Abstract

Introduction

Wastewater in area of focus

Nanotechnology in water purifcation

Nano‑adsorption

Microbial agent

Nanocomposites

Types of nanocomposites

Synthesis modes for nanocomposites

Graphene oxide‑based composites as a disinfectant

Zinc oxide nanocomposites as disinfectant

Copper oxide nanocomposites

Silver/silver oxide nanocomposites

Titanium oxide nanocomposites

Discussion

Conclusion

References

Abstract

     Water is crucial for the existence of life. The world, however, is facing a global water crisis. There are variety of microorganisms, gases and other toxins responsible for water contamination. Various types of nanomaterials exist that have enormous potential to treat contaminated water (water containing metal toxins or specific organic or inorganic impurities) due to their unique properties such as a high surface area and their ability to work effectively even at low concentrations. In recent years, scientists have been giving considerable attention to the application of nanocomposites for water purification, wastewater treatment, microorganism elimination, chemical contaminants, heavy metals removal and so forth. The incorporation of different nanofillers such as carbon nanotubes, graphene oxide, 2D materials, zinc oxide, titanium dioxide, copper and silver nanoparticles into polymeric materials has facilitated important advances, such as suppressing the accumulation of pollutants and foulants, improving the hydrophilicity, increasing the efficiency and improving the mechanical properties. This review discusses leading advances in the development of nanocomposites for antimicrobial and wastewater treatment with the aim of providing an improved understanding of nanocomposites and their applications in antimicrobial and wastewater treatment.

Introduction

     Water is a basic requirement for human life. However, we are far from meeting global requirements for clean water, and this issue will continue to grow over the time (Hillie and Hlophe 2007; Elwakeel et al. 2020b). The demand of clean drinking water is rising as a result of the deterioration of water quality, global climate change and population growth (Tchobanoglous et al. 1991; Elwakeel et al. 2020d). Emissions of organic dyes and heavy metal ions from the paper, leather and textile industries are a serious problem, as they are potentially mutagenic and carcinogenic. To meet environmental requirements, wastewater contaminated with these organic and inorganic species need to be treated before being discharged (Santhosh et al. 2016; Elwakeel et al. 2021). Heavy metals are widely used in various industries for many purposes, including mining and pigment production. Synthetic dyes are also an important type of pollutant, and their sources for water contamination include the textile, pulp and paper, tinting, printing, painting and tanning industries. The removal of dye from such wastewater is a challenging task, as pigments and synthetic dyes are biodegradation-resistant and remain in the environment for a long time. The destruction and handling of organic dyes is therefore an important issue, and a cost-efective method for removing dye substances from wastewater has been developed (Santhosh et al. 2016; Elwakeel et al. 2018).

Conclusion

     This paper explores the existing nanocomposites used to extract heavy metal ions and dyes from wastewater as efective adsorbents. This article addressed recent developments in nanomaterials as economical and environmentally sustainable water purifcation adsorbents. This review highlights fve commonly used nanomaterials/nanoparticles that are used in most existing nanocomposites. In this review, we concluded that TiO2-based nanocomposites have been used for photodegradation activity by most of the researchers in the literature. Silver-based nanocomposites are mostly used for antimicrobial activity. Silver and GO-based nanocomposites were used for the removal of green dye, anionic dye and Cu(II). Copper-based nanocomposites are mostly used for adsorption and photodegradation activity. Zinc oxide nanocomposites are used for adsorption, antimicrobial and photodegradation activity. Finally, we concluded that GO also greatly contributes to the improvement of other materials’ efciency. Further, much needs to be done to control the two-dimensional GO sheets for advanced technologies in the future. There are many challenges and obstacles associated with handling wastewater, and many precautions are required to prevent environmental and health problems. Therefore, new modern wastewater treatment equipment should be versatile, low-cost and commercially efective.

Abstract

1. Introduction

2. Experimental

3. Results and discussion

4. Conclusion

Conflict of Interest

Supplementary Information

References

Abstract

     This study investigates the effect of graphene oxide (GO) on the mechanical and corrosion behavior, antibacterial performance, and cell response of Mg—Zn—Mn (MZM) nanocomposite. MZM/GO nanocomposites with different amounts of GO (i.e., 0.5wt%, 1.0wt%, and 1.5wt%) were fabricated by the semi-powder metallurgy method. The influence of GO on the MZM nanocomposite was analyzed through the hardness, compressive, corrosion, antibacterial, and cytotoxicity tests. The experimental results showed that, with the increase in the amount of GO (0.5wt% and 1.5wt%), the hardness value, compressive strength, and antibacterial performance of the MZM nanocomposite increased, whereas the cell viability and osteogenesis level decreased after the addition of 1.5wt% GO. Moreover, the electrochemical examination results showed that the corrosion behavior of the MZM alloy was significantly enhanced after encapsulation in 0.5wt% GO. In summary, MZM nanocomposites reinforced with GO can be used for implant applications because of their antibacterial performance and mechanical property.

Introduction

     Currently, because magnesium (Mg) alloys have more benefits than common metallic materials, ceramics, and biodegradable polymers, their biomedical applications have been increasing. In terms of mechanical features, metals have higher mechanical strength and fracture toughness than ceramics or polymers; thus, metals are more appropriate for load-bearing usages than ceramics or polymers [1–2]. The density of human cortical bone (1.75 g/cm3 ) is similar to the density of Mg (1.738 g/cm3 ) and Mg alloys (1.75–1.85 g/cm3 ) but lower than the density of biomedical titanium alloy Ti6Al4V (4.47 g/cm3 ) [3–4]. In terms of biocompatibility, certain amounts of Mg ions in the human body are connected with many metabolic reactions and biological mechanisms [5–6]. Mg alloys are suitable orthopedic and cardiovascular implants because further surgery to remove them is not needed [7–8]. However, an important drawback of Mgbased implants is that they do not have good resistance against corrosion in physiological environments [9]. Mechanical strength could be significantly reduced by rapid and uncontrollable corrosion processes, which leads to premature failure [10]. Moreover, the health of patients who have such implants could be at risk because of the evolution of hydrogen gas and alkalinization of the environments close to the interface between implant and tissue [11]. Therefore, to achieve the secure deployment of biomedical devices, the degradation/corrosion rate of Mg alloys needs to be controlled [12]. In this context, several methods, such as alloying, powder metallurgy (PM), and surface modification strategies, have been used in an extensive number of studies that aimed to solve the problem of corrosion in Mg alloys [13–14]. Among the best methods to enhance the corrosion resistance of porous Mg are PM processes, such as mechanical alloying [15–17].

Conclusion

     In this study, using the semi-powder metallurgy method, different contents of GO were embedded in the Mg–Zn–Mn (MZM) matrix to prepare MZM/xGO nanocomposites for orthopedic applications. The corrosion performance and the 24 20 16 12 8 4 0 0 −0.5 −1.0 −1.5 −2.0 Extension / mm MZM/GO Graphene oxide Graphene oxide Graphene oxide Graphene oxide Crack Crack (a) (c) 1.5GO 0.5GO 1GO MZM (b) MZM composite MZM/0.5GO MZM/1GO MZM/1.5GO 49 59 63 64 Compression strength / N 4820 17810 19960 9620 1.12 1.31 1.44 0.72 Force / (10 3 N) Micro hardness, HV Extension / mm Material nanocomposite Fig. 10.    (a) Typical compressive curves and (b) hardness and compressive strength values of the MZM/xGO nanocomposites; (c) schematic diagram of the crack deflection toughening mechanisms of GO in the MZM/xGO nanocomposites. S. Jabbarzare et al., Effect of graphene oxide on the corrosion, mechanical and biological properties of Mg-based … 317 mechanical and biological characteristics of the MZM/xGO nanocomposites were analyzed. The microstructural assessment showed that a uniform distribution was achieved in the MZM/0.5GO and MZM/1GO nanocomposite specimens. However, agglomeration was observed in the MZM/1.5GO nanocomposite specimen. The results showed that the GO content, hardness value, and compressive strength are positively associated. In this context, the MZM/1GO nanocomposite has higher hardness value and compressive strength than the Mg-based nanocomposite without GO. The MZM/ 0.5GO nanocomposite exhibited a nearly comparable corrosion resistance to the MZM/1GO nanocomposite, even though the incorporation of more GO has an unfavorable effect on the Rct value of the MZM matrix. The MTT assay results showed that the MZM/1GO nanocomposite increased the MG63 cell viability and ALP activity, indicating the increasing level of osteogenesis. The results of the analysis of antibacterial activity showed that the MZM/1.5GO nanocomposite had a noticeable effect on antibacterial effectiveness toward bacteria, including Salmonella–Shigella and Klebsiella pneumoniae. In summary, the results indicate the possibility of utilizing the MZM/1GO nanocomposite for implant applications with effective anti-infection characteristics.

Abstract

Keywords

1. Introduction

2. Filler materials

3. Thermal properties of polymer composites

4. Summary

CRediT authorship contribution statement

Declaration of Competing Interest

References

Abstract

Polymer composites are commonly used in industry and are used in various fields such as the aircraft industry, automobile industry, electronic industry and packaging industry, etc. due to their diverse versatility, low cost, light weight, and outstanding chemical consistency. For new technologies, especially in aerospace and aeronautics, thermal properties have become a significant parameter. A reference to a number of research studies is made in this paper and the role of fillers in polymers is studied. The main purpose of this analysis is to identify any possible patterns that control and dictate the thermal properties in polymeric composites.

1. Introduction

There is an increasing demand and development in the field of material science since the last two decades and to fit the requirements of the out-dated products available in the market, material scientists have evolved the polymer composites to outperform their original functions that is being rigid and not buckling. Polymer composite has a large variety of industrial applications due to its many desirable properties ranging from high thermal conductivity to excellent chemical resistance. Polymer composites are mostly anisotropic in nature, these results in them having good mechanical, electrical and thermal properties. Compared to isotropic materials composite materials are much more effective and efficient.

There are many conventional filler materials that are using as a filler material in polymer composites for different applications [1–5]. The ever-alarming concern about the environment can also be put to rest by using the construction, industrial and animal waste as filler which is reinforced with the polymer matrix and enhances the mechanical, physical and thermal properties. However, epoxy polymeric composite despite having so many industrial applications, possess poor mechanical properties. Silica is one of the most ideal inorganic compounds that can be used as reinforcement material along with other inorganic materials. Research also indicates that plant fibres are often used as fillers because of their renewability and high availability. The main sources of natural fibres are both inexhaustible and nonsustainable for example sisal, palm oil and flax. These are then used to make composite material.

Presently the composites that are used in thermal fillers do not provide any electrical properties. Carbon Nanotubes (CNTs) and Graphene Nanotubes (GNTs) have excellent mechanical, thermal and electrical properties. CNTs and GNTs have a strong lattice which gives them good physical and thermal properties [6–8].

With these polymer composite materials integrating into the electronics industry, the developments in thermal properties, especially thermal dissipation heavily influences the performance, reliability and lifetime of these devices. Hence thermal conductivity of these polymer composite materials plays a huge role in a lot of industries. Exhaust heat affects the functioning and the properties of the equipment. A good thermal management system is necessary to protect the equipment from any heat related damages

1- Introduction

2- Modeling of FG-CNTRC laminated cylindrical shells with NPR

3- Solution procedure

4- Numerical results and discussion

5- Concluding remarks

References

Abstract

This paper presents an investigation on the nonlinear flexural vibrations of carbon nanotube-reinforced composite (CNTRC) laminated cylindrical shells with negative Poisson’s ratios in thermal environments. The material properties of the CNTRCs are temperature-dependent and the functionally graded (FG) in a piece-wise pattern in the thickness direction of the shell. An extended Voigt (rule of mixture) model is employed to estimate the CNTRC material properties. The motion equations for the nonlinear flexural vibration of FG-CNTRC laminated cylindrical shells are based on the Reddy’s third order shear deformation theory and the von Kármán-type kinematic nonlinearity, and the effects of thermal environmental conditions are included. The nonlinear vibration solutions for the FG-CNTRC laminated cylindrical shells can be obtained by applying a singular perturbation technique along with a two-step perturbation approach. The effects of material property gradient, the temperature variation, shell geometric parameter, stacking sequence as well as the end conditions on the vibration characteristics of CNTRC laminated cylindrical shells are discussed in detail through a parametric study. The results show that negative Poisson’s ratio has a significant effect on the linear and nonlinear vibration characteristics of CNTRC laminated cylindrical shells.

Introduction

Composite laminated shell structures are widely used in structural applications owing to their specific higher strength-to-weight and stiffness-to-weight ratios, improved chemical and environmental resistance and the ability to tailor properties. These shell structures may be exposed to combined action of loading and various environmental conditions during their service life. This may lead to large amplitude vibration of the shells where the shell deflection may be in the order of the shell thickness. In this regard, the nonlinear vibration of composite laminated shells in thermal environments is an important consideration in engineering analysis and design. Many studies have been carried out on the nonlinear vibration behavior of composite laminated shells [1–6]. As pointed out by Shen [6], unlike in the cases of composite laminated plates, there are unresolved discrepancies between the vibration results obtained by different authors for composite laminated cylindrical shells, in particular for the cases of angle-ply laminated cylindrical shells. With growing interest in the development and manufacturing of high-performance and lightweight composite shells, auxetic composite materials and structures appear to be potential candidates. A consequence of material possessing a negative Poisson’s ratio (NPR) is that many of its mechanical properties are predicted to be enhanced by classical elasticity theory. The auxetic materials have a wide variety of multifunctional applications, for example, in energy storage, biomedical, acoustics, photonics, and thermal management [7]. There are two ways to construct auxetic structures. One way is to use auxetic metamaterial as sandwich core [8]. Another way is to change the stacking sequence and orientation of the laminates to obtain auxetic laminated shells. The production of larger values of negative Poisson’s ratio requires both a particular stacking sequence and the individual ply material being highly anisotropic [9].

1- Introduction

2- Deposition techniques for 3D printing of biomaterials

3- Materials for 3D printing of biomaterials

4- Applications of 3D printed biomaterials

5- 4D printing and its applications for biomaterials

6- Conclusions and future perspectives

References

Introduction

Three-dimensional printing (3D printing) or additive manufacturing (AM) promises to produce complex devices formulated from biomaterials and bioinspired materials from designs that are patient-specific. Since its advent as presurgical visualization technique and fabrication of tooling molds, 3D printing has evolved to yield bespoke devices, implants, scaffolds, diagnostic devices, and drug-delivery systems. As a result of recent public interest and affordable printing platforms, there is the desire to utilize this exciting technology for personalized health care. However, before AM can become a ubiquitous tool for the regeneration of complex tissues, such as bone, cartilage, muscles, vessels, nerves, and complex organs with multifaceted three-dimensional microarchitecture (e.g., kidneys, lymphoid organs), a number of technological limitations must be overcome. The development of advanced bioinks for 3D and 4D printing through the rational design of novel materials and their implementation as functional biomaterials through ever-expanding deposition techniques has improved the diversity and functionality of printed constructs outside of the traditional biofabrication window [1]. While there is the necessity for a compromise between suitability for purpose and biocompatibility, recent developments in materials science and bioink formulations have resulted in an improved range of solutions for biofabrication platforms. New biologically relevant printing formulations with highly consistent and accurate deposition parameters, attractive mechanical properties, high cytocompatibility, and the ability to modulate cellular functions are now being developed and offer prospects as biomaterials for use in a multitude of different applications; however, further work is needed before these novel materials become common place. In this chapter, we explore some of the approaches being pursued to achieve these targets in common 3D and 4D printing techniques, including an overview of the state-of-the-art technologies and formulations used in novel materials and bioinks, which are currently being developed, the techniques which are being utilized to produce 3D and 4D constructs, and the applications for which these new materials may be employed in. Key examples are highlighted to demonstrate the progress of this emerging technology and limitations to its development identified.

1- Introduction

2- Experimental

3- Results and discussion

4- Conclusions

References

Abstract

To develop effective strategies for removing phenolic compounds, in-situ graphene oxide/manganese oxide (GO/MnOX, X = 2, 3/4) composites were fabricated via a sustainable method by synchronously utilizing manganese ions and acidic liquid waste during synthesis of GO. Comparatively, traditionally ex-situ GO/MnO2 composites were synthesized to verify the difference between in-situ and ex-situ synthesis. Based on the schematic and mass flow analysis, in-situ synthesis exhibited better atom economy and less waste emission than ex-situ synthesis. Then, the results of batch experiments exhibited that GO/MnOX composites possessed higher removal efficiency and wider pH range for p-cresol (p-CR) and p-tert-butylphenol (p-TBP) than GO/MnO2 composites. The maximum removal capacities of GO/MnOX composites were 107.68 mg/g for p-CR and 135.41 mg/g for p-TBP. And GO/MnOX composites could retain high removal efficiency for p-TBP (>90%) after five recycles. For in-situ GO/MnOX composites, GO sheets not only promoted the adsorption of phenolic compounds and by-products, but also enhanced the oxidation capacity of MnOX via an electron transfer interaction. Especially, the detection of ring cleavage products indicated further oxidation for p-TBP. Possessing an eco-friendly fabrication strategy and augmented adsorption-oxidation capability, in-situ GO/MnOX composites are expected to be applied in the removal of phenolic compounds.

Introduction

Phenolic compounds have given rise to emerging concerns regarding human health and ecosystems due to their widespread use in the pharmaceutical, petroleum and petrochemical, pesticide, plastic, and paper industries (Danquah et al., 2018). Consisting of a hydroxyl group bonded directly to a benzene ring, phenolic compounds possess a stable conjugated system, leading to biological accumulation and poor biodegradability (Ou et al., 2018). Thus, an urgent need exists to develop an efficient method for removing phenolic compounds (Villar da Gama et al., 2018; Zhong et al., 2018). Various methods, including chemical oxidation (Jiang et al., 2015), adsorption (Villar da Gama et al., 2018), and membrane separation (Zagklis and Paraskeva, 2015), have been reported to remove phenolic compounds. Among them, oxidation constitutes an effective and attractive method due to the potential to disrupt the structural stability of pollutants (Wang et al., 2015). Manganese oxides, ubiquitous in natural soil and synthetic materials, are traditional and cost-effective adsorbents and oxidants in wastewater treatment. Especially, manganese oxides are able to oxidize various aromatic Lewis bases, such as phenolic and aniline compounds (Grebel et al., 2016; Wang et al., 2018b). Previous studies demonstrated that phenolic compounds are susceptible to oxidation by manganese dioxide (MnO2) through sequential one electrontransfer reactions, forming a series of intermediate products (Abdullah et al., 2017; Remucal and Ginder-Vogel, 2014). However, the intermediate products, such as phenolic multimer and benzoquinones, would be released back into the aqueous solution.

1- Introduction

2- The multiscale modeling framework

3- Multi-scale modeling procedure

4- Model validation

5- Damage evolution of the wind turbine blade

6- Conclusions

References

Abstract

Composite structures have been widely used in wind turbine equipment for their high stiffness to mass ratio and high strength. A major concern in the use of composite materials is their susceptibility to various micro damage, such as fiber breakage and matrix crack, which will lead to macroscopic structural fracture. In this paper, a multi-scale modeling strategy is proposed to investigate failure mechanisms and damage evolution of composite blades with initial defects from microscopic damage (including fiber fractures and matrix cracks) to macroscopic fracture. At the microscopic scale, an isoparametric micromechanical model is developed to calculate microscopic stresses and simulate microscopic damage. At the laminar scale, the classic laminate theory is employed to evaluate the laminate stiffness. At the structural scale, a reverse modeling technology is proposed to accurately acquire structural dimensions of a wind turbine blade, and a macroscopic 3D model is implemented into ANSYS/LS-DYNA software. By comparing with the experimental data, it is demonstrated that the proposed multi-scale method is suitable to predict mechanical properties of complex composite structures effectively.

Introduction

As one of the most abundant renewable and green resources, wind energy is increasingly playing an important role in reducing CO2 emission for environmental protection and has viable commercial values [1-3]. It has been one of the most important new energies due to its availability and accessibility. To maximize the energy that can be harvested from wind, an efficient and safe design of a wind turbine, including its strength and damage tolerance, is essential. Complex dynamic loads may lead to a catastrophic failure of wind turbine blades [4-5]. According to the data from Caithness windfarm information forum [6], blade failure is the most common accident of wind turbines, estimated at around 3800 incidents per annum. Therefore, it is crucial for researchers to have a better understanding of the failure mechanisms, which will improve the safety and reliability of wind turbines. Wind turbine blades, which are normally manufactured by continuous glass fiber-reinforced resin matrix composites, accounts for nearly one-fifth of the cost of a wind turbine. Experimental [7-8] and theoretical methods [9-10] have been used to investigate the mechanical features and damage mechanisms of composite blades. However, for a heterogeneous material, it is difficult to reveal the intrinsic relations between its macroscopic and microscopic characteristics, such as fiber arrangements and fiber shape [11-14], by experimental methods. As a result, more and more researchers are using numerical methods to study their mechanical properties and optimally design composite wind turbine blades. Haselbach et al. [15] studied ultimate failure of a 34m long blade.

1- Introduction

2- Experimental program

3- Discussion of results of DIC on FRP materials

4- Conclusions

References

Abstract

Accurately measured strains are critical when investigating the application of Fiber Reinforced Polymer (FRP) materials, but traditional mechanical strain measurement methods have several critical drawbacks related to the installation process and the recording capabilities of the devices. FRP materials typically used in the civil engineering field feature large asymmetries and heterogeneity originated from the manual installation procedures, as opposed to the highly controlled FRP fabrication methods used in other fields that result in more homogeneous materials. The feasibility of using an optical full-field Digital Image Correlation (DIC) technique for measurement of strain fields on FRP materials used in the civil engineering industry has been investigated and the level of error in the DIC method when using more traditional methods was determined. The main advantage of using DIC over more traditional methods, which is the capacity of DIC to measure full field strains instead of strains at isolated points, has been demonstrated by providing exemplar measurements of various specimens of FRP materials. The reported strain fields are examples of what was obtained during an experimental campaign to understand the behavior of FRP anchors and other materials. The main conclusions drawn from the observation of those strain fields are discussed.

Introduction

Determining operational limits and safe working strains, as identified in international guidelines such as ACI 440.2R [1] and CNR-DT 200 [2], is paramount to the application of Fiber Reinforced Polymers (FRP) in civil engineering. One of the most common applications of FRP materials in civil engineering is as Externally Bonded Reinforcement systems (EBR-FRP) to strengthen existing structures. Accurate measurement of the FRP strains when under load in such applications provides insight and understanding of the load distribution within the FRP material. When conducting tests, a number of traditional instruments are available for the measurement of displacements and strains, including Linear Variable Differential Transformer devices (LVDT) or foil Strain Gauges (SG). These instruments have been in use for decades, but feature some significant drawbacks as the installation of the instrumentation is typically invasive, expensive, cumbersome or timeconsuming. But the most significant deficiency of these devices is that they only measure displacements or strains at specific, isolated points. Spatial strain fields allow both general strain distributions and localized strain concentrations to be observed. Spatial strain field measurements are critical when investigating EBR-FRP systems, where the FRP materials are non-homogenous and highly anisotropic as opposed to more traditional metallic or cementitious materials. This effect is exacerbated by “low-tech” in situ manufacturing methodologies typically involved in the installation of EBR-FRP systems. The manufacturing approaches typically used in EBR-FRP systems result in low fiber volume fractions, which is defined as the ratio between the volume of fibers and the total volume, and in large variations in fiber orientation both in-plane and through thickness due to the lack of molding/compression force. Modern full-field imaging techniques such as Digital Image Correlation (DIC), thermograph and particle image velocimetry enable the determination of strain fields during testing.

1- Introduction

2- Experimental

3- Data analysis and discussion

4- Conclusions

References

Abstract

Scope of the present work is to visualize with infrared thermography the impact damaging of basalt-based composites. Two types of specimens are prepared with basalt fibres embedded in a polypropylene (PP) matrix, which is used either pure, or modified with the addition of a coupling agent. The latter improves the fibre/matrix interface strength providing in practice a material of different characteristics. Specimens are impacted at low velocity/energy with a modified Charpy pendulum while the infrared camera views the surface opposite to the impacted one and records thermal images in time sequence. The acquired sequences are post-processed to obtain information which may be exploited for the material characterization. In particular, the attention is to identify initiation and propagation of the impact damage and the overall delamination extension, as well as to discriminate likely differences between grafted and un-grafted composites in their impact-reaction. As a main result, the effects of the specimen’s fixture on the damage extension are highlighted.

Introduction

The growing awareness towards the environment is demanding for environmentally friendly materials, so moving the attention from the petrochemical resources towards more natural ones. Within this scenario, basalt fibres are attracting consideration from the scientific community because they seem to be adequate as reinforcement of composites and to comply with the environment safeguard rules [1]. In fact, basalt is available in nature in volcanic rocks and can be reduced in fibres, which are well suited to be used as reinforcement of both thermoset and thermoplastic matrices to create different types of composite materials. Basalt fibres are ecologically pure and, unlike the conventional asbestos/glass ones, which can cause health hazards, are non-hazardous as they are spun with a diameter higher than 6 m [2]. In addition, abrasion of basalt only produces thick fibre fragments that pose no respiratory hazard, even if, as with most substances, care in its handling is recommended. Basalt fibres are non-reactive toward water and do not cause air pollution and have a wide spectrum of applications. They are mainly produced for structural and electro-technical purposes including electromagnetic shielding structures, automobiles, aircraft, ships and household appliance components [3-5].

1- Introduction

2- Materials and methods

3- Results and discussion

4- Conclusion

References

Abstract

In this work, the mechanical properties, stress-strain behaviors, and microstructure of brucite fiber reinforced cement-based composites are determined. The results reveal that the incorporation of brucite fiber limits the compressive strength reinforcement of cement-based composite but leads to a significant increase of tensile strength by 136% and flexural strength by 73%. The employment of brucite fiber increases the fracture toughness S Kc and Q Kc of the cement-based composite by 450% and 98%. The incorporation of brucite fiber increases the linear elastic fracture toughness energy GF by 455% and elastic-plastic fracture toughness energy JC by 279%. The constitutive model of brucite fiber reinforced cement paste is also established. The diameter of the brucite fiber bundle is 1.5-16.3μm, and the diameter of the single dispersed fiber is around 45-110nm. There are about 15-363 single fibers in a bundle. Due to the brucite fiber possesses an intrinsic fibrous anisotropy, and network topology, the brucite fiber reinforced cement composites exhibit advantages of greater bending strength and crack bridging, as well as better crack resistance properties.

Introduction

Development of construction project applications causes an urgent need to explore higher performance construction materials possessing high strength, toughness, cracking resistance, durability, etc. Fiber reinforced cement composite (FRCC) is one of the engineering materials, which are extensively used to enhance the structural resistance and performance under various loading combinations. However, ordinary FRCC is costly, and the production of FRCC increases the energy consumption and carbon footprint, one possible solution is to employ eco-friendly and economic fibers in FRCC to address the question. Brucite fiber is a kind of naturally existing fibrous mineral which is formed in an alkaline medium [1]. The main chemical composition of brucite is Mg(OH)2, and the crystal structure of brucite fiber belongs to the trigonal crystal system and octahedron structure. The length of brucite fiber used as an additive to reinforce cement or asphalt is generally 10-80 mm [3]. Compared with other fibers such as polyester fiber, basalt fiber, and glass fiber, brucite fiber possesses excellent properties including fiber bundle-splitting, dispersing properties and compatible with the silicate cement [6, 7, 10]. Brucite fiber is also quite different from asbestos in chemical compositions, crystal structures, and chemical properties, and it has been proved that brucite fiber is a harmless mineral to the human body [3-5]. With excellent anti-alkaline property (brucite fiber exists stably in strongly alkaline medium with an alkaline loss of 2%), good mechanical performance (tensile strength is around 900 MPa) [6], reasonable price and abundant resources [5], the employment of brucite fiber is dependable and environmental in the industrial applications.