Increase In Yield Stress Research Articles

Effect of recycled concrete powder on the rheological properties of cement paste: New findings

Recycled concrete powder (RCP) influences cement paste's rheology, but the mechanisms remain unclear. This paper intends to fill this gap by employing a new method for measuring water absorption, the minimum water requirement method, an organic carbon analyser, and a laser particle size analyser. The cementitious material's water absorption (W), packing density (φm), water reducer adsorption (Qad), and particle size distribution are determined. Results show that, as the RCP's content increases from 0 % to 25 %, the cementitious material's W, φm, Qad, volume fraction, and average particle size increase by 21.7 %, 0.9 %, 26.2 %, 1.4 %, and 30.6 %, respectively. Consequently, the particle's surface covered by the water reducer (θ) and distance (H) decrease by 26.5 % and 32.6 %, respectively, resulting in an increase in the paste's yield stress (τ0) and plastic viscosity (ηpl) by 1946.6 % and 45.3 %, respectively. Based on an existing yield stress model, RCP affecting τ0 can be attributed to changes in the particle system's colloidal and contact interactions. A decrease in H increases colloidal interactions. Conversely, an increase in φm and a decrease in fine particle content reduce contact interactions. Colloidal interactions are more significant, thus τ0 increases. Based on the functional expression for the ηpl developed here, RCP affecting ηpl can be attributed to changes in hydrodynamic interactions and contact interactions. A decrease in H increases hydrodynamic interactions. An increase in φm combined with a decrease in fine particle content decrease contact interactions. Additionally, an increase in Qad reduces pore solution's viscosity. Hydrodynamic interactions are more significant, thus increasing ηpl.

Direct ink writing of customized polymeric structures embedded in a nano-silicate based supporting matrix

The increase in use of intricate structures for engineering applications has encouraged researchers to find new fabrication techniques. This work presents an innovative approach of embedded 3D printing, which allows fabrication of freeform structures by directly 3D printing inside a supporting matrix. The polymer ink solution was prepared by blending polylactic acid (PLA) and polypropylene carbonate (PPC) in 1,4-dioxane. Laponite RD was used to prepare the aqueous nano-silicate suspension, which exhibited yield stress and thixotropic properties due to its house-of-cards arrangement. Solidification of the 3D printed polymer ink occurred due to the hydrogen bonding between the oxygen atoms of dioxane molecules and the protons of water molecules. Particle image velocimetry study showed that the increasing nano-silicate concentration caused a reduction in yield region as a result of increasing yield stress. Dimensionless parameters (Oldroyd number and ratio of yield stress to hydrostatic pressure) for nano-silicate concentrations with values less than 1 were found to facilitate the nozzle movement without crevice formation, while the values greater than 1 were found to be unsuitable for printing. Different intricate structures such as tubular structures with varying geometry that mimic the native trachea, and a bifurcated tube were 3D printed as a proof-of-concept study. The proposed method introduced a novel approach by utilizing the solvent-water interaction capability to fabricate objects with overhanging geometry. This approach allows 3D printing of a wide variety of polymers by leveraging the miscibility between its corresponding solvent and supporting matrix.

Foam Properties Evaluation under Harsh Conditions: Implications for Enhanced Eco-Friendly Underbalanced Drilling Practices

Summary Foam drilling offers advantages such as reduced formation damage and faster drilling in underbalanced drilling (UBD) operations. The efficacy of foam drilling is influenced by factors including pressure, temperature, salt content, foam quality, and pH levels. However, a gap exists in the evaluation of foam properties under rigorous conditions, particularly those involving high pH and mixed salt environments common in drilling scenarios, highlighting the need for further research. In this study, a high-pressure, high-temperature (HPHT) foam analyzer and rheometer were employed to examine the stability and rheological behavior of ammonium alchohol ether sulfate (AAES) foam under simulated alkaline drilling conditions. The foaming solution, designed to replicate such conditions, consisted of synthetic seawater (SW) with a salt mixture totaling approximately 67.70 g/L and a 0.5 wt.% foaming agent adjusted to a pH of 9.5. This approach differs from the individual salt studies prevalent in existing literature and provides a unique perspective on foam stability and behavior. Driven by environmental sustainability considerations, the effects of eco-friendly surfactant AAES and various drilling fluid additives: polyanionic cellulose (PAC), carboxymethyl cellulose sodium (CMC), and xanthan gum (XG), were investigated for foam formulation. The apparent viscosity of the AAES foam was evaluated at different pressures and temperatures across varying shear rates. A consistent decrease in foam viscosity with increasing shear rates was observed, irrespective of pressure and temperature. An increase in foam viscosity was also noted with higher pressures (from 14.7 psi to 3,000 psi) at low shear rates, with values rising from 8.04 cp to 14.74 cp, and from 3.71 cp to 5.79 cp at high shear rates of 1,000 s⁻¹. Increasing foam quality from 65% to 85% resulted in significant improvements in viscosity, approximately 37% at low shear rates and about 79% at high shear rates. The introduction of additives to AAES foam at 1,000 psi and 90°C led to a substantial increase in viscosity, with PAC showing the most significant enhancement: 33.28 cp at low shear rates and 18.15 cp at high shear rates. Conversely, the viscosity of both base AAES foam and additive-enhanced foams decreased with rising temperatures, although PAC exhibited the greatest resistance to viscosity variations due to temperature changes. The addition of PAC also resulted in a notable increase in foam yield stress, potentially leading to more efficient cuttings transport and hole cleaning. Furthermore, foam stability was significantly improved by the additives, with XG and CMC doubling stability to 48 minutes, and PAC resulting in a threefold increase in half-life to 65 minutes. This study presents AAES and the tested additives as viable components for eco-friendly foam formulations, promoting enhanced properties suitable for UBD applications.

Variability of lead-zinc sulfide ore slurry rheological properties and its influence on flotation conditions

We investigated how the rheological characteristics of a flotation slurry change in response to variations in mineral species, slurry concentration, and particle size; slurry pH; and trap and rheological control reagent concentrations using slurries containing galena, sphalerite, quartz, and kaolinite. The results indicate that reducing particle size and increasing slurry concentration leads to varying degrees of increase in apparent viscosity and yield stress. At the same particle size, the slurry exhibits the following order of apparent viscosity and yield stress: kaolinite > galena > sphalerite > quartz. In addition, as the slurry’s apparent viscosity and yield stress increase, the rheology decreases, creating progressively unfavorable conditions for the flotation of lead, zinc, and other target minerals. Furthermore, changes in pH have no significant effect on the slurry’s rheology when the slurry is comprised of vein minerals. Moreover, galena and sphalerite depict particle agglomeration in the slurry. Ultimately, the addition of sodium silicate as a rheological control reagent substantially enhances the slurry’s rheological properties. This results in a system where problematic minerals like kaolinite are more effectively dispersed, thereby promoting efficient lead-zinc mineral flotation. Regarding the flotation of lead sulfide and zinc minerals, the addition of kaolinite raises the apparent viscosity of the mixed slurry, hindering the flotation of the target minerals. Conversely, quartz lowers the apparent viscosity aiding the flotation separation process. Understanding the relationship between flotation conditions and the pulp’s rheological properties can provide valuable guidance for subsequent flotation tests.

Hydrogen-enhanced microbanding in an austenitic FeMnAlC low-density steel: Effect on hydrogen embrittlement resistance

We have investigated the influence of 101 mass ppm hydrogen content on the room temperature deformation structure and mechanical behavior of an austenitic Fe30Mn6.5Al0.3C (wt.%) low-density steel by several electron microscopy techniques, such as electron channeling contrast imaging (ECCI), electron backscatter diffraction (EBSD), and scanning transmission electron microscopy (STEM). The steel exhibits a high hydrogen embrittlement resistance associated with a moderated increase in strength (yield stress increase of 10%) and ductility (increase in the elongation to fracture of ∼ 8%). Analysis of the deformation structure reveals that hydrogen influences the deformation behavior by promoting deformation mechanisms associated with inhomogeneous plasticity (hydrogen-enhanced deformation banding (HEDB)) and strain localization (hydrogen-enhanced microbanding (HEMB)). These deformation mechanisms are ascribed to hydrogen-induced effects on dislocation plasticity, resulting in macroscopic kink bands, sub-micron localized strain gradients, and localized shear at cell blocks. We find that HEMB plays a relevant role in the deformation behavior of sub-micron localized strain gradients by promoting plastic relaxation and the enhanced storage of geometrically necessary dislocations within them. These effects mitigate the activation of damage mechanisms and enhance the strain-hardening capacity, contributing to the high HE resistance of the steel, comparable to that of high HE-resistant fcc alloys and steels.

Experimental investigation and fluid-structure interaction modelling of the casting of self-compacting concrete for CRTS III slab track in the curved segments

Ensuring the casting quality of self-compacting concrete (SCC) is crucial for the operational safety and durability of China railway track system (CRTS) III slab track. However, the mechanisms of key factors influencing flow behaviors of SCC and structural responses remain insufficiently understood, nor is the relationship between flow behaviors and structural responses during casting. In this study, fluid-structure interaction (FSI) models of SCC casting were developed and verified by full-scale physical tests, comprising slump flow, L-box flow and casting of SCC in an actual track at the field of Laixi-Rongcheng high-speed railway. Through in-depth analysis on the casting process of SCC in curved segments with a super elevation of 80 mm, the relationship between flow behaviors and structural responses was established. Furthermore, the influence mechanisms of key factors on flow behaviors and structural responses were investigated systematically. Results show that during gravity-fed SCC casting, its flow velocity diminishes, thus increasing the static pressure and the forces exerted on the slab by SCC. These vertical and lateral forces increase to 147.16 and 7.83 kN through three stages of development, acceleration and stabilization, resulting in commensurate structural responses. At the end of casting process, the central region of the slab exhibits maximum vertical deformation of 0.95 mm and tensile stress of 1.07 MPa. The tension rods at the side with lower elevation bear greater vertical and lateral forces than the ones at the side with higher elevation. The rise of funnel height from 1.05 to 1.35 m accelerates the casting process but increases the forces exerted by SCC by up to 26 % and augments the associated response of entire structures, whereas the funnel diameter shows little effect. Increasing yield stress of SCC from 9.3 to 49.3 Pa produces a more uniform flow morphology and thus higher static pressure and force by SCC in the middle region of the slab, impacting the structural responses by up to 15 %. The growth of plastic viscosity from 59 to 99 Pa⋅s significantly affects the volume rate and casting time by up to 66 % but has little effect on the flow morphology, fluid pressure and structural responses. In order to ensure high quality casting of SCC, five clamping beams are suggested with two beams positioned at either side of the slab and the other three evenly placed along the middle region of the slab.

Size-dependent deformation mechanisms in two-phase γ-TiAl/α2-Ti3Al alloys

Polysynthetic twinned (PST) TiAl single crystals, consisting of alternating layers of γ-TiAl and α2-Ti3Al, exhibit excellent mechanical properties. However, size-dependent deformation mechanisms have not yet been fully elucidated. In this work, we investigated the deformation process of two-phase γ-TiAl/α2-Ti3Al alloys with different layered sizes via uniaxial tensile loading using molecular dynamics simulations. The results show that with the decreasing phase boundary (PB) spacing λ or domain boundary (DB) spacing d, the excess free volume at the intersection of DB and PB decreases, leading to increased yield stress. We found that a higher interface density (smaller λ or d) can accommodate more dislocations, and the size-dependent ultimate strength follows an approximate Hall-Petch relation. These findings offer an essential understanding for the size-dependent PST TiAl single crystals with high strength.

Effects of microstructures on dynamic deformation and spallation damage of high-entropy alloy Al0.3CoCrFeNi under plate impact loading

Plate impact experiments are conducted on high-entropy alloy Al0.3CoCrFeNi with different microstructures to investigate the effects of grain size, precipitates and heterogeneous structure on dynamic response. Free surface velocity histories are obtained. All initial and postmortem samples are characterized with transmission electron microscopy and electron backscatter diffraction. Nanoscale L12 precipitates result in a considerable increase in dynamic yield stress. Spall strength is higher for the heterogeneous structure, the large grain size (200 μm) and small grain size (63 μm) with L12 precipitates by ∼4%, 19% and 10% than for the small grain size (77 μm) without precipitates. After shock compression, dislocation slip, stacking faults, the Lomer-Cottrell locks and nanotwins are found in the samples without the L12 precipitates. L12 precipitates increase the energy barrier and inhibit deformation twinning. Spall damage is ductile in Al0.3CoCrFeNi. For the homogeneous structures, intragranular voids are predominant. Voids are preferentially distributed in the fine-grain domains or at the fine-grain–coarse-grain domain boundaries of the heterogeneous structure.

Simulation of UV curing of photosensitive resins with phase change materials

Based on the mechanism of the resin polymerization reaction and free radical diffusion under UV irradiation, here, a mathematical model of the curing process was established for the mixture of photosensitive resin (PAA) and polyethylene glycol (PEG, as the phase change material), and the factor influencing the mechanical performance of the cured samples was analyzed. The yield stress (σs) of the pure resin sample can reach 50 MPa when the monolayer curing depth is 5 mm. σs decreases with the increase in the PEG content and monolayer curing depth. With increasing the monolayer exposure time, the yield stress increases and then decreases, and there is an optimum value. The material has the maximum stress at the monolayer exposure time of 13.5 s when the resin content is 50 %.

Feasibility study on using red mud as a viscosity-modifying agent for self-compacting concrete

Red mud (RM) is a hazardous waste material generated during the alkaline leaching of bauxite in the Bayer process. The feasibility of using RM as a viscosity-modifying agent (VMA) for self-compacting concrete (SCC) was proposed in this study. In addition, RM paste, cement paste, RM-blended paste, SCC that containing RM as VMA were prepared, and those fresh properties were investigated with emphasis. The results show that compared to cement paste, the RM paste exhibited excellent water retention. In the RM-blended cement paste with equivalent fluidity, an increase in RM dosage led to a notable decrease in bleeding rate, accompanied by an increase in yield stress and plastic viscosity. Similarly, in the SCC (containing RM as VMA) with equivalent slump-flow, the segregation rate decreased significantly (17.12 % of segregation for SCC that without RM, and 6.88 % of segregation for SCC that with 12 wt% RM), while yield stress and plastic viscosity increased with higher RM dosages, demonstrating a linear relationship. These findings highlight the feasibility of achieving SCC with high slump-flow and non-segregation by using RM as VMA, and the fresh properties of prepared SCC can be effectively controlled. Meanwhile, the findings of this study offer a novel approach to utilize RM and provide valuable guidance for the application of RM used as VMA.

Effect of physical aging on scratch behavior of polycarbonate

AbstractPhysical aging refers to relaxation of the polymer glassy state toward the amorphous state and this phenomenon affects their physical‐mechanical properties. This work investigates the effect of physical aging on polymer scratch behavior and visibility. It was shown that mechanical properties were significantly modified over the aging time, especially the yield stress, in turn affecting polymer scratch behavior. As a matter of fact, the critical load for the onset of scratch visibility was shown to increase with the aging, thus improving sensitivity of polymer to scratches. Such behavior was strictly related to the yield stress increase with the aging time. The usefulness of the present work is highlighted, and some future perspectives are discussed.

Crack-healing and rheological properties of high content fly ash/slag/silica fume green and sustainable cement-based materials incorporating crystalline admixture and calcium alginate biomass hydrogel

Cracking is an important factor affecting the durability of concrete. Rheological properties are important performance indicators of the workability of fresh concrete. Ion chelator (CA) is one kind of crystalline admixture, which can enhance crack-healing of concrete by promoting the formation of calcium carbonate in wet environment. Calcium alginate hydrogel (CaAlg) can maintain the humidity of cementitious matrix and promote the crystallization of inorganic minerals. Therefore, in this study, CaAlg bead was prepared to further improve the crack-healing of cementitious materials containing CA. Self-healing performance was evaluated by visual crack closure and water permeability test. Rheological property was measured by rotor rheometer. Healing mechanism of cementitious materials with CA and CaAlg was analyzed. Results showed that with the increase of CaAlg dosage, yield stress and plastic viscosity of paste decreased gradually. Meanwhile, fly ash and slag reduced viscosity of pastes, while silica fume increased the viscosity of pastes. CA could evidently improve the permeability and mechanical properties of mortar, especially for slag mortar. Self-healing performance test and characterization showed that CaAlg could further enhance crack-healing process of mortar with CA, especially for pure cement and slag mortar. Microscopic testing indicates that CaAlg could induce the formation of vaterite and calcite on its surface to further improve crack-healing efficiency.

Implication of electromagnetohydrodynamic flow of a non‐Newtonian hybrid nanofluid in a converging and diverging channel with velocity slip effects: A comparative investigation using numerical and ADM approaches

AbstractThis study delves into the intricate interplay of magnetic and electric fields (EMHD) on the flow characteristics of a non‐Newtonian bio‐hybrid nanofluid, consisting of Ag+Graphene/blood, within converging and diverging geometries. The investigation takes into account the effects of velocity slip at the walls, offering a comprehensive examination of this complex fluid system. A novel bio‐hybrid nanofluid model was introduced, featuring a unique combination of Ag+Graphene/blood nanoparticles. To address this multifaceted problem, the research employed mathematical modeling based on nonlinear partial differential equations (PDEs), encompassing continuity and momentum equations. These PDEs were then transformed into a system of nonlinear ordinary differential equations (ODEs) through similarity transformations. The study explored both numerical and analytical solutions, with a particular focus on the application of the Adomian decomposition method (ADM). To validate the findings, the study compared the analytical results with those obtained using the HAM‐based Mathematica package and the Runge–Kutta Fehlberg 4th–5th order (RKF‐45) method in specific scenarios. Active parameters, including nanofluid volume fraction, slip factors, and the influence of magnetic and electric fields, were systematically examined to unveil their impacts on velocity and skin friction within this multifaceted nanofluid system. It is found that the skin friction coefficient decreases with the Increasing both the nanoparticle volume fraction, Hartmann number and the angle in both channels. Results obtained also reveal an in the converging section, higher Casson parameters lead to increased yield stress but are offset by the higher shear rates, resulting in a higher velocity profile. In the diverging section, the fluid resists flow due to the reduced shear stress, leading to a decreased velocity profile.

Development and characterization of 3D printed fish gelatin and vegetable blends as nutritious meal for dysphagic patients

Dysphagia, increasingly prevalent among the aging population, poses significant nutritional challenges. 3D printing technology offers an innovative solution by creating visually appealing and appetizing dysphagia diets, offering new avenues for enhancing the dining experience of individuals with swallowing difficulties. This study explores the feasibility of using 3D printing to produce nutritionally dense meals for individuals with dysphagia. Techniques like SEM and FTIR were employed to examine ingredient interactions. Rheological properties and printing behavior were analyzed, revealing that xanthan gum (XG) as a thickener increases yield stress, elastic modulus (G′), and apparent viscosities of the ink compositions. Modest additions of XG (0.23% and 0.44%) improved the microstructure and mechanical properties, while higher concentrations (XG-0.77%) caused phase separation and reduced mechanical strength. The 3D printed products were evaluated according to IDDSI guidelines and sensory tests. XG-0.44% samples showed precise printing, excellent self-support, smooth textures, and favorable sensory evaluations, qualifying as level 4-pureed/extremely thick dysphagia diets. This study highlights the potential of 3D printing technology in creating nutritious and appealing meals for individuals with dysphagia.

Enhancing mechanical strength in thermosensitive Poly(tetrabutylphosphonium styrene sulfonate) (PTPSS) hydrogels through acrylamide (AAm) copolymerization

Thermosensitive hydrogels are lauded for their smart and tunable responsive behavior, presenting critical application potential in biomedicine and sensing technologies. Traditional thermo-responsive polymers, such as poly(N-isopropylacrylamide) (PNIPAM), typically manifest subpar electrical conductivity, which hinders their integration into biosensing applications. PTPSS hydrogel distinctively responses to temperature and repeatably endures large volume water flux under temperature changes, while catering a significant conductivity (7.438 mS cm−1). However, it possesses suboptimal mechanical strength. In this research, we enhanced the mechanical strength of PTPSS hydrogel by copolymerization of AAm, obtaining a 22-fold increase in compression yield stress and a yield strain reaching up to 75 % The copolymerized hydrogel showcases an elevated transmittance ranging from 86.3–97.1 % within the visible light wavelength spectrum, with the copolymerized hydrogel's conductivity being about 188 times that of PNIPAM copolymerized hydrogel at identical monomer proportions. Simultaneously, the hydrogel maintains explicit thermosensitivity even at a TPSS ratio as low as 60 wt% (grounded on the overall monomer sum). The introduction of AAm copolymerization awards PTPSS with robust mechanical properties, profound transparency, and striking thermosensitivity alongside high conductivity, endorsing enormous potential in the realm of intelligent sensing.

Thermal Properties of Athermal Granular Materials.

Dry granular materials consist of a vast ensemble of discrete solid particles interacting through complex frictional forces at the contact points. The particles are so large that these systems are believed to be completely athermal. Here, we arrest the dynamics of a flowing granular material in a steady-state-flow configuration, enabling an isolated examination of aging at the particle contacts without granular rearrangements. Our findings reveal that the evolution of interparticle forces within the arrested athermal granular network results in the spontaneous increase of the system's yield stress. This strengthening process is logarithmic in time with a rate that depends on the temperature. We demonstrate that the material's stress relaxation exhibits similar time- and temperature-dependent behavior, suggesting a shared origin for aging and stress relaxation in these systems governed by thermal molecular processes at the scale of the grain contacts.

Tailoring starch-lipid complexes for optimized flaxseed oil emulsion stability, antioxidation, and digestion kinetics

Whereas starch-lipid complex emulsifiers are anticipated to possess both an outstanding amphiphilicity and slowly-digesting characteristics, yet a more sustainable and cost-effective approach remains to be explored. Herein, we systematically prepared starch-lauric acid complexes (SLACs) through a solid encapsulation method under varying reaction temperatures (50–90 °C) and times (0.25–60 h). Complexing index analysis, differential scanning calorimetry, and X-ray diffraction analysis revealed an enhanced degree of complexation in SLACs with prolonged reaction time, evidenced by the inward migration of free lauric acid, as further confirmed by confocal laser scanning microscopy. In vitro digestibility, contact angle, and interfacial tension measurements demonstrated that SLACs exhibited high levels of slowly digestible starch, a low digestion rate, and excellent amphiphilicity, which was particularly notable in SLACs produced at 80 °C for 6 h. Emulsions stabilized by SLACs showed a smaller droplet size, a higher oil loading rate, an increased yield stress, and an improved storage stability compared to V-type starch. Oxidation experiments indicated that SLACs enhanced the oxidative stability of flaxseed oil, with elevated initial oxidation temperatures and reduced levels of oxidative products. In a simulated gastrointestinal digestion model, SLACs-stabilized structured emulsions exhibited sustained release and lower final contents of fatty acids, suggesting superior resistance to bile acids and digestive enzymes compared to PG2000, a chemically modified food starch (i.e. OSA-starch) refined from waxy maize. Our findings provide an effective strategy for enhancing lipid antioxidation and regulating intestinal digestion.

Rheological Properties of a Tailing Thickened in an Excavated Ground Channel

Objectives: The recent tailings dam disasters emphasize the need to adopt best management practices focusing on the stability of these structures. This study aims to present the use of a thickening channel as an alternative for ultrafine tailings dewatering in a small iron ore mine in the Quadrilátero Ferrífero. Theoretical Framework: The research is based on the study of rheology, focusing on viscosity and yield stress as key parameters to characterize the behavior of thickened slurry. Method: The study involved the production of thickened slurry in a channel, followed by rheological characterization through sampling at different points in the thickening process. Results and Discussion: The findings indicate that the thickened slurry behaves as a non-Newtonian fluid, with all samples analyzed showing pseudoplastic behavior. There was an increase in viscosity and yield stress with increasing solids content. The deposition of thickened slurry resulted in a 36.9% increase in the volume of the studied reservoirs. Research Implications: This approach offers advantages such as low capital cost, increased water reuse, and improved geotechnical stability of deposition sites, contributing to safer and more sustainable tailings management practices. Originality/Value: The study provides a practical alternative for tailings dewatering, enhancing the safety and sustainability of tailings disposal practices in small iron ore mines.

Effect of air exposure time on erodibility of intertidal mud flats

This study investigates the influence of air exposure time on the erodibility of intertidal mud flats, emphasizing the role of evaporation in altering sediment strength and cohesion. Through a comprehensive approach combining laboratory experiments, fieldwork, and numerical modelling, it explores the dynamic interactions between sediment properties and environmental conditions. The research reveals that drying significantly reduces sediment erodibility, with pronounced effects observed during the initial hours of air exposure. Laboratory tests demonstrate a direct correlation between drying time and increased yield stress for both artificial and field-derived mud samples. Field observations further support these results, showing spatial and temporal variations in water content and shear strength across various locations on a tidal flat. The study emphasizes the critical impact of mud content on water retention and the subsequent effect on sediment stability. The incorporation of drying time into erosion formulations within a numerical model highlights the importance of considering evaporation processes in predicting the morphological evolution of tidal flats. This research contributes to a better understanding of sediment transport dynamics in intertidal zones, offering insights into the mechanisms driving the growth and stability of mud flats. It underscores the necessity of integrating evaporation effects into cohesive sediment transport models to enhance the accuracy of predictions concerning the erosion and accretion of intertidal environments.

Recycling of coal gasification fine ash as a cement cleaning substitute: Performance, microstructure, and sustainability assessment of blended cement

Coal gasification fine ash (CGFA) is a large amount of solid waste produced by the coal chemical industry and has a broad prospect of recycling in building materials. This paper aims to investigate the effect of CGFA on the flowability, rheological behavior, hydration properties, and sustainability of blended cement. CGFA contains mineral components similar to fly ash (FA) and has morphological and physical filling effects that promote the flow of cement pastes. However, water absorption by the residual carbon component in CGFA resulted in severe deterioration of the rheological properties and flowability of the paste. As levels of CGFA replacement increase, the blended cement shows a pattern of decreasing early hydration rate, reducing flowability, and a significant increase in dynamic yield stress. The characteristic hydration reaction peak indicating the transformation of ettringite (AFt) to kuzelite (AFm) was little observed in the mixed samples of CGFA and cement. This phenomenon is attributed to the low content of reactive minerals (mainly aluminates) in CGFA. The residual carbon in CGFA almost did not participate in the hydration reaction of the blended cement system. It also limited the accumulation of hydration products, significantly reducing the strength of the mortar. Considering multiple factors such as cost, carbon emission, embodied energy, and cement consumption, the combined sustainability assessment of the (15%CGFA + 15%FA) combination replacing cement is 14.5% higher than that of pure cement mortar. This study can provide theoretical and technical support for the sustainable development of the coal chemical industry and the construction industry.