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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Vývoj nové technologie pískového pórobetonu s využitím druhotných surovin / Development of new technology of sand autoclaved aerated concrete with using of secondary raw materials

Ondříčková, Pavlína January 2018 (has links)
Autoclaved sand aerated concrete is a modern building material with high thermal insulation properties. Only sand is used as the primary silicate component of aerated concrete in the Czech Republic. For the more favourable economic and ecological properties of aerated concrete, the use of secondary raw materials is used in this work. The secondary raw materials examined included fluidized bed and fly ash, slag and glass recycled. The aerated concrete composite with secondary admixtures was developed under hydrothermal conditions of a laboratory autoclave for 7 and 12 hours at 190°C. From the secondary raw materials tested, a 10% glass recycler additive yielded the highest strength. Other additives that have a positive effect on mechanical properties include SAKO and Oslavany. From the results of the work it is evident that the use of secondary raw materials increases the strength, improves the rheology of the mixture and supports the formation of tobermorite.
22

Studium mikrostruktury autoklávovaného pórobetonu s využitím druhotných surovin / Study of microstructure of autoclaved aerated concrete with using of secondary raw materials

Martanová, Jana January 2018 (has links)
Autoclaved aerated concrete is a used building material, especially for its thermal insulating properties. During autoclaving, an aerated concrete microstructure produces crystalline CSH phases, primarily tobermorite. The ingoing substances are calcium oxide and silica. In addition to commonly used raw materials, secondary raw materials rich in silicon dioxide can be used for production. The use of secondary raw materials gives the opportunity for the construction industry to be more environmentally friendly. Another benefit is the reduction of financial costs. The work explores the influence of individual secondary raw materials on the microstructure. High-temperature fly ash, fluid fly ash, cinder, ground glass and zeolite were used The raw materials were mixed with unalloyed lime at a molar ratio of calcium oxide to silicon dioxide of 0.73 and 1.0. Autoclaving capsules were used to synthesize tobermorite under laboratory conditions. Autoclave was performed at 170 °C and 190 °C with hydrothermal durations of 4, 8 and 16 hours. The most important influence on the microstructure was high-temperature fly ash, on the contrary, the greatest influence on the mechanical properties is attributed to the ground glass.
23

Vývoj speciálních sanačních hmot na beton pro extrémní namáhání s využitím druhotných surovin / DEVELOPMENT OF SPECIAL REHABILITATION MATERIALS FOR CONCRETE FOR EXTREME STRESS WITH USE OF SECONDARY RAW MATERIALS

Hodul, Jakub January 2019 (has links)
The doctoral thesis deals with finding the use of some waste and secondary raw materials in the production of special polymer remediation materials for concrete, which could be applied even in constructions, where extreme mechanical and chemical load is occurred. The aim of this doctoral thesis is experimental examination of the possibility of using selected types of waste, including hazardous waste which represent the highest risk to environment, and secondary raw materials as a substitute for the currently used primary fillers in order to reduce the ecological footprint of the product itself. Some types of secondary raw materials, such as filter fly ash contaminated by flue gas denitrification process, are no longer used as a concrete admixture or partial cement substitution due to unwanted release of toxic ammonia (NH3). Mainly for this reason, the thesis deals with the progressive utilization of such types of secondary raw materials as well as with another currently unused waste into polymeric patching, grouting and anchoring materials while preserving or improving the final properties compared to reference materials using only primary raw materials. The result of this thesis is to find out suitable formulations for efficient preparation of special polymeric remediation materials for concrete containing waste and secondary raw materials as fillers. The partial aim of the thesis and a the scientific contribution is an observation of the developed materials internal structure using a modern device, CT tomography, an influence of the filler type on the long-term durability, and last but not least the observation of the rate of pollutants incorporation, found in hazardous waste, into the polymeric matric with the aid of EDX and FTIR analysis.

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