Rheological Properties Of Materials Research Articles

Experimental investigation of fresh and time-dependent rheological properties of 3D-printed cementitious material

Unlike traditional construction processes, three-dimensional cementitious material printing requires more accurate control of the pumping flow rate. To this end, the predictability of the rheological properties of fresh cementitious mixtures and the property change over time are critical for the fabrication process. In this paper, the fresh rheological properties of twenty different mixtures were measured in the large gap viscometer, and three non-Newtonian fluid models (Bingham model, modified Bingham model, and Herschel-Bulkley) were applied to predict the dynamic yield stress and plastic viscosity of each material. The applicability of these models was assessed, and their relative deviation was quantified and discussed. Using the well-established Bingham model, the temporal evolution of the dynamic yield stress and plastic viscosity of the material was then characterized. Based on the measured and predicted rheological properties, an open loop control method was then implemented to harmonize the flow volume per unit length during printing processes to improve the printing quality and buildability of the material.

Mechanical data corrections for triaxial compression testing at high pressures and high temperatures with a Paterson gas-medium mechanical testing apparatus

Although restricted by a limited range of strain, the triaxial compression test is a mature and common technique for investigating the rheological properties of rock materials at high pressures and high temperatures, especially when establishing the constitutive equations for various flow laws. The Paterson gas-medium high-pressure and high-temperature mechanical testing apparatus (Paterson apparatus) is the best apparatus for triaxial compression testing due to its high stress resolution. However, to derive accurate mechanical information from the raw data recorded by the Paterson apparatus, some technical issues should be addressed, including the simultaneous distortion of the apparatus, the load force supported by the jacketing tube, and the change in the cross-sectional area of the specimen. In this paper, we introduce correction methods corresponding to these three technical issues for triaxial compression on a Paterson apparatus equipped with an internal load cell to significantly reduce experimental errors so that high-precision mechanical data for establishing the constitutive equations of flow laws, such as differential stress, strain, and strain rate, can be obtained. To facilitate corrections for the distortion of the apparatus and the load force supported by the jacketing tube, we determine the distortion of the Paterson apparatus as a function of axial load force by deforming tungsten steel specimens with a known Young’s modulus and the high-temperature flow laws of two common jacketing materials, iron and copper, by triaxial compression experiments at confining pressures of 200–300 MPa. Previous flow laws of iron and copper established by Frost and Ashby (1982) using ambient mechanical data are carefully compared with the flow laws obtained in this study to evaluate their effectiveness for correcting jacket tube strength. Finally, the errors eliminated by each correction step are analyzed and discussed to better understand the necessity of mechanical data corrections.

Rheological characterization of cement pastes with microcrystalline and nano-fibrillated cellulose under static and dynamic regimes

The study of the rheological properties of cement-based materials is essential to the processes directly linked to the flow performance of the fresh mixture. As well, the use of micro- and nano-cellulose-based materials is gaining visibility in its application within cementitious matrices. Despite the great potential represented by those materials, there are still informational gaps to be filled. This work aims at exploring the rheological behavior of cement pastes with micro- and nano-materials beyond the single-point testing customarily presented. An experimental program was developed to characterize and discuss the effects of microcrystalline cellulose (MCC) and nanofibrillated cellulose (NFC) on the rheological behavior of cement pastes. The investigation included both dynamic and static regimes, with a specific range of percentages of MCC and NFC. During the dynamic evaluation both MCC and NFC presence resulted in stiffer cement pastes, with increases in yield stress of up to 136% with 0.040% of NFC and 94% of MCC. MCC-specimens showed non-monotonic behavior regarding the static yield stress values. The rheological characteristics of the NFC gel itself affected the general behavior of the cement paste. The water present in the gel was found to be only partially available as mixing water.

Mathematical model of running-in of tribosystems under conditions of boundary lubrication. Part 2. Simulation results

The paper presents the results of mathematical modeling of tribosystems running-in processes when various factors are changed: design parameters of tribosystems, which are taken into account by the form factor; tribological properties of the lubricating medium; rheological properties of composite materials in the tribosystem; roughness of friction surfaces; load and sliding speed. By comparing the theoretically obtained results, by modeling according to the developed models, with experimental data, it was established that the mathematical model adequately reflects the running-in processes taking into account the changes in constructive, technological and operational factors. Applying the Cochrane criterion, it was established that the obtained experimental results are homogeneous and reproducible. The maximum value of the coefficient of variation of the values of the volumetric wear rate and the coefficient of friction is within the limits v = 12,3 - 26,5%. The value of the simulation error is within the limits v = 7,7 - 12,9%.
 A rating of factors that maximally affect the processes of running-in of tribosystems in the conditions of extreme lubrication has been obtained. In the first place is the roughness of the friction surfaces, the coefficient of variation v = 26,5%. In the second place – the load on the tribosystem during running-in, the coefficient of variation v = 20,8%. In third place is the value of sliding speed during running-in, the coefficient of variation v = 18,6%. The conclusion made must be taken into account when developing a rational program for running-in tribosystems in conditions of extreme lubrication.
 The methodical approach of applying the acoustic emission method in the study of tribosystem running-in processes is presented. It is proved in the work that in order to determine the volume rate of wear during tribosystem running-in, it is necessary to register and analyze the fourth cluster from the general acoustic emission signal. The sources of signal generation of the fourth cluster are microcutting and plastic deformation of protrusions of the roughness of the friction surface, which is characteristic of the first stages of running-in.

Comparative study of effects of various seaweed parietal polysaccharides on rheological, mechanical and water-durability properties of earth-based materials

Comparative study of effects of various seaweed parietal polysaccharides on rheological, mechanical and water-durability properties of earth-based materials

Mechanical recycling of expanded polystyrene and tire rubber waste as compatibilized and toughened blends

AbstractPackaging represents a significant source of all polymer waste produced in the world. Thus, improving recycling methods is essential to achieve an environmentally sustainable condition since the volume of produced polymer and of related waste has grown. Expanded polystyrene (EPS) foam is a thermoplastic with important performance of properties such as thermal isolation and absorption of mechanical energy that allow large application in packaging and other segments. However, the EPS recycling is a challenger due to its low density and poor properties. The rubber incorporation to the recycled EPS is an alternative for the toughening of the polymer matrix as well as improving its mechanical properties. In present study, EPS waste from electric and electronic products packaging was treated by three distinct methods for polymer densification and after it was thermo‐mechanically processed by extrusion with variable content of ground tire rubber (GTR) and compatibilizer agent styrene‐butadiene‐styrene (SBS) copolymer to produce compatibilized and toughened PS/rubber blends. Mechanical, thermal and rheological properties of materials were evaluated by different analyses. The incorporation of rubber to the recycled EPS has significantly improved the mechanical properties of the material and the presence of the SBS agent was effective to compatibilize the PS/rubber blends. Therefore, the preparation of compatibilized PS/rubber blends showed to be a way to the mechanical recycling of EPS and rubber tires waste.

Debris Flow Run-Out Prediction Based on the Shallow-Water Flow Numerical Model—A Case Study of Xulong Gully

Here we present a method for predicting debris flow run-out based on a numerical model for shallow water flows, using a case study conducted on Xulong Gully, a proposed dam site for a hydropower station in the upper reaches of the Jinsha River. A field investigation and remote sensing interpretation methods were used to develop a comprehensive evaluation of debris flow zones and calculate the potential provenance volume in the Xulong Gully. Particle-size analysis was conducted on the early debris flow fan in the Xulong Gully to determine the rheological properties of the debris flow materials. A numerical model for shallow flows was constructed using the finite volume method to verify fluid motion across complex terrain and explore the debris flow run-out range with various provenance volumes. The model showed that for a total debris flow volume of less than two million m3, the debris flow impact area would remain within the Xulong Gully. However, if the total debris flow volume is more than two million m3, the debris flow would flush out into the Jinsha River, blocking a portion of the river. If all the provenance in the Xulong Gully were flushed out, the maximum flow velocity of the generated debris flow would be 11 m/s and the thickness of the debris flow at the Xulong Gully estuary would be about 28.8 m. The debris flow would completely block 470 m of the Jinsha River.

Rheological properties of polymer materials with different types of structures based on EVA and organic filler

A study on the effect of the structure of disperse-filled polymer composite materials (DFPCM) based on EVA grade 11306-075 and rice straw powder (RSP) with a particle diameter of 250 μm on the complex of rheological properties has been carried out.For the first time, a quantitative relationship of generalized parameters, type of structure and lattices with the rheological properties of dispersed systems based on EVA + RSP has been determined. It has been established that during the processing of DFPCM with the DS, LFS, and MFS-1 structure types by traditional methods (extrusion, injection molding, etc.), there are practically no technological difficulties. Systems with the type of structure MFS-2 and HFS have an increased viscosity (~7–15 times) in comparison with unfilled EVA; therefore, they cannot be processed.The results of the experiments and the approach developed in this work makes it possible to design DFPCM compositions with adjustable structural parameters and a set of properties, as well as to choose methods and technological parameters for processing them into products with a given shape, configuration, and dimensions.

Study on Rheological and Mechanical Properties of Rock-Compound-Additive-Modified Asphalt and Its Mixture.

Rutting is one of the most widespread and severe diseases in the service life of asphalt pavement. Enhancing the high-temperature rheological properties of pavement materials is one of the valid measures that can be used to solve rutting disease. In this research, the laboratory tests were carried out to compare the rheological properties of the different asphalts (including neat asphalt (NA), styrene-butadiene-styrene asphalt (SA), polyethylene asphalt (EA), and rock-compound-additive-modified asphalt (RCA)). Then, the mechanical behaviors of different asphalt mixtures were investigated. The results show that the rheological properties of modified asphalt with a 15% rock compound additive performed better compared with the other forms of modified asphalt. The dynamic shear modulus of 15% RCA is significantly higher than the other three asphalt binders, which is 8.2 times, 8.6 times, and 14.3 times that of the NA, SA, and EA at a temperature of 40 °C, respectively. After adding the rock compound additive, the compressive strength, splitting strength, and fatigue life of the asphalt mixtures were significantly enhanced. The results of this research have practical significance for new materials and structures to improve asphalt pavement resistance to rutting.

Effects of zeolite on rheological properties of asphalt materials and asphalt-filler interaction ability

The rheological properties of asphalt materials (asphalt binder and mastic) and asphalt-filler interactions play critical roles in the performance of asphalt mixtures. However, the rheological properties of zeolite-foamed asphalt materials and zeolite-foamed asphalt-filler interactions are significantly influenced by zeolite, which is used as a foaming additive. To study the effects of zeolite on the rheological properties of asphalt materials and asphalt-filler interaction, the base asphalt, limestone filler, and two kinds of zeolites in two dehydrated states were selected to prepare zeolite asphalt/mastic and zeolite-foamed asphalt/mastic. First, the effects of zeolite on the chemical composition and micromorphology of asphalt binders were evaluated using a Fourier transform infrared spectrometer (FTIR) and fluorescence microscopy (FM), respectively. Then, the rheological properties of asphalt binders and mastics were measured by rotational viscosity (RV) and dynamic shear rheometer (DSR) tests. The results indicated that zeolite did not chemically react with the components of asphalt, and zeolite minerals played a role in volume filling and physical adsorption in asphalt, which dispersed in the asphalt in the form of floccules. Adding zeolite minerals to asphalt binders and mastics enhanced the elasticity, which was beneficial to high-temperature performance and adverse to fatigue performance. Conversely, the effect of zeolite water released by zeolite was the opposite. The effect of zeolite on the rheological properties of asphalt materials was consistent with that of zeolite minerals because the enhancing effect of zeolite minerals was dominant, offsetting the weakening effect of zeolite water in asphalt binders and mastics. The three indices, namely, intrinsic viscosity [η], Palierne-C-G* parameter, and Ziegel-B-δ parameter, were selected to evaluate the zeolite asphalt-filler interaction ability and zeolite-foamed asphalt-filler interaction ability. The results showed that the asphalt-filler interaction ability was enhanced after adding zeolite minerals to asphalt, and the influence of zeolite on asphalt-filler interaction was consistent with zeolite minerals. However, the opposite effect was observed for zeolite water.

RheologyNet: A physics-informed neural network solution to evaluate the thixotropic properties of cementitious materials

Thixotropic behaviors can be predicted by rheological partial differential equations (PDEs) of cementitious materials. The ability to solve the rheological PDEs of viscous fluids accurately and efficiently has become an emerging interest in research. However, due to the growing number of parameters in rheological constitutive equations and the non-ideal behavior of materials from experiments, solving the rheological PDEs becomes computationally costive and error-prone. We propose a physics-informed neural network (PINN)-based framework, RheologyNet, as a surrogate solution to predict the general thixotropic behavior of cementitious materials. The complex PDEs are embedded in the well-designed RheologyNet architecture to link macroscopic viscous flow behaviors and microstructural changes. Numerical experiments suggested that RheologyNet can accurately and efficiently predict the rheological properties of cementitious materials compared to the traditional Fully-connected Neural Network (FNN) and mechanistic Finite Element Analysis (FEA). Particularly, RheologyNet demonstrated great promise for simulating history-dependent thixotropic behaviors.

Preparation and Rheological Properties of Paper-Based Superhydrophobic Materials

Preparation and Rheological Properties of Paper-Based Superhydrophobic Materials

Development of sprayable ultra-high ductility magnesium phosphate cement-based composites based on the rheological properties

To develop a sprayable ultra-high ductility magnesium phosphate cement-based composite (UHDMC), this study explored the effects of starch ether content, water–solid ratio, powder-binder ratio, borax content (B/M), fly ash (FA) substitution and volume content of polyvinyl alcohol (PVA) fiber on the shootability and rheological properties of magnesium phosphate cement-based materials. The correlation between shootability factors (build-up thickness and rebound rate) and rheological parameters (yield stress and plastic viscosity) was established, and the optimum mixture proportion suitable for the sprayed UHDMC was selected and then analyzed by the mechanical properties and pore structure between the cast and sprayed specimens. The results showed that the optimum mixture proportion of the sprayed UHDMC was as follows: starch ether content of 0.15%, water–solid ratio of 0.14, powder-binder ratio of 0.3, borax content (B/M) of 8%, FA substitution of 40%, and the PVA fiber volume content of 2.0%. The yield stress and plastic viscosity were both positively correlated with the build-up thickness, and negatively correlated with rebound rate. To some extent, rheological parameters can be used to characterize the shootability factors, in which the best shootability was shown when the ranges of yield stress and plastic viscosity were 91.64–118.77 Pa and 4.85–7.17 Pa·s, respectively. The compressive strength and ultimate tensile stress of the sprayed UHDMC were lower than that of the cast UHDMC, while the ultimate tensile strain of the sprayed UHDMC could still reach above3.6%, presenting good performance to meet the requirement of above 3% strain of high ductility cement-based materials. Moreover, the analysis of pore structure verified that the capillary pores and macropores contents were mainly affected the strength and tensile strain, respectively.

Rheological Properties of Composite Materials for Manufacturing Sprayers of Agricultural Sprinklers

Rheological Properties of Composite Materials for Manufacturing Sprayers of Agricultural Sprinklers

Ageing behaviour of naturally and artificially aged bitumen samples after the addition of rejuvenators

Reusing bitumen and asphalt is an approved practice, but the efficiency highly depends on adding virgin bitumen. Rejuvenators have gained increased importance in reaching independence from crude oil and exploring possibilities of multiple reuses. However, rejuvenators are often tested and evaluated exclusively on artificially aged bitumen samples. Therefore, the main objective of this publication is to investigate the rejuvenation of Reclaimed Asphalt Pavement (RAP) binders using three RAP samples and three rejuvenators. Rheological material properties, chemical effects of rejuvenation processes and the ageing behaviour after rejuvenation are examined. The results are further compared to rejuvenated artificially aged bitumen. It has been found that the rejuvenators reveal varying degrees of impact on RAP binders and artificially aged bitumen samples, as artificially aged bitumen samples tend to show fewer ageing changes than the RAP binders. Moreover, also the ageing behaviour of the pure rejuvenator influences the success of reuse.

Cross-Linking of Sugar-Derived Polyethers and Boronic Acids for Renewable, Self-Healing, and Single-Ion Conducting Organogel Polymer Electrolytes.

This report describes the synthesis and characterization of organogels by reaction of a diol-containing polyether, derived from the sugar d-xylose, with 1,4-phenylenediboronic acid (PDBA). The cross-linked materials were analyzed by infrared spectroscopy (FT-IR), thermal gravimetric analysis (TGA), scanning electron microscopy (FE-SEM), and rheology. The rheological material properties could be tuned: gel or viscoelastic behavior depended on the concentration of polymer, and mechanical stiffness increased with the amount of PDBA cross-linker. Organogels demonstrated self-healing capabilities and recovered their storage and loss moduli instantaneously after application and subsequent strain release. Lithiated organogels were synthesized through incorporation of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) into the cross-linked matrix. These lithium-borate polymer gels showed a high ionic conductivity value of up to 3.71 × 10-3 S cm-1 at 25 °C, high lithium transference numbers (t + = 0.88-0.92), and electrochemical stability (4.51 V). The gels were compatible with lithium-metal electrodes, showing stable polarization profiles in plating/stripping tests. This system provides a promising platform for the production of self-healing gel polymer electrolytes (GPEs) derived from renewable feedstocks for battery applications.

Printing quality control of cement-based materials under flow and rest conditions

Time-dependent rheological properties of cement-based materials have a significant impact on 3D printing processes, where multiple rheological requirements should be met. A proper high rate of structural build-up is recommended to ensure the buildability and stability of printed elements. However, the loss of workability may occur rapidly, resulting in a significant reduction in print quality. Workability and buildability requirements usually interfere due to the time-dependent rheological behavior of cement-based materials under flow and rest conditions. This research aims to highlight the effects of time-dependent behavior on the printability of cement-based materials. The coupling mechanisms of microstructure development at rest and under shearing conditions are discussed. A new thixotropy index is proposed to quantify the printability window of cement-based materials based on their structuration rates. An experimental study was conducted on printable mortars incorporating a viscosity-modifying agent (VMA) to assess printing quality as a function of the degree of thixotropy. Different types of stability failures were captured and discussed.

Rheological properties of cemented gangue backfill material based on fractal characteristics of waste coal gangue.

The study herein was intended to evaluate the rheological properties of cemented gangue backfill material (CGBM). For this purpose, the rheological test of CGBM with fractal aggregate particle size distribution was carried out, and variations of static yield stress, dynamic yield stress, and plastic viscosity were investigated as a function of fractal dimension and time. The results reveal that aggregate particle size distribution exerts a significant influence upon the rheological properties of CGBM, and with the escalation of the fractal dimension of the aggregate, the yield stress and plastic viscosity initially decline and then increase. In addition, with elapsing time, the correlation between the static yield stress and the fractal dimension of CGBM specimens increases, while the correlations between the dynamic yield stress and the plastic viscosity and the fractal dimension decrease. The relationships between rheological parameters and fractal dimensions at different times are established based on the experimental results. The influence mechanism of aggregate particle size distribution on CGBM is analyzed from the perspective of the aggregate packing state. This study can provide a basis for the ratio design of CGBM in backfill mining.

Proper normal waves in a two-layer tube taking into account the rheological properties of materials

The article considers the problem of propagation of proper normal waves in a two-layer pipe, paying to attention the rheological properties of the material. The main purpose of the work is to develop a methodology, an algorithm for investigation the problems of wave propagation in extended two-layer dissipatively inhomogeneous cylindrical structures. The main integro-differential equations in the article are obtained on the basis of methods of the theory of visco-elasticity. In the course of the study, the method of separation of variables, the freezing method, the Muller method and the Godunov orthogonal run method were used. In this paper, for structurally inhomogeneous extended cylindrical mechanical systems, the dependences of several modes (three and four) of the complex phase velocity (real and imaginary parts) on the wave number are comparatively estimated; the results of calculations are compared with experimental and theoretical data of other researchers, and the use of asymptotic and numerical methods for solving dispersion equations with complex output parameters is justified.

Numerical modeling of nonlinear viscoelastic vibrations of vehicles

Nonlinear viscoelastic oscillations of a vehicle in a vertical direction excited by static imbalance are considered. When taking into account the rheological properties of the suspension material and spring, the Boltzmann-Volterra principle was used. Mathematical models of the problem under consideration are obtained, which are described by systems of nonlinear integro-differential equations. A solution method based on quadrature formulas has been developed, and a computer program has been compiled on its basis. The results obtained are reflected in graphs. The influence of the material's rheological properties and the nonlinear characteristics of the suspension and spring on the amplitude and frequency of vertical vibrations of vehicles was investigated.