Papers by Keyword: Strength Properties

Abstract: The growing issue of light expanded clay aggregate (LECA) disposal has become a pressing environmental concern globally, underscoring the need for swift and effective solutions. To mitigate this issue, the construction industry is increasingly adopting sustainable alternatives to traditional concrete. One such innovative approach involves incorporating these waste materials into construction materials, primarily concrete. This study aimed to create a novel, eco-friendly concrete material utilizing recycled LECA, engineered to float on water. The investigation employed a range of polyvinyl alcohol (PVA) fiber volume fractions (0, 0.15, 0.25, 0.35, and 0.45%) to assess their impact on the strength properties of lightweight foamed concrete (LWFC). The combination of LECA and polyvinyl alcohol (PVA) fibers resulted in compressive strengths ranging from 3.51 to 4.15 MPa, accompanied by densities between 600 and 750 kg/m³. Furthermore, ultra-lightweight foam floating concrete (ULWFFC)-P5 demonstrated enhanced load capacity, with a buoyancy force of 26.5 N. This innovation presents a groundbreaking opportunity for the construction sector, offering a sustainable and effective solution for complex projects in building and offshore marine environments.

Abstract: The aim of the presented work is to study polymer ceramic-inorganic composites for electromagnetic radiation absorbing. Epoxy-based polymer composites modified with ceramic-inorganic graphite-ferromagnetic (CIGF) fillers were first obtained: silicon carbide, chromium oxide Cr₂O₃, graphite, humic substances and potassium titanate. As polymer matrix epoxy resin based on Epikote Resin MGS LR 285 and Epikure Curing Agent MGS LH 285 was studied. Primary research was directed to study humic substance, silicon carbide SiC, chromium oxide Cr₂O₃, graphite and potassium titanate nanoparticles introduction impact on polymer ceramic-inorganic composites strength and technological properties. Complex of technological and strength characteristics were researched and compositions with humic substances 0.5 wt%, a higher silicon carbide SiC – 10 wt% content were studied, while chromium oxide Cr₂O₃, graphite content in 5–25 % wt. range was optimized. Results shows, that addition of humic substances, silicon carbide SiC, chromium oxide Cr₂O₃, graphite and potassium titanate nanoparticles into the epoxy resin up to 20 wt% filler content increases the composite impact strength and breaking stress during bending. The CIGF fillers complex system using advantage is proven by studying the nature of modification effect on ceramic-ferromagnetic-graphite polymer composites for electromagnetic radiation absorption.

Abstract: The work is devoted to the study of magnesite influence on the strength properties of glued wood products with aluminosilicate adhesive. It they shown that the introduction of magnesite in the composition of aluminosilicate glue in the amount from 0.5 to 1.5 % contributes to an increase in the shear strength along the fibres by 1.57 times compared to the normative requirement (not less than 4 MPa). It we found that the bending strength of glued wood on a toothed spike is 1.4 times higher than the normative (not less than 26 MPa). After fire tests, no destruction of the glue joint on the spike we observed, and the bending strength of the samples increases proportionally to the introduction of magnesite in the glue composition. Water resistance of glue joints on the toothed spike when the samples we kept for 48 hours at the temperature 20 °С is higher than the standard value and increases with the increase of magnesite content in the glue composition. After boiling at the temperature 100 °С for 3 hours the samples containing 1.5 % magnesite meet the normative requirements (3 MPa).

Abstract: The present study investigates the effect of incorporating metakaolin and silica fumes in the production of high-strength concrete along with partial replacement of coarse granite aggregates in the high-strength concrete. The higher compressive strength, refined microstructure, and decreased permeability of high-strength concrete are some of the properties responsible for its trending use in the modern construction industry. The main purpose of this research is to evaluate the effect of the replacement of coarse granite aggregates with natural aggregates on the mechanical and durability properties of high-strength concrete. For understanding the effect of metakaolin, silica fume, and granite aggregates on the properties of high-strength concrete, various specimens such as cubes, cylinders, and cylindrical discs were cast and tested after 7, 14, and 28 days of curing. Various concrete mixes were prepared by adding silica fume at 5%, 7.5%, and 10% and metakaolin at 5%, 7.5%, 10%, 12.5%, and 15% in concrete production. Furthermore, High-strength concrete mixes were also prepared by replacing natural coarse aggregates with granite coarse aggregates by 25%, 50%, 75%, and 100% to study the effect of replacement percentage on the concrete properties. Test results indicated that the compressive strength and split tensile strength of the concrete mix increased with the increase in the replacement percentage of granite aggregates, with the highest strength seen at complete replacement with granite aggregate due to the enhanced compressive strength of such aggregates in comparison with the natural coarse aggregates. In various mixes cast using metakaolin and silica fume, the highest compressive strength was seen in a mix containing 10% metakaolin and 7.5% silica fume, and results of other mixes indicated that the use of silica fume and metakaolin are viable options for high-strength concrete production in our experimental study.

Abstract: The article aims to investigate polymer inorganic composites for electromagnetic radiation absorption using potassium titanates. The selected polyamide 6 (durethane brand) and sodium polytitanate materials contain TiО₂, K₂СО_3, and KCl received by charge sintering. Results showed that modification of polyamide 6 with sintering products in the form of a fine powder of potassium polytitanate with particle size 1-5 microns that contain the primary phase K₂O × 2TiO₂ with an admixture of a phase K₂O × 4TiO₂, which increased their strength properties. The optimal content of potassium polytitanate was over 10 % by mass. To fully ensure the reinforcing effect due to the filling of potassium polytitanate polyamide 6, it is necessary to use whiskers K₂O × 6TiO_2, which can be collected by the additional crystallization of the amorphous charge sintering product.

Abstract: Radiation sterilization is widely used to sterilize nonwoven SMS medical products. SMS materials have improved filtering and barrier properties, low bacteriopermeability and, due to these properties, are indispensable for medicine. They are used to make such important health care products as disposable surgical clothing and underwear. As a result of the research carried out, the effect of gamma and electron radiation, in the range of absorbed doses from 15 to 25 kGy, on the strength characteristics of nonwoven SMS materials based on polypropylene with a surface density of 35, 40, 50 g/cm² was studied. It has been established that the strength characteristics (tensile strength, tensile strength, and tear strength) of nonwoven materials decrease after exposure to ionizing radiation. The higher the density of the material, the more its characteristics decrease after radiation sterilization. It was also found that gamma radiation, due to its nature, has a stronger effect on nonwoven materials based on polypropylene, and leads to a stronger decrease in strength characteristics. In general, for products sterilized by ionizing radiation and made from SMS materials, it is important to control the strength characteristics, primarily, the tensile strength in the transverse direction of the web stuff.

Abstract: The post-sintering properties of walling high-calcium ceramics based on clay-containing raw materials in low-temperature roasting depend on the chemical-mineralogical composition of clay with different contents of iron, calcium-containing and alkaline oxides that contribute to the formation of new crystalline phases, which provide for the production of low-density ceramic material with high-strength properties.

Abstract: Nowadays, applying new materials is widely used in concrete construction to study their effects in enhancing the properties and the durability of concrete. This research includes studying the using of manufactured aggregate, which is so-called '' Anti-slip sand '' in specific proportions to know its influence on strength properties of normal strength hardened concrete which involves compressive strength, flexural strength, tensile splitting strength, and density. Anti-slip sand at different rates of (25%, 50%, 75%, and 100%) replaces the natural sand in the concrete mixture to investigate its effect on the properties of concrete. The study shows that the best results of concrete properties are found when replaced the natural sand by 100% of anti-slip sand. Compressive, flexural and tensile strengths of concrete are increased with increment ratios of (44%, 40%, and 20%) respectively compared with other concrete mixture contains only natural sand. In addition, the study shows that the density of hardened concrete is decreased from 2420 kg/m³ in concrete with 100% natural sand to 2360 kg/m³ with a decrement ratio of 2.5% in concrete with 100% anti-slip sand.

Abstract: Perspective polymeric materials for use in frictional units as bearings and sliding supports, the mobile sealants of piston rings, cuffs are composites on the basis of polytetrafluoroethylene (PTFE). They significantly improve the performance of equipment at low temperatures, reduce repair expenses and losses from idle times. When modifying polymers, physical methods of exposure are increasingly used, ensuring the activation of materials and high performance characteristics. Objective: the effect of complex fillers, obtained by their joint activation in a planetary mill, on the deformation and strength and tribological characteristics of composites based on PTFE. This work shows the promise of using the joint mechanical activation of components of different nature to obtain complex fillers. The use of the modified ultradispersed polytetrafluoroethylene (UPTFE) of zeolite as a filler of PTFE leads to complex improvement of properties of composites: the tensile strength and elongation at rupture increase by 20% in comparison with initial polymer. The wear resistance increases by 3-6 times in comparison with the composites containing only the activated zeolite and by 900 times in comparison with initial polymer. The addition of the modified UPTFE of a magnesium aluminate spinel (MAS) leads to increase in deformation and strength properties by 10-30% and an increase in wear resistance by 140 times in comparison with initial polymer.

Abstract: Commonly used Grade 20GL cast steel has unstable impact strength values determined on V-notched samples at –60 °C and so cannot provide reliability of cast parts at negative temperatures.