Properties Of Mixtures Research Articles

The influence of acid rain on asphalt and its mixture performance, simulation and micro-mechanism exploration

Acid rain will destroy asphalt roads and affect human production and life. Therefore, this study has designed a new indoor simulated acid rain erosion test, and explored the effects of acid rain on the properties of 70# petroleum asphalt, SBS asphalt and their mixtures and the acid rain erosion mechanism from the micro and macro perspectives. In this paper, the influence of acid rain erosion on the microscopic properties of asphalt has been revealed through microscopic experiments. Through the combination with the basic performance test of asphalt, the effect of acid rain erosion on the conventional properties of asphalt was studied. The effects of acid rain on the properties of road asphalt mixtures were studied by Marshall immersion and high-temperature rutting tests. The results show that there is no obvious chemical reaction between the two kinds of asphalt after acid rain erosion, but the surface structure and morphology have changed significantly. There was a mass loss, the decreases of the softening point and ductility, and an increase of the penetration; the residual stability and high temperature resistance of both asphalt mixtures were reduced. In the worst case, the quality of petroleum asphalt was lost by 82.2%, the softening point and ductility decreased by 9.6% and 16.9% respectively, the penetration degree increased by 3.1% and the residual stability and dynamic stability of petroleum asphalt mixture decreased by 8.82% and 27.9% respectively. The mass loss of SBS asphalt was 82.5%, the softening point and ductility decreased by 5% and 3.3% respectively, the penetration increased by 2.6%, and the residual stability and dynamic stability of SBS asphalt mixture decreased by 4.82% and 25.4% respectively. In general, under the action of acid rain, the performance of 70# oil asphalt, SBS asphalt and their mixtures are affected to varying degrees. The specific performance is to destroy the original shape of asphalt, resulting in the loss of quality of asphalt, the reduction of deformation resistance, high temperature stability and low temperature stability of asphalt, weakening the high temperature stability and water stability of asphalt mixture, and leading to the decline of road performance.

Evaluating environmental and economic benefits of using biochar in concrete: A life cycle assessment and multi-criteria decision-making framework

While several studies have assessed the applicability of using biochar in cement mortar and concrete preparation based on the best mechanical properties, this evaluation method should be improved to consider the techno-economic feasibility and the environmental impacts. To address this research gap, this study attempts to compare between the conventional concrete with 100 % cement as a control mixture (CM) and dumping of sludge into open sites (scenario_1), and biochar concrete using alum sludge biochar (ASB) as a partial cement replacement (scenario_2), regarding the project life cycle assessment (LCA) and economic feasibility. A multi-criteria decision-making (MCDM) framework was used to assign scores to the environmental LCA criteria, material functional performance tests, and cost considerations. The two scenarios were arranged in SimaPro LCA software, and then the different criteria were analyzed using the TOPSIS technique to choose the best alternative. The study demonstrated that the functional properties of the cement mixture containing 5 % of ASB were almost comparable to those of CM, owing to the presence of significant amounts of quartz (SiO2) that bonded strongly with cement molecules. This ASB mixture also enjoyed the least environmental impacts, reducing the global warming potential (GWP) by 32.2 % compared with the CM scenario. The scores of the “Cost” criterion, considering the price of raw materials, energy, production, and maintenance, for the two alternatives were almost comparable, depicting that scenario_2 achieved the highest closeness coefficient of 0.95 in the MCDM overall scoring. This study concluded that biochar could be incorporated into cementitious mixtures due to its lower impact on global warming to maintain a sustainable and economic concrete industrial strategy. Future studies should focus on studying the long-term durability of the biochar-based concrete mixtures and integrating into the MCDM strategy; in addition, determining the correlation between sustainable construction implementation and sustainable development goals achieved.

Enhancing the Mechanical Properties of Green Concrete Blocks Mixture

Abstract Concrete is a very abundant building material and flexible in construction. Yet cement is the main material used in concrete mixture, which consumed a lot of energy and money. Cement is a very un-eco-friendly material when it comes to production and is a main contributor to global warming. On the other hand, Polymers can be toxic to people, fauna, and flora. In the last century, Egyptian citizens complained that the waste has increased, and the inappropriate waste disposal effect the Egyptian health and quality of life. The alternative is to burn the polymers; however, it will produce toxic emissions that will break down the ozone layer. Previous researchers tried to replace cement with an alternative in the concrete mixture. Therefore, this research intends to create a green concrete block with cement-less mixture and use polymers as a binding material in the blocks. This research will follow the experimental method after discussing the properties of the materials. Then a concrete mix will be created, and a percentage of cement will be replaced; thus, making a cheap concrete mixture that has less cement and is more ecological and economical. Tests will be performed to determine if the proposed concrete mixture is suitable for mass production and doesn’t violate the international standards. The performed tests will include compressive strength, tensile strength, and abrasion. finally, a cost analysis will be calculated to compare the construction costs before and after using the proposed concrete mixture.

Potential reuse of fine sediment from hydroelectric dams and recycled concrete sand in road subgrades

Hydroelectric dams play a crucial role in power generation, water storage, and irrigation. However, their continuous operation has led to sediment accumulation, thereby reducing the water storage capacity and impacting the facility's life span. The aim of the current study is to assess the reuse potential of dredged fine sediment in the composition of road subgrades. Nine types of sediment from diverse hydroelectric dams are analyzed for their chemical, environmental, physical, and geotechnical properties. These sediments then were treated with quicklime and a slag-based hydraulic road binder (3% and 6%, respectively). The current investigation involves evaluating: Proctor parameters, the immediate bearing index, treatment ability, and the mechanical properties of the treated sediment. The results reveal that the properties of treated sediment differ from one mixture to another, thus, indicating that some mixtures meet the criteria outlined in the French Roadworks Guide, by virtue of their clay and organic matter contents. Moreover, the current study explores the impact of incorporating recycled concrete sand (RCS) as a granular corrector to enhance the reuse potential of the sediment in road subgrades. The current findings indicate that adding RCS significantly improves mixture properties, particularly mechanical characteristics, by reaching 1 MPa before 7 days of curing. These promising outcomes pave the way for more advanced road construction practices in ensuring environmental compliance and promoting an eco-friendly reuse of sediment.

Fiber Showdown: A Comparative Analysis of Glass vs. Polypropylene Fibers in Hot-Mix Asphalt Fracture Resistance

Cracks in asphalt mixtures compromise the structural integrity of roads, increase maintenance costs, and shorten pavement lifespan. These cracks allow for water infiltration, accelerating pavement deterioration and jeopardizing vehicle safety. This research aims to evaluate the impact of synthetic fibers, specifically glass fiber (GF) and polypropylene fiber (PPF), on the crack resistance of Hot-Mix Asphalt (HMA). An optimal asphalt binder content of 5% was used in all sample designs. Using the dry mixing technique, GFs and PPFs were incorporated into the HMA at dosages of 0.50%, 1.00%, and 1.50% by weight of the aggregate. The effects of these fibers on the mechanical fracture properties of the HMA were assessed using Semi-Circular Bending (SCB), Indirect Tensile Asphalt Cracking Tests (IDEAL-CTs), and Three-Point Bending (3-PB) tests. This study focused on fracture parameters such as fracture work, peak load, fracture energy, and crack indices, including the Flexibility Index (FI) and Crack Resistance Index (CRI). The results from the SCB and IDEAL-CT tests showed that increasing GF content from 0.5% to 1.5% significantly enhances the flexibility and crack resistance of HMA, with FI, CRI, and CT Index values increasing by 247.5%, 55%, and 101.35%, respectively. Conversely, increasing PPF content increases the mixture’s stiffness and reduces its crack resistance. The PP-1 mixture exhibited higher FI and CT Index values, with increases of 31.1% and 10%, respectively, compared to the PP-0.5 mixture, based on SCB and IDEAL-CT test results. The SCB, IDEAL-CT, and 3-PB test results concluded that fibers significantly influence the fracture properties of bituminous mixtures, with a 1% reinforcement dosage of both PPFs and GFs being optimal for enhancing performance across various applications.

Rheological and tribological properties of xanthan gum-fucoidan mixture: Effect of NaCl, KCl, and CaCl2

This study endeavored to investigate the effects of salts (NaCl, KCl, and CaCl2) on the rheological and tribological properties of xanthan gum (XG)-fucoidan mixtures. With increasing salt concentrations, the intrinsic viscosity (56.1–30.9 dL/g) of mixtures decreased, with pronouncedly lower values (30.9–35.8 dL/g) observed with CaCl2 addition compared to monovalent salts addition (36.4–46.6 dL/g). This indicates a contraction of hydrodynamic size of the polymers due to the charge screening effect of cations and the formation of a more compact conformation in the presence of CaCl2 than with either NaCl or KCl addition. FTIR analysis revealed changes in the interaction between the two polymers in the presence of each salt. All samples exhibited shear-thinning behavior, and their thixotropic behavior increased as the salt concentration increased. The apparent viscosity and viscoelastic moduli decreased in the presence of monovalent salts but were increased in the presence of CaCl2. This was attributed to the crosslinking effect of Ca2+; Na+ and K+ did not induce crosslinking. In addition, the friction coefficient (μ) of mixtures containing salts reached the maximum at a lower entrainment speed (0.08–0.17 mm·s−1) than that without salt (1.54 mm·s−1), and the mixtures containing salts exhibited lower maximum μ values (0.28–0.62) compared to that without salt (0.83), indicating an improvement in the lubricant properties of XG-fucoidan mixtures. Our findings may help broaden the application of fucoidan in the food industry.

Molecular Interaction Studies on Physiochemical and Derived Properties of Binary mixtures at Atmospheric Pressure

The physiochemical properties like refractive indices, densities, and static dielectric constants of binary mixtures were measured over the entire concentration range. Refractive index and densities were measured at 293.15 K, and dielectric constants at (293.15, 298.15, and 303.15 K) temperatures for the n-propanol-formamide binary system. From dielectric data, the related and excess properties were calculated and reported in this work. From experimental refractive indices and densities, various related and excess properties were estimated and reported in this study. Static dielectric constants, densities, and refractive index of the binary system increase with the increase in the mole fraction of formamide. The results obtained were discussed in terms of intermolecular interactions, structural effects, hydrogen bonding, and other possible interactions between like and unlike molecules of the binary system.

Getting insights into chemical composition and antiherpetic capability of jujube (Ziziphus jujuba mill.) drupes

Food plant diversity in bioactive compounds makes them an exploitable resource in the search for effective natural products to prevent or treat viral infections. Therefore, in the framework aimed at studying the antiviral properties of extractive mixtures from fruits (and their waste) grown in the Campania Region (Italy), jujube drupes (Zizyphus jujuba Mill.) were our focus. The drupes were dissected into their peel, pulp and seed parts, each of which was extracted by ultrasound-assisted maceration and further fractionated, thus obtaining, beyond the sugar fraction, a polyphenolic fraction and a lipid fraction. UHPLC-HR MS/MS tools highlighted that the polyphenolic component of the seed was strongly dissimilar from that of the edible parts, being constituted by swertisin and its derivatives. Moreover, the peel mostly accounted for triglycosylated flavonols, whereas the pulp was rich in volatile aromatic glycosides. Among lipids, p-coumaroyl triterpenes mainly characterized the peel. All fractions were screened for their cytotoxicity, and non-toxic concentrations of each extract were tested against herpes simplex virus type 1 (HSV-1) by plaque assays. Molecular tests and Western blot analyses were also carried out. The jujube mixtures, in detail the peel and pulp polyphenolic fractions, and peel lipophilic fraction (the latter enriched mainly in ursane-type triterpenes), showed a marked inhibitory activity against HSV-1 acting in the early stages of viral infection and preventing attachment of the virus to the host cell. The acquired data suggest jujube active mixtures as promising candidates for the prevention and treatment of herpetic lesions.

Impact of nano-powders on conduction mechanism during solidification through cold storage tank

In this article, numerical modeling with the aim of decreasing the solidification time is presented. The solidification process is primarily influenced by conduction, leading to the application of two techniques aimed at enhancing this mechanism: the install of fins and the addition of nano-powders. Various shapes and fractions of alumina nanoparticles are introduced into the H2O to accelerate the solidification. To predict the properties of the nanoparticle-infused mixture, single-phase formulations are employed. The Finite Element Method (FEM) is then hired to model the system, with an adaptive grid implemented to enhance accuracy. Validation against previous works demonstrates the capability of the developed code for the present study. The incorporation of nanoparticles results in a significant 32.7 % increase in the freezing rate, highlighting the effectiveness of this approach. Additionally, altering the shape of the nanoparticles can further increase the process rate by approximately 10.73 %. The transition from a water-based system to one infused with nanomaterials leads to a notable decrement in freezing time, from 957.64 s to 6447.35 s. These outputs emphasize the potential of nanomaterial-enhanced cold energy storage systems to significantly improve efficiency and performance. In summary, the study showcases the effectiveness of numerical simulation in optimizing cold energy saving processes through the strategic utilization of nanoparticles.

Non-Linear and Linear Optical Properties of an Organic Laser Dye Mixture

Non-Linear and Linear Optical Properties of an Organic Laser Dye Mixture

PH-induced conformational changes of lupin protein-pectin mixtures and its effect on air-water interfacial properties and foaming functionality

Lupin protein isolate (LPI) has high nutritional value and good foaming properties around neutral pH; however, its functionality becomes poor at acidic pH, due to reduced protein solubility. The addition of pectin to LPI can increase its solubility at acidic pH and hence improve protein functionality. Here, we investigated the air-water interfacial and foaming properties of LPI-pectin (1:1) mixtures at pH 3.5–7.0. We used interfacial shear and dilatational rheology, characterized the air-water interfacial microstructure with AFM of Langmuir-Blodgett films, and linked the results to the foaming properties of the LPI-pectin mixtures. Based on the phase diagram, LPI and pectin formed co-soluble mixtures at pH 6.0 and 7.0, while LPI-pectin electrostatic complexes were formed at pH 3.5 and 4.0. In the co-soluble mixtures, proteins diffused faster towards the air-water interface than the electrostatic complexes, due to smaller particle sizes of the proteins. Their air-water interfaces showed distinct differences with respect to microstructure and mechanical properties. The interfaces stabilized by co-soluble mixtures were dominated by protein aggregates, leading to weaker interfaces in response to shear and dilatational deformation, while the complexes formed thicker and denser polymeric air-water interfaces that were stiffer and more solid-like. As a result, the complex-stabilized foams were more stable than those stabilized with co-soluble mixtures. Findings from this study indicate that soluble LPI-pectin complexes formed at pH 3.5 and 4.0 were more efficient in improving interfacial and foaming properties of LPI than the co-soluble mixtures at pH 6.0 and 7.0, which can be used to tailor the properties of acid aerated products stabilized by LPI.

Effects of different molecular weight polyethylene glycols on the thermophysical properties of caprylic acid and 1-dodecanol eutectic mixture

Cold-chain logistics involve a wide range of temperature-control issues and efforts are being made to improve the efficiency of energy-storage systems. In particular, thermal-energy storage technologies, including sensible, thermochemical, and latent heat storage, have been extensively researched to enhance system efficiency and mitigate peak energy demand. This study investigated the effect of the polymer molecular weight on the heat-storage capacity of eutectic materials. The thermophysical properties and thermal stabilities of caprylic acid (Ca) and 1-dodecanol (Do) eutectic mixtures were examined in conjunction with ethylene glycol (EG) and polyethylene glycol (PEG) with different molecular weights (MWs). The dissolution behavior, heat-storage capacity, latent heat, temperature-retention time, and heat conductivity were strongly influenced by molecular weight, which was attributed to the self-aggregation and dispersion of EG and PEG within the Ca-Do eutectic mixture. PEG-4K and 35K exhibited good dissolution in the Ca-Do eutectic mixture, resulting in increased heat-storage capacity, latent heat, thermal conductivity, and thermal stability. By using PEGs with higher MWs, the temperature-retention durations in the 2–8 °C range were enhanced. Conversely, PEG with an ultrahigh MW of 1000K exhibited flocculation and phase separation within the Ca-Do eutectic mixture owing to exceptionally high self-aggregation. The thermophysical properties of the Ca-Do eutectic mixture were influenced by the variations in the MWs of EG and PEGs, as well as their dispersion within it. Considering the efficacy and commercial availability of PEGs, Ca-Do-35K is a promising candidate for thermal-energy storage applications in the range of 2–8 °C.

Insight into synergistic effect of zinc oxide/expanded vermiculite composite (ZnO/EVMT) on bituminous mixture performances under different aging conditions

Zinc oxide/expanded vermiculite composite (ZnO/EVMT) with synergistic effect can effectively retard bitumen aging behavior, but the effect on road and mechanical performance of bituminous mixture under different aging conditions is unclear, which hinders its application and promotion. Based on the above, this study is meant to reveal the synergistic effect of ZnO/EVMT on bituminous mixture, with the ultraviolet absorber (UVA) compounding with antioxidant (AO) (label as UVA+AO, the same component ratio as ZnO/EVMT) and hydrated lime (HL) modifier serving as comparison. Then, the influence of ZnO/EVMT on the laboratory performances, including road performance and mechanical properties, of bituminous mixtures under four different aging conditions (unaged, long-term oven aging, long-term continuous and long-term all-weather photo-oxidative aging conditions) were investigated. Results show that under unaged condition, the addition of ZnO/EVMT can enhance road performance of bituminous mixture, and has similar effect to that of HL modifier and more positive effect than that of UVA+AO modifier. Under long-term oven aging condition, bituminous mixture containing ZnO/EVMT and HL have similar deformation resistance. ZnO/EVMT and the other two modifiers can enhance the low-temperature property, water stability and fatigue property of bituminous mixture, and ZnO/EVMT modified bituminous mixture has the highest low-temperature property and the lowest property change sensitivity. Under two long-term photo-oxidative aging conditions, ZnO/EVMT modified bituminous mixture generally exhibits higher creep deformation and deformation growth rate but lower mechanical performance changing rate than base bituminous mixture. Therefore, ZnO/EVMT can improve bituminous mixture road performance and reduce its aging sensitivity under different aging conditions. And the expected service life and durability of bituminous pavement will benefit from its promotion practice.

Effects of High-Speed Shearing Treatment on the Physical Properties of Carbohydrate-Binder Mixture during Gelatinization for Preparing Freeze-Dried Soup Products.

Modernization has led to a large convenience food market, and the demand for freeze-dried (FD) soup products is increasing in the Republic of Korea. FD soup products are easy to eat without cooking and can be stored for long periods. However, it is often difficult to ensure sensory satisfaction after rehydration of FD soup products; in particular, the ingredients are not evenly dispersed. Therefore, a stable dispersion or reconstitution of the FD soup products is required after rehydration. Here, the effects of high-speed shearing homogenization on the physical properties of a carbohydrate-binder mixture comprising maltodextrin, potato starch, and rice flour were investigated during hydrothermal gelatinization. To find a suitable treatment condition, different homogenization eras, speeds, and concentrations of the binder mixture were considered; in particular, the homogenization eras were set by considering the hydrothermal property of the binder mixture profiled using differential scanning calorimetry. The viscosity of the binder mixture and the compression strength and microstructure of the FD binder block, including the dispersion stability after rehydration, were evaluated. The quality of the FD binder block was improved by homogenization above 5000 rpm when the core temperature of the binder mixture reached approximately To at 14.5-21.8% concentrations. The improved FD binder block exhibited a fine surface and tiny porous microstructure compared with the control (with continuous agitation at 250 rpm). The control block was divided into two phases, whereas the improved block maintained the initial dispersion stability at 50 °C for 1 h. These results are expected to be referenced for the purpose of improving the quality of the FD soup products.

Parametric optimization of Cement-based solidification combined with vacuum-assisted filtration

This study delves into the parametric optimalization of cement-based stabilized soft clays (CBSC) combined vacuum-assisted filtration (VAF) technique on for engineering applications, focusing on the influence of the retarder, calcium source and intermittent time etc. Key findings include VAF benefiting CBSC’s strength for water discharge from the paste, where the UCS of CBSC treated with VAF can increase more than ten times higher than the untreated samples (e.g., 767 kPa versus 60 kPa). The added retarders extend the initial setting time, thus facilitating the removal of excessive water, that the 0.2 % addition of calcium lignosulfonate causes 6.5 % increment of dewatering mass. Especially, calcium lignosulfonate, working as a versatile agent of imparting significant improvements in the rheological properties of cement mixtures and augmenting the structural integrity of clayey soils, was found to significantly enhance the VAF efficiency and the UCS, of which 28-day’s UCS further increases comparing to referential group after VAF. The study also reveals that calcium sources, such as desulfurized ash and lime, are also vital in replenishing calcium ions lost during VAF and maintaining a strong alkaline environment, significantly contributing to the strength enhancement. Additionally, the intermittent timing is also critical to the filtration efficiency, where the intermittent time was recommended within two hours post-mixing. These findings offer valuable insights for the practical application of CBSC by the VAF assistance, particularly involving soft clays with high water content.

Mechanical properties of teguline clay pellet mixtures during continuous oedometric compression

Clay pellet mixtures are generally compressed to improve their engineering performance. Deepening the comprehension of the mechanical properties of these mixtures in the complete compression process facilitates the benefit to the engineering design and their utilization. In this study, the effects of soil grain size distribution, water content and dry density on the mechanical properties and microstructure of Teguline clay pellet mixtures during a continuous oedometric compression process are explored. Three types of soil pellet mixtures, including mixture A (grain size ≤5 mm), mixture B (≤ 0.4 mm) and mixture C (2–5 mm), were prepared with different water contents of 7%, 8% and 12% respectively. Subsequently, continuous oedometeric compression was undertaken to explore their mechanical behaviours of the soil pellet mixtures. After that, the microstropic structures of the compacted pellet mixtures were investigated using mercury intrusion porosimetry (MIP). The results indicated that mixture A has a minimal initial packing density of pellet mixtures, while mixture C has a maximum one at the initial compression stage. After completion of compression, the compression curves of the pellet mixtures tended to converge uniformity at a semilogarithm coordinate as the vertical stress increased. All of the compression curves presented a concave shape at the plastic compression stage, which is significantly influenced by grain size distribution and water content. In contrast, the elastic compression and rebound behaviours are little affected by the grain size distribution and water content. As far as the microstructure is concerned, compacted samples prepared by mixture A or C presented a unimodal pore structure, while those by mixture B showcased a bimodal pore structure. In comparison with the unimodal pore distribution of the undisturbed stiff clay, the compacted samples displayed a pseudo-unimodal pore distribution because the inter-aggregate pores still existed. A double tangent method was proposed to determine the delimiting pore diameter of the pseudo-unimodal pore distribution curves and found that the delimiting pore diameter decreased with the increase of dry density and water content. Moreover, the inflexion point for the pore diameter of compacted samples prepared by coarse soil was larger than that of fine soil. Combining this work with previous research, it was found that the high compression of coarse soil easily causes the pseudo-unimodal shape, which is also impacted by water content and particle properties. This work could help deepen the understanding of the mechanical characteristics and microstructure of the stiff clay pellet mixtures during continuous oedometric compression.

Influence of co-solvents on properties of terpene-based eutectic mixtures: Implications for skin delivery

Terpene-based eutectic mixtures (EMs) are attractive platforms for transdermal delivery due to their solubilizing potential and ability to alter the barrier function of the stratum corneum (SC). Despite this, little is known about the effect of diluting EMs with co-solvents (CSs) on their solubility- and permeation-enhancing properties. Furthermore, insufficient attention has been paid to comparing these platforms with traditional solvents, such as propylene glycol (PG) or ethanol (EtOH). To address this gap, the present study investigates the impact of the CS content in EM:CS blends on the transdermal delivery of clotrimazole (CLOT). Two CSs, PG and EtOH, and two terpene-based EMs, menthol:thymol and thymol:β-citronellol, were used. Each of the EMs was investigated at two different molar ratios between the terpenes, with one being their eutectic point, to explore its potential benefit for skin permeation. At each step, properties of the blends were compared with those of pure CSs. The EM:CS blends showed a better solubilizing potential for CLOT than EMs or CSs on their own. A higher content of CSs in the blends resulted in a higher skin permeation and retention of CLOT, and a lower degree of disarrangement of the SC structure. Furthermore, the blends of EMs at their EPs led to overall poorer permeation profiles, implying that the permeation rate is more affected by the properties of the individual terpenes than by the specific ratio at the eutectic point between them. In conclusion, addition of CSs to the EMs promotes permeation and retention of CLOT, while reducing the skin impairment caused by the terpenes.

Self-assembly of mixed surfactants sodium dodecylsulfate and polyethylene glycol dodecyl ether in aqueous solutions

The thermodynamic behavior of mixed systems containing the anionic surfactant sodium dodecyl sulfate (SDS) and the nonionic surfactant polyethylene glycol dodecyl ether (Brij L4) in aqueous solutions was investigated. Electrical conductivity and interfacial tension measurements were employed to investigate the concentration-dependent properties of these surfactant mixtures. Two main experiments were conducted: i) constant ratio experiment: the overall surfactant concentration was varied while maintaining a fixed ratio between SDS and Brij L4. It was shown that the critical micelle concentration (CMC) determined from electrical conductivity measurements does not indicate the formation of the first mixed micelles as observed using tensiometry, but the point from which the adsorption of counterions by the existing micelles became important. By using the Regular Solution Theory (RST), it was found that the interaction between SDS and Brij L4 is synergistic, driven by dipole-ion interactions of the hydrophilic regions of the two surfactants. ii) Fixed SDS concentration while increase the Brij L4 concentration: the resulting electrical conductivity exhibited non-trivial behavior which complexity arose from simultaneous phenomena of incorporation of free SDS molecules into the micelles as Brij L4 concentration increased, leading to a decrease in electrical conductivity; liberation of some adsorbed counterions from the mixed micelles to the solution, which increases the conductivity and increase of viscosity due to Brij L4 further addition that leads to a sequential decrease in electrical conductivity.

A study on the synthesis and performance evaluation of fly ash and alccofine as sustainable cementitious materials

Construction and global infrastructure depend on cement production. It is one of the biggest carbon emitters, making it an aspect of environmental sustainability and climate change mitigation. Each stage of cement production releases CO2 and other greenhouse gasses. About 8% of worldwide CO2 emissions come from the cement sector, making it a major contributor. Different supplementary cementitious materials (SCMs) like fly ash (FA), silica fume (SF), and slag are used to partially replace traditional raw materials like limestone, reducing the environmental impact. This study investigated the use of supplementary cementitious materials, specifically FA and alccofine (AF), as partial replacements for cement in concrete to reduce environmental impact. The study first identified an optimal replacement percentage for FA (20%, 30%, and 40%) by weight of cement. Subsequently, using the optimal FA percentage, AF was added at varying percentages (5%, 10%, and 15%) by weight of cement. The study evaluated the mechanical properties of the concrete mixtures, including workability, compressive strength, split tensile strength, and flexural strength. Durability, measured by water sorptivity and rapid chloride penetrability tests, was also assessed. The microstructural properties of the concrete were analyzed to understand their influence on performance. As a result of the significant environmental implications of producing and using concrete for all activities, an in-depth life cycle assessment (LCA) was conducted. Additionally, artificial neural networks were employed to predict the compressive strength of the concrete. The study concluded that incorporating FA and AF in concrete mixtures is a promising approach to producing more environmentally friendly concrete.

Dynamic viscoelastic properties of ultra-large particle size asphalt mixture based on fractional derivative constitutive model

The aim of this paper was to accurately grasp and precisely characterize the dynamic viscoelastic properties of Ultra-Large Particle Size Asphalt Mixture (LSAM-50), and fully explore the features and simplified forms of the generalized fractional derivative Zener (GFDZ) model. The constitutive relations of the GFDZ model with n Abel elements were first given, and a modified GFDZ (mGFDZ) model was proposed. Then the master curves of LSAM-50, AC-13 and AC-20 mixtures were constructed, and the expression effects of different models and the dynamic viscoelastic behaviors of different asphalt mixtures were compared. The results showed that LSAM-50 was a typical viscoelastic material similar to traditional mixture. Both dynamic modulus and energy storage modulus decreased with increasing temperature. The phase angle increased first and then decreased with temperature increasing, and the peak value appeared near 40℃ at low frequency. The loss modulus increased first and then decreased with the temperature increasing. When the loading frequency was 0.1 Hz∼25 Hz, the peak value appeared at 0℃∼20℃. The rutting factors of LSAM-50 became larger with temperature reduction and frequency enhancement. When the number of Abel elements reached 2 in the GFDZ model or reached 3 in the mGFDZ model, the model fitting effects would no longer change significantly. The 2-mGFDZ model with only 5 parameters fitted master curves data satisfactorily and the physical meanings of parameters were clear. Comparing among three mixtures, LSAM-50, with the lowest asphalt content, showed significantly superior elasticity and better deformation resistance at medium and high temperatures. At low temperatures, the viscosity behavior of LSAM-50 was slightly inferior, but it may have pronounced plate properties considering the effect of aggregate skeletonization. The research results would promote new pavement structural design and mechanical response analysis.