1,720,983 research outputs found
Production of pressed biocomposite using hemp stems and research on its properties.
No full textThe aim of the research carried out during the preparation of the master’s thesis is to produce biocomposite samples with different types of binders and various organic wastes, curing them naturally and in a CO2 gas environment, and to determine the physical and mechanical properties of these materials using the results obtained from experiments. The main composition of the samples consists of hemp shives filler. The thesis consists of an introduction, a literature review, a description of the materials used, the equipment, and the production of the samples, the methodology of the studies, the results of the experiments and their analysis, and conclusions. The literature analysis examined the production options for the production of pressed biocomposites using different fillers and binders, different production methods and different curing processes. The analysis of the sources describes the properties of the biocomposite, the applications and the influence of the composition of the pressed biocomposite on the properties of the material. The master’s thesis continues with a description of the materials used, the equipment and the sample production process. The whole production process is broken down into four parts according to the type of binder used, providing useful information in tables with photographs of the samples. The methodology section examines the experiments carried out, explains the calculation equations and indicates the curing methods used, with samples cured both naturally and in a CO2 environment. The analysis of the experimental results shows that the specimens made with treated hemp shives withstand a higher compressive force than those made with dry untreated shives. The strongest materials suitable for forming load-bearing structures were made of cementitious binder, dolomitic siftings or fine sand and treated hemp shives filler, with a compressive strength of 6,5 MPa. The experiments showed that the compressive strength was strongly influenced by carbonisation, with the best results in both the depth of carbonisation and the compressive strength being obtained from carbonisation in a CO2 chamber. The materials suitable for thermal insulation were obtained without the addition of heavy fillers, with densities ranging from 260 kg/m3 to 500 kg/m3 and thermal conductivities ranging from 0,07 W/mK to 0,12 W/mK. Having fulfilled all the aims and objectives of the work, 8 conclusions are presented on the literature analysis, the design of the composition of the pressed biocomposite, the results of the experiments, on the production process and the possibilities of application. The final master’s thesis is 58 pages long. The thesis consists of 13 tables, 40 figures and 46 references
Manufacturing of lightweight concrete using "green" technology by curing in a CO2 environment.
No full textThe aim of this master‘s thesis is to make lightweight concrete using green technology by curing in CO2 environment and to determine its properties. The tasks of this thesis are to produce lightweight foam concrete and to determine its mechanical and physical properties after curing in CO2 environment, as we as to estimate the amount of CO2 absorbed by concrete. Master’s thesis consist of three main parts: literature analysis, composition of concrete and research methods, analysis of experimental results. The analysis of literature describes the methods of production of lightweight concrete and materials required for its production. The basic principles of carbonization, its chemical reactions and carbonation methods were found out. The results of other research and possible influence of environment conditions have been analyzed. In the following section making and compositions of lightweight foam concrete which is used in this work are given. Experiments were performed to select best concrete which will be used to continue testing. One composition with a cement binder and one composition with lime binder were chosen. In this section test methods and devices used are also described. The results of experiments are analyzed in the third part of this work. Test have shown that density of both compositions with cement and lime binder cured in CO2 are always higher than the one cured in the air, due to the formation of calcium carbonate. Also tests have shown that, curing time has significant effect on the compressive strength of the concrete, but it’s not worth to keep specimens in the curing chamber for too long, because effectiveness decreases as time goes. The average depth of carbonation indicated that only few hours of curing in CO2 is enough, to achieve a greater carbonation than specimens which were stored in the air for 28 d. In this part of the work samples consumption of the CO2 was estimated by two methods, density change method and titration method. It’s found that the amount of CO2 used is also highly dependent on the curing time, but specimens with lime binder can absorb more carbon dioxide than specimens with cement binder due to their chemical composition. Finally 6 conclusions were made about results of all the experiments. Master’s thesis consists of 53 pages of text, 24 tables, 23 figures, 43 references
Evaluation of the effectiveness of self-healing concrete in different chemical environments.
No full textIn Lithuania, self-healing concrete additives are increasingly used in the production of concrete and reinforced concrete structures. However, there are no prepared regulatory documents to ensure their effectiveness. This is caused by the low interest of Lithuanian scientists in this direction and the lack of research. This master's final degree project reviews the performance of crystalline admixtures and their effectiveness under natural conditions, and presents the European Cooperation in Science and Technology (COST Association) research on self-healing concrete additives. Reinforced concrete structures are exposed to various environmental factors and chemical elements during their lifetime. These effects have a major impact on the life span of the structures, as they can cause corrosion of both the reinforcement and the concrete itself. Similarly, these factors can negatively or positively influence the performance of concrete admixtures. Concrete and reinforced concrete samples, which were made using crystaline admixtures, are the subject of this project. During the experiments, the effect of chemical solutions on healing of cracks was determined, methods of evaluation of crack healing efficiency were compared, influence of additives in reinforcement corrosion processes, shrinkage deformations were considered. In addition, the depth of carbonation in samples with and without additives is determined. Performed tests can be used to evaluate the crack healing efficiency of self-healing concrete. In addition, considering the environmental conditions under which the structures will be used, it can be determined whether it is rational to use crystalline additives to increase the durability of the structures, since under certain conditions the performance of these additives is reduced
Research of physical and mechanical properties of CO2 cured cementless pavement elements.
No full textThe aim of the master's thesis is to create a cement-free carbonized product and determine its physical and mechanical properties as a paving element according to the testing methods for concrete outdoor paving stones specified in the LST EN 1338 standard. 3 tasks were set to achieve the aim of the thesis. The thesis consists of three main parts: literature analysis, research methodology and research results. The literature analysis part describes the CO2 curing technology, accelerated carbonization methods, the influence of binders and materials on carbonization, as well as the physical and mechanical properties of carbonized products, their CO2 gas emissions and the production technology of pressed products. The research methodology part describes the materials used, the composition of the samples, and their production process. The course of the research methods is also described and the formulas used to calculate the results are presented. The research results part describes and analyses the results obtained during the research. First, according to the compressive strength of the samples and the depth of carbonization, the composition that showed the best indicators was selected, which was further improved and studied by the tests described in the research methodology section. The physical and mechanical properties of the most optimal composition were determined and its CO2 gas absorption rate was calculated. The master's thesis is summarized in 7 conclusions. The volume of the thesis is 51 pages, the work contains 35 figures, 5 tables and 48 references
Research of produced and pressed biocomposite with wood waste and its properties.
No full textThe aim of the Master's thesis project is to produce biocomposites with wood chips and determine their physical and mechanical properties. Project objectives: 1. To analyse scientific articles and to present them in a targeted way in the conception of the topic on materials used for biocomposites, production methods, their properties and applicability; 2. To produce compressed biocomposites with wood waste and cement binder and to investigate their physical and mechanical properties; 3. To produce compressed biocomposites with wood waste and lime binder and investigate their physical and mechanical propertie; 4. Determine the effect of wood chip preparation on the properties of the pressed biocomposite; 5. To maintain the compressed biocomposites in a CO2 gas saturated chamber and to determine the effect of carbonisation on the properties of the pressed products. The literature review describes the structure of the biocomposite and the variety of fillers and binders. The variety of biocomposite materials, compositions, production methods, physical and mechanical properties, durability and drawbacks of biocomposites have been analysed. The analysis also presents the applications of biocomposites in construction. Chapter 2 presents the individual compositions of the biocomposites with cementitious and lime binder and the technology for their production. The chapter analyses and identifies the best cement and lime binder formulations. It also describes the test methods, the instruments used and the test procedures. Chapter 3 analyses the results of the experiments. The sawdust preparation methods and pH values are presented, the influence of carbonisation on the properties of the samples and the depth of carbonisation are analysed, and the influence of water absorption on the properties of the biocomposites is assessed. The tests showed that the densities and compressive strengths of both cement and lime samples depend on the binder and sawdust content of the samples, the method and size of the sawdust preparation, and the amount of carbonation. It was found that the lime specimens can abdorb more CO2 gas than the cement specimens. Master’s thesis consists of 13 tables, 30 figures and 43 references
Research of UV resistance and physical-mechanical properties of thermally treated wood.
No full textMaster‘s thesis aims to investigate the influence of hydrothermal and thermal treatment in oil on construction wood's physical, mechanical, and UV resistance properties. The aim of the work is implemented through the 5 work tasks, which include literature analysis, heat treatment of samples by changing the temperature regime and agent, and research on physical, mechanical and UV resistance properties. The literature analysis discusses wood's structure, chemical composition, physical and mechanical properties, the effects of thermal, hydrothermal, and thermal oil treatment on wood, and the possibilities of using treated wood. The experimental part describes the research equipment and the research process. During the study, wood samples were hydrothermally treated at different temperature regimes in an autoclave, and thermally in oil under open conditions. The following altered wood properties were observed: dimensional stability, physical properties, mechanical properties, resistance to biological factors, and changes in surface structure
Manufacturing of pressed concrete products using “green” technology by curing in a CO2 environment.
No full textThe aim of Master‘s Thesis is to produce pressed concrete products using „green“ technology by curing them in CO2 and determine their properties. Master‘s Thesis consists of three main parts: literature analysis, research methodology and research results. Master's Thesis is summarized in 8 conclusions. The volume of the final work (without appendixes) is 53 pages, the work contains 48 figures, 9 tables and 30 references
Evaluation of the efficiency of self-healing concrete using different methodologies.
No full textIn this Master‘s final work self-healing concrete was analyzed and tested by using different methodologies. The final work consists of theoretical and experimental parts. In theoretical part analysed methodology and operation principles of self-healing concrete nad conditions that are necessary for it. The causes of cracking of concrete structures, impact of cracks on concrete structures and the applicability of self-healing concrete were analysed as well. Methods to determine the efficiency of self-healing concrete were discussed. The experimental part investigates self-healing concrete modified with mineral additives. The influence of additives on concrete mixture and hardened concrete samples was determined. The tests were carried out by creating non-standard cracks in samples. The effectiveness of crack sealing was determined by using water permeability and water absorbtion tests. Results of crack recurrence and conclusions are presented
Self-cleaning and air-cleaning construction material analysis, under UV.
No full textThe aim of master‘s thesis is to determine self-cleaning and air cleaning construction material analysis acting them under UV light. Master‘s thesis consists of three main parts: literature review, TiO2 study methods and geralization of results. In the first part different principles of TiO2 formation and operation are given, possibilities of its application and useful properties depending on type are presented. Analyzing scientific publications also desribed the effect of TiO2 self-cleaning and air-cleaning effect on different speicimens and surfaces under UV light. In the second part self-cleaning and air cleaning construction material analysis methods are presented. In the description of the experiments the instruments and testing tools are indicated for testings that were done, the course of testing that has been conducted were given to determine the properties of the materials, and needed equations to calculate results are given. In the third part of master‘s thesis the results of the research are presented. Results are analyzed to create graphs and curves that are used to compare the properties of the different samples. Differences between samples tested in the laboratory and under field conditions are also analyzed
Three-layer sandwich panels production technology.
No full textIn the final Master’s degree project, a three-layer reinforced concrete wall panel manufacturing plant was being designed. The production intricacies and technical requirements of the product were taken into account throughout the factory’s development process. The structures constructions were based to meet existing functionality, economical and architectural requirements. Elements for the manufacturing plant’s truss were chosen in regard to calculation and analysis results. Multilayered reinforced concrete wall panel production process technological scheme, operation time schedule and production line were developed based upon the raw material, product’s and production’s base requirements, norms as well as calculations of the production technology. The economical expenses of the wall panel production and the factories building expenditure were measured to determent the average return on investment time of the facility. Sand’s small fractions ratio influence on the concrete surface quality was researched and overviewed. Tests on samples were conducted using picture analysis method, the results were categorized using pre-existing evaluation criteria
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