Papers by Keyword: Resistance

Abstract: The results of experimental studies of a separate contact dynamic interaction of a spherical non-deformable pellet with a plastic flat metal surface at different angles of attack (20° ≤ α ≤ 90°) at high speeds (v ≈ 100m/s) are presented. A method is described for determining the nature of the viscoelastic resistance of a surface layer attacked by a pellet during contact displacement along the normal to the surface and rigid plastic resistance during tangential displacement, which can be used to establish the processing regimes of products by a mass flow of abrasive particles, in particular, shot-blasting cleaning. The results of comparing the obtained and known theoretical data with each other and with experimental studies are presented.

Abstract: The study results of the calcareous composites made with the use of activated mixing water are presented. Quicklime and slaked lime are used as lime binders. The mixing water was activated by the electric current and magnetic field in various modes. The effect of water activation on the physical and mechanical properties of slaked and quicklime composites and the resistance to the effects of the biological environment are studied. The water for mixing electromagnetic treatment effectiveness analysis is presented. The increase in the density of materials based on lime, trapped in activated water using ultrasound tests is proven. It was found that the mixing water activation affects the structure formation of composites and, under certain activation conditions, leads to an increase in such physical and mechanical parameters as strength and hardness. The positive effect of the mixing water activation on the lime-based materials’ resistance to microbial growth has been established, and the decrease in the growth of composites based on quicklime and slaked lime has been proved.

Abstract: This paper briefly discusses the basic theoretical findings about sulphate-induced corrosion of concrete and also the possibilities how to determine the degree of concrete resistance to such corrosion in the most effective way. The described experiment involves a twofold comparative test – monitoring of selected parameters of two model mortars stored in both the corrosive and the reference environments (water bath). During the test, these model mortars represent commonly used concrete for the manufacture of concrete sewer pipes. The article also explains why and how the mortars were designed and tested instead of concrete. The conclusion of the paper presents the results and their evaluation.

Abstract: Worldwide, natural fiber insulation is in high demand, offering not only thermal comfort but also soundproofing. Another important aspect for which these biodegradable materials is popular is that it presents no health risk. Due the soft texture, natural fibers can be introduced very simply in any type of construction. Regardless of the vertical or inclined mounting, the stapling or gluing of the material gives stability. For example, the wool insulation is made from natural fibers, washed and treated. These wool fibers are held together either mechanically or using up to 12% polyester fibers to form semi-rigid tiles/mattresses or rollers. With a higher price than mineral wool, natural insulation is ideal for eco-friendly wooden houses. Depending on the type of construction, the wool can be mounted in a single layer or several layers, of different thicknesses [1]. For the evaluation of the thermal efficiency of the wool panel’s insulation four variants of insulating panels based on 100% wool were accomplished. Using a specialized simulation program, it is found that the heat losses through the walls themselves represent 86% of the total heat loss and the heat losses through the windows/doors to the outside represent 14% of the total heat losses.

Abstract: Abrasion measurement of surface of specific concrete elements is presented in this paper. This article is focus on determination of wear resistance and strength of concrete floor. This concrete contains silicon carbide binder and part of it is recycled origin. This material are high on Mohr hardness scale and are they are suitable for use in indoor and outdoor areas with the heaviest traffic loads. From the results, follows that the even small differences in mixture (using new and recycled binder) has impact on the mechanical parameters. However, it is possible design mixture with recycled binder and reach characteristic of concrete, which are almost similar to the normal concrete.

Abstract: The results of the study the fire safety of coatings, based on silicate and sol silicate paints, are presented. The rapid method of the fire tube (based on the definitions of the duration of self-combustion or smoldering and on the mass loss of the sample after exposure to an open flame) established that the coatings belong to the group of non-flammable material, for coatings, based on poly-silicate solutions, have a lower loss of mass, in comparison with coatings based on liquid glass. At the flammability test on the TPR it was established, that coating based on potassium liquid glass and potassium poly-silicate solution did not ignite seen, even at a temperature of 760 degrees. There is no smoke emission. However, a change in the shape and color was recorded. The weight loss of the sample of the coating, based on potassium liquid glass, was 30.14% by weight, and the coating sample, based on the potassium poly-silicate solution, was 27.14%. The evidence of improvement of fire hazard characteristics of coatings based on poly-silicate solutions is obtained.

Abstract: The third generation of solar cells found by Gratzel in 1991 was called Dye-sensitized Solar Sell (DSSC). DSSC is composed of five parts, namely transparent conductive glass as a substrat; titanium dioxide as a semiconductor materials; chlorophyll as a dye sensitizer, carbon as a catalyst which can convert energy of light into electrical energy. Characterization of DSSC will be carried out in this research covering electrical characterization using RLC meter & I-V meter, optical characterization using Spectrophotometer. TiO₂ nanoparticle in in anatase phase having size of 13 nm used in this experiment was synthesized by co-precipitation method. Photoanode with thickness of 10 μm has the lowest resistance compared to the other thickness of 30 μm and 50 μm. The device applying photoanode of 10 μm shows the highest efficiency up to 0.1141 %, while those with other thicknesses respectively gives 0.0378%, and 0,0283%, revealing the efficiency becomes lower with the increasing thickness of TiO₂.

Abstract: The results of the study provide information on the resistance of coatings based on the solof silicate paint in the process of freezing and thawing. It was found, that coatings based on sol silicatepaints are characterized by a higher resistance compared of silicate coatings. It is shown, that thecoatings withstood 50 cycles of alternate freezing and thawing. The surface energy of the coatingswas calculated using the critical surface tension of the fluid at the interface with the solid. Thedispersion contribution in the intermolecular interaction between the particles of the coatings wasestimated. The values of the surface tension of the coatings and the values of the dispersioncomponent of the surface energy of the coatings — the complex Hamaker constant — are calculated.It was revealed, that after testing a decrease in the values of the Hamaker constant is observed. It wasestablished, that after testing for frost resistance, the values of the Hamaker constant for coatingsbased on sol of silicate paint are higher compared to coatings based on silicate paint.

Abstract: The paper compares the sulphate ion attack resistance in several mixtures of high-performance concrete. The corrosion tests were not performed with the actual concretes, but with model mortars derived from them. The resistance was compared by means of a comparative, specifically double-comparative, methodology. The paper devotes much attention to describing this method, deriving the model mortars, and choosing the correct specimens and parameters to be observed. All important test results, which confirm the effectiveness of the method, are listed. The resistance of each mortar was identified with sufficient accuracy.

Abstract: The paper discusses an experimental technique of comparing different concretes in terms of their resistance to leaching corrosion. Specifically, the experiment compared the resistance of three different high-performance concretes exposed to deionised water with aggressive carbon dioxide. To control the duration of the laboratory tests, they were not performed on these particular concretes, but rather on model mortars derived from them; the mortars proved perfectly sufficient to give the desired information. The paper also describes how these mortars were created on the basis of known or assumed concrete formulae. The actual corrosion test was designed as a double-comparative experiment. The paper lists all the basic test results, which confirm the effectiveness of the comparative method – the experiment was successful in drawing clear comparison between the concrete variants.