The paper presents the impact of carrageenan addition on rheological characterisation of some hydrocolloid aqueous solutions during stirring with rotational speed changes. Carboxymethyl cellulose, guar gum and xanthan gum were used. Measurements were conducted in a vessel equipped with an anchor stirrer under rotational speed increase and decrease conditions, equivalent to a hysteresis loop rheological test. Rheological parameters were calculated using the power-law equation. It was found that a carrageenan addition generally causes a reduction of liquid apparent viscosity and time-dependent rheological behaviour intensification, with some exceptions.

The aim of the study was to determine the influence of selected nanoparticles, namely diesel exhaust particles, Arizona test dust, silver and gold on the rheology of human blood. The rheological properties of human blood were determined with the use of a modular rheometer, at two various temperatures, namely 36.6◦C and 40◦C. Experimental results were used to calculate the constants in blood constitutive equations. The considered models were power-law, Casson and Cross ones. The obtained results demonstrate that the presence of different nanoparticles in the blood may have different effect on its apparent viscosity depending on the type of particles and shear rate.

The study presents the manners of determination of the Darcy friction factor λ for a homogenous hydromixture of alum sludge of varied hydration and temperature for the laminar flow zone. The rheological evaluation of the hydromixture as a viscoplastic body has been conducted with use of measurements of viscosity. The curves of flow were approximated with use of the generalized Vočadlo model. The Darcy friction factor λ of the pipeline was determined with use of the non-dimensional criterion λ(Regen) and λ(Re, He).

Transport properties of bronchial mucus are investigated by two-stage experimental approach focused on: (a) rheological properties and (b) mass transfer rate through the stagnant layer of solutions of mucus components (mucine, DNA, proteins) and simulated multi-component mucus. Studies were done using thermostated horizontal diffusion cells with sodium cromoglycate and carminic acid as transferred solutes. Rheological properties of tested liquids was studied by a rotational viscometer and a cone-plate rheometer (dynamic method). First part of the studies demonstrated that inter-molecular interactions in these complex liquids influence both rheological and permeability characteristics. Transfer rate is governed not only by mucus composition and concentration but also by hydrophobic/hydrophilic properties of transported molecules. Second part was focused on the properties of such a layer in presence of selected nanostructured particles (different nanoclays and graphene oxide) which may be present in lungs after inhalation. It was shown that most of such particles increase visco-elasticity of the mucus and reduce the rate of mass transfer of model drugs. Measured effects may have adverse impact on health, since they will reduce mucociliary clearance in vivo and slow down drug penetration to the bronchial epithelium during inhalation therapy.

Many open-pit mines are gradually converted to underground mining, the problem of roadway surrounding rock damage caused by expansive soft rock is becoming increasingly problematic. To study the seasonal evolution of expansive rock mass containing clay minerals, an underground mine transferred from an open-pit was selected as the experimental mine. The experimental results of SEM electron microscopy and X-ray diffraction confirmed that the surrounding rock of the main haulage roadway contains a large number of expansive clay minerals. The expansive grade of the main transport roadway’s surrounding rock could then be identified as the medium expansive rock mass, which has a large amount of exchangeable cation and strong water absorption capacity, based on the combined test results of dry saturated water absorption and free expansion deformation. The water swelling can cause the roadway to considerably deform, and then the surrounding rock will have strong rheological characteristics. From the research results in the text, the seasonal evolution law of the main haulage roadway in the experimental mine was obtained, and the deformation law of the expansive rock mass under different dry and wet conditions was revealed. The research results provide a reference for studying the stability evolution law of expansive soft rocks in underground mines.

On the Polish-Czech Odra river section between Chalupki (Poland) and the Olza river mouth there are unique in European scale meanders (km 21.3 - 26.8). In the 20th century the break-up of two meanders caused by floods in 1967 and 1997 occurred. The total length ofmeandering section has become shorter and the hydraulic gradient increased. The sediments eroded and transported by the stream have settled in different zones of the meandering section. In 1997 the inlet to the meander I was blocked by settled sediments causing the break-up of this meander. The paper presents the preliminary estimation ofmorphological changes of the river bed and the physical and rheological characteristics for settled sediments.

This study investigates the effects of repetitive injection molding on the properties of feedstock using the AISI 4140 feedstock. The properties of feedstock are evaluated from the mixing homogeneity of powder and binder, rheological properties, and dimensional accuracy of parts sintered. The feedstock after the 1st injection molding shows a better homogeneity than as-received feedstock due to re-mixing effects between the screw and barrel during the injection molding process. As the number of recycling numbers increases, the homogeneity, viscosities ad shrinkage ratio of recycled feedstocks show slight differences with those of the as-received feedstock until the 6th molding injection. However, some rheological parameters like the moldability index sharply increased up to the 4th injection but shows a tendency to decrease thereafter.

The article is an attempt to compare the impact of the use of various types of limestone as the main constituent of cement on selected mortar properties. Four different limestones were added in amount of 15, 30, 40% to CEM I 42.5 R to obtain limestone cemens. Rheological properties (yield stress, plastic viscosity) of fresh mortar, tensile and compressive mortar strength, early shrinkage, and drying shrinkage were tested. Obtained results indicate that both tensile and compressive strength decreases with the increase of the limestone content in cement. Limestone can worsen or improve workability, depending on distribution of limestone grains. The addition of limestone increases the early shrinkage, but reduces the shrinkage after 28 days. Studies show that the granulation of limestone plays an important role in determining the influence of limestone on mortar properties.

This study presents the rheological properties of sewage sludge after conditioning with the application of biomass ash. The impact of sewage sludge pre-treatment on its viscosity, flow curves and thixotropy was investigated. The increase of shear stress and the decrease of viscosity were observed with the increase of shear rate. Obtained results were compared with raw sewage sludge and the sludge after modification by means of polyelectrolyte in the dosage of 1.5 g (kg d.m.)^-1. The findings proved that samples of raw and conditioned sewage sludge had thixotropic characteristics. The correlation between moisture content and capillary suction time reduction as well as selected rheological parameters were also determined. On the basis of the obtained results it was stated that the Ostwald de Vaele model best fits the experimental data.

The paper presents a research work on the process of emulsion separation by filtration-coalescence method in the presence of solid particles. A polyester PBT coalescence medium was used in experiments of water removal from diesel fuel. Apart from parameters representing the geometry and inherent properties of coalescence filters, the additional emulsion constituents such as surfactants and solid particles also affect the process. These constituent can cover fibres and they can also influence emulsion properties. It has been experimentally confirmed that contrary to surface active compounds, which stabilise the emulsion, the presence of specific solid particles decreased the system stability. If surface active compounds are present in the system, the influence of solid particles is different at the same concentration level depending on their type. The destabilization of emulsion due to the presence of Arizona dust was more pronounced. Although the presence of particles mitigated the effect of surfactants, their deposition in the filter media oppositely affected the coalescence process depending on solid type. Oleophilic iron oxide particles improved the separation efficiency of water from diesel fuel, while Arizona test dust had a negative impact on the separation process performance.

The targeted modification of the material composition is a common procedure used to improve the parameters of the final products. This paper deals with the targeted modification of polymer systems composition using two various types of alternative fillers. The first type of alternative filler (SVD) has been obtained from energetics where it arises as a by-product of flue gas desulfurization. The second alternative filler used (KAL) is based on waste from glass production. The elastomeric systems designed for the production of car tires and solid wheels for transport systems were used in the role of modified polymer systems. Alternative fillers (SVD, KAL) have been applied as a substitution of commonly used fillers (carbon black, silica). The filler – elastomeric matrix interaction, rheology, cure characteristics, as well as hardness and rebound resilience of vulcanizates, which are important parameters for their industrial application, have been studied in the new prepared polymeric systems. The main output of the work is a new formulation of an elastomeric system for industrial applications with high rebound resilience and low rolling resistance, which is the subject of the international patent [1]. The modification of composition using raw material substitution can also bring significant environmental and economic effects.

Fiber reinforced polymers (FRPs) due to their specific high-strength properties become more and more popular and replace traditional structural materials like conventional steel in prestressed concrete structures. FRP reinforced structures are relatively new when compared to structures prestressed with steel tendons. For that reason only several studies and applications of pre-tensioned FRP reinforcement have been conducted until now. Moreover, researchers only considered short-term behavior of FRP reinforced concrete members. The precise information about long-term behavior of FRP reinforcement is necessary to evaluate the prestress losses, which should be taken into account in the design of prestressed RC structures. One of the most important factor influencing long term behavior of FRP reinforcement is stress relaxation. The overview of experimental tests results described in the available literature considering the prestress losses obtained in FRP prestressed concrete members is presented herein.

The present contribution reports on the rheological investigations concerning influence of high hydrostatic pressure on the molecular structure of gelatin gels. For the purpose of the study, a torsional shear wave rheometer for in-situ investigations of viscoelastic substances under high pressure was developed. Small amplitude vibrations generated by piezoelectric elements are used to determine the storage modulus of the investigated medium. The system is able to stand pressures up to 300 MPa. The experiments have been carried out with household gelatin (0.1 w/w aqueous solution). The gelification curves revealed similar time course. However, the values of G0 obtained for the gels curing 300 minutes under 100 MPa and 200 MPa were observed to be respectively 2.1 and 4 times higher than at ambient conditions. The increased number of triple helix junction zones is hypothesised to be the cause of this phenomenon as a result of reinforcement of the hydrogen bonds due to pressure. An attempt to cognize the characteristic dimensions of the molecular structure based on the theory of rubber elasticity is made.

Sewage sludge is a two-phase mixture, generated during the treatment of domestic sewage in waste water treatment plants. It consists of 90-99% water and an accumulation of settleable solids. mainly organic that are removed during primary, secondary or advanced wastewater treatment processes. The hydration of the sludge is one of its main properties which determines sludge management and waste disposal cost. The flow properties of the sewage sludge, such as settling properties and concentration of solids. may affect its hydraulics. Application of rheology in wastewater treatment is determined by the flow character of the sludge. The basic purpose of the investigation was to define the rheological properties of sludge taken from secondary settling tanks in a typical municipal wastewater treatment plant. A laboratory investigation was conducted using a coaxial cylinder with a rotating torque and gravimetric concentration of the investigated sludge ranged from 2.21 to 6.56%. Approximation was made after transforming the pseudo-curve obtained from the measurements into the true flow curve, which was made according to the equation provided by Krieger, Elrod, Maron and Svec. In order to describe rheological characteristics the 3-parameter Herschel-Bulkley model was applied. The correlation between rheological parameters -r , k, n and concentration C was calculated as well as between periods of time when the samples of sludge were 'taken. The research has allowed calculating the dimension of the main transport installation pumping sludge and optimizing the pump discharge pressure, when transporting viscous sludge in pipelines. Determination of rheological parameters, especially yield stress tr), is important in sludge management, for instance in designing parameters transporting, storing, spreading.

This paper presents simulation results of the consolidation process of the flotation waste landfill “Żelazny Most”. The mathematical model used in presented research is based on Biot’s model of consolidation and is extended with rheological skeleton. The load is the mass pressure of the landfill itself. The initial point selected for calculations was based on the ground water level calculated in a landfill. The creeping process in this waste landfill was analyzed along the north – south section. The solution is therefore 2D with the assumption of a plane strain state. Effective model parameters data were obtained in laboratory tests on the material from the waste landfill. Results obtained for a stress state in a storage state can help to determine whether the adopted linear model of visco-elastic medium does not lead to changes in the Coulomb – Mohr potential yield, showing the emergence of plasticity of material storage areas.

The paste content in the self-compacting concrete is about 40% in unit volume. The rheological properties of paste directly determine the properties of self-compacting concrete. In this paper, the effect of silica fume (2, 3, 4, and 5%), limestone powder (5, 10 and 15%), and the viscosity modified admixture (2, 3, 4, 5, 6, and 7%) on the rheological properties were investigated. The effect of admixtures on shear thickening response was discussed based on the modified Bingham model. The results indicate that yield stress and plastic viscosity increased with increased silica fume and viscosity modified admixture replacement. The paste’s yield stress increases and then decreases with limestone powder replacement. The critical shear stress and minimum plastic viscosity are improved by silica fume and viscosity modifying admixture. The critical shear stress first increases and decreases as the limestone powder replacement increases. A reduction in the shear thickening response of paste was observed with silica fume and viscosity modified admixture replacement increase.