Limited by mining technology,mineral exploitation can produce large amounts of tailings.Heavy summer rainfall or seasonal freeze-thaw can lead to physical and chemical modification of tailing material in mountainous a...Limited by mining technology,mineral exploitation can produce large amounts of tailings.Heavy summer rainfall or seasonal freeze-thaw can lead to physical and chemical modification of tailing material in mountainous areas,resulting in fluidized tailings flow and severe disaster losses.Therefore,aiming at the problem of tailings fluidization catastrophe,this paper tried to reveal the rheological mechanism of tailings fluidization transformation by combining rheological tests and theoretical analysis.The results show that the yield stress increases with decreasing temperature,and when the density of debris flow(ρ)is more than 1.9 g/cm~3,this behavior becomes more pronounced as the density increases.The storage modulus decreases by at least two orders of magnitude at the solid-fluid transition under amplitude test sweep.Storage and loss modulus in the linear viscoelastic range and yield stress have an exponential growth relationship with sediment concentration.In addition,a stress constitutive relation and a new exponential law describing the evolution of yield stress required for solid-liquid transformation were proposed,and the relationship is further strengthened through a comprehensive analysis of existing results,which expands the evaluation application of the rheological characteristics of tailings flow.This paper provides a new insight into the rheological properties of tailing and how they occur through solid-liquid transition under different environments,which is beneficial to geological hazard prevention and the ecological remediation of the mining area.展开更多
In order to evaluate the feasibility of steel slag powder as filler,the coating properties of steel slag and limestone aggregate were compared by water boiling test,the micro morphology difierences between steel slag ...In order to evaluate the feasibility of steel slag powder as filler,the coating properties of steel slag and limestone aggregate were compared by water boiling test,the micro morphology difierences between steel slag powder and mineral powder(limestone powder)were compared by scanning electron microscope(SEM),and the high-temperature rheological properties of asphalt mortar with difierent ratio of filler quality to asphalt quality(F/A)and difierent substitution rates of mineral powder(S/F)were studied by dynamic shear rheological test.The results show that the surface microstructure of steel slag powder is more abundant than that of mineral powder,and the adhesion of steel slag to asphalt is better than that of limestone.At the same temperature,the lower the ratio of S/F is,the greater the rutting factor and complex modulus will be.In addition,the complex modulus and rutting factor of the asphalt mortar increase with the increase of F/A,and the filler type and F/A have a negligible efiect on the phase angle.展开更多
Rod milling sand(RMS)—a coarse sand aggregate—was recycled for cemented paste backfill(CPB)for the underground mined area at the Jinchuan nickel deposit,named rod milling sand-based cemented paste backfill(RCPB).The...Rod milling sand(RMS)—a coarse sand aggregate—was recycled for cemented paste backfill(CPB)for the underground mined area at the Jinchuan nickel deposit,named rod milling sand-based cemented paste backfill(RCPB).The adverse effects of coarse particles on the transportation of CPB slurry through pipelines to underground stopes resulting in weakening of the stability of the backfill system are well known.Therefore,sulfonated naphthalene formaldehyde(SNF)condensate was used for the performance improvement of RCPB.The synergistic effect of solid content(SC),lime-to-sand ratio,and SNF dosage on the rheological and physicomechanical properties,including slump,yield stress,bleeding rate,uniaxial compressive strength(UCS),as well as mechanism analysis of RCPB,have been explored.The results indicate that the effect of SNF on RCPB performance is related to the SNF dosage,lime-to-sand ratio,and SC.The slump of fresh RCPB with 0.1wt%-0.5wt%SNF increased by 2.6%-26.2%,whereas the yield stress reduced by 4.1%-50.3%,indicating better workability and improved cohesiveness of the mix.The bleeding rate of fresh RCPB decreased first and then rose with the increase of SNF dosage,and the peak decrease was 67.67%.UCS of RCPB first increased and then decreased with the increase of SNF dosage.At the optimal SNF addition ratio of 0.3wt%,the UCS of RCPB curing for 7,14 and,28 d ages increased by 31.5%,28.4%,and 29.5%,respectively.The beneficial effects of SNF in enhancing the early UCS of RCPB have been corroborated.However,the later UCS increases at a slower rate.The research findings may guide the design and preparation of RCPB with adequate performance for practical applications.展开更多
Polypropylene(PP)grease holds great potential for special industrial applications.In this study,synthetic conditions,thickener content,and the ratio of two different molecular weight PPs were investigated systematical...Polypropylene(PP)grease holds great potential for special industrial applications.In this study,synthetic conditions,thickener content,and the ratio of two different molecular weight PPs were investigated systematically using a rheometer,scanning electron microscope,X-ray diffraction,Fourier transform infrared spectrometer,oscillating tribometer,and 3D surface profiler measurements.The results showed that suitable synthetic conditions are two quenching cycles,and the synthetic temperature and time is 240℃for 12 h.The rheological analysis showed that thickener content and different proportions of the two PP molecular weights have a significant influence on the rheological properties of PP grease.High molecular weight PP(H-PP)has a stronger thickening ability than low molecular weight PP(L-PP).The higher the amount of H-PP in the fixed thickener content or the higher the thickener content with a specific proportion,the higher the viscoelasticity of PP grease.The tribological performance is related to the rheological properties.The proportion of two different molecular weight PPs in the thickener content should be appropriate;excessive H-PP content leads to lubrication failure.展开更多
The filler-bitumen interaction mechanism is one of the most essential phases for comprehending the asphalt mixture's performance.However,despite numerous studies,in-depth knowledge of filler-bitumen reciprocity at...The filler-bitumen interaction mechanism is one of the most essential phases for comprehending the asphalt mixture's performance.However,despite numerous studies,in-depth knowledge of filler-bitumen reciprocity at a microscale level is yet to be ascertained.The goal of this research is to gain a better understanding of the fillerbitumen microscale interaction in terms of the synergy and coaction between the physicochemical and rheological performance of mastics due to filler inclusions.The rheological properties of two sustainable mastics,dolomite powder(DP)and lime kiln dust(LKD),together with a neat PEN 60/70 binder,were analysed based on a temperature sweep at elevated temperature conditions.Meanwhile,frequency sweep and multiple stress creep recovery(MSCR)tests were also conducted at pavement serviceability temperature using the dynamic shear rheometer(DSR).Physicochemical tests using a scanning electron microscope(SEM)and energy dispersive X-rays(EDX)were conducted to analyse the impact of parameters such as particle shape,grain size,texture,and chemical compositions.The DSR test results showcased how the incorporation of fillers in asphalt binder considerably improved the performance of the binder in terms of rutting and fatigue.Likewise,its strain and nonrecoverable compliance parameters were substantially reduced at higher filler and binder concentrations.Physical filler attributes of low rigden voids(R.V),high fineness modulus(FM),and high specific surface area(SSA)led to greater interfacial stiffness and elasticity in LKD mastics compared to DP mastics at different loading frequencies and temperature levels.The SEM/EDX results also indicated that the elemental calcium and carbon composition of each filler component,together with its grain morphology,strongly influenced its rheological performance.展开更多
With many major projects under construction,more and more attention is paid to rheological mechanical properties of rock mass,and extensive researches are carried out for rheological constitutive modeling of rock mass...With many major projects under construction,more and more attention is paid to rheological mechanical properties of rock mass,and extensive researches are carried out for rheological constitutive modeling of rock mass.Based on viscoplastic theory,a new rheological constitutive model is proposed.The rationality and validity of proposed model are verified through the creep test data.The results show that the rheological constitutive model based on viscoplastic theory is able to simulate the typical creep curves of rock mass and the identified parameters are reasonable.Therefore,the rheological constitutive model could be used to describe the rheological mechanical behaviour of rock mass.展开更多
On a self-made super-high shear strain rate rheometer, the rheological characteristics and apparent viscosity curves of a high-speed bearing grease were obtained under different working conditions. A new grease rheolo...On a self-made super-high shear strain rate rheometer, the rheological characteristics and apparent viscosity curves of a high-speed bearing grease were obtained under different working conditions. A new grease rheological model suited to a shear strain rate range of 0—3.5×10~6s^(-1) was presented. The results showed that the shear stress increased linearly at first and then increased nonlinearly with the increase in shear strain rate up to 1.5×10~6s^(-1), and finally the shear stress decreased slightly with the successive increase in shear strain rate. The shear stress increased with a decreasing rolling speed and an increasing contact pressure. The apparent viscosity decreased rapidly with the increase of shear strain rate at beginning and could approach the viscosity of the base oil if the shear strain rate surpassed 1.5×10~6s^(-1). The fits between the test data and the predicted values by the new model were fairly good.展开更多
The Haihe cohesive sediment, which is typical in China, is studied systematically for its basic physical and incipientmotion properties. Following the requirements of dredging works in the Haihe Estuary, cohesive sedi...The Haihe cohesive sediment, which is typical in China, is studied systematically for its basic physical and incipientmotion properties. Following the requirements of dredging works in the Haihe Estuary, cohesive sediment samples weretaken from three locations. Laboratory experiments were conducted to determine the rheological properties of these sam-ples and to examine the incipient motion of the cohesive sediment. It is found that the cohesive sediment has an obviousyield stress τb, which increases with the mud density in a manner of an exponential function, and so does the viscosityparameter η. The cohesive sediment behaves like a Bingham fluid when its density is below 1.38 ～ 1.40 g/cm3, andwhen denser than these values, it may become a power-law fluid. The incipient motion experiment also revealed that theincipient velocity of the cohesive sediment increases with the density in an exponential manner. Therefore, the incipientmotion is primarily related to the density, which is different from the case for non-cohesive sediment in which the incipi-ent motion is correlated with the diameter of sand particles instead. The incipient motion occurs in two different ways de-pending on the concentration of mud in the bottom. For sufficiently fine particles and a concentration lower than1.20 g/cm3, the cohesive sediment appears as fluidized mud, and the incipient motion is in the form of instability of aninternal wave. For a higher concentration, the cohesive sediment appears as general quasi-solid-mud, and the incipientmotion can be described by a series of extended Shields curves each with a different porosity for newly deposited alluvial mud.展开更多
The rheological behavior of a soft interlayer is critical to understanding slope stability, which is closely related to the water content of the soft interlayer. This study used the soft interlayer of the Permian Maok...The rheological behavior of a soft interlayer is critical to understanding slope stability, which is closely related to the water content of the soft interlayer. This study used the soft interlayer of the Permian Maokou Formation in Southwest China as an example to perform ring shear creep tests with different water content amounts. The effect of water content on the creep properties of the soft interlayer was analyzed, and a new shear rheological model was established. This research produced several findings. First, the ring shear creep deformation of the soft interlayer samples varied with the water content and the maximum instantaneous shear strain increment occurred near the saturated water content. As the water content increased, the cumulative creep increment of the samples increased. Second, the water content significantly affected the long-term strength of the soft interlayer, which decreased with the increase of water content, exhibiting a negative linear correlation. Third, a constitutive equation for the new rheological model was derived, and through fitting of the ring shear creep test data, the validity and applicability of the constitutive equation were proven. This study has developed an important foundation for studying the long-term deformation characteristics of a soft interlayer with varying water content.展开更多
It is an effective way to use coal slime as fuel for circulating fluidized bed boilers, which will not only solve its pollution to the environment, but also turn waste to treasure. In order to provide basic technical ...It is an effective way to use coal slime as fuel for circulating fluidized bed boilers, which will not only solve its pollution to the environment, but also turn waste to treasure. In order to provide basic technical information for transportation of coal slime from the coal preparation plant to the boiler, this paper experimentally studied the rheological behaviors of coal slime produced by filter-pressing. By using a rotational viscometer, the influences of water content, temperature, and shear time on the rheological behaviors of coal slime were investigated. Experimental results show that the coal slime will behave like Bingham plastics with low water content and like Bingham pseudo-plastics with 37.5% water content,while like pseudo-plastics with 40% water content. This indicates that the water content of coal slime must be controlled in consideration of both transportation resistance and combustion efficiency. Study results also show that, the apparent viscosity of coal slime at 5℃ is about 1.5–1.7 times of that at 40℃ for water contents 32%–37.5%, while the influence of temperature can be neglected when the water content is 40%. With increasing of water content, the influences of shear time on the apparent viscosity of coal slime becomes less. When the water content is more than 30%, the effect of shear time is negligible. It indicates that water content has the most important influence on the rheological behaviors of coal slime. There must be an optimal water content in considering conveying resistance and combustion efficiency. The environmental temperature must also be considered in coal slime transportation.展开更多
The traction capacity of the mining machine is greatly in?uenced by the traction rheological properties of the deep-sea sediments. The best simulative soil was prepared for substituting the deep-sea sediment based on ...The traction capacity of the mining machine is greatly in?uenced by the traction rheological properties of the deep-sea sediments. The best simulative soil was prepared for substituting the deep-sea sediment based on the deep-sea sediment collected from the Paci?c C-C mining area. Traction rheological properties of the simulative soil were studied by a home-made test apparatus. In order to accurately describe the traction rheological properties and determine traction rheological parameters, the Newtonian dashpot in Maxwell body of Burgers model was replaced by a self-similarity spring-dashpot fractance and a new rheological constitutive model was deduced by fractional derivative theory. The results show the simulative soil has obvious non-attenuate rheological properties. The transient creep and stable creep rate increase with the traction, but they decrease with ground pressure. The fractional derivative Burgers model are better in describing non-attenuate rheological properties of the simulative soil than the classical Burgers model. For the new traction rheological constitutive equation of the simulative soil, the traction rheological parameters can be obtained by ?tting the tested traction creep data with the traction creep constitutive equation. The ground contact length of track and walking velocity of the mining machine predicted by the traction rheological constitutive equation can be used to take full advantages of the maximum traction provided by the soil and safely improve mining effciency.展开更多
The rheological properties of two kinds of oil-based drilling fluids with typically composition were studied at pressures up to 138 MPa and temperatures up to 204 ℃ using the RheoChan 7400 Rheometer.The experimental ...The rheological properties of two kinds of oil-based drilling fluids with typically composition were studied at pressures up to 138 MPa and temperatures up to 204 ℃ using the RheoChan 7400 Rheometer.The experimental results show that the apparent viscosity,plastic viscosity and yield point decrease with the increase of temperature,and increase with the increase of pressure.The effect of pressure on the apparent viscosity,plastic viscosity and yield point is considerable at ambient temperature.However,this effect gradually reduces with the increase of temperature.The major factor influencing the rheological properties of oil-based drilling fluids is temperature instead of pressure in the deep sections of oil wells.On the basis of numerous experiments,the model for predict the apparent viscosity,plastic viscosity and yield point of oil-based drilling fluids at high temperature and pressure was established using the method of regressive analysis.It is confirmed that the calculated data are in good agreement with the measured data,and the correlation coefficients are more than 0.98.The model is convenient for use and suitable for the application in drilling operations.展开更多
As for ceramic stereolithography technique,the preparation of suitable resin-based ceramic slurry is of primary importance.In this study,the effects of powder characteristics such as specific surface area,particle siz...As for ceramic stereolithography technique,the preparation of suitable resin-based ceramic slurry is of primary importance.In this study,the effects of powder characteristics such as specific surface area,particle size and distribution,particle morphology on the rheological behavior of zirconia resin-based suspensions were investigated intensively.Results show that the specific surface area of the powder is the most important factor affecting slurry viscosity.Choosing low specific surface area and quasi-spherical shaped powder is more likely to obtain low viscosity slurries.In addition,the influence of solid loading on the flow behavior were also studied using Krieger-Dougherty model.Zirconia samples with the relative density of(97.83±0.33)%were obtained after sintering at 1550℃.No obvious abnormal grain growth in the microstructure of the sintered body is observed.Results indicate that after the optimization of the processing parameters with the help of rheology characterization,complex-shaped high-quality zirconia parts can be obtained using the stereolithography technique.展开更多
A series of polycarboxylate-based superplasticizers(PCs) with different structures were synthesized and the effects of chemical structure on zeta potential and rheological property of cement paste were studied. Residu...A series of polycarboxylate-based superplasticizers(PCs) with different structures were synthesized and the effects of chemical structure on zeta potential and rheological property of cement paste were studied. Residual monomers in each sample of PCs were quantitatively determined. The property of the polymers in cement was tested by micro-electrophoresis apparatus and R/S rheometer. Results showed that the zeta potential and its rheological properties are related with the side-chain length and density of PCs. The PCs having shorter side chain and lower side chain density exhibit higher anionic charge density, thus resulting in higher zeta potential. The effect of side chain density on zeta potential is more notable compared with that of side-chain length, and thus affecting the initial shear yield stress and apparent viscosity of the cement paste. In addition, although increasing the side chain length will result in reduction of the anionic charge density, the steric hindrance effect is obvious, which can effectively improve the dispersion of the cement particles, and reduce the viscosity and shear yield stress of slurry.展开更多
The influence of aging on the evolution of structural,morphological and rheological properties of neat asphalt was investigated by Fourier transform infrared(FTIR),atomic force microscopy(AFM) and dynamic shear rheome...The influence of aging on the evolution of structural,morphological and rheological properties of neat asphalt was investigated by Fourier transform infrared(FTIR),atomic force microscopy(AFM) and dynamic shear rheometer(DSR),respectively.Asphalt was suffered under 20 W/m2 of UV radiant intensity and under the condition of aging time(0,48,96 and 144 h) with film thickness of 100 μm and film thickness of 50,100,200 and 500 μm after aging for 120 h,respectively,at certain UV radiant intensity 20 W/m2.Rheological results tested by DSR exhibit higher the complex shear(stiffness) modulus(G*) and lower phase angle(δ),compared to the virgin at the same test condition.The compositions analysis of asphalt before and after aging show an increase of carbonyl and sulfoxides,while a decrease of aromatic functional groups.With the increase of the component of asphaltene,obvious agglomerates of asphalten appear in neat asphalt surfaces after aging.展开更多
The microstructure and rheological behavior of semi-solid Mg2Si/AM60 magnesium matrix composite at steady state were investigated.The results show that the primary α-Mg phases are knapped by mechanical stirring and t...The microstructure and rheological behavior of semi-solid Mg2Si/AM60 magnesium matrix composite at steady state were investigated.The results show that the primary α-Mg phases are knapped by mechanical stirring and the Chinese script type reinforced Mg2Si phases exist in liquid phase and grain boundary.The analysis of apparent viscosity indicates that the apparent viscosity of semi-solid Mg2Si/AM60 magnesium matrix composite at steady state increases with increasing the volume fraction of Mg2Si and solid fraction of primary α-Mg,but decreases with increasing the shearing rate and shearing time,and the apparent viscosity keeps stable when shearing time reaches 300 s.展开更多
It is known that some internal defects exist in metal materials. Preliminary attempt to relate dislocation evolution with metal rheological forming was done. By the attempt, it is learned that the evolution of disloca...It is known that some internal defects exist in metal materials. Preliminary attempt to relate dislocation evolution with metal rheological forming was done. By the attempt, it is learned that the evolution of dislocation density ρ(x, y, t) is essentially the change of n independent internal variables q α(α=1, 2, …, n) with material. The preliminary research in theory and experiments showed that dislocations piling up could be avoided. One can improve the internal microstructure and mechanical properties of products by rheological forming method.展开更多
Considering the rheological properties of rock and soil body,and exploiting the merit of strength reduction technique,a theory of couple analysis is brought forward on the basis of strength reduction theory and rheolo...Considering the rheological properties of rock and soil body,and exploiting the merit of strength reduction technique,a theory of couple analysis is brought forward on the basis of strength reduction theory and rheological properties.Then,the concept and the calculation procedure of the safety factor are established at different time.Making use of finite element software ANSYS,the most dangerous sliding surface of the slope can be obtained through the strength reduction technique.According to the dynamic safety factor based on rheological mechanism,a good forecasting could be presented to prevent and cure the landslide.The result shows that the couple analysis reveals the process of the slope failure with the time and the important influence on the long-term stability due to the rheological parameters.展开更多
基金supported by The National Nat ural Science Foundation of China(No.42207184)Nature Science Basic Research Plan in Shaanxi Provi nce of China(No.2022JQ-253)。
文摘Limited by mining technology,mineral exploitation can produce large amounts of tailings.Heavy summer rainfall or seasonal freeze-thaw can lead to physical and chemical modification of tailing material in mountainous areas,resulting in fluidized tailings flow and severe disaster losses.Therefore,aiming at the problem of tailings fluidization catastrophe,this paper tried to reveal the rheological mechanism of tailings fluidization transformation by combining rheological tests and theoretical analysis.The results show that the yield stress increases with decreasing temperature,and when the density of debris flow(ρ)is more than 1.9 g/cm~3,this behavior becomes more pronounced as the density increases.The storage modulus decreases by at least two orders of magnitude at the solid-fluid transition under amplitude test sweep.Storage and loss modulus in the linear viscoelastic range and yield stress have an exponential growth relationship with sediment concentration.In addition,a stress constitutive relation and a new exponential law describing the evolution of yield stress required for solid-liquid transformation were proposed,and the relationship is further strengthened through a comprehensive analysis of existing results,which expands the evaluation application of the rheological characteristics of tailings flow.This paper provides a new insight into the rheological properties of tailing and how they occur through solid-liquid transition under different environments,which is beneficial to geological hazard prevention and the ecological remediation of the mining area.
基金Funded by National Natural Science Foundation of China(No.52278446)。
文摘In order to evaluate the feasibility of steel slag powder as filler,the coating properties of steel slag and limestone aggregate were compared by water boiling test,the micro morphology difierences between steel slag powder and mineral powder(limestone powder)were compared by scanning electron microscope(SEM),and the high-temperature rheological properties of asphalt mortar with difierent ratio of filler quality to asphalt quality(F/A)and difierent substitution rates of mineral powder(S/F)were studied by dynamic shear rheological test.The results show that the surface microstructure of steel slag powder is more abundant than that of mineral powder,and the adhesion of steel slag to asphalt is better than that of limestone.At the same temperature,the lower the ratio of S/F is,the greater the rutting factor and complex modulus will be.In addition,the complex modulus and rutting factor of the asphalt mortar increase with the increase of F/A,and the filler type and F/A have a negligible efiect on the phase angle.
基金financially supported by the National Natural Science Foundation of China(Nos.52104156,52074351,52004330)the Science and Technology Innovation Program of Hunan Province,China(No.2021RC3125)the Natural Science Foundation of Hunan Province,China(No.2022JJ30714)。
文摘Rod milling sand(RMS)—a coarse sand aggregate—was recycled for cemented paste backfill(CPB)for the underground mined area at the Jinchuan nickel deposit,named rod milling sand-based cemented paste backfill(RCPB).The adverse effects of coarse particles on the transportation of CPB slurry through pipelines to underground stopes resulting in weakening of the stability of the backfill system are well known.Therefore,sulfonated naphthalene formaldehyde(SNF)condensate was used for the performance improvement of RCPB.The synergistic effect of solid content(SC),lime-to-sand ratio,and SNF dosage on the rheological and physicomechanical properties,including slump,yield stress,bleeding rate,uniaxial compressive strength(UCS),as well as mechanism analysis of RCPB,have been explored.The results indicate that the effect of SNF on RCPB performance is related to the SNF dosage,lime-to-sand ratio,and SC.The slump of fresh RCPB with 0.1wt%-0.5wt%SNF increased by 2.6%-26.2%,whereas the yield stress reduced by 4.1%-50.3%,indicating better workability and improved cohesiveness of the mix.The bleeding rate of fresh RCPB decreased first and then rose with the increase of SNF dosage,and the peak decrease was 67.67%.UCS of RCPB first increased and then decreased with the increase of SNF dosage.At the optimal SNF addition ratio of 0.3wt%,the UCS of RCPB curing for 7,14 and,28 d ages increased by 31.5%,28.4%,and 29.5%,respectively.The beneficial effects of SNF in enhancing the early UCS of RCPB have been corroborated.However,the later UCS increases at a slower rate.The research findings may guide the design and preparation of RCPB with adequate performance for practical applications.
基金the financial support provided by the National Natural Science Foundation of China Project (U21A20315,21978186)the Fund for Shanxi“1331 Project” (1331)。
文摘Polypropylene(PP)grease holds great potential for special industrial applications.In this study,synthetic conditions,thickener content,and the ratio of two different molecular weight PPs were investigated systematically using a rheometer,scanning electron microscope,X-ray diffraction,Fourier transform infrared spectrometer,oscillating tribometer,and 3D surface profiler measurements.The results showed that suitable synthetic conditions are two quenching cycles,and the synthetic temperature and time is 240℃for 12 h.The rheological analysis showed that thickener content and different proportions of the two PP molecular weights have a significant influence on the rheological properties of PP grease.High molecular weight PP(H-PP)has a stronger thickening ability than low molecular weight PP(L-PP).The higher the amount of H-PP in the fixed thickener content or the higher the thickener content with a specific proportion,the higher the viscoelasticity of PP grease.The tribological performance is related to the rheological properties.The proportion of two different molecular weight PPs in the thickener content should be appropriate;excessive H-PP content leads to lubrication failure.
文摘The filler-bitumen interaction mechanism is one of the most essential phases for comprehending the asphalt mixture's performance.However,despite numerous studies,in-depth knowledge of filler-bitumen reciprocity at a microscale level is yet to be ascertained.The goal of this research is to gain a better understanding of the fillerbitumen microscale interaction in terms of the synergy and coaction between the physicochemical and rheological performance of mastics due to filler inclusions.The rheological properties of two sustainable mastics,dolomite powder(DP)and lime kiln dust(LKD),together with a neat PEN 60/70 binder,were analysed based on a temperature sweep at elevated temperature conditions.Meanwhile,frequency sweep and multiple stress creep recovery(MSCR)tests were also conducted at pavement serviceability temperature using the dynamic shear rheometer(DSR).Physicochemical tests using a scanning electron microscope(SEM)and energy dispersive X-rays(EDX)were conducted to analyse the impact of parameters such as particle shape,grain size,texture,and chemical compositions.The DSR test results showcased how the incorporation of fillers in asphalt binder considerably improved the performance of the binder in terms of rutting and fatigue.Likewise,its strain and nonrecoverable compliance parameters were substantially reduced at higher filler and binder concentrations.Physical filler attributes of low rigden voids(R.V),high fineness modulus(FM),and high specific surface area(SSA)led to greater interfacial stiffness and elasticity in LKD mastics compared to DP mastics at different loading frequencies and temperature levels.The SEM/EDX results also indicated that the elemental calcium and carbon composition of each filler component,together with its grain morphology,strongly influenced its rheological performance.
基金Sponsored by the Natural Science Foundation of Fujian Province(Grant No.2008J0171)
文摘With many major projects under construction,more and more attention is paid to rheological mechanical properties of rock mass,and extensive researches are carried out for rheological constitutive modeling of rock mass.Based on viscoplastic theory,a new rheological constitutive model is proposed.The rationality and validity of proposed model are verified through the creep test data.The results show that the rheological constitutive model based on viscoplastic theory is able to simulate the typical creep curves of rock mass and the identified parameters are reasonable.Therefore,the rheological constitutive model could be used to describe the rheological mechanical behaviour of rock mass.
基金financially supported by the National Natural Science Foundation of China (No. 51475143)the Tianjin Natural Science Foundation (No.16JCYBJC18900)
文摘On a self-made super-high shear strain rate rheometer, the rheological characteristics and apparent viscosity curves of a high-speed bearing grease were obtained under different working conditions. A new grease rheological model suited to a shear strain rate range of 0—3.5×10~6s^(-1) was presented. The results showed that the shear stress increased linearly at first and then increased nonlinearly with the increase in shear strain rate up to 1.5×10~6s^(-1), and finally the shear stress decreased slightly with the successive increase in shear strain rate. The shear stress increased with a decreasing rolling speed and an increasing contact pressure. The apparent viscosity decreased rapidly with the increase of shear strain rate at beginning and could approach the viscosity of the base oil if the shear strain rate surpassed 1.5×10~6s^(-1). The fits between the test data and the predicted values by the new model were fairly good.
基金This research was supported by the National Natural Science Foundation of China(NSFC&RGC)under contract Nos.59809006 and 50279030and also supported by the Science Foundation of Tianjin Municipality under contract No.983702011,RGC of the Hong Kong Specia
文摘The Haihe cohesive sediment, which is typical in China, is studied systematically for its basic physical and incipientmotion properties. Following the requirements of dredging works in the Haihe Estuary, cohesive sediment samples weretaken from three locations. Laboratory experiments were conducted to determine the rheological properties of these sam-ples and to examine the incipient motion of the cohesive sediment. It is found that the cohesive sediment has an obviousyield stress τb, which increases with the mud density in a manner of an exponential function, and so does the viscosityparameter η. The cohesive sediment behaves like a Bingham fluid when its density is below 1.38 ～ 1.40 g/cm3, andwhen denser than these values, it may become a power-law fluid. The incipient motion experiment also revealed that theincipient velocity of the cohesive sediment increases with the density in an exponential manner. Therefore, the incipientmotion is primarily related to the density, which is different from the case for non-cohesive sediment in which the incipi-ent motion is correlated with the diameter of sand particles instead. The incipient motion occurs in two different ways de-pending on the concentration of mud in the bottom. For sufficiently fine particles and a concentration lower than1.20 g/cm3, the cohesive sediment appears as fluidized mud, and the incipient motion is in the form of instability of aninternal wave. For a higher concentration, the cohesive sediment appears as general quasi-solid-mud, and the incipientmotion can be described by a series of extended Shields curves each with a different porosity for newly deposited alluvial mud.
基金supported by the National Natural Science Foundation of China(Grant No.41521001)the Natural Science Foundation of Hubei Province(Grant No.2018CFB385)
文摘The rheological behavior of a soft interlayer is critical to understanding slope stability, which is closely related to the water content of the soft interlayer. This study used the soft interlayer of the Permian Maokou Formation in Southwest China as an example to perform ring shear creep tests with different water content amounts. The effect of water content on the creep properties of the soft interlayer was analyzed, and a new shear rheological model was established. This research produced several findings. First, the ring shear creep deformation of the soft interlayer samples varied with the water content and the maximum instantaneous shear strain increment occurred near the saturated water content. As the water content increased, the cumulative creep increment of the samples increased. Second, the water content significantly affected the long-term strength of the soft interlayer, which decreased with the increase of water content, exhibiting a negative linear correlation. Third, a constitutive equation for the new rheological model was derived, and through fitting of the ring shear creep test data, the validity and applicability of the constitutive equation were proven. This study has developed an important foundation for studying the long-term deformation characteristics of a soft interlayer with varying water content.
基金the National Key Technology R&D Program for the 12th Five-Year Plan of China (No. 2014BAB01B03)the National Natural Science Foundation of China (No. 51304192)
文摘It is an effective way to use coal slime as fuel for circulating fluidized bed boilers, which will not only solve its pollution to the environment, but also turn waste to treasure. In order to provide basic technical information for transportation of coal slime from the coal preparation plant to the boiler, this paper experimentally studied the rheological behaviors of coal slime produced by filter-pressing. By using a rotational viscometer, the influences of water content, temperature, and shear time on the rheological behaviors of coal slime were investigated. Experimental results show that the coal slime will behave like Bingham plastics with low water content and like Bingham pseudo-plastics with 37.5% water content,while like pseudo-plastics with 40% water content. This indicates that the water content of coal slime must be controlled in consideration of both transportation resistance and combustion efficiency. Study results also show that, the apparent viscosity of coal slime at 5℃ is about 1.5–1.7 times of that at 40℃ for water contents 32%–37.5%, while the influence of temperature can be neglected when the water content is 40%. With increasing of water content, the influences of shear time on the apparent viscosity of coal slime becomes less. When the water content is more than 30%, the effect of shear time is negligible. It indicates that water content has the most important influence on the rheological behaviors of coal slime. There must be an optimal water content in considering conveying resistance and combustion efficiency. The environmental temperature must also be considered in coal slime transportation.
基金Supported by the National Natural Science Foundation of China(Nos.11502226,51274251,51434002)the Key Research and Development Plan of Hunan Province(No.2017WK2032)+1 种基金the Research Foundation of Education Bureau of Hunan Province,China(Nos.15C1317,16C1542)the Hunan Provincial Innovation Foundation For Postgraduate(No.CX2017B342)
文摘The traction capacity of the mining machine is greatly in?uenced by the traction rheological properties of the deep-sea sediments. The best simulative soil was prepared for substituting the deep-sea sediment based on the deep-sea sediment collected from the Paci?c C-C mining area. Traction rheological properties of the simulative soil were studied by a home-made test apparatus. In order to accurately describe the traction rheological properties and determine traction rheological parameters, the Newtonian dashpot in Maxwell body of Burgers model was replaced by a self-similarity spring-dashpot fractance and a new rheological constitutive model was deduced by fractional derivative theory. The results show the simulative soil has obvious non-attenuate rheological properties. The transient creep and stable creep rate increase with the traction, but they decrease with ground pressure. The fractional derivative Burgers model are better in describing non-attenuate rheological properties of the simulative soil than the classical Burgers model. For the new traction rheological constitutive equation of the simulative soil, the traction rheological parameters can be obtained by ?tting the tested traction creep data with the traction creep constitutive equation. The ground contact length of track and walking velocity of the mining machine predicted by the traction rheological constitutive equation can be used to take full advantages of the maximum traction provided by the soil and safely improve mining effciency.
基金Project(50574061) supported by the National Natural Science Foundation of ChinaProject(IRT0411) supported by the Changjiang Scholars and Innovative Research Team,Ministry of Education
文摘The rheological properties of two kinds of oil-based drilling fluids with typically composition were studied at pressures up to 138 MPa and temperatures up to 204 ℃ using the RheoChan 7400 Rheometer.The experimental results show that the apparent viscosity,plastic viscosity and yield point decrease with the increase of temperature,and increase with the increase of pressure.The effect of pressure on the apparent viscosity,plastic viscosity and yield point is considerable at ambient temperature.However,this effect gradually reduces with the increase of temperature.The major factor influencing the rheological properties of oil-based drilling fluids is temperature instead of pressure in the deep sections of oil wells.On the basis of numerous experiments,the model for predict the apparent viscosity,plastic viscosity and yield point of oil-based drilling fluids at high temperature and pressure was established using the method of regressive analysis.It is confirmed that the calculated data are in good agreement with the measured data,and the correlation coefficients are more than 0.98.The model is convenient for use and suitable for the application in drilling operations.
基金National Key Research and Development Program of China(2017YFB0310400)National Natural Science Foundation of China(51572277,51702340)+1 种基金Shanghai Sailing Program(17YF1428800)Natural Science Foundation of Shanghai(17ZR1434800)。
文摘As for ceramic stereolithography technique,the preparation of suitable resin-based ceramic slurry is of primary importance.In this study,the effects of powder characteristics such as specific surface area,particle size and distribution,particle morphology on the rheological behavior of zirconia resin-based suspensions were investigated intensively.Results show that the specific surface area of the powder is the most important factor affecting slurry viscosity.Choosing low specific surface area and quasi-spherical shaped powder is more likely to obtain low viscosity slurries.In addition,the influence of solid loading on the flow behavior were also studied using Krieger-Dougherty model.Zirconia samples with the relative density of(97.83±0.33)%were obtained after sintering at 1550℃.No obvious abnormal grain growth in the microstructure of the sintered body is observed.Results indicate that after the optimization of the processing parameters with the help of rheology characterization,complex-shaped high-quality zirconia parts can be obtained using the stereolithography technique.
基金Funded by the Western Region Traffic Construction Technology Program of the Ministry of Communications of China(No.2007319811130)
文摘A series of polycarboxylate-based superplasticizers(PCs) with different structures were synthesized and the effects of chemical structure on zeta potential and rheological property of cement paste were studied. Residual monomers in each sample of PCs were quantitatively determined. The property of the polymers in cement was tested by micro-electrophoresis apparatus and R/S rheometer. Results showed that the zeta potential and its rheological properties are related with the side-chain length and density of PCs. The PCs having shorter side chain and lower side chain density exhibit higher anionic charge density, thus resulting in higher zeta potential. The effect of side chain density on zeta potential is more notable compared with that of side-chain length, and thus affecting the initial shear yield stress and apparent viscosity of the cement paste. In addition, although increasing the side chain length will result in reduction of the anionic charge density, the steric hindrance effect is obvious, which can effectively improve the dispersion of the cement particles, and reduce the viscosity and shear yield stress of slurry.
基金Project(200631800076) supported by 2006 West Science and Technology Project of the Department of Transportation
文摘The influence of aging on the evolution of structural,morphological and rheological properties of neat asphalt was investigated by Fourier transform infrared(FTIR),atomic force microscopy(AFM) and dynamic shear rheometer(DSR),respectively.Asphalt was suffered under 20 W/m2 of UV radiant intensity and under the condition of aging time(0,48,96 and 144 h) with film thickness of 100 μm and film thickness of 50,100,200 and 500 μm after aging for 120 h,respectively,at certain UV radiant intensity 20 W/m2.Rheological results tested by DSR exhibit higher the complex shear(stiffness) modulus(G*) and lower phase angle(δ),compared to the virgin at the same test condition.The compositions analysis of asphalt before and after aging show an increase of carbonyl and sulfoxides,while a decrease of aromatic functional groups.With the increase of the component of asphaltene,obvious agglomerates of asphalten appear in neat asphalt surfaces after aging.
基金Project(50765005) supported by the National Natural Science Foundation of Chinasupported by Key Laboratory of Ministry of Education for Conveyance and Equipment (East China Jiaotong University),China
文摘The microstructure and rheological behavior of semi-solid Mg2Si/AM60 magnesium matrix composite at steady state were investigated.The results show that the primary α-Mg phases are knapped by mechanical stirring and the Chinese script type reinforced Mg2Si phases exist in liquid phase and grain boundary.The analysis of apparent viscosity indicates that the apparent viscosity of semi-solid Mg2Si/AM60 magnesium matrix composite at steady state increases with increasing the volume fraction of Mg2Si and solid fraction of primary α-Mg,but decreases with increasing the shearing rate and shearing time,and the apparent viscosity keeps stable when shearing time reaches 300 s.
文摘It is known that some internal defects exist in metal materials. Preliminary attempt to relate dislocation evolution with metal rheological forming was done. By the attempt, it is learned that the evolution of dislocation density ρ(x, y, t) is essentially the change of n independent internal variables q α(α=1, 2, …, n) with material. The preliminary research in theory and experiments showed that dislocations piling up could be avoided. One can improve the internal microstructure and mechanical properties of products by rheological forming method.
文摘Considering the rheological properties of rock and soil body,and exploiting the merit of strength reduction technique,a theory of couple analysis is brought forward on the basis of strength reduction theory and rheological properties.Then,the concept and the calculation procedure of the safety factor are established at different time.Making use of finite element software ANSYS,the most dangerous sliding surface of the slope can be obtained through the strength reduction technique.According to the dynamic safety factor based on rheological mechanism,a good forecasting could be presented to prevent and cure the landslide.The result shows that the couple analysis reveals the process of the slope failure with the time and the important influence on the long-term stability due to the rheological parameters.
