Addition Of Sepiolite Research Articles

Effect of acid treatment on the reactivity of natural sepiolite used as a supplementary cementitious material

In this study, natural sepiolite samples were treated with hydrochloric and acetic acid solutions at three different concentrations (0.1 M, 0.5 M, and 1.0 M). The effect of acid treatment on the reactivity of natural sepiolite and the change in cement hydration following the addition of natural sepiolite were studied using X-ray diffraction, particle size distribution analysis, inductively coupled spectrometry, thermogravimetric analysis, and isothermal calorimetry. Although acid treatment leads to a slight decrease in the amorphous phase content in natural sepiolite, the reactivity of sepiolite increased. The results indicate that the increase in sepiolite reactivity most likely stemmed from the activation of the Si phase. In addition, acid-treated sepiolite can modify the hydration of cement during the early curing period and hinder the hydration of cement during the later curing period. The compressive strength of specimens with strong acid-treated sepiolite was higher compared with specimens with weak acid-treated sepiolite.

Preparation and properties of an intelligent adjustable functional paper for organic cultural relics

Abstract Precious organic cultural relics are easily affected by temperature, humidity, and harmful gases in the environment, resulting in embrittlement, fading, mildew, moth damage and other aging forms. An energy-saving and environmentally friendly material is needed to stabilize humidity and adsorb harmful gases in the environment. In this paper, with an intelligent adjustment function, functional paper containing sepiolite and tourmaline natural minerals was successfully prepared. The component of 80 % of wingceltis and 20 % of straw in dry pulp as main raw material was conducive to the desorption of water molecules. As favorable structure inside functional paper, the adsorption point and the adsorption contact area increased by the rough surface of fiber bundles, the addition of sepiolite and the ordered molecular chains of copolymers destroyed. So, the relative humidity could be adjusted to 55 % ± 3 within 2 hours and was stable with functional paper. At the same time, 1.11 ppm sulfur dioxide and 2.98 ppm ammonia could be effectively adsorbed in 10 and 12 h, respectively, by 1 g of paper in a 5 L container. The pH of the paper was adjusted to neutral with tourmaline, even if the pH was changed by acidic or alkaline gas absorption. Therefore, for long-term organic cultural relic preservation, preparing a constant-humidity and clean environment is of great significance. This is possible through this paper.

Efficient Congo Red Removal Using Porous Cellulose/Gelatin/Sepiolite Gel Beads: Assembly, Characterization, and Adsorption Mechanism.

Porous sustainable cellulose/gelatin/sepiolite gel beads were fabricated via an efficient ‘hydrophilic assembly–floating droplet’ two-step method to remove Congo red (CR) from wastewater. The beads comprised microcrystalline cellulose and gelatin, forming a dual network framework, and sepiolite, which acted as a functional component to reinforce the network. The as-prepared gel beads were characterized using FTIR, SEM, XRD, and TGA, with the results indicating a highly porous structure that was also thermally stable. A batch adsorption experiment for CR was performed and evaluated as a function of pH, sepiolite addition, contact time, temperature, and initial concentration. The kinetics and isotherm data obtained were in agreement with the pseudo-second-order kinetic model and the Langmuir isotherm, with a maximum monolayer capacity of 279.3 mg·g−1 for CR at 303 K. Moreover, thermodynamic analysis demonstrated the spontaneous and endothermic nature of the dye uptake. Importantly, even when subjected to five regeneration cycles, the gel beads retained 87% of their original adsorption value, suggesting their suitability as an efficient and reusable material for dye wastewater treatments.

Pozzolanic activity of calcinated low-grade natural sepiolite and its influence on the hydration of cement

In this study, the pozzolanic activity of low-grade natural sepiolite was enhanced by calcination for further utilizing as a supplementary cementitious material. Sampled sepiolite was calcinated at 400, 600, 700, 800, 900, and 1000 °C, and the calcinated sepiolite were characterized and respectively blending with pastes for examining their rheological and hydration behaviors. It was found the pozzolanic activity of sepiolite was maybe mainly determined by the active Si phase content, and 800-SP showed the highest pozzolanic activity. The rheological behaviors of fresh paste blended with sepiolite calcinated at different temperatures shows obviously different. In early curing stage, the addition of sepiolite obviously accelerated the cement hydration. But in later curing stage, comparing with U-SP, the calcinated sepiolite showed hindering effect on cement hydration, and this effect was obviously regular with the increasing calcinated temperature. Additionally, by comparing with all pastes blended with sepiolite, which blended with 800-SP showed the highest compressive strength values.

Highly permeable and selective sepiolite hybrid mixed matrix carbon membranes supported on plate carbon substrates for gas separation

The development of promising dopants is essential for fabricating mixed matrix membranes with high gas separation performance. Here, mixed matrix carbon membranes (MMCMs) were produced by using polyimide as precursor and sepiolite as dopants on plate phenolic resin-based carbon supports via the processes of membrane formation and pyrolysis. The thermal stability, surface functional groups, microstructure and morphology of membrane samples were characterized by the thermogravimetric analysis, Fourier-transform infrared spectroscopy, X-ray diffraction and scanning electron microscope, respectively. The effects of sepiolite amount on the microstructure and property of MMCMs were investigated. Besides, the change tendency of gas permeation with permeation temperature and permeation pressure was further examined. The results showed that the addition of sepiolite enhanced the thermal stability of the precursor membranes and the microstructural compactness of resultant MMCMs. Especially, it greatly improved the gas permeability and selectivity of MMCMs. The maximum separation performance was reached for MMCMs made by the sepiolite content of 0.2%, with the gas permeabilities of 8412.9Barrer (H2), 6711.5Barrer (CO2), 6062.0 Barrer (O2) and 220.9 Barrer (N2), and the selectivities of 38.1 (H2/N2), 30.4 (CO2/N2) and 27.4 (O2/N2). Moreover, the MMCMs can directly concentrate the mole fraction of O2 from compressed air to 93%.

Preparation, optimization, and characterization of chitosan-sepiolite nanocomposite films for wound healing

In this study, a series of chitosan-sepiolite (CS-SEP) nanocomposites films were prepared by using a conventional solution casting method. The effect of sepiolite on physicochemical and biological properties of the prepared nanocomposite films was studied by various techniques such as Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and x-ray diffraction (XRD) to name a few. In WCA measurements, the decrease of contact angle from 78.51° (CS) to 71.29° (CS7SEP3) reaffirms the water holding nature of sepiolite, which enables to create moist environment essentially required for wound healing. Further, addition of sepiolite tremendously increased WVTR, folding endurance, porosity, and blood clotting ability of the prepared nanocomposites. Furthermore, CS-SEP nanocomposite films exhibit better antibacterial activity than that of chitosan against gram positive (B. subtilis) and gram negative bacteria (E. coli). Moreover, the percentage of hemolysis and degradation study indicated that the prepared nanocomposite films were non-hemolytic in nature and decomposed nearly 40% in four weeks. In addition, cytotoxicity assay showed that the prepared nanocomposite film i.e. CS7SEP3 exhibited better cell viability and cell proliferation rate against L929 mouse fibroblast cells as compared to CS and hence, the prepared nanocomposite film can be used as a promising candidate for wound management.

Hydrophobic composite foams based on nanocellulose-sepiolite for oil sorption applications

TEMPO (2,2,6,6-tetramethylpiperidin-1-oxyl)-oxidized cellulose nanofibers (CNF) were assembled to fibrous clay sepiolite (SEP) by means of a high shear homogenizer and an ultrasound treatment followed by lyophilization using three different methods: normal freezing, directional freezing, and a sequential combination of both methods. Methyltrimethoxysilane (MTMS) was grafted to the foam surface by the vapor deposition method to introduce hydrophobicity to the resulting materials. Both the SEP addition (for the normal and directional freezing methods) and the refreezing preparation procedure enhanced the compressive strength of the foams, showing compressive moduli in the range from 28 to 103 kPa for foams loaded with 20% w/w sepiolite. Mercury intrusion porosimetry shows that the average pore diameters were in the range of 30–45 µm depending on the freezing method. This large porosity leads to materials with very low apparent density, around 6 mg/cm3, and very high porosity >99.5%. In addition, water contact angle measurement and Fourier-transform infrared spectroscopy (FTIR) were applied to confirm the foam hydrophobicity, which is suitable for use as an oil sorbent. The sorption ability of these composite foams has been tested using olive and motor oils as models of organophilic liquid adsorbates, observing a maximum sorption capacity of 138 and 90 g/g, respectively.

Cooperative Effects of Cellulose Nanocrystals and Sepiolite When Combined on Ionic Liquid Plasticised Chitosan Materials.

Cellulose nanocrystals (CNCs) and/or sepiolite (SPT) were thermomechanically mixed with un-plasticised chitosan and chitosan/carboxymethyl cellulose (CMC) blends plasticised with 1-ethyl-3-methylimidazolium acetate ([C2mim][OAc]). Examination of the morphology of these materials indicates that SPT aggregates were reduced when CNCs or [C2mim][OAc] were present. Inclusion of CNCs and/or SPT had a greater effect on material properties when the matrices were un-plasticised. Addition of SPT or CNCs altered the crystalline structure of the un-plasticised chitosan matrix. Moreover, a combination of SPT and CNCs was more effective at suppressing re-crystallisation. Nonetheless, the mechanical properties and surface hydrophobicity were more related to CNC/SPT–biopolymer interactions. The un-plasticised bionanocomposites generally showed increased relaxation temperatures, enhanced tensile strength, and reduced surface wettability. For the [C2mim][OAc] plasticised matrices, the ionic liquid (IL) dominates the interactions with the biopolymers such that the effect of the nanofillers is diminished. However, for the [C2mim][OAc] plasticised chitosan/CMC matrix, CNCs and SPT acted synergistically suppressing re-crystallisation but resulting in increased tensile strength.

Fire Protective Surface Coating Containing Nanoparticles for Marine Composite Laminates

A poly(vinyl alcohol) (PVA)-based coating containing ammonium polyphosphate (APP) and sepiolite nanofillers (SP) and supported by a glass fabric was developed to fire-protect a glass-fiber-reinforced unsaturated-polyester-based (UP) polymer (GFRP). The fire behavior and thermal stability of the PVA coatings were characterized using thermogravimetric analysis (TGA) and a cone calorimeter. The coatings’ residues were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results from the cone calorimeter showed that the addition of sepiolite significantly improves the flame retardancy of PVA/APP/SP coatings. The addition of both additives promoted the formation of a cohesive layer composed of a silico-phosphate structure resulting from the reactivity between APP and SP. The fire resistance of the composite laminate protected by PVA coatings was evaluated using a cone calorimeter by measuring the temperature of the back face. Photogrammetry was used to assess the swelling of residues after heat exposure. The interaction between APP and SP in PVA coating leads to the formation of an effective thermal barrier layer. The presence of SP reduces the layer expansion but greatly decreases the backside temperature during the initial period of exposure. The effect was assigned to high thermal stability of the layer and its ability to dissipate heat by re-radiation.

Influence of the Solidification Process on the Mechanical Properties of Solid-State Drawn PCL/Sepiolite Nanocomposite Tapes

In this research, poly(ε-caprolactone) (PCL) was melt-mixed with sepiolite nanoclays in a twin-screw extruder. In a subsequent step, the extruded films were drawn in the solid state to highly oriented nanocomposite films or tapes. A twin-screw extruder equipped with a Sultzer mixer for improved mixing in combination with a bench top drawing unit was used to prepare oriented nanocomposite tapes of different sepiolite loading and draw ratios. In order to study the influence of the solidification step on the drawability of the materials, different cooling procedures were applied prior to drawing. Optical microscopy images showed that slow or fast solidification using different chill rolls settings (open or closed) for the cast films resulted in different morphological conditions for subsequent drawing. The addition of sepiolite nanofillers led to nucleation and faster crystallization kinetics and oriented tapes which deformed by homogenous deformation rather than necking. The addition of sepiolite significantly improved the mechanical properties of both undrawn and drawn PCL tapes and Young’s modulus (1.5 GPa) and tensile strength (360 MPa) for composites based on 4 wt% sepiolite were among the highest ever reported for PCL nanocomposites. Interestingly, samples cooled with open chill rolls (slow crystallization) showed the highest modulus while solidification with closed rolls (fast crystallization) showed the highest tensile strength after drawing.

Effect of glauconite and sepiolite together with oil supplementation on pellet quality criteria in broiler and laying hen concentrate

The aim of this study was conducted to determine the effect of glauconite and sepiolite together with oil usage on pellet quality criteria in broiler and laying concentrate. In recent years, no study was found in the literature focusing on the use of glauconite in pelleting. Therefore, the effect of sepiolite and glauconite on pellet quality criteria was investigated in pellet production in our study. Concentrated feeds were made by the rations research team, whose raw materials were taken from a commercial feed factory. Pellet concentrate feeds were produced with 7 batch (each batch was 100 kg). Disc that has hole diameter 3.5 mm and wall thickness of 70 mm was used in production. The study was carried out in two different. Firstly, 1% and 2% levels sepiolite and glauconite were added to each concentrate in pellet production without adding oil. Secondly, 1% and 2% levels sepiolite and glauconite and 1% vegetable oil were added to the concentrates during pelleting. In both experiments, the trial consisted of 1 control and 4 trial groups.The end of study, dry matter level of the pellets was statistically influenced by the addition of sepiolite and glauconite in broiler and laying hen pellet concentrates (with or without vegetable oil addition) (p<0.05). Pellet durability index of broiler and laying hens pellet concentrates (with or without vegetable oil addition) were not statistically affected by the addition of sepiolite and glauconite. Pellet water activity of broiler and laying hens pellet concentrates (with vegetable oil addition). were not statistically affected by the addition of sepiolite and glauconite. However, pellet water activity of laying hens pellet concentrates (without vegetable oil addition) were statistically affected by the addition of sepiolite and glauconite (p<0.05). Pellet water activity has the lowest value especially in the groups in which glauconite is added. Consequently, vegetable oil addition did not affect pellet durability and water activity, but it did not adversely affect pellet production by increasing the dry matter level of pellets. Due to the positive effects of glauconite and sepiolite on the dry matter and water activity of pellets, it was concluded that glauconite can be used as feed additive in broiler and laying hens pellets and it can improve the pellet storage conditions.

Inhibition of pyrite oxidation using PropS-SH/sepiolite composite coatings for the source control of acid mine drainage.

Pyrite, as one of the most abundant sulfide minerals, can be easily oxidized to generate acid mine drainage (AMD). In the present study, a new composite passivator named PropS-SH/sepiolite (PSPT) using γ-mercaptopropyltrimethoxysilane (PropS-SH) as the main passivator and natural sepiolite particles as filler was fabricated and used to suppress the oxidation of pyrite. Electrochemical tests and chemical leaching experiments were carried out to evaluate the passivation performance of PSPT coatings with different amount of sepiolite particles on pyrite oxidation. The results showed that the addition of appropriate sepiolite could significantly improve the inhibition ability of PropS-SH against pyrite oxidation. However, excessive addition of sepiolite particles weakened the inhibition ability of the PSPT coatings owing to aggregations of sepiolite. Additionally, the coating mechanism of PSPT on pyrite was also proposed based on the characterization of FTIR, XPS, and 29SiNMR measurements, which indicated that sepiolite particles could be embedded in PropS-SH network through oxygen bridges, thus improving the stability of the composite coatings.

Effect of glauconite, sepiolite and oil supplementation on pellet quality parameters in poultry compound feed

The aim of this study was conducted to determine the effect of glauconite, sepiolite and oil on pellet quality parameters in poultry compound feed. There are limited studies with supplementation of different levels of sepiolite and glauconite clay minerals in diets about pellet quality during the pelleting processes. Thus, the effect of sepiolite and glauconite on pellet quality parameters was investigated in our study. The study was carried out in two different. Firstly, 1% and 2% levels sepiolite and glauconite were added to each concentrate in pellet production without adding oil. Secondly, 1% and 2% levels of sepiolite, glauconite and 1% oil were added to the concentrates during pelleting. In both experiments, the trial consisted of 1 control and 4 trial groups. Pellet concentrate feeds were produced with 7 batches (each batch was 100 kg). The disc that has hole diameter 3.5 mm and wall thickness of 70 mm was used in production. At the end of the study, dry matter level of the pellets was statistically influenced by the addition of sepiolite, glauconite and oil in poultry compound pellet feed The lowest pellet dry matter value belongs to C and CO groups (p&lt;0.05). Pellet durability index of poultry compound pellet feed were not statistically affected by the addition of sepiolite, glauconite and oil. Pellet water activity of poultry compound pellet feed were not statistically affected by the addition of sepiolite, glauconite and oil. However, the pellet water activity of laying hens pellet concentrates (without oil addition) were statistically affected by the addition of sepiolite and glauconite (p&lt;0.05). Pellet water activity has the lowest value especially in the groups in which glauconite is added. In conclusion, these findings showed that glauconite, sepiolite and oil can be used for pellet quality in poultry compound feed (especially laying hen feed) and improve pellet storage conditions and due to the positive effect of glauconite and sepiolite on pellet water activity.

A novel humidity regulating material hydrothermally synthetized from concrete waste

To promote the recycling of construction wastes, a low temperature (≤ 200 ℃) hydrothermal technology for solidifying construction (concrete) waste into a tough and humidity self-regulating material has been developed, in which more than 60% of concrete waste could be recycled. During the process, the whole concrete waste including aggregates could be converted hydrothermally into tobermorite or C–S–H. The formed tobermorite could not only enhance the strength but also improve the porosity and thus enhance the humidity regulating capability. The maximum flexural strength reached up to 22 MPa, and the increased porosity could provide a good moisture adsorption/desorption performance (170 g/m2). With the addition of sepiolite, the performance could be further improved (250 g/m2) due to the coexistence of the formed tobermorite and remained sepiolite. The materials also exerted a remarkable damping effect on relative humidity (RH) variation indoors, e.g., the RH variation even could be decreased to 1/3 compared to that of empty reference (no humidity regulating materials were used).

A novel and improved hydrophilic vanadium oxide-based cathode for aqueous Zn-ion batteries

The preparation of cathode materials for aqueous Zn-ion batteries (ZIBs) with excellent electrochemical properties is an attractive research focus. However, the large size and high polarization of hydrated zinc ions limit the diffusion kinetics of Zn2+/electron, and the side reactions in the system also affect the performance of the battery. Herein, we present a novel hydrophilic self-supporting composite cathode for aqueous ZIBs, which employs V10O24·12H2O as active materials, acid-treated natural sepiolite and carbon nanotubes as structural and interfacial modifiers. It is demonstrated that the devices exhibit a high specific capacity of 191 mAh g−1 at a current density of 500 mA g−1 (93.6% retention after 100 cycles) and excellent rate performance. This good electrochemical performance is mainly related to the formation of hydrophilic surface/interface, the design of self-supporting and the good conductivity of the composite electrode. Specifically, the addition of acid-treated natural sepiolite and carbon nanotubes could improve the mechanical properties, hydrophilicity and the conductivity of electrode materials, respectively, making this strategy a promising choice for ZIBs.

Improving Thermal Conductivity Coefficient in Oriented Strand Lumber (OSL) Using Sepiolite.

An issue in engineered wood products, like oriented strand lumber (OSL), is the low thermal conductivity coefficient of raw material, preventing the fast transfer of heat into the core of composite mats. The aim of this paper is to investigate the effect of sepiolite at nanoscale with aspect ratio of 1:15, in mixture with urea-formaldehyde resin (UF), and its effect on thermal conductivity coefficient of the final panel. Sepiolite was mixed with UF resin for 20 min prior to being sprayed onto wood strips in a rotary drum. Ten percent of sepiolite was mixed with the resin, based on the dry weight of UF resin. OSL panels with two resin contents, namely 8% and 10%, were manufactured. Temperature was measured at the core section of the mat at 5-second intervals, using a digital thermometer. The thermal conductivity coefficient of OSL specimens was calculated based on Fourier’s Law for heat conduction. With regard to the fact that an improved thermal conductivity would ultimately be translated into a more effective polymerization of the resin, hardness of the panel was measured, at different depths of penetration of the Janka ball, to find out how the improved conductivity affected the hardness of the produced composite panels. The measurement of core temperature in OSL panels revealed that sepiolite-treated panels with 10% resin content had a higher core temperature in comparison to the ones containing 8% resin. Furthermore, it was revealed that the addition of sepiolite increased thermal conductivity in OSL panels made with 8% and 10% resin contents, by 36% and 40%, respectively. The addition of sepiolite significantly increased hardness values in all penetration depths. Hardness increased as sepiolite content increased. Considering the fact that the amount of sepiolite content was very low, and therefore it could not physically impact hardness increase, the significant increase in hardness values was attributed to the improvement in the thermal conductivity of panels and subsequent, more complete, curing of resin.

Effects of sepiolite and biochar on microbial diversity in acid red soil from southern China

ABSTRACTSepiolite and biochar can immobilize heavy metals and organic pollutants in soil effectively, but their impact on the soil microbial community and diversity is still unclear. High-throughput Illumina MiSeq method was used to study the effects of sepiolite and biochar on the diversity of microbial communities in acid red soil amended with cadmium and atrazine. A total of 47,472 microbiological Operational Taxonomic Units (OTUs) were found in all the treated soil samples. Sepiolite and biochar enriched the diversity of soil microbes at different classification levels and OTUs, but the effect of biochar was stronger than that of sepiolite. A Venn diagram showed that compared with other treatments, adding 2% biochar could promote the growth of specific microbes, which is better than the case for 5% biochar. The heat map of species abundance cluster showed that the dominant microbes in soil were different for different treatment doses of sepiolite and biochar. Among all the soil treatments, the top ten dominant bacterial phyla (from high to low dominance) were: Actinobacteria, Proteobacteria, Firmicutes, Bacteroidetes, Acidobacteria, Gemmatimonadetes, Chloroflexi, Planctomycetes, Cyanobacteria­, and Verrucomicrobia. The addition of sepiolite and biochar promoted the restoration of the microbial community diversity in contaminated soil.

Effect of sepiolite addition on fibre-cement based on MgO-SiO₂ systems

The addition of sepiolite in fibre-cement is analysed as a possible additive constituent of MgO-SiO2 binders. In order to optimise the Mg-SiO2 cementitious system in fibre-cement sheets, small cement replacement (1 and 2 wt%) by sepiolite is introduced and its effects are studied, firstly, in hardened cement pastes and, later, in fibre-cement systems. When used only in cement pastes, non-destructive studies are employed to assess flexural performance over time as well as the possible reactivity between additive and cement, proving that Elastic Modulus is increased. When sepiolite is introduced in fibre-cement, the properties of the slurry suspensions and its interference in the Hatschek process are studied. It is shown that sepiolite addition increases floc size of MgO-SiO2 systems. Finally, flexural tests are performed to understand the outcome of this additive of the mechanical performance of the samples, proving that sepiolite improves the product homogeneity, which is essential for industrial applications.

Effect of Citric Acid on immobilization of Heavy Metals

Heavy metal pollution of soils has become increasingly serious, and chemical immobilization is usually used to remediate heavy metal contaminated soil. With changing environmental conditions, the immobilization heavy metal may be released again, which is a risk to ecological environment and human health. In the study, sepiolite is applied to the heavy metal contaminated soil (0.5%, 2%, 5%), training for 60 days, adding 2mmol/Kg, 10mmol/Kg and 20mmol/Kg citric acid into the contaminated soil. This research adopted characteristic leaching procedure (TCLP) to evaluate the remedition effect and BCR to analysis the change of heavy metal species of soil. The results show that, no adding citric acid, the content of TCLP-Cd decreased with the increase of sepiolite addition ratio. When the sepiolite addition ratio was 5%, TCLP-Cd is lower than its of TCLP international standards. It shows that sepiolite can effectively remediate heavy metals in soil. When the proportion of sepiolite is constant, low concentration of citric acid is helpful to remedition, while high concentration of citric acid is not conducive to remediation of heavy metals. BCR method showed that the exchangeable content increased with the increase of citric acid concentration, but the oxidizable content decreased, indicating that citric acid could increase the bioavailability of heavy metals.

Iron–sepiolite magnetorheological fluids with improved performances

This work is focused on the characterization and magnetorheological (MR) study of MR fluids composed of iron particles and sepiolite fibers, used as a thickening agent. The work is aimed at (a) understanding the effect of the sepiolite addition on the MR response and (b) finding an appropriate formulation allowing a good sedimentation stability keeping a relatively low off-state viscosity and providing an enhanced MR effect. In the presence of an applied magnetic field, the composite MR fluid exhibits a yielding behavior with a progressive enhancement of the field-induced static yield stress with increasing volume fractions of both iron and sepiolite. Such an effect is attributed to a friction between gap-spanning aggregates composed of iron particles and sepiolite–oil viscoplastic matrix. The field-induced dynamic yield stress shows an initial increase with the sepiolite concentration (explained by a partial expulsion of the sepiolite fibers from the aggregates) followed by a decrease. The proposed mechanisms are supported by developed qualitative theoretical models, one of which is based on the homogenization approach of Château et al. [J. Rheol. 52, 489–506 (2008)]. From the practical point of view, the formulation containing 10 vol. % of iron and 4 vol. % of sepiolite seems to combine a perfect sedimentation stability with moderate values of the plastic viscosity and of the off-state static yield stress (only ∼5 Pa) and with a relatively important static and dynamic yield stress enhancement (30% and 60%, respectively).