Papers by Keyword: Physical and Mechanical Properties

Abstract: This article presents the results of a research dealing with the use of construction and demolition waste - recycled concrete in the production of fresh concrete, as a partial substitute for natural aggregate. It describes the properties of concrete recyclate that is used for the proposed recipe of fresh concrete. The properties include the results of grain size analysis, bulk density and water absorption capacity. 2 recipes of fresh concrete were prepared for the research. Recipe 1 based on recycled concrete combined with natural aggregate fraction (fr.) 8/16 mm. Recipe 2 based on natural aggregate, which also served as the comparison recipe to demonstrate the effect of recycled concrete fr. 0/16 mm on the physical-mechanical and deformation properties of concrete. The presented results show that the substitution of natural aggregate fr. 0/16 mm with recycled concrete has caused: a reduction of cubic strength by about 12%, crushing strength of cylinders by about 7%, and static and dynamic modulus of elasticity values by about 22% and 25%.

Abstract: This paper presents the findings of experimental studies of the physical and mechanical properties of wood-filled composites based on polylactide (PLA) and vegetable filler in the form of wood flour (WF) thermally modified at 200-240 °C. It also reveals the dependence of the tensile strength, impact strength, bending elastic modulus, and density of composites on the amount of wood filler and the temperature of its thermal pre-modification. We established that an increase in the concentration of the introduced filler and the degree of its heat treatment results in a decrease of the tensile strength, impact strength and density of composite materials, while with a lower binder content, thermal modification at 200 °C has a positive effect on bending elastic modulus. We also found that 40 % content of a wood filler heated to 200 °C is sufficient to maintain relatively high physical and mechanical properties of composite materials. With a higher content of a wood filler, the cost can be reduced but the quality of products made of this material may significantly deteriorate. However, depending on the application and the life cycle of this product, it is possible to develop a formulation that includes a high concentration of filler.

Abstract: The paper describes the influence of the composition of the sealer used to form a composite coating on the surface of a steel sample by electrical discharge machining along the sealing layer on the structure and properties of the coating. The object of this study is samples made of steel 45. All samples are treated by electrical discharge machining with the use of ПР-В3К (Stellite) hard alloy-based anode and modifying sealers, based on CrCNi, TiCNi, and non-stoichiometric W and Mo compounds. Besides, the paper presents the physical and mechanical properties of the obtained coatings, examined during a set of tribological tests. The conducted experiment demonstrated that the wear resistance of coated samples is higher, compared to coatless ones. The strong point of our study lies in functionality to employ sealers, based on the SHS-reagents and non-stoichiometric W and Mo compounds with ESA processing in friction units.

Abstract: The work presents the results of development of the composite gypsum binder (GB) with nanostructured binder on the basis of silica component (NBC). Introduction of NBC changes the kinetics of hardening, as well as improves physical and mechanical properties of gypsum system. Analysis of the microstructure of the GB has demonstrated in the presence of the NB the size and morphology of crystals are changed, promoting the formation of fine-crystalline structure and increase the contact area between new formations, compared to NBC – free gypsum system. Experimental studies have shown that the mechanical properties of the composite gypsum application of NBC increased, reduced water absorption, density increases, and increases the setting time.

Abstract: Physical and mechanical properties of 40 kinds of typical wood species in Zhejiang province were studied in this experiment. Density, shrinkage rate, modulus of rupture,bending strength, compression strength, shear strength and hardness were measured and wood species were classified and evaluated by clustering analysis mehtod (CA) combined with membership function (MF) comprehensive evaluation according to these properties. The results showed that the two analysis methods achieved the similar results when screening first class wood which can be conclued that among the 40 kinds of species Quercus fabri, Dalbergia hupeana Cyclobalanopsis glauca, Lithocarpus harlandii and Lagerstroemia indica were the excellent quality. In the mean while the two analysis methods got the similar conclusion that wood properties of Pterocarya stenoptera were the worest as well. In addation, Camptotheca acuminata and Alniphyllum fortune according to CA and Ilex rotunda, and Cyclocarya paliurus according to MF were also the worest qulaity. The study provided powerful references for wood processing, application and directional cultivation of indigenous tree species in Zhejiang.

Abstract: In this paper, the tailings dam material physical and mechanical properties of Jilin Banmiaozi Gold Mining Co., Ltd. is studied by using of penetration test, compression test, triaxial test, dynamic shear modulus ratio and damping ratio. According to the test results, the physical and mechanical material experimental data and the experimental curve for the materials are described. These data and curves can provide available basis for systematic analysis, mechanical characteristics analysis of dam materials and seismic dam stability analysis.

Abstract: In order to study the mechanics of the deformation of the wall rock, the right roadway in Chengshan mining field, Jixi Mine was chosen to determine the physical property, micro-structure, ingredients, clay and the inner-relationships between these properties using scanning electron microscope (SEM) and theoretical analysis. For further understanding the deformation mechanics within the wall rock, hollow inclusion stress release method was used. At the end, mechanism of the wall rock in the deep was established and corresponding deformation control technology was discussed by numerical simulation.

Abstract: Power stations provide a huge influence on the environment. This influence can be diverse and integrated: (1) land avulsion, (2) dusting from the open storage spaces of fuel, ash and slags, (3) huge amounts of ash-slug wastes containing toxic metals. The aim of the research is to evaluate the effect of ash-slug wastes of the coal-burning power station (CBPS) Partizanskaya on the ecological state of soils. Transformation of the physical properties of the soils appears in the increasing fraction of coarse grain size, reducing of the sludge content in the soils, which lowers the surface area of the soils and their sorption properties. Ash particles input to the surface of soil leads to the decrease in their antierosion properties. Water capacity properties of the soils are reduced and with the moisture up to 50% soils can flow. The obtained information about the properties of the abiotic components of the industrial area of the CBPS Partizanskayaash-slags, soils are the first step in studying the environmental situation in this area. One of the possible solutions aimed to improve the environmental situation in the industrial area of the CBPS Partizanskaya is recultivation of the ash dump and development of the technologies for the usage of the ash in the household economy.

Abstract: In the coal mine of Huaibei Mining Area, based on the character of thick dirt band in the coal seams and the influences to top coal caving, the physical and mechanical properties of dirt band were analyzed. In order to improve the recovery rate of top coal, the failure mechanism of dirt band was analyzed through the cantilever beam model, and the sensitivity analysis to the length of dirt band overhang was done in the conditions of different mining height and dirt band thickness. The results show that, the average water absorption of dirt band samples is 3.5%, and the soften coefficient is 0.71, which presents that the dirt band have large softening property and poor engineering geological property. When the thickness of dirt band was more than 3.5 m, the top coal could not be caved smoothly. However, the bigger underground pressure would be helpful to the broken of dirt band and top coal seams, and the recovery rate of top coal was improved.

Abstract: Study was carried out to develop a composite material from agro waste consisting of sawdust and palm kernel shell and to determine its physical and mechanical properties. The sawdust / palm kernel shell compositions by weight were in the ratios of 100: 0, 90: 10, 80: 20, 70: 30, 60: 40 and 50:50. Urea formaldehyde was used as the test binder at concentrations of 20% of oven dry weight of agro waste. Particle size of agro waste used was 300µm .Yield strength, ultimate tensile strength, modulus of elasticity, modulus of rupture, internal bond strength, density, thickness swelling and water absorption of the formed composite materials were determined and observed to be enhanced at high palm kernel shell composition. The composite composition by weight that gave the best results out of the six compositions tested was the one with sawdust: palm kernel composition of 50%:50% with its properties as: yield strength ( 4.47 N/mm²) ,ultimate tensile strength (7.75 N/mm²), modulus of elasticity (2603 N/mm²), modulus of rupture (16.67 N/mm² ), internal bond strength ( 0.54 N/mm² ), thickness swelling (10.30%) ,water absorption (18.90%) and density (996.18kg/m³).