Wollastonite Fibers Research Articles

Mitigating autogenic shrinkage in high‐performance concrete using wollastonite: A structural enhancement approach

AbstractThis study investigates the influence of wollastonite fiber as a reinforcement in high‐performance concrete (HPC), focusing on its potential to mitigate autogenic shrinkage and enhance overall structural properties. HPC known for its superior strength and low permeability, often suffers from intensified autogenic shrinkage, leading to micro‐cracking and compromising durability. To address this challenge, wollastonite was incorporated at different substitutions (0%, 5%, 10%, and 15%) for both cement and aggregate. The experimental program involved a systematic evaluation of compressive strength, flexural strength, porosity, water absorption, and corrosion resistance with tests conducted at different curing periods. We found that the addition of 10% wollastonite significantly enhances compressive strength (up to 20% after 90 days) and flexural strength (maximum improvement of 21%). The water permeability was decreased by 29% and improved resistance to steel reinforcement corrosion, demonstrating enhanced durability compared to conventional HPC. However, diminishing returns were observed at higher wollastonite replacement levels (15%), indicating a threshold beyond which mechanical and durability benefits were reduced due to potential issues with fiber dispersion and workability. Our findings suggest that wollastonite is a promising, cost‐effective additive for improving HPC. The study contributes new understandings into optimizing HPC mixtures for greater durability and sustainability, while also reducing the environmental footprint through partial cement replacement. Future research is needed to explore the long‐term performance of wollastonite‐reinforced HPC under different environmental conditions and its combination with other supplementary cementitious materials for further enhancement.

Enhancement of flame retardancy in ceramic polymer composite materials with ammonium polyphosphate/melamine cyanurate

AbstractTo enhance the flame‐retardant characteristics of ceramifiable polyethylene (PE) composites, a composite flame retardant comprising ammonium polyphosphate (APP) and melamine cyanurate (MCA) was integrated. This addition markedly bolstered their flame‐retardant attributes. A meticulous exploration was conducted to ascertain the impacts of APP and MCA on the ceramifiable PE composites' visible morphology, mechanical robustness, and dimensional constancy, and to study the phase transition and microstructure deformation during sintering. Findings underscored that the amalgamation of APP/MCA markedly enhanced the flame resistance of these ceramifiable composites, registering a limiting oxygen index of 25.6% and achieving the vertical burning test (UL‐94) rating of V‐0. The collaborative flame‐retardant action of APP/MCA significantly enhanced the flame resistance of the PE composites while effectively mitigating the composite's propensity to drip. Upon detailed phase analysis, a eutectic reaction was observed between APP and wollastonite fiber, culminating in the genesis of a novel crystalline phase, calcium pyrophosphate (Ca2P2O7). When subjected to elevated temperatures, glass–ceramics manifest with both crystalline and vitreous phases. The proportion of the vitreous phase plays a pivotal role in influencing the ceramic's overall performance.

Fiber-reinforced friction materials: Experimental, statistical and computational universal analysis

In this paper, the experimental, statistical and computational universal analysis methods applicable to most fiber-reinforced friction materials (FMs) are presented for four natural wollastonite fibers (WFs) with different length-to-diameter (L/D) ratios. Machine learning (ML) methods for friction coefficient prediction of friction materials are compared and screened. Numerical statistics and calculations are used in conjunction with the use of finite element (FE) models to determine the performance metrics and friction wear mechanisms of FMs. The experimental and computational results show that the artificial neural network (ANN) model performs the best in COF prediction with an accuracy of 0.961. The friction fluctuation, friction stability and integrated friction performance of the WF-containing samples are better than those of the blank samples. For the first time, the FE model was used to explain the swirling phenomenon on the wear surface of FMs. This study provides new ways and ideas for the design, experimentation, data processing and application of friction composites.

Improving the Creep Resistance of Hardened Cement Paste through the Addition of Wollastonite Microfibers: Evaluation Using the Micro-Indentation Technique

This paper evaluates the creep behavior of wollastonite-microfiber-reinforced hardened cement paste. A parametric study was performed for cementitious mixtures with partial replacement of cement using wollastonite. The samples were subjected to uniaxial compression and microindentation experiments. The compressive strength significantly improved by up to 30% for the mixture containing 10% wollastonite fiber. Microindentation experiments were performed to evaluate the creep response and time-dependent performance of both the control and the wollastonite-fiber-reinforced samples. Approximately 36% increase in creep modulus was observed with 10% wollastonite fiber content. This indicates a significant improvement in creep behavior, which can be attributed to the micro-reinforcing effect of the fibers. No significant impact was observed for time characteristic of creep with the incorporation of wollastonite fibers. Overall, the study establishes a cost-effective, sustainable, and efficient route to enhance the creep behavior of hardened cement paste for a wide range of infrastructural applications.

Effect of glass frits on ceramifiable properties of polyethylene composites

AbstractCeramification of polymer composites is an excellent method for enhancing the flame retardancy of the materials. The low temperature softening glass frit added in the composites plays a key role in the ceramification process of the composites. Ceramizable polyethylene (PE)/wollastonite fiber (WF) composites are processed by mixing with three types of glass frit. The ceramic residues formed were characterized by the linear shrinkage, weight loss, flexural strength, apparent porosity, and self‐supporting property measurements. The density and strength of the ceramic increased with the increasing sintering temperature, but were affected by the wettability and fluidity of the glass frit. The addition of glass frit can increase the thermal decomposition temperature of PE. X‐ray diffraction (XRD) analysis found the form of a new phase of hydroxyapatite (Ca10(PO4)6(OH)2) in the ceramifiable PE/WF composites by adding phosphate glass frit, which improved the self‐supporting properties of the ceramic residues.

Ultrahigh Low-Temperature Toughness of Polypropylene Composites with Low Ductile-Brittle Transition Temperature by Introducing Traces of Needlelike Wollastonite

In order to survive harsh settings, such as outer space, deep sea and high plains, needlelike wollastonite fibers (WF) were incorporated into polypropylene/ethylene octene block copolymer/β-nucleating agent (PP/OBC/β-NA) blends with the hope of tailoring the low-temperature toughness. The results revealed that WF showed very satisfactory toughening effects in the PP/OBC/β-NA/WF composites at low temperature (–20 °C). The impact strength of the WF-0.05 was as high as 32.1 kJ/m2 at −20 °C, which was 286.6% higher than that of the WF-0 sample, and even 832.6% higher than that of the pure PP sample. SEM characterization showed that by simultaneously adding WF and β-NAs, much coarse and tremendous plastic deformation appeared in the WF-0.05 after impacting. The low-temperature toughening mechanism is systematically discussed. The increase of β-crystallinity, caused by the synergy of β-nucleating agent and WF fillers, was mainly responsible for the enhancement of the impact strength of the composites with WF. On the other hand, when the transmitting of the stress, the overlapping of the stress and the hindering effect of WF on cracks occurred simultaneously; it resulted in the excellent low temperature toughness of the PP composites. Such outstanding-performance material with the advantages of facile processing and low cost is unprecedented. It shows a promising future application in many fields, especially aerospace, navigation, and the automotive industry.

Comparative study on the mechanical and thermal properties of polycarbonate composites reinforced by KH570/SA/SDBS modified wollastonite fibers

AbstractIn order to increase the applicability of wollastonite (Wo) in polycarbonate (PC) polymer, surface modification of Wo was carried out using different modifiers containing silane coupling agent KH570, stearic acid (SA), and sodium dodecylbenzene sulfonate. The physical, physic‐chemical, and application properties of modified Wo were evaluated. Results showed that KH570 modified Wo had narrower particle size distribution, higher absolute zeta potential and were more evenly distributed. Scanning electron microscope study confirmed their changes in morphology and aspect ratio during the modification process. The tensile strength of Wo/PC composites, in which KH570‐modified Wo was used were superior to those in which original Wo or other modifiers modified samples were used. The maximum tensile strength of 65 ± 1 MPa was obtained by adding 15 wt% KH570‐modified Wo. Thermal analysis indicated that adding Wo to the polycarbonate increased the residue content but decreased the thermal decomposition temperature and glass transition temperature slightly, regardless of unmodified or modified Wo. These results indicated that the well‐modified Wo mineral had the potential to replace expensive carbon and glass fibers as fillers in polycarbonate products.

Effects of Wollastonite Fiber and Styrene–Butadiene Latex Polymer on the Long-Term Durability of Cement-Based Repair Materials

Concrete structures are constructed in various geographical environments and climates, and frequently fail to fulfill their original functions over time due to issues such as aging and damage. Research on concrete structure repair materials is being conducted to solve these problems. This study evaluated the durability of a repair material composed of ultra-rapid hardening cement, styrene–butadiene (SB) latex polymer, and wollastonite mineral fiber. The performance targets were as follows: compressive strength of 20 MPa at 1 day of age and 45 MPa at 28 days of age, chloride ion charge passed of less than 1000 Coulombs, carbonation depth of 20 mm or less, and resistance to repeated freezing and thawing (relative dynamic modulus of elasticity) of 80% or more. The ultra-rapid hardening cement:silica sand ratio of 1:1.5 was the experimental variable, and the unit weight of each material in the mix proportion was determined to satisfy the flow requirement of 200 ± 5 mm. This flow ensured sufficient fluidity for spraying, which is the most widely used method for applying repair material. Wollastonite mineral fiber and SB latex polymer were added at 3% and 5% of the unit weight of the binder, respectively. The mechanical property of the repair material was evaluated through compressive strength, and durability was evaluated through chloride ion penetration, alkali resistance, resistance to carbonation, water absorption, and repeated freezing and thawing tests. The compressive strength satisfied both target values, regardless of the addition of SB latex polymer and wollastonite mineral fiber. The chloride ion penetration test, which was used as an indicator of durability, showed that mixtures without SB latex and wollastonite mineral fiber were not satisfied the target charge passed of 1000 Coulombs, while mixtures with latex and mineral fiber reached the target value. Notably, the co-addition of latex and wollastonite fiber showed the highest resistance to chloride ion penetration, alkali ion, carbonation, repeated freezing and thawing, and the least absorption. The results confirmed that the durability of the repair material based on ultra-rapid hardening cement was most effectively improved by the co-addition of SB latex polymer and wollastonite mineral fiber.

Improved shape stability and ceramifiable properties of ceramifiable polyethylene composites by crystallization reaction

Wollastonite fiber (WF) was added to further improve shape stability and ceramifiable properties of polyethylene (PE)/ mica/ phosphate glass frits (PGF) composites. To evaluate shape stability property, the surface cracking of ceramic-like residues obtained by calcining at different temperatures were observed, and dimensional variation and self-supporting properties of the residues were measured. The ceramifiable properties (flexural strength and apparent porosity) of the PE composites were also investigated. Results showed that the addition of WF reduced surface cracking effectively, improved dimensional stability and self-supporting properties. Furthermore, at high temperatures, the flexural strength of the PE composites was enhanced by incorporation of WF, accompanying with the reduction of porosity. X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used to analyze the effect of WF on the performance of the PE composites. Results showed that there was a novel crystalline phase hydroxyapatite (HAP) was formed within the residues. During the heat treatment process, WF acted as the promoter to participate in a crystallization reaction with molten phosphate glassy phase by the way of ion diffusion to generate the HAP. The crystallization thermodynamics demonstrated that the reaction could occur spontaneously above 873 K. Crystallization reaction improved the crystallinity, which was beneficial to enhance the flexural strength. Moreover, crystallization kinetic analysis was investigated. The results indicated that the growth of crystal HAP was promoted with the increase of temperature and the flow of glassy phase was limited, which improved the shape stability. Therefore, it was inferred that crystallization reaction played an important role in the improvement of the shape stability and ceramifiable properties of PE composite simultaneously.

Fracture response of wollastonite fiber-reinforced cementitious composites: Evaluation using micro-indentation and finite element simulation

The paper presents indentation studies on wollastonite fiber incorporated cementitious systems. The acicular nature of the fibers is poised to delay the coalescence of micro-cracks in such systems thus leading to tougher building materials. Towards that end, load-penetration depth results from the indentation studies are employed to ascertain elastic and fracture properties of wollastonite-incorporated cementitious composites. While up to 10% mass-based cement-replacement by wollastonite results in comparable elastic moduli as compared to conventional binders, the fracture toughness increases by as much as 33%. In order to gain insights into the toughening mechanisms brought about by the fine fibers, a microstructure-guided numerical simulation strategy is adopted towards effective fracture performance prediction. The performance enhancement of the wollastonite systems is corroborated by the finite element-based simulations carried out on the virtual microstructures that accurately capture the heterogeneity of such systems. Besides fracture performance enhancement, the wollastonite-incorporated cementitious systems also contribute towards development of sustainable cement replacing compositions. Moreover, the micromechanical predictive tool developed in this study facilitate efficient means to tune the materials structure for desired performance.

Preparation and fireproofing performance of the wollastonite-metakaolin-based geopolymer foams

This paper aims to investigate the physical properties and fire resistance of wollastonite-metakaolin-based geopolymer foams (WMGFs). Both compressive and flexure strengths of WMGFs are significantly improved since wollastonite fibers possess inherent stiffness and provide effective crack control. Meanwhile, wollastonite addition promotes viscosity of geopolymer slurry to some extent and then determines pores formation in foaming process, which is also crucial for mechanical strength development. The thermal conductivity of the specimens rises triflingly with elevated wollastonite addition corresponding to slightly decrease in porosity. Owing to the steady skeleton structure of WMGFs, the highest reverse-side temperature of sliced blocks is merely 202.7 °C after exposed to fire for 3 h, showing that the reduction in thermal conductivity has no negative impact on fire resistance of specimens. Physicochemical stability of wollastonite under high temperature and alkaline environment is confirmed to be vital for sustaining integrated porous skeleton structure of geopolymer foams. Therefore, geopolymer foams reinforced by wollastonite possess extraordinary mechanical strength and fire resistance, revealing strong possibility for fire protection.

Finite Element-Based Numerical Simulations to Evaluate the Influence of Wollastonite Microfibers on the Dynamic Compressive Behavior of Cementitious Composites.

This paper investigates the dynamic compressive behavior of wollastonite fiber-reinforced cementitious mortars using multiscale numerical simulations. The rate dependent behavior of the multiphase heterogeneous systems is captured in a multiscale framework that implements continuum damage towards effective property prediction. The influence of wollastonite fiber content (% by mass) as cement replacement on the dynamic compressive strength and energy absorption capacity is thereafter elucidated. An average compressive strength gain of 40% is obtained for mortars with 10% wollastonite fiber content as cement replacement, as compared to the control mortar at a strain rate of 200/s. The rate dependent constitutive responses enable the computation of energy absorption, which serves as a comparative measure for elucidating the material resistance to impact loads. Approximately a 45% increase in the dynamic energy absorption capacity is observed for the mixture containing 10% wollastonite fibers, as compared to the control case. Overall, the study establishes wollastonite fibers as a sustainable and dynamic performance-enhanced alternative for partial cement replacement. Moreover, the multiscale numerical simulation approach for performance prediction can provide an efficient means for the materials designers and engineers to optimize the size and dosage of wollastonite fibers for desired mechanical performance under dynamic loading conditions.

ВЛИЯНИЕ ВОЛЛАСТОНИТА НА МЕХАНИЧЕСКИЕ СВОЙСТВА БЕТОНА

Improvement of the physical and mechanical properties of cement composites should be accompanied by the disposal of industrial waste of various generation. Therefore, the paper proposes the principles of controlling the strength properties of concrete, which consist in the complex effect of wollastonite obtained from boron production waste on the processes of structure formation of the cement matrix. When this introduced in an amount of 2-8 wt. % wollastonite has a dual function as a mineral filler and a reinforcing fiber. It has been proven that in the presence of wollastonite, the concrete mix becomes lighter without reducing its physical and mechanical properties. It was revealed that the early strength for all the developed compositions with the addition of wollastonite increases due to the acceleration of hydration processes. Calcium silicate, which is wollastonite CaSiO3, has a close chemical composition with cement clinker, especially with Ca2SiO4 belite and Ca3SiO5 alite. This leads to the formation of a chemically homogeneous and, as a result, hardened microstructure. Elongated wollastonite fibers with good adhesion to the cement stone provide effective micro-reinforcement of the concrete composite. Using the results will lead to the possibility of designing high-strength concretes, including for special structures

Research on the influence of wollastonite fibers on the stability of foam extinguishment agent and its effect on the extinguishing efficiency of pool fire

SummaryAqueous film‐forming foam (AFFF) is a frequently used foam extinguishment agent for oil fires, but the foam stability of AFFF is not perfect, which results in poor fire extinguishing performance. In order to improve the foam stability of AFFF, wollastonite fibers were explored to increase the performance of foam extinguishment agent. The influences of wollastonite fibers' concentration on foam extinguishment agent's stability are studied. When the concentration of wollastonite fibers is 30.00 g/100 mL, the drainage time is prolonged, which is the best among all the formulas. Moreover, the fire resistance and fire‐fighting performances are increased significantly due to the incorporation of wollastonite fibers. In order to reveal the effect of wollastonite fibers on the stability of foam extinguishment agent, the structure of the foam and the diameter of the bubbles are investigated. The results show that the complexity and compactness of foam layer's structure are very important for foam stability, and the fire‐extinguishing performance is improved due to the introduction of wollastonite fibers.

Mechanical properties and mechanism of wollastonite fibers reinforced oil well cement

Wollastonite fibers (WFs) were used to reinforce the oil well cement (OWC). The compressive strength, flexural strength, tensile strength and stress–strain curves of WFs reinforced oil well cement pastes (OWCPs) were studied. The strengthening mechanism was studied by analyzing WF-reinforced OWCPs with scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), nitrogen adsorption method (BJH), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The results show that compared with those for pure OWCP, the compressive strength, flexural strength and tensile strength of the OWCP with a WF content of 15% cured at 90 °C for 7 days increased by 34.64%, 98.79% and 46.46% respectively. In addition, the toughness of the OWCP with a WF content of 15% improved. The microstructure analysis showed that a good interface adhesion appeared between the WFs and OWCP due to the presence of chemical bonds. The addition of WFs reduced the content of cement hydration products, namely lamellar CH, by reacting with CH to form hydrated calcium silicate (C-S-H), which improved the mechanical properties of the OWCPs. Adding WFs improved the pore structure distribution of the OWCPs. The improvement in the toughness of the OWCP with a WF content of 15% was attributed to the “crack bridging” and “fiber pull- out” toughening mechanisms.

Hybrid Effect of Wollastonite Fiber and Carbon Fiber on the Mechanical Properties of Oil Well Cement Pastes

Oil well cement is a type of natural brittle material that cannot be used directly in cementing operations. Fiber is a type of material that can effectively improve the strength and toughness of cement stone, and hybrid fiber materials can more effectively improve the performance of a cement sample. To overcome the natural defects of oil well cement, the new mineral fiber, i.e., wollastonite fiber, and common carbon fiber were used in oil well cement, and the micromorphology, mechanical properties, and stress‐strain behavior of the cement were evaluated. The experimental results show that carbon fiber and wollastonite fiber are randomly distributed in the cement paste. The mechanical properties of the cement paste are improved by bridging and pulling out. The compressive strength, flexural strength, and impact strength of cement stone containing only carbon fiber or wollastonite fiber are higher than those of the pure cement, but too many fibers are not conducive to the development of mechanical properties. A mixture of 0.3% carbon fiber with 6% wollastonite fiber in oil well cement slurry results in a greater increase in compressive strength, flexural strength, and impact strength. In addition, compared with blank cement stone, the strain of the mixed cement stone increases substantially, and the elastic modulus decreases by 37.8%. The experimental results supply technical support for the design of a high‐performance cement slurry system.

Chrysotile fibers in tissue adjacent to laryngeal squamous cell carcinoma in cases with a history of occupational asbestos exposure.

Asbestos describes a group of naturally occurring fibrous silicate mineral compounds that have been associated with a number of respiratory maladies, including mesothelioma and lung cancer. Additionally, based primarily on epidemiologic studies, asbestos has been implicated as a risk factor for laryngeal and pharyngeal squamous cell carcinoma (SCC). The chief objective of this work was to strengthen existing evidence via empirical demonstration of persistent asbestos fibers embedded in the tissue surrounding laryngeal and pharyngeal SCC, thus providing a more definitive biological link between exposure and disease. Six human papillomavirus (HPV)-negative laryngeal (n = 4) and pharyngeal (n = 2) SCC cases with a history working in an asbestos-exposed occupation were selected from a large population-based case-control study of head and neck cancer. A laryngeal SCC case with no history of occupational asbestos exposure was included as a control. Tissue cores were obtained from adjacent non-neoplastic tissue in tumor blocks from the initial primary tumor resection, and mineral fiber analysis was performed using a scanning electron microscope equipped with an energy dispersive x-ray analyzer (EDXA). Chrysotile asbestos fiber bundles were identified in 3/6 of evaluated cases with a history of occupational asbestos exposure. All 3 cases had tumors originating in the larynx. In addition, a wollastonite fiber of unclear significance was identified one of the HPV-negative pharyngeal SCC cases. No mineral fibers were identified in the adjacent tissue of a case without occupational exposure. The presence of asbestos fibers in epithelial tissue surrounding laryngeal SCC in cases with a history of occupational asbestos exposure adds a key line of physical evidence implicating asbestos as an etiologic factor.

Preparation and electrical properties of wollastonite coated with antimony-doped tin oxide nanoparticles

Composite antistatic powders of wollastonite coated with antimony-doped tin oxide nanoparticles (Sb-SnO2/wollastonite, SSW) were prepared by heterogeneous nucleation method. The samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Scanning electronic microscopy (SEM), Transmission electron microscopy (TEM) and Energy-dispersive X-ray spectrometry (EDS). Effects of pH value, hydrolysis temperature, coating amount, SbCl3 to SnCl4·5H2O molar ratio, calcination temperature and time on the resistivity of SSW powders were studied. It was shown that after coated with Sb-SnO2 particles, the whiteness of wollastonite has been decreased from 91.7 to 90.5, the specific surface area has been increased from 1.41 to 3.65m2/g, the volume resistivity has been reduced from 3.36 × 1010 Ω·cm to 0.85 × 105 Ω·cm. The fibriform wollastonite particles were coated with a layer of 30-50 nm thickness of well crystallized and uniform antimony-doped tin oxide (Sb-SnO2). A possible mechanism for coating of Sb-SnO2 nanoparticles on the surface of wollastonite fiber was proposed.

Formation and Biomimetic Deposition of Bone-like Hydroxyapatite on Wollastonite-gypsum Composites

Bone cements are often used for bone repair and fixation. The main objective of formulating a bone cement is to achieve structure and properties similarity to bone. In addition, bioactivity of a bone cement provides a major advantage that helps achieving better binding and interaction with the surrounding tissues. In the current study, gypsum was used as a matrix for a composite that comprises highly crystalline prestine and acid-treated wollastonite (CaSiO3) fibers. Composites made by mixing their powder precursors with deionized water at room temperature, were investigated for their composition using X-ray diffraction (XRD) and Thermogravimetric Analysis (TGA), for their microstructure using Scanning Electron Microscopy (SEM), for their compressive strengths and modulus of elasticity, and for setting time measurements. In addition, cement composites were evaluated for their preliminary bioactivity in a protein-free Simulated Body Fluid (SBF) for up to 14 days. Results show the improvement of mechanical properties and bioactivity of the composites using acid-treated wollastonite fibers. This was attributed to the formation of hydrated silica layer on the surface of the acid-treated fibers which improved the binding with the gypsum matrix and provided nucleating sites for the deposition of bone-like apatite spherolites from SBF media.

Influence of wollastonite shape and amount on tribo-performance of non-asbestos organic brake friction composites

In the present investigation, applicability of wollastonite as a potential non-asbestos based fibre/filler cum friction modifier is explored taking in to account the shapes of the wollastonite used for manufacturing the brake friction composite. Hence, brake friction composites containing wollastonite in the form of powder and fibres are prepared and characterized for their physical, mechanical and tribological properties. Experimental results indicated that wollastonite in the form of powder, improve the coefficient of friction and fade performance, whereas wollastonite in the form of fibres enhanced the wear and recovery performance of these brake friction composites. The wear surface morphology of the friction composites having wollastonite fibres aided in the formation of smooth contact plateaus which are in turn beneficial in decreasing the wear. From the study it is clear that not only judicious selection of ingredients for making brake friction composites is important but also their shapes help in formulating composites having desired friction and wear attributes.