PULLOUT BEHAVIOR OF OXYGEN PLASMA TREATED POLYMER FIBERS FROM CEMENT MATRIX

The aim of this work is to describe bonding properties between surface treated polymer fibers and a cement matrix. In order to increase an interaction between the matrix and fiber surfaces, two fiber types having approx. 0.5 mm in diameter were modified by mean of oxygen plasma treatment. Surface physical changes of treated fibers were examined using SEM morphology observation and interfacial adhesion mechanical tests. The principle of mechanical tests rested on a single fiber pulling out from the matrix (cement paste, CEM I 42.5 R, w/c 0.4). The embedded length was equal to 50 % of original fiber length (50 mm), where the fiber free-end displacement and force resisting to the displacement were monitored. It was pointed out that interfacial shear stress needed to break the bond between the modified fibers and the matrix increased almost by 15–65 % if compared to reference fibers. When the fiber free-end displacement reached to 3.5 mm, the shear strength increased almost twice

RECYCLING OF CONSTRUCTION WASTE USING HIGH-SPEED MILLING PROCESS: DETERMINATION OF WASTE CONCRETE

This paper deals with the use of high-speed milling process for recycling old concrete and direct determination of the potential of input waste. For this purpose, three different types of waste concrete were used: prefabricated railway sleeper, structural concrete of monolithic pillar and prefabricated drainage gutter. The paper directly examines the chemical and phase composition by XRF, X-Ray Diffraction (XRD), Energy Dispersive X-ray Spectrometry (EDS) and microscopic analysis, particle size distribution and pH of the recycled material. Results of those analysis are used to select suitable recycled material. The suitability of choice is supported by mechanical tests of 28-day old cement pastes, where the compressive strength and dynamic modulus of elasticity are observed properties. Specimens measuring 40 × 40 × 160mm are composed of 70 wt.% Portland cement and rest is micronized concrete. In all cases, the results are compared with the reference material

ASSESSMENT OF ADHESION BETWEEN BITUMINOUS BINDER AND MINERAL AGGREGATE USING DIGITAL IMAGE ANALYSIS

Asphalt mixtures often fail due to a low adhesion of bituminous binder to mineral aggregate, which leads to surface coarse damages like potholes and fatigue cracking. To avoid this phenomenon, different types of adhesion promoters may be admixed into bituminous binder but a new question about their effectiveness arises. This paper presents two semi-automatic methods, which reliably replace the subjective assessment. Both of them use a digital image of asphalt mixtures as an input. The first is based on a gray level thresholding, while the second one on an entropy-based image segmentation. Asphalt mixtures composed from Zbraslav aggregate (fraction 8–16 mm), paving grade bitumen 50/70 and several types of adhesion promoters were made and subjected to the adhesion assessment. It was shown that aggregate grains coated by binder was equal to ca. 83–88% in the case of reference binder, while that was increased by ca. 10–13% if whatever adhesion promoters were used

PULLOUT BEHAVIOR OF OXYGEN PLASMA TREATED POLYMER FIBERS FROM CEMENT MATRIX

The aim of this work is to describe bonding properties between surface treated polymer fibers and a cement matrix. In order to increase an interaction between the matrix and fiber surfaces, two fiber types having approx. 0.5 mm in diameter were modified by mean of oxygen plasma treatment. Surface physical changes of treated fibers were examined using SEM morphology observation and interfacial adhesion mechanical tests. The principle of mechanical tests rested on a single fiber pulling out from the matrix (cement paste, CEM I 42.5 R, w/c 0.4). The embedded length was equal to 50 % of original fiber length (50 mm), where the fiber free-end displacement and force resisting to the displacement were monitored. It was pointed out that interfacial shear stress needed to break the bond between the modified fibers and the matrix increased almost by 15–65 % if compared to reference fibers. When the fiber free-end displacement reached to 3.5 mm, the shear strength increased almost twice

Polynomial substitutions and decompositions

Tato bakalářská práce se zabývá rozkladem polynomů. Čtenáři je nejprve připomenuta problematika konkrétních operací s funkcemi. Následně jsou vysvětleny pojmy týkající se polynomů, které jsou v práci využívány. Hlavní částí je vyřčení a objasnění Ritterovy věty o polynomiálním rozkladu a vysvětlení algoritmu, kterým dosáhneme kompletního rozkladu polynomů. V práci jsou uvedeny příklady počítání hodnot polynomů, využití rozkladu polynomů a řešení rovnic vyjádřené v radikálech.ObhájenoThis bachelor thesis is concerned with polynomial decomposition. At the first, the readers could remember some mathematical problems relating to functions. Next, it is explained terms relating to polynomials, which are used in the next parts. Explaining Ritter´s theorem about polynomial decomposition and explaining the complete decomposition algorithm of polynomials are the main parts of this bachelor thesis. In the end, readers could see examples of counting value of the polynomial, using polynomial decomposition and solutions of equations expressed in radicals

Analyses of the competitiveness of the company

The aim of this thesis is to evaluate the competitiveness analyses of the company. On the basis of acquired informatics I carried out financial analyses of the company. This part of my thesis covers the company´s assets and liabilities, the value of woodland, receivables, cost and profits. I was also interested in the area of the human resource managemenent. For analyses of HR I used the checklist examination for gaining useful information. On the basis of the results I carried out a SWOT analyses and beside the evaluation of the internal environment I realized the evaluation of the external environment by means of the Step analyses and the other methods

Evaluation of the internal environment of the company

The aim of this thesis is to evaluate the internal environment of the company. On the basis of acquired information I carried out a financial analysis of the company for the years 2004 - 2006. This part öf my thesis covers the company´s assets and liabilities, the value of woodland, receivables, costs and profits. It also includes a comparison with competitors in the same field. In addition I was also interested in the area of human resource management and to a lesser degree in production and marketing. On the basis of the results I carried out an evaluating of the company´s strenghts, weaknesses, opportunities and threats and put forward proposal for a new strategy for the company

Influence of spa tourism on inhabitants of Karlovy Vary

Katedra sociální geografie a region. rozvojeDepartment of Social Geography and Regional Develop.Faculty of SciencePřírodovědecká fakult

PULLOUT BEHAVIOR OF OXYGEN PLASMA TREATED POLYMER FIBERS FROM CEMENT MATRIX

The aim of this work is to describe bonding properties between surface treated polymer fibers and a cement matrix. In order to increase an interaction between the matrix and fiber surfaces, two fiber types having approx. 0.5 mm in diameter were modified by mean of oxygen plasma treatment. Surface physical changes of treated fibers were examined using SEM morphology observation and interfacial adhesion mechanical tests. The principle of mechanical tests rested on a single fiber pulling out from the matrix (cement paste, CEM I 42.5 R, w/c 0.4). The embedded length was equal to 50 % of original fiber length (50 mm), where the fiber free-end displacement and force resisting to the displacement were monitored. It was pointed out that interfacial shear stress needed to break the bond between the modified fibers and the matrix increased almost by 15–65 % if compared to reference fibers. When the fiber free-end displacement reached to 3.5 mm, the shear strength increased almost twice