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Number of results: 5
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Abstract

This paper presents the analysis of the influence of works related to the dynamic replacement column formation on the bridge pillar and the highway embankment located nearby. Thanks to DR columns, it is possible to strengthen the soil under road embankment in a very efficient way. However, the construction of such support carries risk to buildings and engineering structures located in the neighbourhood. Therefore modelling and monitoring of the influence of the conducted works should be an indispensable element of each investment in which dynamic replacement method is applied. The presented issue is illustrated by the example of soil strengthening with DR columns constructed under road embankment of DTŚ highway located in Gliwice. During the inspection, the influence of vibrations on the nearby bridge pillar and road embankment was examined. The acceleration values obtained during these tests were used to verify the elaborated numerical model.
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Abstract

The paper covers problems of the owners of a fleet of long-operated conventional power plants that are going to be decommissioned soon in result of failing to achieve new admissible emissions levels or exceeding pressure elements design lifetime. Energoprojekt-Katowice SA, Siemens AG and Rafako SA presents their joint concept of the solution which is a 2on1 concept – replacing two unit by two ultra-supercritical boilers feeding one turbine. Polish market has been taken as an example.
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Abstract

Plastic obtained from the discarded computers, televisions, refrigerators, and other electronic devices is termed as e-plastic waste. E-plastic waste is non-biodegradable waste. This paper focuses to investigate the replacement of fine aggregate with plastic aggregate obtained from e-plastic. The paper presents a detailed comparison of concrete properties (i.e.: compressive strength, tensile strength, flexural strength, density and workability) for normal concrete and concrete containing e-plastic fine aggregates. The testing was conducted according to the ASTM standards. 28-day Compressive, Flexural and Split tensile strengths were determined. In addition to the effect of e-plastic fine aggregate, silica fume is added as an admixture to find the effect on strengths. Authors have performed a compressive, flexural and tensile test of concrete mix with various percentages of e-plastic aggregates (i.e., 0, 5, 10, 15 and 20%) and silica fume (i.e.: 0, 5 and 10%) and concrete densities are also considered. It has been concluded that an increase in the e-plastic fine aggregate results in reduction in densities, compressive, flexural and tensile strength values. However, when we add silica fume to the concrete mixture it leads to strength values similar to the control mixture. The optimum obtained concrete blend contained 5% e-plastic fine aggregates and 10% silica fume. The addition of silica fume in concrete mixtures increases the 28-day compressive, flexural and tensile strengths. Moreover, the density of concrete decreases with the increase in the e-plastic aggregates.
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Abstract

Recycling construction and demolition waste not only reduces project costs; and saves natural resources, but also solves the environmental threat caused by construction waste disposal. In this paper, C25 waste road concrete is used as an experimental material, the uniaxial compression strength and tensile splitting strength of C25 RAC whose coarse aggregate replacement rate is 0%, 25%, 50%, 75%, and 100% are tested under the condition that the water-to-cement ratio is 0.47, 0.55 and 0.61. The results show: (1) the uniaxial compression strength and tensile splitting strength decrease with the increase of RAC; (2) for concrete with the same water-to-cement ratio, when the coarse aggregate replacement rate changes from 0% to 50%, the uniaxial compression strength and tensile splitting strength of RAC changes slightly. When the coarse aggregate replacement rate changes from 50% to 100%, the uniaxial compression strength and tensile splitting strength of RAC decreases rapidly
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Abstract

The paper presents an analysis of factors influencing the accuracy of reproduction of geometry of the vertebrae and the intervertebral disc of the lumbar motion segment for the purpose of designing of an intervertebral disc endoprosthesis. In order to increase the functionality of the new type of endoprostheses by a better adjustment of their structure to the patient’s anatomical features, specialist software was used allowing the processing of the projections of the diagnosed structures. Recommended minimum values of projection features were determined in order to ensure an effective processing of the scanned structures as well as other factors affecting the quality of the reproduction of 3D model geometries. Also, there were generated 3D models of the L4-L5 section. For the final development of geometric models for disc and vertebrae L4 and L5 there has been used smoothing procedure by cubic free curves with the NURBS technique. This allows accurate reproduction of the geometry for the purposes of identification of a spatial shape of the surface of the vertebrae and the vertebral disc and use of the model for designing of a new endoprosthesis, as well as conducting strength tests with the use of finite elements method.
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