analysis of rheological and spectral data identified patterns and significant differences. The analysis revealed that 3D printing affects rheological properties, reducing structural stiffness and modifying the relationship between elastic and viscous behavior. Spectral vibrations associated with NH, CH3, O-H, and C=O functional groups indicated significant structural changes due to the printing process. These results suggest that the printing process influences food inks' rheological and structural properties.

Development of sustainable Lignin-Based coatings for layered double Hydroxides: Enhancing synergistic Anti-Aging properties in bitumen

Layered Double Hydroxides (LDHs) have poor dispersibility in bitumen and limited effectiveness in enhancing its thermal oxidative aging resistance. To address these issues, this study aims to purify lignin to improve its radical scavenging efficiency and use the purified lignin to coat LDHs (Φ@LDHs), thereby increasing their lipophilicity and radical scavenging efficiency for use in bitumen. sodium lignosulfonate (SL) was fractionated into five parts using a stepwise water/ethanol fractionation method, and these fractions were then applied to coat the LDHs to produce Φ@LDHs. The morphology, antioxidant activity, and chemical structure of Φ@LDHs were analyzed. Subsequently, the effect of Φ@LDHs on the aging properties of bitumen was evaluated. The test results indicated that SL and its fractions effectively coated the surfaces of LDHs, thereby enhancing their interlayer spacing and hydrophobicity. Among all fractions, lower molecular weight fractions, F4 and F5, retained most of the phenolic hydroxyl groups in SL, demonstrating significant antioxidant activities. The incorporation of F4@LDHs and F5@LDHs effectively mitigated changes in rheological properties of bitumen and oxidation product formation during thermal oxidation and UV aging, with F5@LDHs showing the best performance. Furthermore, a synergistic anti-aging mechanism was elucidated for the F4@LDHs and F5@LDHs composites. The purified F4 and F5 fractions not only improved the compatibility of LDHs with bitumen but also delayed the oxidative reactions initiated by free radicals to achieve a synergistic anti-aging effect.

Stress modeling for the upper and lower crust along the Anninghe, Xianshuihe, and Longmenshan Faults in southeastern Tibetan plateau

Earthquake occurrence depth in the crust is related to stress, temperature, and brittle–ductile transition, which is also near the transition depth of the upper to lower crust. The composition variation between the upper and lower crust causes remarkable changes of rheological properties and variation in stress distribution. Clarifying the detailed stress distribution in the upper and lower crust is crucial for understanding the brittle–ductile transition and the stress environment of the seismogenic zone. The Southeastern Tibetan Plateau (SETP), with wide spread of active strike−slip faults and clustered earthquakes, provides a natural field for investigating the relationships between crustal stresses, deformation behaviors, and earthquake mechanics. By considering the rheological properties of granite and anorthite, this paper established stress models with different boundary depths (15, 20 and 25 km) between the upper and lower crust along the Anninghe, Xianshuihe, and Longmenshan Faults in the SETP with a horizontal strain of 6 × 10−4 extracted from in situ stress data. The stress model with different geothermal gradients and a boundary depth of 20 km between the upper and lower crust suggests two distinct types of the brittle–ductile transition below these three faults. Simultaneously, the stress model can account for the continuity of earthquake depth distribution below the Longmenshan Fault and the seismic gap below the Anninghe and Xianshuihe Faults. The continuity of earthquake depth distribution or seismic gap below these three faults can be explained by their different geothermal gradients. These findings provide new insights for understanding the stress environment of the seismogenic zone in the SETP. Our model reveals the relationships between differential stress, seismicity, brittle–ductile transition, and boundary depth of the upper and lower crust in the continental crust, and connects the multiple observations from geophysics and geology. Furthermore, our model provides insights for studying multiple processes in the continental crust, such as crustal deformation, fault slip, and earthquake occurring.

The Application of Lophatherum Gracile Brongn Flavonoids in Wheat Flour Products: Effects on the Structural and Functional Characteristics of Wheat Dough.

The effects of lophatherum gracile brongn flavonoids on the multiscale structure and functional properties of wheat dough were investigated. Wheat dough samples with varying contents of lophatherum gracile brongn flavonoids were analyzed to assess changes in thermal-mechanical rheological properties, microstructure, chemical interactions, water distribution, and macropolymer formation by Mixolab mixer, fluorescence microscopy, and low-field nuclear magnetic resonance (LF-NMR). The findings revealed that lophatherum gracile brongn flavonoids disrupted the three-dimensional network of gluten proteins in the wheat dough, leading to decreased water-binding capacity and reduced gluten protein crosslinking while enhancing thermal stability and inhibiting the starch retrogradation of the dough. This study provided important insights into the interaction mechanisms between lophatherum gracile brongn flavonoids and the proteins/starch in wheat dough, offering theoretical guidance for the development of novel wheat-based products for industrialization and practical production.

Effect of Oil Content on the Printability of Coconut Cream.

We developed a method to perform direct ink writing (DIW) three-dimensional (3D) printing of coconut-based products with high oil content by varying compositions of the coconut oil and the coconut cream. The addition of oils is particularly crucial in providing energy, developing neurological functions, and improving the palatability of food. Despite the potential merits of high oil-content foods, there have been limited studies on 3D printing of high oil-content foods. In particular, the effect of oil content on the printability of food inks has not been studied to date. 3D printing of food inks with high oil contents is challenging due to oil separation that leads to unpredictable changes in rheological properties. In this work, we surveyed the behavior of the mixture of the coconut oil and the coconut cream and identified the appropriate conditions for the food inks that show the printability in DIW 3D printing. We initially formulated coconut cream inks added with coconut oil that did not exhibit oil separation, and characterized the rheological properties of such inks. We successfully 3D-printed coconut cream with additional coconut oil and successfully fabricated 3D structures with inks containing 25% water with an additional 10% (w/w) of coconut oil. Texture profile analysis (TPA) suggested that the hardness index and the chewiness index of mesh-shaped 3D-printed coconut cream decreased due to an increase in the water content of the ink. Overall, this study offered an understanding of the stability of the food inks and demonstrated the fabrication of 3D colloidal food with controlled oil content, which can be applied to formulating foods with tunable oil content to cater to individual nutritional needs without compromising the stability of the inks.

Entanglements of Macromolecules and Their Influence on Rheological and Mechanical Properties of Polymers.

Flexible macromolecules easily become entangled with neighboring macromolecules. The resulting network determines many polymer properties, including rheological and mechanical properties. Therefore, a number of experimental and modeling studies were performed to describe the relationship between the degree of entanglement of macromolecules and polymer properties. The introduction presents general information about the entanglements of macromolecule chains, collected on the basis of studies of equilibrium entangled polymers. It is also shown how the density of entanglements can be reduced. The second chapter presents experiments and models leading to the description of the movement of a single macromolecule. The next part of the text discusses how the rheological properties change after partial disentangling of the polymer. The results on the influence of the degree of chain entanglement on mechanical properties are presented.

Utilization of Nanocenospheres a waste material to improve the physical and rheological properties of SBS asphalt binders

The performance enhancement of asphalt binders by incorporating innovative additives has been a subject of significant research and industry interest. This study emphasizes the potential of Nano polymer composites as a promising additive for improving the performance of asphalt binders, providing valuable insights into developing advanced asphalt materials for sustainable road infrastructure construction and maintenance. It explores the utilization of nano cenospheres to amplify the attributes of Styrene-Butadiene-Styrene (SBS) modified asphalt binders. It introduces a novel approach by incorporating Nano polymer composites (NPC) comprising nanocenosphere particles and Styrene-butadiene-Styrene Particles. Nanocenosphere particles are the waste materials derived from coal combustion in thermal power plants. Styrene-butadiene-styrene is a type of thermoplastic elastomer, a synthetic rubber. A series of experimental tests, penetration, softening point, ductility, performance grading, temperature sweep, multiple stress and creep recovery, frequency sweep, linear amplitude sweep, and rutting aging index, is conducted to evaluate changes in physical and rheological properties. Results indicate that adding nano cenospheres particles in SBS asphalt binder enhances its softening point, elasticity recovery, rutting resistance, fatigue life, storage stability, and aging resistance compared to traditional SBS-modified asphalt binders. Statistical analyses were accomplished to comprehend the influence of the Nano polymer composites. This analysis provides valuable insights into the effects of nanocenospheres on SBS-modified binders. Through rigorous statistical analysis, a thorough interpretation of how the incorporation of nanocenospheres influences the attributes of Nano-polymer composites.

A Rheological Study on the Effect of Tethering Pro- and Anti-Inflammatory Cytokines into Hydrogels on Human Mesenchymal Stem Cell Migration, Degradation, and Morphology.

Polymer-peptide hydrogels are being designed as implantable materials that deliver human mesenchymal stem cells (hMSCs) to treat wounds. Most wounds can progress through the healing process without intervention. During the normal healing process, cytokines are released from the wound to create a concentration gradient, which causes directed cell migration from the native niche to the wound site. Our work takes inspiration from this process and uniformly tethers cytokines into the scaffold to measure changes in cell-mediated degradation and motility. This is the first step in designing cytokine concentration gradients into the material to direct cell migration. We measure changes in rheological properties, encapsulated cell-mediated pericellular degradation and migration in a hydrogel scaffold with covalently tethered cytokines, either tumor necrosis factor-α (TNF-α) or transforming growth factor-β (TGF-β). TNF-α is expressed in early stages of wound healing causing an inflammatory response. TGF-β is released in later stages of wound healing causing an anti-inflammatory response in the surrounding tissue. Both cytokines cause directed cell migration. We measure no statistically significant difference in modulus or the critical relaxation exponent when tethering either cytokine in the polymeric network without encapsulated hMSCs. This indicates that the scaffold structure and rheology is unchanged by the addition of tethered cytokines. Increases in hMSC motility, morphology and cell-mediated degradation are measured using a combination of multiple particle tracking microrheology (MPT) and live-cell imaging in hydrogels with tethered cytokines. We measure that tethering TNF-α into the hydrogel increases cellular remodeling on earlier days postencapsulation and tethering TGF-β into the scaffold increases cellular remodeling on later days. We measure tethering either TGF-β or TNF-α enhances cell stretching and, subsequently, migration. This work provides rheological characterization that can be used to design new materials that present chemical cues in the pericellular region to direct cell migration.

Selenium-enriched yeast, a selenium supplement, improves the rheological properties and processability of dough: From the view of yeast metabolism and gluten alteration

This study investigated the effect mechanism of selenium (Se)-enriched yeast on the rheological properties of dough from the perspective of yeast metabolism and gluten alteration. As the yeast Se content increased, the gas production rate of Se-enriched yeast slowed down, and dough viscoelasticity decreased. The maximum creep of Se-enriched dough increased by 29%, while the final creep increased by 54%, resulting in a softer dough. Non-targeted metabolomics analyses showed that Se inhibited yeast energy metabolism and promoted the synthesis of stress-resistance related components. Glutathione, glycerol, and linoleic acid contributed to the rheological property changes of the dough. The fractions and molecular weight distribution of protein demonstrated that the increase in yeast Se content resulted in the depolymerization of gluten. The intermolecular interactions, fluorescence spectrum and disulfide bond analysis showed that the disruption of intermolecular disulfide bond induced by Se-enriched yeast metabolites played an important role in the depolymerization of gluten.

Application of black tea waste as eco-friendly deflocculant and rheology stabilizer for water-based mud

Maintaining and regulating the rheological properties of the drilling mud at the desired level is essential for successful drilling operations. Bentonite is the key additive used in most water-based drilling mud for enhanced rheological properties. However, the flocculation tendency of bentonite particles poses a significant challenge for the industry due to the undesirable and unpredictable changes in rheological properties of the fluid with downhole increasing temperature. This study aims to develop a low-cost and eco-friendly deflocculant from black tea waste (BTW) that can prevent the aggregation and flocculation of the bentonite and stabilize the rheology of bentonite-polymer muds. Rheological properties were evaluated with different concentrations (0.25%, 0.5%, 0.75%, and 1%) of BTW at 95 °F and 140 °F. The Bingham Plastic (BP) and Power Law (PL) models were studied to characterize the flow behavior and identify the best-fit model through statistical analysis. Along with rheological properties, thinning efficiency, mud stability, thermal aging effect, thixotropic behavior, and shear thinning behavior were investigated through different shear-temperature-time dependent tests. In addition, the lubricating properties and filtration loss characteristics were assessed at ambient conditions. Finally, the findings were compared with the industrially used deflocculant, lignosulphonate (LS). The results revealed that BTW can effectively prevent bentonite flocculation and stabilize the mud rheology even at a very low concentration of 0.25%. Significant improvements were observed in the lubricating and filtration characteristics. With the addition of 1% BTW, the filtrate loss, mud cake thickness, and friction coefficient were reduced by 22.2%, 50%, and 13.29%, respectively. The multifunctional activities of black tea waste (BTW) are attributed to its polyphenolic compounds, the presence of which was confirmed through UV–visible spectroscopy testing. The TG analysis confirmed that BTW remains thermally stable up to 200 °C. Considering the synergistic performance compared with lignosulphonate, availability, and environmental and economic acceptance, BTW may be effectively utilized as a multifunctional deflocculant and rheology stabilizer for water-based bentonite-polymer muds.

Thermadapt shape memory vitrimeric polymyrcene elastomer

Earlier studies of β-Myrcene (Myr)/ β-ketoester functional (acetoacetoxy)ethyl methacrylate (AAEMA) copolymers exhibited compositional drift, leading to ambiguity in microstructure/thermomechanical property correlations while shape memory recovery times were excessively long ~1 h. The terpene-based 1,3-diene Myr and AAEMA were copolymerized via nitroxide-mediated polymerization (NMP) with an initial Myr molar feed ratio ranging from 0.1 to 0.9. Reactivity ratios estimated by the Meyer-Lowry method were rMyr = 0.20 and rAAEMA = 0.22 with respective 95% confidence intervals of [0.13, 0.37] and [0.15, 0.23], suggesting alternating copolymerization. Bulk terpolymerization with styrene (Sty) afforded linear poly(Myr-stat-Sty-stat-AAEMA) prepolymers designed to modulate glass transition temperature Tg and stiffness. Subsequent cross-linking with isophorone diamine (IPDA) formed catalyst-free vinylogous urethane dynamic linkages. ATR-FTIR, dynamic mechanical analysis (DMA), and tensile measurements confirmed the recyclability of vitrimers through hot pressing at 110 °C, demonstrating minimal changes in rheological and mechanical properties even after four cycles. By heating the vitrimers to above their Tg (to ~45 °C), they exhibited a shape memory effect with high shape fixity and fast shape recovery (< 1 min). The vitrimers could undergo permanent shape reprogramming through reconfiguration of dynamic bonds at ~110 °C. This work shows the adaptability of Myr-based rubbers by vitrification and appropriate copolymerization for the synthesis of more sustainable elastomers with stimuli responsive properties.

Dynamic changes in the aggregation-depolymerization behavior of Ovomucin-Complex and its binding to urease during in vitro simulated gastric digestion

Ovomucin-Complex extracted from egg white is expected to have a barrier function similar to gastric mucin. In this study, the dynamic changes in structure, rheological properties and binding ability of Ovomucin-Complex during in vitro simulated gastric digestion were investigated. The results from HPLC and CLSM showed that extremely acidic pH (pH = 2.0) promoted Ovomucin-Complex to form aggregation. Acid-induced aggregation may hinder its binding to pepsin, thus rendering Ovomucin-Complex resistant to pepsin. Consequently, most of the polymer structure and weak gel properties of Ovomucin-Complex retained after simulated gastric digestion as verified by HPLC, CLSM and rheological measurement, although there was a small breakdown of the glycosidic bond as confirmed by the increased content of reducing sugar. The significantly reduced hydrophobic interactions of Ovomucin-Complex were observed under extremely acidic conditions and simulated gastric digestion compared with the native. Noticeably, the undigested Ovomucin-Complex after simulated gastric digestion showed a higher affinity (KD = 5.0 ± 3.2 nm) for urease - the key surface antigen of Helicobacter pylori. The interaction mechanism between Ovomucin-Complex and urease during gastric digestion deserves further studies. This finding provides a new insight to develop an artificial physical mucus barrier to reduce Helicobacter pylori infection.

STUDY OF SOLUBILITY OF CO(NH2)2 - HOOC - COOH · NH2C2H4OH - H2O SYSTEM

In this work, the interaction of components in the CO(NH2)2 - HOOC - COOH ·NH2C2H4OH - H2O system was studied by visual polythermic method in the temperature range from -11.2 to 61°C. A polythermal solubility diagram of the system was constructed and the crystallization sites of ice, urea, monoethanolammonium oxalate, and the new phase ureamonoethanolammonium oxalate were determined.During the addition of monoethanolammonium oxalate to urea solutions of different concentrations, changes in rheological properties (pH, density, refractive index, viscosity) were recorded, and the results were found to be consistent with the polythermal solubility diagram. A new phase formed during the study of the CO(NH2)2 - HOOC-COOH · NH2C2H4OH - H2O system, ureamonoethanolammonium oxalate, was isolated and analyzed by confirmed using appropriate analytical methods (IR, Thermal, X-ray phase).

Effects of incubation time of plasma activated water (PAW) combined with annealing for the modification of functional properties of potato starch

The present study investigates the application of annealing and plasma-activated water (PAW) for starch modification, as alternative methods compared to the chemical one. Native potato starch was subjected to PAW, annealing with distilled water (DW-ANN), and the combination of the two (PAW-ANN) at different incubation times (1, 4, 8, and 12 h). The changes in rheological, pasting, and thermal properties were evaluated. The results showed that all treatments promoted significant modifications of the investigated parameters. In particular, while the pasting properties of the potato starch remained unchanged after the PAW treatment, G’ (elastic) and G’’ (viscous) of the PAW-treated starch were significantly (p < 0.05) higher than those of the native. DW-ANN significantly increased all rheological parameters and reduced peak viscosity, breakdown, and setback and significantly (p < 0.05) incremented pasting temperature, holding strength, and final viscosities of the potato starch may be due to cross-linking reaction. The combination of treatment (PAW-ANN) showed a synergistic effect leading to strong gel formation up to 4 h, while further treatment reduced the possibility of depolymerization. In conclusion, the combined treatment is a promising new green method to modify the properties of starch and improve its stability within a short treatment time.

Changes in rheology and components during the processing of Chinese traditional handmade hollow dried noodle

The study of the changes in rheological properties and components during the processing of Chinese traditional handmade hollow dried noodle (HHDN) is essential to explaining the excellent quality of HHDN. The dynamic oscillation frequency sweep, stress relaxation, and uniaxial extension characteristics of the dough after kneading, stretching, and resting were investigated at six sampling points during the processing of HHDN. The result showed that stretching led to an increase in G' and G0, and a significant decrease (P < 0.05) in extensibility from 131.02 mm to 57.99 mm. Confocal laser scanning microscopy (CLSM) was used to observe the microstructure of the gluten network, which was destroyed during stretching and restored during resting. Studies of changes in components showed that the stretching process resulted in a decrease in GMP content from 3.24 (g/100 g) to 3.18 (g/100 g), and the resting process resulted in β-sheets decreasing significantly (P < 0.05). The degree of starch pasting increased significantly (P < 0.05) after stretching. The results of the correlation analysis showed that components changes were highly correlated with the rheological properties during the processing of HHDN.

Valorization of engineered biochar to develop ultra-high-performance fiber-reinforced concrete with low carbon emission

This research introduces an innovative approach to developing carbon-negative Ultra-High-Performance fiber-reinforced Concrete (UHPC) by incorporating substantial quantities of biochar, both as a binder and as an aggregate, replacing up to 25% by weight of Ordinary Portland Cement (OPC) and quartz sand (QS). The study examines the impact of biochar on cement hydration processes, microstructure evolution, and various other performance metrics in the modified UHPC. Samples were formulated with 3% double-hooked steel fibers and biochar quantities ranging from 5 to 25% by weight as substitutes for OPC and QS. The investigation included assessments of changes in rheological properties, strength metrics, long-term shrinkage, resistance to sulfate attacks, freeze-thaw durability, microstructure analysis, and a cost-benefit evaluation. Test results indicated that biochar-incorporated samples exhibited up to a 20% increase in heat evolution by the end of the seventh day and plastic energy at 28 days that rose to 32.14% as compared to control samples in 20% biochar-augmented versions. Shrinkage reduction varied between 58 and 69% at 210 days for samples with 20% biochar. Specifically, the mix containing 20% biochar (G2-M5-BC-20) significantly improved the 90-day compressive and flexural strength by 8.9 and 9.3%, and 30.6 and 36.8%, respectively, while further inclusion of biochar showed no marked enhancement in performance metrics. The G2-M5-BC-20 mix also demonstrated excellent resistance to sulfate attacks and freeze-thaw cycles, exhibiting the least mass loss and highest residual compressive strength. An initial cost-benefit revealed that biochar-enhanced UHPC could offer compelling financial benefits. Given its mechanical behavior, potential for harmful CO2 emissions, and economic viability, the G2-M5-BC-20 mix emerged as the most promising formulation, potentially generating an overall profit of $36 per cubic meter.

Rheological Properties and Segregation of Fresh UHPC with Fibers Affected by Initial Temperature of Concrete Mix

Within the framework of the project GAČR 21-24070S Model of fibre segregation in dependence on rheological properties of fresh HPC, the rheological properties and fibre segregation in fresh concrete mix depending on temperature changes have been verified. The rheological properties and fibre segregation have been verified under three temperature conditions (very low temperatures around 5 °C, normal temperature conditions around 20 °C and high temperatures above 30 °C). Comparison of the properties of UHPC with fibres at different temperature conditions has been performed on fresh mixtures mainly by spill tests. Subsequently, hardened test bodies, i.e. 40/40/160 beams, were verified in tensile bending and compression in all cases. The actual fibre segregation within the individual samples has also been verified by microscopic analysis. Different temperature conditions have been simulated by heating or cooling the input raw materials. The results have been compared by degree of changes in rheological properties and mechanical parameters.