Strength Properties Of Materials Research Articles

Recycling gold mine tailings into eco-friendly backfill material for a coal mine goaf: Performance insights, hydration mechanism, and engineering applications

Recycling gold mine overflow tailings for coal mine filling is crucial for sustainable mining. In this work, an eco-friendly, performance-controllable overflow tailings-fly ash-based backfill material is developed for coal mine filling. The effects of three critical factors, namely, the slurry concentration (SC), cement-sand ratio (C:S), and tailings-fly ash ratio (T:F), on the workability and uniaxial compressive strength (UCS) properties of the novel backfill material are thoroughly investigated, and an optimization of the corresponding formulation is conducted. The optimal formula for the backfill is determined to be a CS of 60 %, a C:S of 0.10, and a T:F of 6:6. The hydration mechanism of the chosen typical mixtures is analyzed via X-ray diffraction (XRD), Scanning electron microscopy (SEM), and Fourier transform infrared (FTIR) spectroscopy, and the results show that a needle-like Aft gel, identified as the major gelatinous product, is intricately intertwined to create an intricate network structure. As the T:F increases, the content of calcium and silicon oxide initially decreases but then increases, and the optimal mixture reaches a minimum value of 63.66 %. The optimum specimen exhibits a peak wavenumber at 1109.46 cm−1 involving a Si-O stretching vibration bond. A comprehensive filling program at the Liangjia Coal Mine is successfully implemented. Approximately 0.27 tons of overflow tailings are utilized for every ton of backfills. The underground core-pulling backfill achieves a peak uniaxial compressive strength (UCS) of 7.56 MPa after 28 d, surpassing design requirements and showing promise for coal mine filling applications. This study is expected to achieve the transformation of a coal mine goaf into a gold mine tailings pond.

Research Trends and Challenges in the Strength Properties of Materials Used in Hydrogen Environments

Research Trends and Challenges in the Strength Properties of Materials Used in Hydrogen Environments

Effect of granulated blast furnace slag on uniaxial compression fatigue properties of engineered geopolymer composites

Engineered geopolymer composites (EGCs), emerging as a novel eco-friendly cementitious material, exhibit considerable potential in diverse applications. Granulated blast furnace slag (GBFS) is a by-product of the blast furnace ironmaking process. Owing to its exceptional cementing properties, GBFS is frequently incorporated into geopolymer materials to enhance strength and stability, while also achieving slurry solidification at ambient temperature. The study examined the effect of different rates of GBFS replacement on the fatigue behavior of EGCs using uniaxial compression fatigue testing, with a particular focus on the changes in fatigue life and fatigue deformation. The results indicate that the fatigue life of EGC conforms to a Weibull distribution. While a higher GBFS replacement rate can improve the compressive strength of EGC, it has a detrimental effect on the fatigue life. Furthermore, when subjected to fatigue loading, the total strain accumulation, residual strain, and fatigue stiffness of EGC exhibited a three-stage evolutionary pattern, and remained constant during the secondary creep stage. Therefore, the comprehensive effect of adding GBFS to EGC on material strength and fatigue properties should be taken into account. This study uncovers the potential negative impacts of GBFS on the fatigue properties of EGC, contradicting the previous belief that GBFS could enhance the mechanical properties of geopolymers. Therefore, a comprehensive and meticulous assessment is necessary when contemplating the use of GBFS as a reinforcement material for EGC.

Mechanical and tribological properties of FeS/Cu–Bi self-lubricating materials reinforced with copper-plated steel fibers

PurposeThis study aims to investigate the effect of steel fibers on the mechanical and tribological properties of FeS/Cu–Bi self-lubricating materials.Design/methodology/approachThe microstructure of the material was characterized by scanning electron microscopy. Tests on the crushing strength, impact toughness and tribological properties of materials were conducted using a universal electronic testing machine, a 300 J pendulum impact testing machine and an M200 ring-block sliding tribometer, respectively.FindingsThe mechanical properties of the material initially increased and then stabilized with increased copper-plated steel-fiber length. When the length of the copper-plated steel fiber was 7 mm, the mechanical properties of the material reached stability. Compared with the material without a copper-plated steel fiber, its crushing strength and impact toughness increased by 32.6% and 53%, respectively. A copper-plated steel fiber with a length of 7 mm lay flat in a copper matrix can strengthen the friction interface and enrich the lubricant. Accordingly, the antifriction and wear resistance of the materials increased by 17.6% and 55%, respectively.Originality/valueThe effects of copper-plated steel fibers on the properties of FeS/Cu–Bi self-lubricating materials were clarified. This work can serve as a reference for improving material performance and its engineering applications.

The Influence of Filler Particle Size on the Strength Properties and Mechanical Energy Dissipation Capacity of Biopoly(Ethylene Terephthalate) BioPET/Eggshell Biocomposites

This work aims to evaluate how the particle size of a waste filler in the form of eggshells changes the mechanical properties of biopoly(ethylene terephthalate) (bioPET). BioPET was modified with three different waste fractions: 1.60–3 mm—large particles; 1.60–1 mm—medium particles; 1 mm–200 μm—small particles. Waste filler was added to the biopolymer matrix in the amount of 10 wt.%. Static tensile tests, as well as bending and impact tests, were carried out to assess the strength properties of the waste-enriched materials. Dissipation energy changes and relaxation processes were observed and evaluated by means of a low-cycle dynamic test. Waste particles were shown to be an effective modifier of bioPET by increasing its stiffness (all particle sizes) and strength (the smallest ones). Studies of the wetting angle and mechanical energy dissipation in the first hysteresis loops indicate the better adhesion of small particles to the biopolymer and their greater ability to dissipate mechanical energy.

Impact of speed sintering on the mechanical and optical properties of multilayered zirconia

Speed sintering techniques have been introduced to shorten the sintering time of zirconia ceramics, yet their impact on multilayered zirconia properties remains understudied. The purpose of this in vitro study was to assess the effect of speed sintering on the optical properties and the mechanical flexural strength of multilayered zirconia materials. A total of 360 disks (Ø14 ±2 mm ×1.2 ±0.02 mm) were fabricated by following the International Organization for Standardization (ISO) 6872:2015 standard using 2 types of Vita A2 shade multilayered zirconia materials: IPS e.max ZirCAD Prime (ZP) and IPS e.max ZirCAD Prime Esthetic (ZPE). Each material comprised translucent (Tr), gradient l (Gr), and dentin (De) layers, with 60 disks per layer. Half were sintered using a standard sintering protocol and half using a speed sintering protocol. Biaxial flexural strength was accessed using a universal testing machine equipped with the Blue Hill Universal software program by following the ISO 6872:2015 standard, with 20 disks per subgroup. The spectrophotometric analysis of optical properties (contrast ratio [CR], translucency parameter [TP], and total transmittance [Tt%]) was performed using a dual-beam spectrophotometer (Ultrascan VIS) in accordance with the ISO 7491:2000 standard, with 10 disks per subgroup. The comparison of the optical properties and the mechanical flexural strength between the speed and standard protocol was analyzed using an unpaired t test (α=.05). Speed sintering reduced biaxial flexural strength in all ZP layers (P<.05) and in ZPE-Gr (P<.05). A statistically significant difference in the CR was observed in the ZP-Tr, ZP-Gr, and ZPE-Gr layers (P<.05). The TP of the ZP-Gr, ZP-De, and ZPE-Gr layers was significantly lower when using the speed sintering protocol. Tt% was significantly lower with speed sintering for both materials (P<.05). Speed sintering statistically changed both the optical (CR, TP, Tt%) and mechanical (flexural strength) properties of multilayered zirconia materials, but the differences may not be clinically relevant.

Microstructure and strength of a 3D-printed Ti–6Al–4V alloy subjected to high-pressure torsion

Currently, one of the effective 3D printing methods is wire-feed electron-beam additive manufacturing (EBAM), which allows producing large-sized commercial billets from Ti–6Al–4V titanium alloy. However, Ti–6Al–4V alloy produced by this method demonstrates reduced strength properties. It is known that it is possible to increase the strength properties of metallic materials by refining their grain structure by high-pressure torsion (HPT). This work is aimed at studying the influence of high-pressure torsion on the microstructure, and mechanical strength of a structural Ti–6Al–4V titanium alloy produced by the wire-feed electron-beam additive manufacturing method. The microstructure of a 3D-printed Ti–6Al–4V alloy in the initial state, and after high-pressure torsion, was studied using optical, scanning and transmission electron microscopy. An EBSD analysis of the material in its original state was carried out. The microhardness of the material in the initial and deformed states was measured. Using the dependence of the yield strength on microhardness, the estimated mechanical strength of the material after processing by the high-pressure torsion method was determined. The microstructural features of the 3D-printed Ti–6Al–4V alloy after high-pressure torsion, which provide increased strength of this material, are discussed. The research results demonstrate that 3D printing, using the electron-beam additive manufacturing method, allows producing a Ti–6Al–4V titanium alloy with a microstructure unusual for this material, which consists of columnar primary β-grains with a transverse size of 1–2mm, inside of which martensitic α'-Ti needles are located. Thin β-Ti layers with a thickness of about 200nm are observed between the α'-Ti needles. Further deformation treatment of the alloy, using the high-pressure torsion method, allowed forming an ultrafine-grained structure in its volume, presumably consisting of α-grains with an average size of (25±10)nm. High-pressure torsion of the 3D-printed alloy allowed achieving rather high microhardness values of (448±5)НV0.1, which, according to the HV=2.8–3σy ratio, corresponds to the estimated yield strength of approximately 1460MPa.

Multi-objective optimization of micro crystalline cellulose and montmorillonite filled poly lactic acid bio–composite and its characterizations

In this research study, the synthesis of poly lactic acid (PLA) based bio composite material factors contributions were investigated through the Taguchi-based grey relational analysis (GRA) technique. Effects of micro crystalline cellulose (MCC) and montmorillonite (MTT) nano clay filler, sorbitol (S) plasticizer, and temperature (T) operating factor on the PLA matrix through melt-mixing preparation method. The tensile strength (TS), Young modulus (YM), flexural strength (FS), flexural modulus (FM), hardness, impact strength (IS), water absorption (WA), and density properties of bio composite material were investigated for each experimental setup (orthogonal array, L16). Additionally, neat PLA and optimal sample structural, thermal, and morphological properties were examined through Fourier transform infrared spectroscopy (FTIR), X-Ray diffraction (X-RD), thermal gravimetry analysis/differential thermal gravimetry (TGA/DTG), and DSC and SEM analyses. The obtained result for optimal mechanical and physical properties of MCC/MTT/S/PLA bio composite was MCC at level 3 (6%), MTT at level 4 (9%), S at level 2 (10%), and T at level 4 (175 °C). Analysis of variance (ANOVA) shows that MTT has the greatest significant effect on mechanical and physical properties of MCC/MTT/S/PLA bio composite followed by MCC, T, and S. The confirmation test indicates that the improvement of weighted grey relational grade (GRG) from 0.7896 to 0.846 and the FTIR, XRD, thermal gravimetry/differential scanning calorimetry (TG/DSC), and scanning electron microscopy (SEM) results indicates that the good interaction between PLA and fillers, improvement of thermal and morphological properties of optimal (6MCC/9MTT/10S/175 °C) bio composite samples. Therefore, the multi-response characteristics of MCC/MTT/S/PLA bio composite can be highly improved by this technique.

THE EFFECT OF SUPPORT LAYER MATERIAL AND ADHESIVE TYPE ON COMPRESSIVE DYNAMIC BENDING AND SHEAR STRENGTH IN LAMINATED WOOD

In this study, strength properties of wood material reinforced with carbon fiber fabric, steel wire mesh and bamboo veneer were determined. Polyvinylacetate (PVAc) and polyurethane (PUR) glues (D4)were used for the lamellas obtained from Scotch pine (Pinus sylvestris L.) and eastern beech (Fagus orientalis L.). Compressive strength according to TS EN 408+A1; dynamic bending (shock) strength according toTS ISO 13061-10 and shear strength according to ASTM D 3110 were determined on 3 and 5-layers samples. According to the results, the highest compressive strength (62.8 N/mm2) was found in 5-layerseastern beech samples reinforced with carbon fiber fabric and bonded with PUR glue. The highest dynamic bending strength value (110.8 kJ/m2) was found in 5-layerseastern beech samples reinforced with carbon fiber fabric and bonded with PUR glue and the highest shear strength value (12.3 N/mm2) in 3-layered eastern beech samples reinforced with steel wire mesh and bonded with PUR glue.

Evaluation of dimensional stability, setting time, tensile strength, and rheological properties of kaolin clay incorporated alginate impression material

This study aims to determine and compare the dimensional stability, setting time, tensile strength, and rheological properties of kaolin clay powder-modified and unmodified alginate impression material. Commercially available alginate-based impression material was considered as a control (C) while experimental groups E-1, E-2, and E-3 were fabricated by adding 2%, 4%, and 8% of kaolin clay powder in the control, respectively. Analytical techniques were used for the characterization of the samples. A tensile strength, rheological property, dimensional stability, and setting time were recorded for control and experimental groups. FTIR analysis confirmed the presence of kaolin clay powder in all experimental groups. SEM showed a round solid structure and irregular shape particle appearance in all experimental groups as well as a control group. The dimensional stability was improved by the addition of kaolin clay powder to the alginate impression material. The percentage dimensional change at 5 min, 6, and 12 h was increased for E3 adding (8% kaolin clay powder) and decreased for the control group. The mean value of tensile strength was highest for E3 followed by E2, E1, and least in control groups. Higher Young’s Modulus and lower deformation values were measured for E3. The mean value of setting time was highest for E3 and the least was in the control group. The results for both setting time and tensile strength were very highly statistically significant (p < 0.001). The mean values of viscoelasticity, flow, and drip test were increased statistically by adding various concentrations of kaolin clay powder to the alginate impression material.

Data-driven integration of synthetic representative volume elements and machine learning for improved microstructure-property linkage and material performance in ceramics

Ceramic materials, characterized by their heat resistance, dielectric properties, and mechanical performance, are often compromised by brittleness due to microstructural inclusions. These inclusions, such as defects, secondary phases, and pores, are critically analyzed for their impact on material strength and fracture properties. In this study, the linkage between microstructure and properties in ceramic materials is explored through a methodological approach that combines experimental observations with physics-based and machine learning models. A data-driven approach has been employed, utilizing synthetic Representative Volume Elements (RVEs) derived from X-ray computed tomography scans of ceramics. The methodology involves an automated finite element (FE) simulation process for progressive failure analysis under uniaxial compression and tension. The analysis is conducted using statistical, data-driven, and machine learning techniques, including principal component analysis and k-means clustering, to assess the microstructural features' impact on material performance. The study focuses on the use of RVEs for accurately capturing essential microstructural characteristics and addresses the challenges in developing synthetic models and the limitations of simulation capabilities. The study's findings reveal that less uniform inclusion distribution and a higher standard deviation in inclusion size correlate to lower mechanical performance. By applying data-driven methods, this research contributes to the optimization of material performance and the establishment of structure-property relationships, with a particular emphasis on the influence of inclusions and defects on the mechanical behavior of ceramic materials.

In vitro evaluation of the mechanical and optical properties of 3D printed vs CAD/CAM milled denture teeth materials

This laboratory research aimed to assess the Flexural strength, fracture toughness, Volumetric wear and optical properties of various recent 3D-printed denture tooth materials and compare them to CAD/CAM milled materials. Four 3D-printed denture tooth materials (Lucitone Tooth, OnX, Flexcera Ultra +, and VarseoSmile Crown Plus) and one CAD/CAM milled denture teeth material (Ivotion Dent) were used to fabricate fifteen specimens for each material (with total no. of 300 specimens). Tests were conducted according to ISO standards to assess flexural strength, fracture toughness, color staining, and volumetric wear. All materials were printed, washed, cured, or milled following the manufacturer’s instructions. Flexural strength and fracture toughness values were obtained by a universal testing machine. Volumetric wear was evaluated using a non-contact optical profilometer. Color stability outcomes were obtained via a spectrophotometer for determining L*a*b* values, with color change (ΔE2000) based on the CIEDE2000 formula. Data were analyzed using one-way ANOVA and Tukey post-hoc analysis (α = 0.05). All 3D-printed materials exhibited higher flexural strength values than the milled material (p < 0.05). For fracture toughness, two of the 3D-printed materials showed higher values than the milled material, while the other two had lower values. Insignificant variances in volumetric wear were detected between the materials (p > 0.05). Color staining results varied, with milled materials generally demonstrating better-staining resistance compared to the 3D-printed materials. 3D-printed denture tooth materials exhibit good mechanical and optical properties, presenting a cost-effective and efficient alternative to CAD/CAM milled materials for denture tooth fabrication.

LABORATORY DETERMINATION OF THE MAXIMUM DENSITY AND OPTIMAL HUMIDITY OF LARGE-BLOCK SOILS

he purpose of our field research was to develop and select a method of work on laying and compacting the material of large-block soils, ensuring the receipt and determination of maximum density and optimal soil moisture. On the basis of these studies, technical conditions for the construction of thrust prisms are further drawn up. This article presents the results of the work performed with a brief methodology of field and laboratory research. The article provides data characterizing the material intended for installation in the body of the dam. The currently existing methods for determining the control parameters of laying large-block soils are contradictory and require experimental work. A number of parameters are taken into account: grain composition, humidity, density. Therefore, the article considers a laboratory method for determining the maximum density and optimal humidity of stone material when laying in the body of the dam. The results of the research carried out on the development of our quarry area, the thickness of the uncompacted layer was determined, the choice of a sealing mechanism, the number of passes along one track, the determination of the density of dry soil in experimental field sites intended for use in filling the body of the dam, graphs of the required densities for full-scale grain composition are presented. The strength properties of the stone material were determined experimentally for the average grain composition and for the upper curve of the accepted “fish”

A size‐dependent energy‐based strain burst criterion

AbstractThis paper presents a size‐dependent energy‐based strain burst criterion linking strength, elasticity, fracture energies and specimen size effect with stress state due to changes in boundary conditions. It proposes the concept of a ‘Burst Envelope’, a surface in three‐dimensional principal stress space derived based on energy storing and dissipation characteristics of a rock sample, taking into account the size of the specimen and potential localised failure pattern. A scalar burst index is also proposed to quantify the bursting scale. To illustrate and verify its functioning, a numerical modelling framework based on the distinct element method and employing a new cohesive‐frictional contact model is used to perform virtual strain burst experiments under different polyaxial loading‐unloading scenarios, mimicking various underground excavation scenarios. The obtained results are in good agreement with the theoretical prediction of burst occurrence. On that basis, the variation of burst possibility and magnitude are investigated with key factors, including confinement level and the material's elastic, strength and fracture properties. The effect of the specimen's aspect ratio and size on the rock burst potential is elaborated and verified using virtual strain burst experiments, facilitating the linking of the proposed theoretical framework with the evaluation of in‐situ strain bursts in rock masses around underground openings.

Effects of post-curing duration on the mechanical properties of complex 3D printed geometrical parts

This study aims to assess the efficacy of post-curing guidance supplied by 3D printing resin manufacturers. Current guidance applies generically to all geometries with the caveat that post-curing should be extended for ‘large’ or ‘complex’ geometries but specific guidance is not provided.Two vat-polymerisation 3D printers (Form3B, Figure 4 Standalone) were used to print test models in 6 biocompatible resins (Pro Black, Med White, Med Amber, Biomed Black, Biomed White, Biomed Amber). The test model is of a complex geometry whilst also housing ISO 527 test specimens in concentric layers. Two separate intervals of curing were applied (100%, 500% stated guidance) creating different curing treatments of the specimens throughout the model. Post processed test models were disassembled and pull testing performed on each of the specimens to assess the mechanical properties.The analysis showed that extending the curing duration had significant effects on the mechanical properties of some materials but not all. The layers of the model had a significant effect except for elongation at break for the Med Amber material.This research demonstrates that generic post-curing guidance regarding UV exposures is not sufficient to achieve homogenous material strength properties for complex geometries. Large variations in mechanical properties throughout the models suggest some material was not fully-cured. This raises a query if such materials as originally marketed as biocompatible are fully cured and therefore safe to use for medical applications involving complex geometries.

An alternative method for predicting internal friction angle of rock materials

The shear strength properties of rock materials, cohesion and internal friction angle, are determined by carrying out tri-axial strength test on cylindrical core specimens in laboratory. But determination of these parameters by triaxial tests in accordance with standards and suggested methods, particularly for weak, fractured and weathered rocks is exteremely difficult and/or impossible due to difficulties related to preparation of test specimens suitable for this test. In addition, the tri-axial test requires high cost equipment and too much time for sample preparation and testing. In such cases, there is a need to precisely estimate the friction angle and estimation of rock shear strength properties using some indirect methods, as they are economical and easy to carry out. In this study, the traditional method, which is recommended to be used for the prediction of internal friction angle (ϕ) when triaxial test data is not available, was briefly assessed with its some limitations and an alternative method using theoretical tensile strength and uniaxial compressive strength to predict ϕ was proposed. Then the prediction performances of traditional and proposed methods were compared using a very large data set collected from published literature. The statistical reliability of the derived equations was assessed using F- and t-tests and according to the test results the prediction equations were found to be statistically reliable. The results indicated that the method proposed in this study using the theoretical tensile strength yields best predictions of ϕ when compared to those estimated from the traditional methods based on direct and Brazilian tensile strength values.

Research of the strength properties of nonwoven materials of sheep wool

The work carried out physical and mechanical studies of nonwoven materials using universal tensile testing machine “Tinius Olsen H25S”. Nonwoven materials were produced at the enterprise of IE “Miras” (Taraz city). A mechanical needle punching method was used for the production of nonwoven fabric. This method is environmentally friendly, since adhesives or impregnation is not used in production, and the use of high temperatures at which harmful substances are released into the atmosphere is not provided. The following strength indicators of the nonwoven material were determined: the average value of the breaking load, strength and elongation at break along and across the edge of the nonwoven material. The studied nonwoven materials can be used in the footwear industry in the form of insoles, linings and insulating intermediate parts, as building insulation materials, as well as in products for various technical purposes. The production of nonwoven materials is low-cost, which ensures affordable prices for products made from them.

The Initial Stage of Climatic Aging of Basalt-Reinforced and Glass-Reinforced Plastics in Extremely Cold Climates: Regularities.

Detailed analyses of the reasons for changes in the mechanical parameters of fiberglass exposed to different climatic zones have been made available in the literature; however, such detailed studies of basalt plastic do not yet exist. It is possible to make reasonable conclusions on the climatic resistance of reinforced plastics by monitoring the deformation-strength characteristics in combination with fractographic and DMA analyses of the solar- and shadow-exposed parts of the plastics; additionally, one can conduct analyses of the IR spectrum and the moisture sorbtion kinetics. As a starting point for the climatic aging of polymer composite materials, it is necessary to accept the time of exposure in which the maximum values of the elastic strength properties of polymeric materials are achieved. Based on the results of the DMA analysis, it was found that, unlike basalt-reinforced plastics (where the material is post-cured exclusively at the initial stage of the exposure), in glass-reinforced plastic, a process of destruction occurs. The formation of internal stresses in the material and their growth were determined through observing the duration of climatic exposure. The formation of closed porosity, depending on the duration of exposure, can be assessed using the values of the increase in the average moisture content. A set of experimental studies has established that glass-reinforced plastics are subject to greater destruction under the influence of a very cold climate than the basalt-reinforced plastic.

INFLUENCE OF FILLERS ON THE STRUCTURE AND PROPERTIES OF POLYMER MATRIX

Purpose. Enhancement of the mechanical properties of the polymer matrix through the incorporation of finely dispersed fillers, namely aluminum oxide and talc, as potential modifiers.&#x0D; Research methods. Research was conducted on polymer specimens subjected to tensile testing according to DSTU EN ISO 527-5:2018. The tests were performed using a URM-5 tensile testing machine with a maximum force of 50 kN. Metallographic analysis was carried out using a KEYENCE VHX microscope at magnifications of 50 and 500. The microstructure of the polymer matrix was assessed through etching-free procedures.&#x0D; Results. The study demonstrates that the incorporation of finely dispersed aluminum oxide particles increased the strength parameter from 4.69 MPa to 13.07 MPa, as compared to the unfilled sample. Additionally, it was observed that the introduction of finely dispersed talc particles at a concentration of 0.75 % by mass led to an enhancement in strength values from 4.69 MPa to 12.74 MPa, in comparison to the unfilled sample.&#x0D; Scientific novelty. A polymer matrix with enhanced mechanical properties was achieved through the addition of fillers acting as modifiers. The optimal concentration of aluminum oxide and talc additives was determined. By comparing the results with previous studies involving aluminum oxide and talc at various concentrations in different types of polymer matrices, it can be concluded that the investigated concentrations of modifiers with epoxy resin ED-20 led to the production of a polymer composite with superior mechanical characteristics. The obtained results underscore the significant potential of aluminum oxide and talc as effective modifiers for improving the strength and other crucial properties of composite materials.&#x0D; Practical value. The obtained results highlight the significant potential of utilizing aluminum oxide and talc as modifiers for polymer matrices to enhance their mechanical characteristics. From a practical standpoint, the use of these fillers can exert a substantial impact on the development of new composite materials with improved properties, finding application in composite reinforcement production. Considering the heightened strength and resilience of the resulting materials, these composites can be effectively employed to create lighter and stronger structures in construction and other industries. Additionally, their application may lead to reduced repair and maintenance costs due to increased durability and resistance to mechanical loads. Thus, the implementation of the obtained results could have a substantial influence on the practice of composite material manufacturing, ensuring the creation of products with enhanced characteristics for various applications.

Influence of Starch Powder on Compressive Strength and Microstructural Properties of Geopolymer Composite Materials Based on Metakaolin

The main objective of the present study is the investigation of the behaviour of starch powder incorporated at different levels (0, 5, 10, 15, 20, 25, and 30 wt%) on the compressive strength and microstructural properties of metakaolin-based geopolymers. Sodium silicate with a molar ratio of SiO2/Na2O of 1.6 was used as the hardener and standard metakaolin was used as the aluminosilicate source. The results showed that when metakaolin was replaced by starch from 0 to 15 wt%, the compressive strength increased from 36.50 to 64.12 MPa. When metakaolin was replaced by starch above 15 wt%, the compressive strength decreased from 64.12 to 29.43 MPa. That of the reference geopolymer material is 36.50 MPa.The infrared spectra of the geopolymer composites indicate that the Si-O-C bonds are formed. The thermal behaviour of geopolymer composites containing starch shows a mass loss at around 100 and 278 °C. The geopolymer material without starch only shows a loss of mass at around 100 °C. The micrographs of the geopolymer composite with 15% by weight of starch show that the matrix is more compact, more homogeneous, and denser than the one without starch. On the contrary, possibly due to a large amount of unreacted starch in its network, the micrographs of the geopolymer composite obtained after the incorporation of 30 wt% starch show a heterogeneous microstructure. It can be concluded that suitable starch content for the synthesis of geopolymer composites would be around 15% by weight.