Optimal Mechanical Properties Research Articles

Mechanical properties, microstructural evolution, and environmental impacts of recycled polypropylene fiber stabilized loess

The deterioration of polypropylene fiber (PF) stabilized loess and its environmental performance are crucial factors for assessing the effectiveness of its reinforcement against frequent collapse and spalling induced by drying and wetting (D-W) cycles. For this purpose, the influence and underlying mechanisms of recycled PF content (0%, 0.1%, 0.3%, 0.5%, and 0.7%) and the number of D-W cycles on the strength, ductility, and resistance to deterioration of PF stabilized loess were investigated. Additionally, a life cycle assessment (LCA) was conducted to analyze the environmental impact of PF production. The results demonstrate a significant improvement in the strength, ductility, and resistance to deterioration of the samples upon the addition of PF. Although the initial five D-W cycles led to a decrease in specimen strength, they concurrently enhanced the ductility. Optimal mechanical properties were observed at fiber content of 0.5%, resulting in a remarkable increase in strength by 123.26% and resistance to deterioration by 25.49%. Specimens with 0.5% fiber content exhibited a three-dimensional network structure, contributing to enhanced mechanical properties compared to specimens with lower and higher fiber contents that exhibited dispersed and planar agglomerated structures. The study advocates for the use of industrial recycled PF in loess reinforcement, which exhibits significant advantages in terms of greenhouse gas emissions and energy demand when compared to virgin PF and domestic recycled PF. This innovative investigation provides insights into the durability and environmental impact of PF-stabilized loess and establishes a theoretical foundation for promoting the widespread utilization of PF in the loess foundation reinforcement market.

Zirkonya ile Güçlendirilmiş Lityum Silikat, Zirkonya ve Lityum Disilikatın Translüsensi ve Bükülme Dayanımının Karşılaştırılması

Objectives: Optimal mechanical and aesthetic properties are expected from all ceramic restorations in dentistry to maintain good prognosis. Zirconia restorations have had mechanical advantages and lithium disilicate ceramics have provided aesthetic advantages. This study intended to compare the four-point flexural strength and translucency of zirconia reinforced lithium silicate with solid zirconia and lithium disilicate. 
 Material and Methods: 90 bars (1x4x18 mm) for flexural strength test (n=30) and 30 square shaped (1x10x10 mm) samples for translucency measurement (n=10) were obtained from solid zirconia (BR-BruxZir), zirconia reinforced lithium silicate (VS-Vita Suprinity) and lithium disilicate (EM-Emax CAD) blocks. All BR samples were sintered, VS and EM were crystallized according to the manufacturer's recommendations. These samples were grinded and polished. Subsequently, they were ultrasonically cleaned and flexural strength values (MPa) were obtained in a universal test device. Color measurements were performed with a dental spectrophotometer using black and white backgrounds to determine the translucency values. Statistical analysis was performed using one-way ANOVA and Tukey HSD tests. Results: BR showed the highest mean flexural strength. There was no significant difference between EM and VS (p>0.05), while BR showed significantly different flexural strength (p

Interfacial properties of PPBES/CF composites reinforced by ammonified carbon fibers through thiol-ene click reaction

Our previous work has shown that the amino group is beneficial to improve the interface properties of PPBES/CF composites. However, the existing methods for introducing amino groups have many reaction steps, long reaction time and harsh reaction conditions. A one-step efficient click reaction can effectively avoid the above disadvantages. In this paper, 2-aminoethanethiol (AET) was grafted to CF via a thiol-ene click reaction. The reaction time has been reduced from over 9 h to just 1.5 h. The successful introduction of amino group into CF was testified by FTIR, Raman and XPS. The influence of different ratios of CF:AET on the interfacial properties of the composites was studied emphatically. When CF: AET was 1:3 (T3), the composite exhibited optimal mechanical properties. The ILSS and flexural strength of the resulting composite increased by 24.45% and 33.1%, respectively. The Tg of the PPBES/T3 composite was increased to 242 °C as verified by DMA.

Investigation on enhancing the mechanical properties of Alkali-Activated concrete based on fly ash with wollastonite

Alkali-activated concrete (AAC) is one of the cement-free concretes. It has attracted attention as a notable alternative to conventional Portland Cement Concrete (PCC) due to its superior mechanical properties and environmental benefits. This study investigates the impact of wollastonite, an industrial mineral composed chemically of calcium, silicon, and oxygen, on the mechanical properties of fly ash-based AAC. The compressive strength, split tensile strength and flexure strength at the different liquid-to-binder ratios (such as 0.35, 0.40 and 0.45) are examined. The partial replacement of fly ash with mineral wollastonite powder was carried out at different percentages varying from 5% up to 30%. Samples are cured using both oven curing and ambient curing procedures, and the test results are obtained. In the observation, the best test results are obtained at 20% replacement of fly ash with wollastonite irrespective of liquid-to-binder ratio values. Hence, the AAC with a composition of 20% wollastonite and 80% fly ash has been recognized to have optimum mechanical properties. The findings of this study would largely help to achieve the goals of “zero-waste” production.

A Study of Mechanical and Thermal Properties Polymer Blend from Polystyrene with Poly(ԑ-Caprolactone) that Obtained Using Bis(Dibenzoylmethanato)Zirconium(IV) Chloride Catalyst

Polystyrene (PS) is one form of the plastic that is most widely utilized for household application. However, plastics made from PS can pollute the environment. Hence, it is necessary to modify PS by mixing it with a biodegradable polymer like poly (ɛ-caprolactone) (PCL). The focus of this research was to determine the mechanical and thermal properties of PS/PCL polyblends. In this research, polyblend are prepared by mixing PS with PCL that acquired using the bis(dibenzoylmethanato)zirconium(IV) chloride bis(dibzm)2Zr catalyst. The method employed is solvent casting with a ratio of PS/PCL of 10/0, 10/1, 10/2, 10/3, and 10/4 (w/w). The optimum mechanical properties were obtained in 10/2 mixing which had a tensile strength of 6.72 MPa with 1.01% in elongation. Furthermore, the optimum PS/PCL polyblend was also characterized using DSC to determine its thermal properties.

Bamboo fiber strengthened poly(lactic acid) composites with enhanced interfacial compatibility through a multi-layered coating of synergistic treatment strategy

In this study, a mild and eco-friendly synergistic treatment strategy was investigated to improve the interfacial compatibility of bamboo fibers with poly(lactic acid). The characterization results in terms of the chemical structure, surface morphology, thermal properties, and water resistance properties demonstrated a homogeneous dispersion and excellent interfacial compatibility of the treated composites. The excellent interfacial compatibility is due to multi-layered coating of bamboo fibers using synergistic treatment involving dilute alkali pretreatment, polydopamine coating and silane coupling agent modification. The composites obtained using the proposed synergistic treatment strategy exhibited excellent mechanical properties. Optimal mechanical properties were observed for composites with synergistically treated bamboo fiber mass proportion of 20 %. The tensile strength, elongation at break and tensile modulus of the treated composites were increased by 63.06 %, 183.04 % and 259.04 %, respectively, compared to the untreated composites. This synergistic treatment strategy and the remarkable performance of the treated composites have a wide range of applicability in bio-composites (such as industrial packaging, automotive lightweight interiors, and consumer goods).

Synthesis and Properties of Polystyrene Composite Material with Hazelnut Shells.

In this study we evaluated the potential use of hazelnut shell powder in the production of a composite material. Polystyrene was used as a polymer matrix. This work presents the results of modifying hazelnut powder particles to create a polystyrene shell on their surfaces. Modification of the filler increased its contact angle wetted with water from θ=60.16±1.03° to θ=87.02±1.10°. Composite materials containing from 10 to 50 wt.% of modified hazelnut shell powder were prepared and studied. As a result of the experiments, it was found that the composites have optimal physical, mechanical, and operational properties at the following ratio: polystyrene 60-80 wt.%, modified hazelnut shell powder 20-40 wt.%. If the introduction of polystyrene was more than 90 wt.%, the flexural strength and Vickers hardness were quite low at the load of 200 g, and accordingly, the durability of such materials was not satisfactory. These samples are characterized by small percentages of hazelnut shells; therefore, the resulting material will be of pale, unsaturated color. The upper limit of the working temperature range for the composite lies between 265.0-376.0 °C, depending on the percentage of the hazelnut shell powder filling.

Synergic effects between vacuum residue and polymers for preparing high-performance bitumens

This research presents a laboratory study on a polymer-modified bitumens (PMBs) made with a vacuum residue (VR) as a bitumen extender. Two different PMBs were prepared, one with a plastomeric Elvaloy and the other one with an elastomeric styrene-butadiene-styrene SBS. The mechanical properties of the samples were determined by means Multi Stress Creep Recovery tests (MSCR) and temperature sweep test. The results show that polymers can improve the mechanical properties of bitumen, and the vacuum residue can be used as softening bitumen extender. However, their simultaneous presence highlights non-additive effects giving optimal mechanical properties with a lowered temperature dependence of the viscoelastic properties and a high extension of the usage temperature range. The peculiar effect of the combined action of polymers and vacuum residue was also confirmed by chemical-physical analyses. In fact, Atomic Force Microscopy (AFM) and Nuclear Magnetic Resonance (NMR) relaxometry have shown that vacuum residue and polymers are able to effectively interact with the inner structures of the bitumen to give enhanced performances, with an increased stability upon temperature changes.

Reinforcement effect of glass fiber modified by tannic acid and polyethyleneimine on polyamide 6 composites with no volatile organic compounds emission

AbstractAs an important surface modifier, conventional silane coupling agents generally emit volatile organic compounds (VOCs) like methanol or ethanol during the modification of glass fiber. To avoid VOCs emission, a phenol/amine co‐deposition of tannic acid (TA) with polyethyleneimine (PEI) was used to modify glass fiber (TP‐GF) based on mussel‐inspired surface chemistry. The reinforcement effect of TP‐GF on polyamide 6 (PA6) matrix was investigated, and the corresponding results were compared with those of γ‐aminopropyltriethoxysilane (KH550) modified glass fiber (KH550‐GF)/PA6 composites. The results showed that the interfacial adhesion between TP‐GF and PA6 matrix was superior to that between KH550‐GF and PA6 matrix, and thus TP‐GF/PA6 composites manifested more excellent mechanical properties than KH550‐GF/PA6 composites. Among these composites, TP‐GF (1.05 wt% of coating amount)/PA6 composites exhibited the optimal mechanical properties (tensile strength: 151.3 MPa, notched impact strength: 13.8 kJ m−2) compared with KH550‐GF (1.33 wt% of coating amount)/PA6 composites (tensile strength: 144.8 MPa, notched impact strength: 9.5 kJ m−2). In particular, the notched impact strength was significantly increased by 45%. Notably, there was no VOCs generation during the preparation of TP‐GF, indicating that TP‐GF could be used as an environmentally friendly glass fiber for the fabrication of high‐performance PA6 composites.

A Systematic Study on Impact of Binder Formulation on Green Body Strength of Vat-Photopolymerisation 3D Printed Silica Ceramics Used in Investment Casting.

Additive ceramics manufacturing with vat-photopolymerisation (VP) is a developing field, and the need for suitable printing materials hinders its fast growth. Binder mixtures significantly influence the mechanical properties of printed ceramic bodies by VP, considering their rheological properties, curing performances and green body characteristics. Improving mechanical characteristics and reducing cracks during printing and post-processes is mainly related to binder formulations. The study aims to develop a binder formulation to provide the printed ceramic specimens with additional green strength. The impact on mechanical properties (ultimate tensile strength, flexural strength, Young's and strain at breakpoint), viscosity and cure performance of Urethane Acrylate (UA) and thermoplastic Polyether Acrylate (PEA) oligomers to monofunctional N-Vinylpyrrolidone (NVP), 1,6-Hexanediol Diacrylate (HDDA) and Tri-functional Photocentric 34 (PC34) monomers were investigated under varying concentrations. The best mechanical characteristic was showcased when the PC34 was replaced with 20-30 wt.% of UA in the organic medium. The Thermogravimetric Analysis (TGA) and sintering test outcomes revealed that increasing the content of NVP in the organic medium (above 15 wt.%) leads to uncontrolled thermal degradation during debinding and defects on ceramic parts after sintering. The negative effect of UA on the viscosity of ceramic-loaded mixtures was controlled by eliminating the PC34 compound with NVP and HDDA, and optimum mechanical properties were achieved at 15 wt.% of NVP and 65 wt.% of HDDA. PEA is added to provide additional flexibility to the ceramic parts. It was found that strain and other mechanical parameters peaked at 15 wt.% of PEA. The study formulated the most suitable binder formulation on the green body strength of printing silica ceramics as 50 wt.% HDDA, 20 wt.% Urethane Acrylate, 15 wt.% NVP and 15 wt.% PEA.

Effect of BN content on the structural, mechanical, and dielectric properties of PDCs‐SiCN(BN) composite ceramics

AbstractHexagonal boron nitride (h‐BN) with low dielectric loss and high temperature resistance opens up new opportunities for the preparation of polymer‐derived SiCN ceramics (PDCs‐SiCN ceramics) with excellent mechanical and dielectric properties. BN‐containing polymer‐derived SiCN composite ceramics (PDCs‐SiCN(BN) composite ceramics) with different BN content were prepared via a pyrolysis process of ball‐milling‐blended Polyvinylsilazane/boron nitride (PVSZ/BN) precursors. BN is stably embedded in the SiCN tissue and tightly bound with it. The appropriate content of BN greatly improves the mechanical properties of PDCs‐SiCN ceramics, as BN reduces the number of pores and prevents crack expansion. Additionally, BN is also beneficial in lowering the dielectric loss of PDCs‐SiCN ceramics because of the weakened polarization relaxation behavior. PDCs‐SiCN (BN) composite ceramics have optimal mechanical and dielectric properties when the BN content is 1 wt%. The flexural strength, flexural modulus and compression strength of PDCs‐SiCN(BN) composite ceramics with 1 wt% BN doping content were 189.37 MPa, 46.38 GPa, and 399.02 MPa, respectively. Its average dielectric loss (tanδε) at 12.4‐18 GHz is 0.0049.

Sustainable biopolymer stabilized earthen: Utilization of chitosan biopolymer on mechanical, durability, and microstructural properties

Earthen construction materials are of great importance in terms of having natural and sustainable properties. Bio-stabilization of earthen construction is defined as the products or biological processes used to improve earthen construction properties. Earthen constructions are usually stabilized with stabilizers such as cement and calcium-based binders, but biopolymers may provide green alternatives. The main purpose of this study is to investigate the mechanical properties, durability, microstructure, and sustainability of earthen constructions stabilized with chitosan biopolymer. To achieve this, 0.5 to 3 wt% of dry soil mass chitosan was added to a base soil at 0.5 wt% increments. After the curing process was completed,the mechanical properties of the mixtures were investigated. Durability performance of stabilized soil with optimum chitosan content was measured and underpinned with microstructure. The findings indicate that the optimum mechanical and durability properties can be achieved in soils mixed with 2.5 wt% chitosan biopolymer content and 28 days of curing. Compared to control samples with 8% cement, the average compressive strength and average flexural strength were 27% and 11% higher, respectively, for soils stabilized with 2.5 wt% chitosan additives. The findings provide evidence of the benefits of chitosan biopolymer as a stabilizer for the engineering of earthen construction materials.

Miscibility and related rheological, physical, and optical properties of polycarbonate/poly(methyl methacrylate-co-phenyl methacrylate) blends: Effect of varying phenyl methacrylate composition

This study presents a systematic investigation of miscibility, rheological, and physical/optical properties of polycarbonate (PC)/poly (methyl methacrylate-co-phenyl methacrylate) (PMMA-co-PPhMA) blends with varying copolymer composition and blend weight percentage (wt%). Herein, single glass transition behavior from miscible blends was confirmed through differential scanning calorimetry (DSC) and dynamic mechanical analyzer (DMA), while further analysis revealed differences in blend homogeneity. X-ray scattering and rheometer measurements complemented this different phase homogeneity in the blends. PMMA-co-PPhMA with 14 mol% of PhMA (denoted as PMPA-2) demonstrated the most favorable miscibility and phase homogeneity among the prepared blends. Enhanced scratch resistance was achieved by increasing the wt% of PMMA-co-PPhMA, but phase inhomogeneity resulted in decreased optical transparency. The blend between PC and PMPA-2 exhibited optimal rheological, mechanical, and optical properties. This study provides insights into the PC-based blend materials for applications in various industrial fields.

Investigation of low-percentage graphene reinforcement on the mechanical behaviour of additively manufactured polyethylene terephthalate glycol composites

The current work investigates the influence of graphene on the mechanical properties of additive-manufactured polyethylene terephthalate glycol (Prince Edward IslandTG) composites. To this end, the graphene content is varied by 0.02 wt.%, 0.04 wt.%, 0.08 wt.%, and 0.1 wt.% to obtain different compositions of PETG/graphene composites. The filaments were prepared by mixing the PETG pellets and graphene flakes into the required quantity. Further, the mixture is extruded using a single screw extruder into small filaments with a 1.75 mm diameter. Using fused deposition modelling (FDM), the specimens were 3D printed following ASTM requirements. The fabricated PETG/graphene specimens are assessed for their mechanical properties, such as tensile, compression, flexural and impact characteristics. Finally, the fractography of the tested specimens is analysed using a scanning electron microscope (SEM). The experimentation of PETG/graphene composites reveals that the optimum mechanical properties can be achieved when PETG is reinforced with 0.04 wt.% of graphene. As opposed to virgin PETG, an increment of 89.71%, 81.76%, 21.60%, and 81.25% is witnessed in the tensile, compression, flexural, and impact strengths of the PETG/0.04 wt.% graphene composite. The outcome of this work is believed to pave the way for broadening the applications of graphene-based composites in electromechanical and smart structure engineering domains.

Unravel hardening mechanism of AlCrNbSiTi high-entropy alloy coatings

Novel high-entropy alloys (HEAs) coatings deposited using physical vapour deposition technique are potential candidates of protective coatings due to their excellent performance. However, the correlation between properties and microstructure of HEAs coatings has not been completely established and the hardening mechanism remains unclear. In this paper, the AlCrNbSiTi HEA coatings were deposited under different bias voltages by radio-frequency magnetron sputtering. The morphology, chemical composition, structure, mechanical properties and thermal stability are discussed in detail. All coatings exhibit smooth surface without obvious elemental segregation and the columnar structure tends to densify with increasing bias. The coatings possess a nanocomposite structure of amorphous-nanocrystalline silicides, in agreement with the results calculated based on three phase prediction parameters (ΔHmix: enthalpy of mixing, δ: atomic size difference and Ω: ratio of entropy of mixing ΔSmix to ΔHmix). The coating deposited at bias of − 50 V presents optimal mechanical properties with nanohardness of ∼15.2 GPa, scratch crack propagation resistance of 1042 N2 and wear rate of 5.4 × 10−8 mm3N−1m−1. Annealing treatment further unravels that the presence of hard silicides is the hardening mechanism of coatings with super-hardness of ∼24 GPa. The results indicate that the AlCrNbSiTi coating is a promising protective coating with broad industrial application prospects.

Bone-Patellar Tendon-Bone Allograft Preparation Technique for Anterior Cruciate Ligament Reconstruction

Background: Allograft anterior cruciate ligament (ACL) reconstruction, while it may have a higher failure rate in younger and more active populations, continues to serve as a viable graft option for the appropriately indicated patient. Efficient bone-patellar tendon-bone (BTB) allograft preparation is beneficial to reduce operating time and ensure optimal reconstruction with bony fixation. Indications: ACL reconstruction with BTB allograft is indicated for skeletally mature and older patients, patients who are less active and have fewer physical demands, patients who have had previously harvested autograft, circumstances where an autograft harvest is inadequate, patients with multiligament knee injuries, and patients who prefer allograft use. Technique Description: The central third of the BTB allograft is harvested, aiming for a graft diameter of 10 mm along the tendon. The tibial bone plug is first cut to a length of 25 to 30 mm and width of 10 mm with the saw at a 70° angle to the bone. The patellar bone plug is cut to a length of 25 mm and width of 10 mm with the saw at a 45° angle to the bone. The bone plugs are mobilized, and soft tissue is dissected to free the graft. The graft is trimmed until it fits through a 10-mm sizer on each side. A single hole is created with a k-wire in the patellar bone plug, and a #5 Ethibond suture is passed. On the tibial bone plug, 2 holes are made perpendicular to one another, and a #2 Fiberwire suture is passed through each of these holes. These sutures allow for facilitated graft passage and tensioning. Once the graft is affixed with interference screws, the graft is arthroscopically evaluated throughout range of motion. Results: ACL reconstruction with BTB allograft provides high success rates in appropriately selected patients. Data demonstrate more optimal mechanical properties by harvesting the central third of the allograft tendon in younger donors. Non-irradiated and less chemically processed grafts are also preferred to optimize biomechanical properties. Discussion/Conclusion: Bone-patellar tendon-bone allograft with 2 bone plugs offers a reliable alternative to other allografts or autografts. Preparing the allograft in a fashion similar to an autograft harvest may increase familiarity with techniques and facilitate surgical efficiency and graft passage. Patient Consent Disclosure Statement: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Influence of squeeze casting pressure on nanoparticle distribution and mechanical properties of nano-SiCp/Al−Cu composites assisted with ultrasonic vibration

The influence of squeeze casting pressure on nanoparticle distribution and mechanical properties of 2 wt.% nano-SiCp/Al−Cu composites assisted with ultrasonic vibration was investigated. Results show that as the applied pressure increases from 0 to 400 MPa, the α(Al) grains are significantly refined at first and then the refinement trend slows down, and the porosity of composites is gradually reduced. When the applied pressure is 400 MPa, α(Al) grain size is reduced from 105 to 25 μm, and the nanoparticle distribution is significantly improved, resulting in the optimal mechanical properties of the composites. The ultimate tensile strength, yield strength and elongation of the composites are 290 MPa, 182 MPa and 10%, which are 52.6%, 25.5% and 400% higher than those of the nano-SiCp/Al−Cu composites prepared by gravity casting (0 MPa). The enhancement in strength and elongation of nano-SiCp/Al−Cu composites under high pressure is mainly attributed to grain refinement, reduction of porosity and uniform distribution of nanoparticles.

Achieving superior mechanical properties and biocompatibility in an O-doping TiZrNb medium entropy alloy

The present work aimed to develop a novel medium entropy alloy (MEA) with superior mechanical properties and biocompatibility for the metallic-bioimplant application. A series of (TiZrNb0.7)100-xOx (x = 0, 0.5, 0.75 at. %) MEAs were carefully designed and prepared. The microstructure, mechanical properties, corrosion resistance, and biocompatibility were investigated in detail. Single-phase body-centered cubic (BCC) structural (TiZrNb0.7)100-xOx MEAs consisted of as-cast dendritic morphology. Interestingly, the yield strength and ductility of (TiZrNb0.7)100-xOx MEAs were improved simultaneously with their O concentration. The (TiZrNb0.7)99.25O0.75 MEA had optimal mechanical properties, exhibiting a yield strength of 911 ± 11 MPa, a fracture elongation of 16.1 ± 0.7%, and an elastic modulus of 70.5 ± 1.2 GPa. According to the potentiodynamic polarization and cell culture experiment, the (TiZrNb0.7)99.25O0.75 MEA exhibited superior corrosion resistance and biocompatibility, equivalent to the commercially pure titanium (CP-Ti). These findings provide a paradigm for achieving outstanding comprehensive properties in MEA via O doping.

Effect of CaF2@SiO2 on Si3N4/TiC Composite Ceramic Materials: Molecular Dynamics Analysis and Material Preparation

Molecular dynamics simulations allow to investigate the microscopic evolution of a structure, and can also point the way to tool material design. In this paper, the effect of adding CaF2 and CaF2@SiO2 on the Si3N4/TiC system is studied using molecular dynamics simulations. The results show that the system with the addition of CaF2@SiO2 to the model has a higher hardness than the system with the addition of CaF2. In order to obtain the optimum parameters for self-lubricating ceramic tools, the effect of adding different amounts of CaF2@SiO2 on the Si3N4/TiC system was investigated. The Si3N4/TiC/CaF2@SiO2 system achieved optimum mechanical properties when four CaF2@SiO2 were included in the model. By analyzing the effect of the sintering temperature on the system, it was deduced that the hardness achieved a maximum value of 15.89 GPa and the modulus of elasticity reached 132.53 GPa when the sintering temperature was at 2073 K. Based on this sintering parameter, the Si3N4/TiC/CaF2@SiO2 composite ceramic tool material was experimentally prepared with the mechanical properties of 15.66 GPa hardness and 128.08 GPa modulus of elasticity. The experimental results were consistent with the simulation results.

Effect of Nanographite Conductive Concrete Mixed with Magnetite Sand Excited by Different Alkali Activators and Their Combinations on the Properties of Conductive Concrete

In order to obtain conductive concrete with good electrical conductivity and good mechanical properties, nanographite and magnetite sand excited by different activators and their combinations are added to ordinary concrete to obtain high quality and efficient conductive concrete. The optimal mixture ratio of alkali-excited conductive concrete and the effects of different activators and their combinations on the mechanics and electrical conductivity of concrete were studied. The microstructure of alkali-excited conductive concrete was analyzed by scanning electron microscope (SEM) to study its conductive mechanism. Results show that the conductive concrete obtained by compounding sodium hydroxide, sodium sulfate and calcium hydroxide has optimal mechanical and electrical properties when the graphite is 6% cement, and magnetite sand is 40% fine aggregate. The conductive concrete sample prepared by this method has a flexural strength of 6.84 MPa, a compressive strength of 47.79 MPa and a resistivity of 4805 Ω·cm (28 days). Compared with ordinary concrete (no nanographite and no magnetite sand), the compressive strength of conductive concrete is increased by 122.3%, the bending strength is increased by 116.5%, and the resistivity is reduced by 99.1%. SEM shows that the distribution of conductive materials in concrete is more uniform due to alkali excitation and calcium silicate hydrate (CSH) gel can be formed, which leads to better performance. The research in this paper is only a preliminary exploration of the characteristics of green conductive concrete, and the conductive heating characteristics and electromagnetic wave absorption properties of concrete, along with strength characteristics after adding conductive fillers, need to be further studied. It is suggested that further research should be carried out on the deicing characteristics of conductive concrete and the electromagnetic wave absorption properties used in stealth military engineering.