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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.
1

Additives to increase the sustainability of concrete paving blocks

Limbachiya, V. January 2015 (has links)
The aim of this study was to break through current limits with cement substitutes in concrete paving block and introduce high levels of cementitious constituents. As well as meeting the current strength and durability requirements stated in BS EN 1338:2003 the study reported on the effect of materials variability and leaching properties. The cementitous materials used to replace Portland cement (PC) were Pulverised Fuel Ash (PFA also known as Fly Ash), Ground Granulated Blast Furnace Slag (GGBS), Metakaolin (MK), Silica fume (SF), Glass Powder (GP), Basic Oxygen Slag (BOS) and By Pass Dust (BPD). The first phase of the study analysed 11 groups of ternary cement paste blends using Minitab, a statistical programme to help determine mix designs and optimised mix. Analysis of ternary cement pastes in the first phase concluded that mixes containing GGBS over PFA produced greater strengths at early ages. Mixes confirmed that PC-GGBS-GP provided good strengths due to the SiO2 content within GP providing secondary CSH gel. PC-GGBS-BPD provided good strengths due to SO3 within BPD activating the GGBS through sulphates. The best results in forms of strength were found in PC-GGBS-SF and PC-GGBS-BOS ternary pastes. The fine particles along with the high SiO2 content of SF provided greater pozzolanic reactivity and a greater matrix densification. Fourteen of the best mixes were then taken into the second phase. This is when concrete paving blocks were made from these mixes with the method that was developed at Coventry University. The two mixes with the greatest splitting tensile strength consisted of varying levels of PC-GGBS-SF and were known as the candidate mixes. The durability criteria set out in BS EN 1338:2003 was met, however the minimum strength requirement was not. The candidate mixes were still chosen to be produced in the factory as the manufacturing and curing procedure in the factory was more effective and efficient in comparison to the laboratory procedure. The site trial successfully achieved the minimum requirements for the mechanical properties and durability performance stated in BS EN 1338:2003 and reduced the cement content of concrete paving blocks by 40% wt of PC, with a ternary blend consisting of 60% PC, 25% GGBS and 15%SF. Analysis of material variability was conducted on PFA (regulated commercially available replacement) and BPD (replacement waste material). Results showed that when using regulated commercially available cementitious constituents the chemical composition of the material should be within a given range (For replacement by weight of 10%, 20%, 30%, difference in main oxide should be no greater than 1%, 2.5% and 3.5% respectively) and for the waste material the chemical composition (Limits as stated for regulated commercially available material) as well as fineness (Replacement by weight of 5% and 10% should not have a variability in average particle size of more than 15μm) should be within a range. The two candidate mixes were finally tested for their leaching properties against a leachate that was derived from used oil concentrations. The increase in permeability with the use of GGBS and SF lead to the block absorbing less of the leachate in comparison to the control mix. The study set out to introduce high levels of cementitious constituents in concrete paving blocks. Although it is known that high levels of replacement would cause deterioration, this was done in order for the study to create a database in which the company could refer to and determine which constituents performed well and what the maximum level of replacement could be. The study successfully replaced PC by 40% with 25% GGBS and 15% SF. With blocks actually producing greater strengths than the control mix (100% PC) at 28 days and meeting all the minimum requirements that were set out in BS EN 1338:2003.
2

Reaproveitamento do resíduo Terra da Shredder através da técnica de solidificação/estabilização em matrizes de cimento Portland para aplicação na construção civil / Shredder\'s soil recycling by solidification/ stabilization (S/S) technique in Portland cement matrices for application in construction

Juliana Argente Caetano 29 June 2016 (has links)
A Shredder é o equipamento para a trituração da sucata ferrosa que permite a reciclagem do aço nas siderúrgicas. A sucata é em sua maioria procedente da reciclagem de veículos de fim de vida. Por isso, esse resíduo é conhecido como ASR (Automotive Shredder Residue). A Terra da Shredder é a fração do ASR de pequena granulometria (<2mm) apresentando o aspecto de solo. Esse resíduo é tratado como rejeito e em sua totalidade destinado aos aterros industriais. O grande volume de resíduo gerado contribui para a saturação dos aterros, provoca impactos ambientais, despende um alto custo de disposição e assim exige o desenvolvimento de tecnologias para seu reaproveitamento. Este trabalho propõe utilizar a Terra da Shredder, resíduo sólido gerado na Shredder localizada em Iracemápolis-SP-BR, em peças de concreto para pavimentação através da técnica de solidificação/estabilização (S/S) em matrizes de cimento Portland. Na primeira etapa do experimento, o resíduo foi classificado como Classe IIA. A segunda etapa consistiu na produção de matrizes compostas com cimento, agregados e água, foram produzidos corpos de prova com os seguintes teores de substituição, em massa, da areia natural pelo resíduo: 5%,10%,15% e 20%. A matriz com o teor de substituição de 20% apresentou uma resistência mecânica compatível com a norma ABNT NBR 9781, por isso foram fabricadas peças de concreto com esse teor de substituição. As peças de concreto apresentaram bom desempenho mecânico, físico e, com exceção do alumínio, fenóis totais e cádmio, as outras substâncias que ultrapassaram os limites de solubilização (ferro total, fluoretos, manganês, selênio, surfactantes) foram encapsuladas pelo cimento, sendo que o cádmio também estava presente em peças de concreto para pavimentação fabricadas apenas com os materiais convencionais, sem o resíduo. Dessa forma, conclui-se que os blocos podem ser utilizados na construção civil. / The Shredder is the equipment for the processing of ferrous scrap which allows the recycling of steel. Scrap is in its majority coming from the recycling of end of life vehicles. Therefore, the residue formed in this grinding process is known as ASR (Automotive Shredder Residue). The fine fraction of the ASR has soil aspect so will be called Shredder\'s soil. This residue is treated as waste and in its entirety for the landfills. It is estimated that for each ton of metallic material separated in Shredders approximately 227 kg of waste are produced. This large volume of waste generated contributes to the saturation of landfills,causes environmental impacts, expends a high cost of disposal and thus requires the development of technologies for its reuse. This paper proposes to use the fine fraction (<2mm) of the solid waste generated in a shredder in the city of Iracemápolis-SP-BR in concrete paving blocks through the techinique of solidification/stabilization (S/S) in Portland cement matrix. The experimental research began with completion of leaching tests and solubilization for the classification of waste class IIA , substances that exceeded solubility limits were total phenols, total iron, fluoride, manganese, selenium, aluminum, cadmium and surfactants. The second stage was the production of cement matrix that is composed by cement, aggregates and water they were produced matrices with the following replacement levels of natural sand by the waste: 5%, 10%, 15% and 20%. The matrice with the 20% replacement level, showed a consistent resistance to compatible with standard ABNT NBR 9781, therefore concrete paving blocks were manufactured content this level of replacement. The blocks had good mechanical, physical and with the exception of aluminum and cadmium, other substances that exceeded solubility limits were encapsulated. Cadmium also appear in paving blocks manufactured with conventional materials, without residue. Thus, it is concluded that the concrete paving blocks can be used in construction.
3

Reaproveitamento do resíduo Terra da Shredder através da técnica de solidificação/estabilização em matrizes de cimento Portland para aplicação na construção civil / Shredder\'s soil recycling by solidification/ stabilization (S/S) technique in Portland cement matrices for application in construction

Caetano, Juliana Argente 29 June 2016 (has links)
A Shredder é o equipamento para a trituração da sucata ferrosa que permite a reciclagem do aço nas siderúrgicas. A sucata é em sua maioria procedente da reciclagem de veículos de fim de vida. Por isso, esse resíduo é conhecido como ASR (Automotive Shredder Residue). A Terra da Shredder é a fração do ASR de pequena granulometria (<2mm) apresentando o aspecto de solo. Esse resíduo é tratado como rejeito e em sua totalidade destinado aos aterros industriais. O grande volume de resíduo gerado contribui para a saturação dos aterros, provoca impactos ambientais, despende um alto custo de disposição e assim exige o desenvolvimento de tecnologias para seu reaproveitamento. Este trabalho propõe utilizar a Terra da Shredder, resíduo sólido gerado na Shredder localizada em Iracemápolis-SP-BR, em peças de concreto para pavimentação através da técnica de solidificação/estabilização (S/S) em matrizes de cimento Portland. Na primeira etapa do experimento, o resíduo foi classificado como Classe IIA. A segunda etapa consistiu na produção de matrizes compostas com cimento, agregados e água, foram produzidos corpos de prova com os seguintes teores de substituição, em massa, da areia natural pelo resíduo: 5%,10%,15% e 20%. A matriz com o teor de substituição de 20% apresentou uma resistência mecânica compatível com a norma ABNT NBR 9781, por isso foram fabricadas peças de concreto com esse teor de substituição. As peças de concreto apresentaram bom desempenho mecânico, físico e, com exceção do alumínio, fenóis totais e cádmio, as outras substâncias que ultrapassaram os limites de solubilização (ferro total, fluoretos, manganês, selênio, surfactantes) foram encapsuladas pelo cimento, sendo que o cádmio também estava presente em peças de concreto para pavimentação fabricadas apenas com os materiais convencionais, sem o resíduo. Dessa forma, conclui-se que os blocos podem ser utilizados na construção civil. / The Shredder is the equipment for the processing of ferrous scrap which allows the recycling of steel. Scrap is in its majority coming from the recycling of end of life vehicles. Therefore, the residue formed in this grinding process is known as ASR (Automotive Shredder Residue). The fine fraction of the ASR has soil aspect so will be called Shredder\'s soil. This residue is treated as waste and in its entirety for the landfills. It is estimated that for each ton of metallic material separated in Shredders approximately 227 kg of waste are produced. This large volume of waste generated contributes to the saturation of landfills,causes environmental impacts, expends a high cost of disposal and thus requires the development of technologies for its reuse. This paper proposes to use the fine fraction (<2mm) of the solid waste generated in a shredder in the city of Iracemápolis-SP-BR in concrete paving blocks through the techinique of solidification/stabilization (S/S) in Portland cement matrix. The experimental research began with completion of leaching tests and solubilization for the classification of waste class IIA , substances that exceeded solubility limits were total phenols, total iron, fluoride, manganese, selenium, aluminum, cadmium and surfactants. The second stage was the production of cement matrix that is composed by cement, aggregates and water they were produced matrices with the following replacement levels of natural sand by the waste: 5%, 10%, 15% and 20%. The matrice with the 20% replacement level, showed a consistent resistance to compatible with standard ABNT NBR 9781, therefore concrete paving blocks were manufactured content this level of replacement. The blocks had good mechanical, physical and with the exception of aluminum and cadmium, other substances that exceeded solubility limits were encapsulated. Cadmium also appear in paving blocks manufactured with conventional materials, without residue. Thus, it is concluded that the concrete paving blocks can be used in construction.
4

Posouzení stávajících zkušebních postupů používaných při výrobě vibrolisovaného zboží s vazbou na reálné vlastnosti výrobků / Assessment of existing test procedures used in the production of goods vibropressed linked to the real properties of products

Maňák, Jan January 2016 (has links)
This master´s thesis is focused on assessment of properties of vibropressed concrete products. The important point of the thesis is measuring fresh concrete air permeability by Qaver control tool and confrontation this results with results of hardened concrete. The relationship between results obtained is examined.

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