Dissertations / Theses: 'Production of concrete blocks'

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Felipe, Alexsandro dos Santos [UNESP]. "Contribuição para a otimização de traços de concreto utilizados na produção de blocos estruturais." Universidade Estadual Paulista (UNESP), 2010. http://hdl.handle.net/11449/91466.

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Universidade Estadual Paulista (UNESP)
Diante do grande crescimento da alvenaria estrutural no país, muitas fábricas de blocos de concreto vieram por necessidade, buscar por otimizações do seu processo produtivo, visto que, projetos mais arrojados, acabam exigindo maiores controles de qualidade. A proposta deste estudo é melhorar a produção destes artefatos de concreto por meio de otimizações simples que reduzem o custo e garantem uma produção eficiente na fábrica. Estudar a fundo os vários parâmetros de formação de um traço de concreto seco, tais como coesão, textura, energias de adensamento e resistência à compressão axial, todos os fenômenos dependentes entre si, torna-se muito complexo se avaliado em um único trabalho. No entanto, propor um estudo que colete informações apresentadas por vários autores, facilita na otimização e criação de uma pesquisa que possa contribuir na dosagem para concretos secos, em especial, na fabricação de blocos estruturais. Neste estudo, adaptaram-se para laboratório alguns equipamentos de uso comum para confecção destes artefatos de concreto, possibilitando a correlação direta de corpos de prova cilíndricos com os blocos. Uma das adaptações é o estudo baseado na padronização da energia de compactação, proporcionada pelo equipamento para ensaios de mini-proctor, simulando assim, a máquina vibro-prensa. Outras correlações como coesão e resistência à compressão, também foram possíveis de obter no laboratório, reduzindo então, as interferências constantes no processo produtivo da fábrica, ocasião verificada em vários outros estudos. Diante do exposto, foi possível avaliar com boa segurança os resultados. O estudo foi desenvolvido em três etapas, sempre buscando a maior massa específica seca compactada da mistura de agregados, inicialmente na primeira etapa, foi utilizado somente dois agregados (areia fina e pedrisco), conforme...
Given the substantial growth of structural masonry in Brazil, many concrete block companies have seen the need to optimize their production process, since more challenging projects require greater quality control. This study proposes to improve the production of concrete artifacts by means of simple optimizations that reduce costs and ensure the company’s efficient production. Studying in depth the various parameters of the formation of dry concrete trace, such as cohesion, texture, density energy and axial compressive strength, all the particularities interdependent on one another become very complex when assessed in a single study. However, proposing a study that collects the information submitted by various authors, expedites optimizing and creating a research study which may assist in improving the dosage for dried concrete, particularly in the manufacture of structural blocks. In this study, some commonly used manufacturing equipment, such as concrete artifacts, were laboratory-adapted, enabling a direct correlation of the cylindrical specimens with the blocks. One of the adjustments is the study based on the standardization of compaction energy, provided by the mini-proctor testing equipment, thus simulating the vibro press machine. Other correlations such as cohesion and compressive strength were also obtained in the laboratory, therefore reducing the constant interferences in the plant’s production process, observed in many other studies. In this manner, it was possible to reliably assess the results. The study was conducted in three stages, always seeking the highest compressed dry specific mass of the mixture of aggregates. In the first stage, only two aggregates were used (fine sand and pebbles), commonly used at the plant. The second stage included adding the coarse sand and stone powder to correct the lack of resistance promoted by the high amount of fine sand from... (Complete abstract click electronic access below)

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Pinto, Bruno Henrique. "Execução de blocos para alvenaria estrutural utilizando concreto fluido." Ilha Solteira, 2018. http://hdl.handle.net/11449/154404.

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Orientador: Maria da Consolação Fonseca Albuquerque
Resumo: As complicações ocasionadas pelas irregularidades presentes na face de assentamento dos blocos de alvenaria estrutural, provenientes de procedimentos correntes de fabricação, possibilita um campo de estudo para otimização na melhoria dessas irregularidades. Para tanto, este trabalho tem por finalidade propor uma alternativa de fabricação dos blocos de alvenaria estrutural através do uso e aplicação de concreto fluido com os traços 1:3, 1:5 e 1:7, cujas resistências à compressão deles e dos prismas, atendam às exigências das normas NBR 15961-1 e NBR 15961-2. Assim, além de moldados e confeccionados os blocos e os prismas, neste trabalho são apresentados ensaios de ambos, bem como os ensaios das argamassas de assentamento mista e polimérica. Em alguns destes ensaios utilizaram-se LVDTs e Strain-Gages, com objetivo de verificar os seus deslocamentos e suas deformações, e consequentemente as tensões atuantes, nos blocos e nos prismas.
Abstract: Complications arising from imperfections on the bonded surface of structural masonry blocks, from current manufacturing procedures, makes it a field of study for optimization in the improvement of these irregularities. To this end, this paper aims to propose an alternative to the manufacture of structural masonry block through the use and application of fluid concrete with mixture 1:3, 1:5 and 1:7, whose resistance to compression them and prisms, meet the requirements established by the Brazilian technical standards NBR 15961-1 and NBR 15961-2. Thus, this work describes tests performed on blocks and prisms. The prisms were tested with mixed and polymeric block-laying mortars. In some of these tests using LVDTs and Strain Gages to check their displacements and their deformations, and consequently tensions, in the blocks and prisms.
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Felipe, Alexsandro dos Santos. "Contribuição para a otimização de traços de concreto utilizados na produção de blocos estruturais /." Ilha Solteira : [s.n.], 2010. http://hdl.handle.net/11449/91466.

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Resumo: Diante do grande crescimento da alvenaria estrutural no país, muitas fábricas de blocos de concreto vieram por necessidade, buscar por otimizações do seu processo produtivo, visto que, projetos mais arrojados, acabam exigindo maiores controles de qualidade. A proposta deste estudo é melhorar a produção destes artefatos de concreto por meio de otimizações simples que reduzem o custo e garantem uma produção eficiente na fábrica. Estudar a fundo os vários parâmetros de formação de um traço de concreto seco, tais como coesão, textura, energias de adensamento e resistência à compressão axial, todos os fenômenos dependentes entre si, torna-se muito complexo se avaliado em um único trabalho. No entanto, propor um estudo que colete informações apresentadas por vários autores, facilita na otimização e criação de uma pesquisa que possa contribuir na dosagem para concretos secos, em especial, na fabricação de blocos estruturais. Neste estudo, adaptaram-se para laboratório alguns equipamentos de uso comum para confecção destes artefatos de concreto, possibilitando a correlação direta de corpos de prova cilíndricos com os blocos. Uma das adaptações é o estudo baseado na padronização da energia de compactação, proporcionada pelo equipamento para ensaios de mini-proctor, simulando assim, a máquina vibro-prensa. Outras correlações como coesão e resistência à compressão, também foram possíveis de obter no laboratório, reduzindo então, as interferências constantes no processo produtivo da fábrica, ocasião verificada em vários outros estudos. Diante do exposto, foi possível avaliar com boa segurança os resultados. O estudo foi desenvolvido em três etapas, sempre buscando a maior massa específica seca compactada da mistura de agregados, inicialmente na primeira etapa, foi utilizado somente dois agregados (areia fina e pedrisco), conforme... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Given the substantial growth of structural masonry in Brazil, many concrete block companies have seen the need to optimize their production process, since more challenging projects require greater quality control. This study proposes to improve the production of concrete artifacts by means of simple optimizations that reduce costs and ensure the company's efficient production. Studying in depth the various parameters of the formation of dry concrete trace, such as cohesion, texture, density energy and axial compressive strength, all the particularities interdependent on one another become very complex when assessed in a single study. However, proposing a study that collects the information submitted by various authors, expedites optimizing and creating a research study which may assist in improving the dosage for dried concrete, particularly in the manufacture of structural blocks. In this study, some commonly used manufacturing equipment, such as concrete artifacts, were laboratory-adapted, enabling a direct correlation of the cylindrical specimens with the blocks. One of the adjustments is the study based on the standardization of compaction energy, provided by the mini-proctor testing equipment, thus simulating the vibro press machine. Other correlations such as cohesion and compressive strength were also obtained in the laboratory, therefore reducing the constant interferences in the plant's production process, observed in many other studies. In this manner, it was possible to reliably assess the results. The study was conducted in three stages, always seeking the highest compressed dry specific mass of the mixture of aggregates. In the first stage, only two aggregates were used (fine sand and pebbles), commonly used at the plant. The second stage included adding the coarse sand and stone powder to correct the lack of resistance promoted by the high amount of fine sand from... (Complete abstract click electronic access below)
Orientador: Jefferson Sidney Camacho
Coorientador: Maria da Consolação F. de Albuquerque
Banca: Jorge Luís Akasaki
Banca: Paulo César Primo Agostinho
Mestre

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MACIEL, Kuelson Rândello Dantas. "Desenvolvimento de blocos de concreto para construção de silos circulares de alvenaria sem função estrutural." Universidade Federal de Campina Grande, 2002. http://dspace.sti.ufcg.edu.br:8080/jspui/handle/riufcg/1084.

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Atualmente estima-se que 25% da produção de grãos produzidos no Brasil, são perdidos nas fases de colheita e pós-colheita, parte desta perda referente ao armazenamento, pode ser minimizada, caso o país estimule a estocagem da produção nas próprias fazendas. Para isso é necessário ter disponível tecnologia simples, entre as quais, a de construção de silos para que se possa construir nos locais de produção. Com intuito de colaborar para uma política de armazenagem de grãos em fazendas, o presente trabalho tem o objetivo de estudar blocos de concreto para serem utilizados na construção de silos cilíndricos de alvenaria. Logo foi desenvolvido um bloco com geometria especial para se utilizar em silos cilíndricos, e analisando-se a absorção de água , as resistência à compressão e tração dos blocos confeccionados com traço de 1:3, 1:4 e 1:6 submetendo-os a dois tipos de cura: natural e submersa. Dentre os traço estudados para confecção de blocos de concreto o único que não atingiu resistência à compressão exigida pela NBR 7173 foi o traço 1:6, mas a resistência dos blocos em todos os traços foram superior aos esforços atuante no silo com dimensões estudadas. Enquanto que para resistência à tração não há norma especifica, com isso foi desenvolvida uma metodologia para simular o esforço de tração que as paredes dos silos cilíndricos estão submetidos e o blocos que foram moldados com traço 1:3 e 1:4 obtiveram resistência superior a necessária para um silo de 4m de altura e relação altura /diâmetro igual a 1.
Nowaday it's estimated that 25% o f the grains produced in Brazil are lost in the crop and post-crop phases, some of this refer to storage, but it can be minimized if the country stimulate stocking up the production in the farms. So it's neccssary to havc a simple technology available, as the construction of bin in the production places. In order to help a crop storage politic in the farms, in the prcscnt work we studied concrcte blocks that can be used to build masonry cylindrical bin. We developed a block with a special geometry to use in these bin, the water absorption, compression and traction resistances of the blocks were analyzed they were made with 1:3, 1:4 and 1:6 mixture and then submitted to two types o f cure: natural and submerged. Among the mixture studied to build the blocks the 1:6 mixture didn't reach the required resistance by the NBR 7173, but the resistance of the block with ali mixture was superior to the efforts in a bin with the same dimensions. There isn't an specilic norm for traction resistance, so we developed a methodology to simulate the traction efforts that the cylindrical bin walls were submitted, the blocks were moulded with 1:3 and 1:4 mixture, we get a superior resistance to the onc required to an bin with 4 metros in height and height/diameter relation equal to one.

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Palnati, Mahendra. "Design, Fabrication and Analysis of a Paver Machine Push Bar Mechanism." Scholar Commons, 2015. http://scholarcommons.usf.edu/etd/6007.

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Now-a-days, the major challenge that’s being faced by the concrete industry is the cleaning of concrete handling equipment. Concrete consists of aggregates, which harden with time, and the transportation of concrete mixture within the plant is a significant problem. This will not only increase the overall maintenance cost, but will lead to loss of raw materials, affect the rate of production, and reduce the lifetime of concrete handling equipment. The present study focuses on the design and implementation of an adaptive cleaning mechanism in the concrete industry and its importance in achieving efficient cleaning, which is tested to verify its performance in the Paver production plant. The goal of this study is to provide practical evidence about the importance of adaptive cleaning mechanisms for industrial applications. The first chapter gives a detailed introduction about pavers and the production process, the cause of material loss that occurs during transportation of wet concrete mixture inside a paver plant, and its effect on handling equipment and work environment. The second chapter explains design and working of the paver machine push bar mechanism, which can be implemented in a hydraulic press production process of pavers. The third chapter includes analysis and results of the mechanism obtained using Solidworks and Autodesk Inventor followed by observations that are achieved based on practical application of this mechanism in a paver production plant.

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Baker, Raymond. "Concrete blocks for dam spillways." Thesis, University of Salford, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334011.

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Ptáčková, Eva. "Polygrafická výroba PROGRAF." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-372030.

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The aim of this Diploma thesis is the elaboration of the project documentation of a construction part for realization of the new building of the production hall and administrative building in a city of Slavkov u Brna. According to the local zoning plan, both buildings are designed on a plot in the development part of the city. The selected plot is conveniently located due to good accessibility to the D1 motorway. The office building will consist of two above-ground floors. On the first floor there will be the management of the company and the head of the press, the economic and commercial department, hygienic facilities. On the second floor there wil be a graphic studio, a day room and a spacious terrace. The construction system of an office building will be a wall longitudinal. The ground plan of the object is rectangular. the roof is designed as a mono-pitched roof. The factory is a single-storey building. Inside the factory hall there will be a polygraphical technological equipment. The location of the machines is only indicative as well as their choice. The hall will have its own equipment equipped with air conditioning and heating. It is designed as a precast concrete frame. The system is designed longitudinal. The object is a rectangular ground plan with a saddle roof.

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Lee, Tachen. "Latent and sensible heat storage in concrete blocks." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ39095.pdf.

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Arslan, Guray. "Strengthening Of Reinforced Concrete Frames By Custom Shaped High Strength Concrete Masonry Blocks." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/2/12610335/index.pdf.

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Located on one of the highly active seismic fault systems in the world, the building stock in Turkey is mainly composed of reinforced concrete frames with 4-5 stories. Due to design and construction deficiencies resulting from the use of unqualified personnel and insufficient supervision, many of these buildings lack lateral stiffness, ductility and strength. For many structures, there is a need to alleviate these deficiencies by means of some rehabilitation techniques prior to earthquakes. One approach also used very widely in Turkey is to fill some of the frame bays by cast-in-place R/C panels. The procedure appears to be very practical at first glance. It also appears to be very economical as far as the production of the panels is concerned. However, the production phase is slow, dirty, destructive and disruptive to occupants. Moreover, it requires relatively skilled personnel and special equipment. Therefore, the real life experience shows that the actual cost in practice is much higher when all other hidden costs are taken into account. The aim of this experimental study is to explore the potential of using infill walls made of custom shaped and high strength concrete blocks as a simpler and more practical alternative to cast-in-place R/C panels to increase the lateral load bearing capacity of frame structures. The effectiveness of FRCM (Fiber Reinforced Cementitous Matrix) system on damaged structures is also investigated in this study.

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Aslantas, Onur. "A Study On Abrasion Resistance Of Concrete Paving Blocks." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12605709/index.pdf.

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Concrete block pavement (CBP) can be an alternative pavement to asphalt and concrete pavements. CBP is formed from individual concrete paving blocks (CPBs) that fit next to one another on a suitable sub base leaving a specific joint space among them to be filled with jointing sand. CBP differ from other pavements according to their mechanical behavior, manufacturing technique, structural design, installation technique and structural behavior. For a serviceable pavement all of these subjects have to be studied. The literature about the mechanical behavior of CPBs is not adequate. This study aims to determine the performance of CPBs formed from different mixes prepared with a white portland cement. For this purpose, 10 mixes with different cement contents and W/C ratios and 2 mixes from a commercial CPB manufacturer were tested. The compressive strength, tensile splitting strength, abrasion resistance, density and % water absorption tests were performed on each mix at 7, 14, 28 days. It was concluded that, the cement content in the mix, optimum water volume for a given cement content, the way the manufacturing equipment is operated and their interaction was effective on the mechanical properties of CPBs. It was also observed that there was no handicap to stop the abrasion resistance test at 8*22 revolutions instead of 16*22 revolutions given in TS 2824.

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Limbachiya, V. "Additives to increase the sustainability of concrete paving blocks." Thesis, Coventry University, 2015. http://curve.coventry.ac.uk/open/items/a70b1134-4ee6-4aef-a68d-23328be6ec71/1.

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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.

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Deumic, Emina, and Damir Sadic. "FE analysis of interlocking C3C solid concrete blocks without casting." Thesis, Linnéuniversitetet, Institutionen för teknik, TEK, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-12051.

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Solid concrete Lego blocks can be used as temporary retaining wall systems or as wall separators between different materials such as sand, salt, compost, etc. The advantage of concrete blocks is that you can create temporary constructions. It is easy to move or expand the constructions when no casting is required between the blocks. The purpose of this study is to make models in the Finite Element (FE) software Abaqus/CAE that can be used for calculations of the capacity for interlocking blocks. FE method is an approximate method for solving differential equations. As the concrete blocks are stacked without casting, it is important to find out the construction’s load capacity when it is subjected to a horizontal load. Several types of structures have been modeled in the FE program Abaqus/CAE. These FE models were created with boundary conditions consisting of springs and a pinned connection that allows rotation.The evaluation has been focused on rotating the interlocking blocks. With the help of the FE models, reaction forces have been calculated. The FE results in term of reaction forces have been compared with hand calculations made for the same models. Moreover, a wall and a wall with lateral supports have been simulated to determine the horizontal reaction force for the interlocking concrete blocks.
Massiva Lego betongblock kan ändvänds som tillfälliga stödmurar eller vägg avskiljare för olika material som salt, kompost, sand mm. Fördelen med betongblocken är att man kan skapa tillfälliga konstruktioner. Det är lätt att flytta eller bygga ut konstruktionen när ingen fog krävs mellan blocken. Syftet med denna studie är att skapa modeller i Finita Element (FE) programmet Abaqus/CAE som kan senare användas för beräkning av kapaciteten för sammankopplade block. FE Metoden är en approximativ metod för att lösa differential ekvationer. Eftersom betongblocken är staplade på varandra utan fog är det viktigt att ta reda på konstruktionens lastupptagnings förmåga när den är belastade med horisontalkrafter. Flera typer av konstruktioner har modellerats i FE programmet Abaqus/CAE. Dessa FE modeller har skapats med randvillkor som består av fjädrar och fasta lager som tillåter rotation. Utvärderingen har gjorts med fokus på vältningen i betongblocken. Med hjälp av dessa FE modeller har reaktionskraften tagits fram. FE resultaten i form av reaktionskrafter har sedan jämförts med handberäkningar gjorda för samma modeller. Vidare har en vägg och en vägg med sidostöd FE modellerats för att utvärdera horisontala deformationsegenskaper.
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Coetzee, Gerrit. "The mechanical and volumetric behaviour of sisal fibre reinforced concrete blocks." Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/80010.

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Thesis (MScEng)--Stellenbosch University, 2013.
ENGLISH ABSTRACT: Natural fibre reinforced concrete (NFRC) is a type of concrete that has become of particular interest in recent years, due to its potential for being used as a sustainable and economically viable building material. Natural fibres are often cheap and widely available in developing nations. Sisal is one such fibre predominantly grown in Brazil and has been identified as having the potential to be commercially cultivated in Southern Africa. The durability of sisal fibres in a cementitious environment tends to be adversely affected due to the high alkalinity of pore water and the presence of calcium hydroxide. This research dealt with the use of sisal fibre reinforced concrete (SFRC) blocks. It focused on the mechanical and volumetric properties of blocks with varying fibre and condensed silica fume content (CSF). Two different SFRC blocks were produced (solid and hollow) using an average fibre length of 10 mm. Two matrix types were used: one using a 70:30 cement:fly-ash ratio and another using a 60:30:10 cement:fly-ash:CSF ratio by weight. Samples of each matrix type were prepared with 0, 0.5 and 1% fibre content by volume. Hollow blocks were tested for compressive strength and capillary water absorption, while solid blocks were tested for compressive strength, flexural strength, capillary water absorption, dimensional stability, drying shrinkage, density, total water absorption and void content. All tests were performed on samples with an age of 28 days. Solid block compressive tests were also performed on samples with an age of 7 days. The hollow blocks had significantly lower average compression strength than the solids, but an increase in fibre content caused a slight increase in strength. For solid blocks, it was found that the addition of natural fibres decreases the strength, although a partial substitution of cement with CSF, in conjunction with fibres, did increase the strength relative to blocks without CSF. The flexure strength was also lowered somewhat by the addition of fibres, but an increase in ductility was noted, although not quantified. The addition of CSF to fibre-containing blocks led to an increase in capillary water absorption, but a decrease in absorption through immersion. This shows that the addition of CSF does significantly alter the pore system of a cementitious matrix reinforced with natural fibres. Also, the dimensional stability increased with the addition of CSF and fibres. The same can be said for drying shrinkage. Even though an increase in fibre and CSF caused samples to shrink more under drying, they were more stable under cycles of wetting and drying. It was concluded that the addition of fibres to a matrix had a detrimental effect on strength, although ductility did increase. The volumetric properties of concrete were also adversely affected by the addition of fibres, although dimensional stability was improved. The partial substitution of cement with CSF did improve many of the mechanical and volumetric properties of samples containing sisal fibre.
AFRIKAANSE OPSOMMING: Natuurlike vesel bewapende beton (NVBB) is ’n tipe beton wat onlangs heelwat belangstelling ontlok het weens die potensiaal om gebruik te word as ‘n volhoubare en ekonomiese haalbare boumateriaal. Natuurlike vesels is dikwels baie goedkoop en wyd beskikbaar in ontwikkelende lande. Sisal is een so ‘n vesel wat verkry word vanaf die blare van ’n garingboom. Die plant word hoofsaaklik in Brasilië verbou en is al uitgewys weens sy potensiaal om op kommersiële skaal in Suidelike Afrika verbou te word. Die duursaamheid van sisal vesels is geneig om nadelig geaffekteer te word in die teenwoordigheid van kalsium hidroksied en ’n hoë-alkali omgewing, soos gevind in die porie-water van beton. Hierdie navorsing handel oor die gebruik van sisal vesel bewapende beton (SVBB) boublokke. Dit fokus op die meganiese- en duursaamheids eienskappe van blokke met verkillende inhoude van vesel en gekondenseerde silika dampe (GSD). Twee verskillende SVBB blokke is geproduseer (solied en hol) deur gebruik te maak van 10 mm vesels. Twee matriks tipes is gebruik: een met ’n 70:30 sement:vliegas verhouding en een met ’n 60:30:10 sement:vliegas:GSD verhouding, volgens gewig. Blokke van elke matriks tipe is geproduseer met 0, 0.5 en 1% vesel inhoud, volgens volume. Hol blokke is getoets vir druksterkte en kapillêre water absorpsie, terwyl soliede blokke getoets is vir druksterkte, buigsterkte, kapillêre water absorpsie, dimensionele stabiliteit, krimp onder uitdroging, digtheid, totale water absorpsie en luginhoud. Alle toetse is gedoen op blokke met ’n ouderdom van 28 dae. Druktoetse is ook gedoen op soliede blokke met ’n ouderdom van 7 dae. Die hol blokke het ’n aansienlike laer gemiddelde druksterkte as die soliede blokke gehad, maar ’n toename in veselinhoud het gelei tot ’n effense verhoging in druksterkte. ’n Toename in veselinhoud van soliede blokke het gelei tot ’n afname in druksterkte, alhoewel ’n gedeeltelike vervanging van sement met GSD gelei het tot ’n hoër druksterkte vir blokke met vesels. Die buigsterkte van soliede blokke het ook afgeneem met ’n verhoging in veselinhoud. ’n Verhoging in duktiliteit is waargeneem met ’n toename in veselinhoud, alhoewel dit nie gekwantifiseer is nie. Die toevoeging van GSD tot blokke bevattende vesels het gelei tot ’n verhoging in kapillêre water absorpsie, maar ’n verlaging in totale water absorpsie. Dit kan daarop wys dat die toevoeging van GSD die poriestelsel van NVBB noemenswaardig verander. Beide die dimensionele stabiliteit en krimp onder uitdroging het toegeneem met die toevoeging van GSD en vesels tot die blokke. Dus, die toevoeging het gelei tot ’n hoër krimpvervorming tydens uitdroging en ’n hoër stabiliteit tydens nat/droog siklusse. Daar is tot die gevolgtrekking gekom dat die toevoeging van sisal vesels tot ’n beton blok oor die algemeen ’n negatiewe effek het op sterkte, alhoewel duktiliteit toeneem. Die volumetriese eienskappe van beton word ook negatief geaffekteer met die toevoeging van sisal vesels, alhoewel dimensionele stabiliteit verbeter. Die gedeeltelike vervanging van sement met GSD lei tot die verbetering van beide meganiese en volumetriese eienskappe van beton blokke wat sisal vesels bevat.

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Hall, James P. "The early developmental history of concrete block in America." Muncie, Ind. : Ball State University, 2009. http://cardinalscholar.bsu.edu/613.

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15

Alkan, Anil. "Production And Assesment Of Compacted Graphite Iron Diesel Engine Blocks." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613874/index.pdf.

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In Diesel engine blocks properties such as tensile strength, heat conductivity, sound damping, engine vibration and noise are strongly influenced by graphite shape and volume percent in the matrix microstructure. In this study, the engine blocks were produced at ELBA Basinç
li Dö
kü
m Odö
ksan Cast iron foundry in Osmaneli Turkey by performing casting into furan resin sand and preparing cast iron liquid alloy in induction furnace that were treated with Mg by using ladle method. The main purpose of this study is to achive 0 &ndash
25% volume nodularity and remaining is compacted graphite in the produced engine blocks. The shape and volume percent of graphite particles were characterized by an image analyze system. In the first part of this work, after the diesel engine blocks were produced at ELBA Basinç
li Dö
kü
m Odö
ksan Cast iron foundry in Osmaneli Turkey, the blocks were cut and samples were obtained from 14 different thicknesses of diesel engine blocks. Afterwards, the samples were examined under optical microscope, Soif XJP-6A. The nodularity and compacted graphite values were obtained numerically with the help of Materials Plus image analyzer systems, which is attached to the optical microscope. v In the second part of the study, the diesel engine blocks which are produced at Odö
ksan were examined by ultrasonic test that was done by using USM 35 flaw detector test machine. Solidification &ndash
time and temperature &ndash
time simulations were also done by using NovaCast NovaFlow simulation code. Finally mathematical formulas for 13 different thickness of diesel engine blocks were obtained by using excel linest code. The compacted graphite volume percent observed at different sections of the diesel engine blocks were found to be a function of cooling rate and chemical composition. Best results were obtained when chemical Mg/S ratio was approximately 1 and C.E.V. was between 4.40 &ndash
4.50.

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16

Gooding, Dominic Edward Maxwell. "Improved processes for the production of soil-cement building blocks." Thesis, University of Warwick, 1994. http://wrap.warwick.ac.uk/4453/.

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Stabilised-soil cement building blocks are an established building material in many areas of the Less Developed World. This thesis has been split into three parts. Part A presented an overview of the process of soil-stabilisation and outlined the roles which soil structure and curing play in stabilisation. It examined methods of testing soils, highlighting errors presented in the published literature and presenting corrected testing procedures and unified plans for their implementation. Part B examined the conventional quasi-static block compaction process (slowly applied pressure) and established that no cost-effective increase in the compacted block density can be achieved by altering such moulding configurations as mould-wall roughness, mould-wall taper, number of applied pressure cycles and double-sided pressure application. The tests were also used to assess the plausibility of several theoretical mechanisms underlying quasi -static compaction. Cement may be traded against compaction pressure for a given final cured strength. The relation of compaction pressure and cement content to well-cured strength was established for 50 mm diameter cylinders and used to assess the financial benefit of high-pressure compaction. It was shown that savings in the cost of cement associated with high-pressure compaction were outweighed by the additional cost of such machinery. However there were additional benefits found to high-density compaction, beyond the saving in stabiliser costs. It was established that a highdensity moulding machine in the range £1000 - £1500 would allow these benefits to become cost competitive. Part C examined both experimentally and theoretically an alternative dynamic (impact blow) compaction process, establishing that optimised dynamic compaction may produce strength equivalent to quasi-static high-density moulding while requiring only 25-50 % of the energy. Five theoretical models of the process were developed and the Combined Airlock/Friction/Compression Wave Model was shown to have the most explanatory power.

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Matenda, Amanda Zaina. "GEOPOLYMER CONCRETE PRODUCTION USING COAL ASH." OpenSIUC, 2015. https://opensiuc.lib.siu.edu/theses/1654.

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Coal powered power plants account for more than 40 percent of the electricity production of the United States. The combustion of coal results in a large number of solid waste materials, or coal combustion byproducts (CCBs). These waste materials are stored in landfill or ponds. The construction industry is heavily reliant on concrete which is used to make the building blocks for any type of structures, bricks. Concrete is a composite material made of a binder and coarse and fine aggregate. The most widely used binder in concrete production is Ordinary Portland Cement (OPC). Since cement manufacture is costly and environmentally damaging, research has increased in recent years to find a more readily available binder. This study aims at investigating the properties of Illinois fly ash as a binder in the production of geopolymer concrete. Geopolymer concrete is an innovative material made by using Alumina and Silica rich materials of geological origins as a binder as well as an alkali activated solution. Sodium Silicate and Sodium Hydroxide were used to make the activator solution of two different ratios. Geopolymer Concrete with a ratio of 1:1 of Sodium Silicate to Sodium Hydroxide reached a compressive strength above 6000 psi while samples made with a ratio of 1:2 reached a compressive strength above 4000 psi. This environmentally-friendly, green concrete was also found to have a cost comparable to conventional concrete.

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18

Thannon, Ammar Y. "The appraisal and management of multi-storey dwelling blocks using large concrete panel systems." Thesis, Aston University, 1989. http://publications.aston.ac.uk/14271/.

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This exploratory study is concerned with the integrated appraisal of multi-storey dwelling blocks which incorporate large concrete panel systems (LPS). The first step was to look at U.K. multi-storey dwelling stock in general, and under the management of Birmingham City Council in particular. The information has been taken from the databases of three departments in the City of Birmingham, and rearranged in a new database using a suite of PC software called `PROXIMA' for clarity and analysis. One hundred of their stock were built large concrete panel system. Thirteen LPS blocks were chosen for the purpose of this study as case-studies depending mainly on the height and age factors of the block. A new integrated appraisal technique has been created for the LPS dwelling blocks, which takes into account the most physical and social factors affecting the condition and acceptability of these blocks. This appraisal technique is built up in a hierarchical form moving from the general approach to particular elements (a tree model). It comprises two main approaches; physical and social. In the physical approach, the building is viewed as a series of manageable elements and sub-elements to cover every single physical or environmental factor of the block, in which the condition of the block is analysed. A quality score system has been developed which depends mainly on the qualitative and quantitative conditions of each category in the appraisal tree model, and leads to physical ranking order of the study blocks. In the social appraisal approach, the residents' satisfaction and attitude toward their multi-storey dwelling block was analysed in relation to: a. biographical and housing related characteristics; and b. social, physical and environmental factors associated with this sort of dwelling, block and estate in general.The random sample consisted of 268 residents living in the 13 case study blocks. Data collected was analysed using frequency counts, percentages, means, standard deviations, Kendall's tue, r-correlation coefficients, t-test, analysis of variance (ANOVA) and multiple regression analysis. The analysis showed a marginally positive satisfaction and attitude towards living in the block. The five most significant factors associated with the residents' satisfaction and attitude in descending order were: the estate, in general; the service categories in the block, including heating system and lift services; vandalism; the neighbours; and the security system of the block. An important attribute of this method, is that it is relatively inexpensive to implement, especially when compared to alternatives adopted by some local authorities and the BRE. It is designed to save time, money and effort, to aid decision making, and to provide ranked priority to the multi-storey dwelling stock, in addition to many other advantages. A series of solution options to the problems of the block was sought for selection and testing before implementation. The traditional solutions have usually resulted in either demolition or costly physical maintenance and social improvement of the blocks. However, a new solution has now emerged, which is particularly suited to structurally sound units. The solution of `re-cycling' might incorporate the reuse of an entire block or part of it, by removing panels, slabs and so forth from the upper floors in order to reconstruct them as low-rise accommodation.

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Lopez, Paola Andrea, Katherine Reynolds, Sarina Sedgwick, and Jean Wilkening. "INDUSTRIAL SCALE PRODUCTION OF SELF-HEALING CONCRETE." Thesis, The University of Arizona, 2016. http://hdl.handle.net/10150/613256.

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When exposed to varying temperatures, water, and stress, concrete develops tiny undetectable cracks that can spread and threaten its integrity until eventually it must be replaced. Self-healing concrete offers significant economic and environmental benefits. The goal of this project is to investigate the feasibility of using bacteria as a self-healing additive, and to design a plant for producing self-healing concrete. The concrete designed by the team includes dormant bacteria that are reactivated by water entering a crack. The bacteria naturally produce calcium carbonate, which seals the cracks resulting in a stronger, longer-lasting concrete. The team designed a system of bioreactors to cultivate the bacteria, Bacillus subtilis, which is added to lightweight aggregate, a component of concrete. The team also designed a plant to produce the cement necessary to make concrete. This design involves balancing the energy needs of several large crushers and grinders, a heating and cooling system, and a large kiln. The cement and aggregate are combined with water to form self-healing concrete.

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Sedgwick, Sarina Ann, Paola Lopez, Katherine Reynolds, and Jean Wilkening. "INDUSTRIAL SCALE PRODUCTION OF SELF-HEALING CONCRETE." Thesis, The University of Arizona, 2016. http://hdl.handle.net/10150/613599.

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Concrete is one of the most versatile and common building materials used in industry. However, concrete is prone to cracks, which can eventually lead to collapse of structures. Self-healing concrete, which prevents large cracks by filling micro-cracks as they form, has the potential to mitigate the problems associated with cracking. The mechanism behind self-healing concrete uses a biological agent, such as the Bacillus Subtilis bacteria, which is added to the concrete mix and autonomously heals small cracks by precipitating calcium carbonate. Encapsulating the bacteria with the aggregate not only improves bacterial survival, but also increases the overall tensile strength of the concrete. In addition to the bacteria and aggregate, a cement plant was also designed. Cement is a fine powder which, when mixed with water, has a cohesive property which holds the other components of concrete together. The manufacturing process of cement starts with crushed limestone, which is heated in a kiln until it forms the nodules of calcium silicates that make up clinker, which is then crushed into cement powder. Although more research is necessary to determine the long-term performance and impact, the further development and implementation of self-healing concrete is a worthwhile and potentially profitable pursuit.

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Sätterman, Johan, Oscar Idman, and Oscar Lenhav. "Hollow Blocks in Tanzania : A Study Regarding the Domestic Market for Sustainable Concrete Block Innovations." Thesis, Linnéuniversitetet, Ekonomihögskolan, ELNU, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-19859.

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Abstract Purpose: The purpose of the study is to identify why the Tanzanian market for cement blocks have not adapted hollow blocks instead of solid ditto and, if possible, present recommendations for market activities. Design/methodology/approach: Implemented by action research methodology, this minor field study financed by Swedish International Development Cooperation Agency targets issues regarding the relatively poor housing standard in Tanzania through a business development perspective. Furthermore, the study covers what obstacles for new, more sustainable and price-efficient products are to identify in the Tanzanian market. Findings: An implementation of hollow blocks in the concrete block market surrounding Dar es Salaam would be beneficial from several aspects (e.g. economical, environmental, societal), but there are also factors that hinder such an implementation. The market’s consumers tend to not get the information about new techniques and innovations; hence to this lack of knowledge and awareness of alternatives, they stick to more traditional ways that they know more of. The consumers that do know of the new materials often disbeliefs the producers’ ability to make the quantity or quality demanded. Unawareness and distrust results in that few ask for new alternatives. The producers who put their main focus on supplying what the customers specifically asks for will therefore not start to produce the new alternatives, in this case hollow blocks. Thus, new innovations and the knowledge of the production of it do not spread easily. To implement new innovations some actor(s) to bare the risk is needed - pioneers that either commence producing the material themselves or, at least, encourage/provide incitements for producers and consumers to gain knowledge of them. The ones who have the possibility to carry risks in the concrete market surrounding Dar es Salaam are the large cement producers and the governmental institutions. They are also stakeholders who will benefit the most from taking the pioneer approach. Originality/value: The study offers insights into the Tanzanian market for cement blocks for building construction by focusing on adaption of a block innovation that can reduce the Co2 emissions due to less raw material use per block. Keywords: Sustainable Business Development, Innovation, Housing standard, Tanzania. Type of study: Bachelor Thesis in Enterprising and Business Development, Linnaeus University, Sweden.
Minor Field Study

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22

Scheinman, David Eliot. "Discrete event simulation and production system design for Rockwell hardness test blocks." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/55233.

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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2009.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 41).
The research focuses on increasing production volume and decreasing costs at a hardness test block manufacturer. A discrete event simulation model is created to investigate potential system wide improvements. Using the results from the simulation a production work-cell is proposed that will allow a single worker to operate 7 machines at a rate that exceeds existing production rates. This results in the workforce being reduced by a factor of four while reducing product lead-time by 30% and increasing throughput by 50%.
by David Eliot Scheinman.
M.Eng.

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23

Morshed, Md Abu. "Early carbonation curing of fresh concrete and its applications in precast concrete production." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=117115.

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Carbonation curing of fresh concrete at early age and the feasibility to integrate the technology into precast concrete production were investigated. It was found that equilibrium of relative humidity between ambient environment and interior concretes was not possible to achieve in early carbonation of fresh concrete even with preconditioning. Instead, the degree of carbonation was dominated more by the water content in the concrete than by its internal humidity. A fan-drying precondition seemed to be necessary and practically feasible to justify the water content in industry scale application. The process was applied to the production of precast lightweight concrete panels and normal weight hollow core concrete slabs. The lightweight aggregates were utilized as internal water reservoirs to balance the moisture equilibrium during preconditioning, carbonation reaction and subsequent hydration. Water movement from the internal reservoirs was postulated by resistivity measurements; and was further verified in terms of CO2 uptake, strength development, plastic shrinkage compensation and alkalinity regain. A near-surface diffusion carbonation curing was developed to partially replace the heat curing in hollow-core concrete slab production. The hollow core slab so produced had shown much better strength than the hydration reference or by the heat curing alone, with reduced porosity and less vulnerability to delayed ettringite formation. Besides the technical benefits, CO2 sequestration potential is an added value to the process. An average 15% CO2 uptake could lead to sequestration of approximately 10,000 tonnes of CO2 per year by precast hollow-core concrete plants in Canada alone.
La carbonatation du béton frais effectuée à son plus jeune âge, ainsi que la possibilité de potentiellement intégrer cette technologie dans la production du béton préfabriqué a été analysé dans cette étude. Il a été constaté que l'équilibre de l'humidité relative entre l'intérieur du béton et le milieu ambiant dans lequel il se trouve n'était pas possible à établir au début du processus préalable de la cure du béton frais par carbonatation. De plus, la quantité d'eau présente affecte le degré de carbonatation bien plus que l'humidité relative interne. Le séchage préalable du béton par ventilateurs d'es trouvé nécessaire et pratique afin de justifier la présence d'eau à l'échelle industrielle. Le processus a été utilisé pour la production des panneaux de béton préfabriqué de poids léger, ainsi que pour les dalles de béton alvéolées de poids ordinaire. L'utilisation des granulats légers en tant que réservoirs d'eau internes a servi à balancer l'humidité d'équilibre durant le déroulement de tout le processus, voir du début de l'étape préalable, durant la période de carbonatation jusqu'à l'hydratation postérieure. La circulation d'eau des réservoirs internes est due aux mesures de résistivité; ceci a été validé en termes de l'étendu de carbonatation, du développement de la résistance mécanique, par la compensation du rétrécissement plastique, et par le regain de l'alcalinité. De plus, la carbonatation dynamique près de la surface du béton a été conçue afin de partiellement remplacer le procédé d'étuvage compris dans la production de dalles de bétons alvéolées. Ce type de dalles a démontré un bien meilleur niveau de résistance mécanique que celui atteint par les dalles ordinairement hydratées ou par les dalles étuvées. En plus d'avoir une meilleure résistance, ces dalles possèdent moins de porosité et sont moins vulnérables au développement tardif d'ettringite. Outre les avantages techniques, la possibilité de séquestration du CO2 est un gain ajouté au procédé. En moyenne, un contenu de 15% de CO2 dans la production Canadienne des dalles de bétons alvéolées pourrait séquestrer 10,000 tonnes de CO2 chaque année.

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24

Peaston, Christopher Hugh. "Production, properties and design of sprayed fibre concrete." Thesis, Loughborough University, 1993. https://dspace.lboro.ac.uk/2134/26951.

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This research has tackled the major problem in the field of sprayed fibre reinforced concrete composites, the lack of detailed design information. An extensive series of sprayed fibre concrete field trials and laboratory testing of hardened specimens was complemented by an investigation of flexural testing of cast specimens. Post-cracking toughness and ductility were examined in accordance with the current ASTM (1989a) proposals for toughness index determination. Some of the requirements of ASTM standard C1018 were shown to be impractical.

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25

Myers, John Joseph. "Production and quality control of high performance concrete in Texas bridge structures /." Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.

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26

Holm, Magnus. "Adaptive Decision Support for Shop-floor Operators using Function Blocks." Doctoral thesis, Högskolan i Skövde, Institutionen för ingenjörsvetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-13503.

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In manual and semi-automation production systems, flexibility and adaptability are affected by the shop-floor operators’ skills, abilities and knowledge. Such dependencies highlight the vital importance of developing and utilising the knowledge, achievements and abilities of the operators working with production on the shop-floor. Teamwork, including both novice and highly experienced shop-floor operators, in a production environment with a high level of automation, is essential already today and is predicted to increase, when the complexity and demands of future production systems intensify. This trend is confirmed in both the research literature and by specialists within industry. The key to future competitiveness and effectiveness of the manufacturing industry is the shop-floor operators who handle the production systems. In addition, the future information intensive working environment, with its increasing complexity and less time available for decision-making, demands adaptive decision support and adaptive control systems that facilitate collaborative work on the shop-floor. It is therefore important to emphasise how decisions are supported in the time-limited working environment of the shop-floor, because this has a large impact on production output and quality and is vital to the success of the company. Consequently, this dissertation presents a framework for an adaptive decision support system that concentrates on shop-floor operators, in order to enhance their development and future contribution to leading edge production systems. The overall aim of the research presented is to define a framework for an Adaptive Decision Support System, to address the scope and demands of the future shop-floor, as indicated in the research literature, and confirm its relevance, as well as further elaborate it on the basis of interviews with production managers and HR specialists The research presented uses the design science research process. In parallel, decision support systems and the industrial shop-floor have been studied in the research literature and the current state of industrial practice has been assessed. These areas together form the basis for the research on adaptive decision support for shop-floor operators. A framework enabling adaptive decision support and adaptive system control, based on event-driven function block technology and Augmented Reality technology, is formulated. The gap of research on decision support for shop-floor operators, indicated in the research literature is addressed by the research preformed. Adaptive and dynamic decision support and system control able to process vast amounts of information in real time demonstrates utility for shop-floor operators. The research presenting the Adaptive Decision Support System has demonstrated its utility for shop-floor systems and production operatives in two extensive studies using demonstrators based on real-life production environments. A methodology, the ‘User group’, has been formulated for research collaboration and bi-directional knowledge transfer between academia and the industrial partners. It provides tools that enable cooperation between the experienced research partner and the novices, despite their different levels of engagement in the same project, without dividing them into separate groups. The ‘user group’ case study presented describes how both the inexperienced and the research mature companies gain new knowledge and engage in ongoing research. By doing so, the industrial project partners have extensively supported the research presented and will subsequently be the expected beneficiaries.

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Ferris, Mika. "Mama D's 2 Blocks: A Documentary Film." Thesis, University of North Texas, 2007. https://digital.library.unt.edu/ark:/67531/metadc3674/.

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Mama D's 2 Blocks tells the story of a neighborhood home in New Orleans that was transformed into a distribution center and used to assist residents impacted by Hurricane Katrina's devastation in 2005. Mama D stayed at her home throughout the storm and remained there until the floodwaters had subsided. After the water had drained, socially minded youth from all over the country were drawn to Mama D's home and stayed there while supporting local renewal efforts. The film documents their joining together, without electricity or running water, and assisting in the rebuilding process undertaken by Mama D and other neighborhood residents. This film captures a community in action, how it survived, and the first steps taken towards the rebuilding of New Orleans.

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28

Matsuoka, Katsunari. "Green tea polyphenol blocks H2O2-induced interleukin-8 production from human alveolar epithelial cells." Kyoto University, 2003. http://hdl.handle.net/2433/149367.

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29

Price, Steven Dwight 1961. "Microbial catalyzed acid production in Los Angeles County sewers." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/277006.

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Corrosion of concrete sewer crowns will cost the County Sanitation Districts of Los Angeles County approximately $150 million for repairs to their deteriorating sewage system. Other parts of the country are experiencing similar problems. Crown corrosion is induced by microbial oxidation of reduced sulfur to sulfuric acid, which attacks the concrete. Bacteria, of the genus Thiobacillus are generally responsible for catalyzing these reactions. Thiobacillicollected from sewers were used to establish stoichiometry and biochemical aspects of sulfide oxidation. Metals inhibition was studied among the same cultures. Thiobacilli collected from extremely corroded sewers possess a greater tolerance for metals than those from lightly corroded areas. Acidophilic isolates grow at greater rates and oxidize sulfide more efficiently than non-acidophiles. Chemical inhibitor studies indicated that S(-II) oxidation is tightly linked to respiration by T. thiooxidans. It is doubtful that initial steps in bacterially catalyzed S(-II) oxidation are linked to oxidative phosphorylation.

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30

Josephson, Deco. "Quality Control of Concrete Piles Based on Historical Data : Machine learning of concrete piles production line." Thesis, Karlstads universitet, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-86031.

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This master thesis investigates the parameters influencing the quality of concrete piles produced by NCC in Sweden. Furthermore, the thesis provides an in-depth review of the production and existing issues associated with concrete pile production. By analysing data from the production site at Ucklum, it is observed that the concrete piles produced have a large variation in strength. Production during the winter months results in higher strength and stability compared to the summer months. This may depend on the heat generated by the concrete during the summer which is much higher than during winter and may therefore affect the late strength negatively while it increases the rate of obtaining early age strength. The production uses a slightly higher cement content than what is necessary for the strength class C50/60 throughout the whole year to mainly counteract the tough strength development in the winter and also to increase the rate of strength development in the summer. Particularly when a large order of concrete piles comes in late. Achieving a high strength quickly is desirable so that the piles can be installed early in order to increase the rate of production. In this case, admixtures such as accelerators can be used instead of having a higher cement content. In addition, summer production can be improved by testing different methods presented in this report.
Detta examensarbete utreder parametrarna som påverkar kvalitén på betongpålar som produceras i en av NCCs produktionslinor. Den undersökta produktionslinjen är placerad i Ucklum, Sverige. Det görs också en utredning för att få en djup förståelse av produktionen och hur det går att påverka dess nuvarande problem. Genom analys av data från produktionen uppmärksammas det att produktionen har en stor spridning på hållfastheten på de producerade betongpålarna. Orsaken till variationen av hållfastheten undersöks och definieras. Det framgår att produktionen under vintern har högre hållfasthet och mer stabil än den under sommaren. Detta kan bero på att värmen som genereras av betongen under sommartiden är mycket högre än under vintertiden vilken kan leda till att den sena hållfastheten påverkas negativt, medan den snabbar upp den tidiga hållfastheten. Produktionen använder sig av lite högre cementhalt än vad som är nödvändigt för hållfasthetsklassen C50/60 genom hela året för att främst motverka den sega hållfasthetsutvecklingen på vintertid och även för snabba upp hållfasthetsutvecklingen på sommartid när en stor order av betongpålar kommer in utan god framförhållning. Att uppnå en hög hållfasthet snabbt är önskad så att pålarna kan installeras tidigt för att upprätthålla högre produktionstakt. I detta fall så kan tillsatser så som acceleratorer användas istället för att ha högre cementhalt. Dessutom kan sommarproduktionen förbättras genom att testa olika metoder som presenteras i denna rapport.

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31

Price, Andrew D. F. "An evaluation of production output for in situ concrete work." Thesis, Loughborough University, 1986. https://dspace.lboro.ac.uk/2134/7285.

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The overall aim of this thesis is to develop reliable methods of measuring output levels for construction plant and labour, with a view to establishing realistic output rates for concreting operations. This thesis demonstrates that most of the variability in production rates can be quickly explained, leaving relatively constant levels of output f or individual construction operations (i.e. basic operation times). The primary factors in determining output rates were found to be work rate, delays and waiting caused by poor management, and poor motivation. The latter two items accounted f or more than fifty per cent of the available working time on many sites, whereas work rate varied only slightly. This last finding may be surprising, but the results indicated that when work was being done the effort applied appeared fairly constant to the observer. However, the time spent working was largely dependent upon the level of motivation induced through the payment system. Where a combination of good direct supervision and satisfactory financial incentives were present, high levels of motivation were observed, conversely, low motivation occurred on sites where minimum day-work payments were present. Investigations into several construction trades indicate that work study techniques can be modified to meet the requirements of most construction operations, sites and companies, whether the requirements be a complex synthesis of basic operation times or the more simple determination of site efficiency. The key to this portability lies in the isolation of basic operation times via the application of site efficiency factors. In this thesis, primary work study techniques are identified and discussed. The need for specific construction work study techniques is shown to be of paramount importance. The results from over seventy concrete pours are combined and statistically analysed to produce realistic output rates arid current levels of production. Site factors are combined and statistically analysed to produce a relationship between efficiency and level of remuneration. A comparison is drawn between: the production rates achieved on several sites; and the output rates currently being used in the planning and estimating processes.

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32

Garbis, Leonidia Maria. "Lightweight concrete : investigations into the production of natural fiber reinforcement." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/82261.

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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Architecture, 2013.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 34).
The purpose of this study is to investigate the benefits of adding natural fiber tensile reinforcement to aerated concrete. Concrete is a great composite material which can be created in various proportions and with various materials to alter its strength, density and porosity, amongst other properties. Concrete which is used commonly in construction of columns, beams, and slabs acts well in compression but fails under tension. The common solution is to reinforce the structure in areas where it experiences tension with steel. There are other materials besides steel which also take tension well. Natural fibers for example come in various strengths and types and would create lighter and perhaps more sustainable beam designs. Natural fibers have been used for their availability, workability, and high tensile strengths for centuries. This research discovers how the natural fibers distribute within the mixture and how they affect the aeration of the concrete, as well as how they affect the strength. Multiple samples are cured with different fiber types and in different proportions within the mixture. Furthermore, similar experimentation is conducted to discover an ideal ratio of aggregate to aerated concrete mix. The aggregate gives the concrete greater strength and economy, but could negatively affect the aeration. The various concrete mixes are poured and allowed to cure to maximum strength before indirect tensile tests and compression tests are conducted. The effects of creating smooth aerated concrete molds are also investigated. All experiments conducted are precursory to an ultimate tensile reinforced aerated concrete beam design with an aggregate mix and smooth surfaces.
by Leonidia Maria Garbis.
S.B.

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33

Alqahtani, Fahad Khshim. "Production of novel manufactured plastic aggregate and its utilisation in concrete." Thesis, University of Birmingham, 2017. http://etheses.bham.ac.uk//id/eprint/7821/.

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Plastic waste and its low recycling rate make a significant contribution towards the pollution of the environment. Therefore , it is essential that plastic waste is utilised in different applications . One of the applications is its use either as an aggregate or to form aggregate for use in the concrete. New aggregates were developed using plastic waste and by-product or low cost granular materials. These aggregates have a relatively low density and water absorption as compared to conventional aggregates , and were successfully used to produce sustainable or green lightweight concrete. The new aggregates were used to replace the conventional coarse fraction of either nonnal weight or lightweight aggregates at full or partial replacements; where both properties of fresh and hardened concrete were investigated. It was found that the effect of the replacement level of the conventional aggregate with the manufactured recycled plastic aggregates was less prominent on density as compared to the other properties. The hardened concrete showed a reduction in mechanical properties , with an increase in the proportions of manufactured recycled plastic aggregates in the mix . The assessment of durability properties, thermal conductivity and curing temperature was also carried out. The concrete ductility, drying shrinkage, creep strain and thennal conductivity increased as the content of manufactured recycled plastic aggregate increased in the mix. Whilst, the chloride penneability was found to decrease with an increase in the percentage of recycled plastic aggregate. Finally, models were proposed to predict the mechanical and durability properties utilising the results of this study.

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Cooke, Timothy Graham. "Lightweight concrete : investigations into the production of variable density cellular materials." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/78505.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Architecture, 2012.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 123-127).
This research focuses on the intersection between material composition and form in the development of a new type of concrete. As concrete is the most widely used building material in the world, innovation in this material has more potential to effect change in our built environment than innovation in any other. With the objective of minimizing raw material consumption and energy use, this work attempts to develop methods for creating a cellular lightweight concrete with variable density that can be cured at room temperature. Most aerated concretes traditionally require high temperature and high pressure curing; the goal of this research is to create a lower embodied energy product through the use of room temperature curing, while at the same time maximizing performance through variation of the density of the material through its section-essentially locating stronger material where it is needed. This more durable and versatile concrete product will be able to compete with traditional lightweight concretes, which provide benefits such as insulation, as well as normal-weight concrete, which is harder and stronger. The research aims to capitalize on the inherent heterogeneity of the material by producing a substance whose internal properties can be varied based on the needs of a specific part of a building. I am interested in replacing the concept of the "assembly" of materials to gain a desired function with a more unitary concept: the manipulation of a single material to meet a building's multiple needs. A desired outcome of the work is to reconceive how we put buildings together, not as assemblies of discrete elements but as monolithic yet malleable wholes.
by Timothy Graham Cooke.
S.M.

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35

Puschenreiterová, Kristína. "Polyfunkční dům v Bratislavě v části Podunajské Biskupice." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227479.

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Master thesis contains project documentation of low-energy multifunctional house with a full basement, three floors and finished with a flat roof. It is a detached house situated in a residential building area in capital city of Slovakia - Bratislava, district Podunajské Biskupice. The basement walls and columns are made of reinforced concrete. The basement is used as a garage with twenty-two parking spaces for flats owners and there is also placed a workshop room. Above-ground floors are designed as a reinforced concrete frame filled circumferentially with light-weight concrete blocks. Exterior cladding is covered by heat insulation. The interior vertical, non-load-bearing walls are made of plasterboard. On the ground floor are two shops and a restaurant with a terrace. There are eleven flats on the other two floors. On the second floor are seven double-bedroom flats with an open plan kitchen lounge area, four of them have a balcony. On the third floor are four flats with a terrace, three of them are two double bedroom flats with an open plan kitchen lounge area, and the fourth one is a one double bedroom flat with open plan kitchen lounge area. The entrance for shops and main entrance for flats are on the north-west side. The entrance for the restaurant is on the north-east side.

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36

Kumaraswamy, Pillai Subha. "Functionalized polymer building blocks for high performance bioplastic production using novel green catalysts and recycled vegetable oil." Doctoral thesis, Université Laval, 2014. http://hdl.handle.net/20.500.11794/25339.

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Cette thèse de doctorat a pour objectif le développement d'un catalyseur hétérogène très actif et sélectif pour la conversion d'huiles végétales usées en monomères pour le développement de bioplastiques via la réaction d’auto-métathèse. Le méthyltrioxorhénium supporté sur l’alumine mésoporeuse modifiée avec ZnCl2 s’est avéré un catalyseur actif pour l'auto-métathèse de l'oléate de méthyle, une molécule modèle pour les triglycérides des huiles. Les produits obtenus à partir de la métathèse de l'oléate de méthyle comprennent, un diester, le 1,18-octadecenedioate et un alcène, 9-octadécène, qui peut être utilisé comme monomère pour la synthèse des polymères lorsqu'il est associé à d'autres molécules. Les conditions de réaction telles que la température, le temps de réaction et le promoteur utilisé ont été optimisées pour obtenir un rendement élevé en produits de la métathèse de l'oléate de méthyle. Le catalyseur 3% MTO/ZnCl2-Al2O3-meso avec un rapport Al/Zn de 8 à la température de réaction de 45°C pendant 60 min a été trouvé actif pour la métathèse de l'oléate de méthyle. Il a été également observé que les autres halogénures métalliques et des chlorures n'ont pas favorisé la réaction comme le ZnCl2. L'amélioration de l'activité du catalyseur par l’addition de ZnCl2 à Al2O3-méso a été expliquée en raison de la nature acide de Lewis améliorée par le ZnCl2. Les études cinétiques ont montré que le catalyseur a été très actif permettant une conversion supérieure à 80% en 30 min de réaction entre 25°C et 60°C. L'activité catalytique à la température ambiante était aussi encourageante pour l'auto métathèse de l'oléate de méthyle. Les conditions opératoires optimisées pour la métathèse de l'oléate de méthyle ont par la suite été étendues à l'application de triglycérides, en l’occurrence la trioléïne qui est abondante dans l’huile de tournesol et autres huiles végétales. Le catalyseur a été trouvé actif avec la formation de l'alcène 9-octadécène ainsi que des dimères et des trimères de la trioléine. Le catalyseur à base de MTO a été actif pour la formation des produits de métathèse désirés et le produit non désiré de métathèse comme le polymère réticulé formé par la réaction à catalyse homogène a été évité.Les résultats prometteurs pour la métathèse des trioléïnes prouvent que le catalyseur 3% MTO/ZnCl2-Al2O3-meso peut être utilisé pour la métathèse des huiles végétales comme l'huile de tournesol riche en acide oléique qui contient la trioléïne comme sa principale composante.
This doctoral thesis aims at the development of highly active and selective heterogeneous catalyst for conversion of used vegetable oils into monomers for bioplastic development using self-metathesis reaction. The catalyst based on methyltrioxorhenium supported on mesoporous alumina modified with ZnCl2 was found to be an active catalyst for self-metathesis of methyl oleate, a model molecule for triglycerides of oils with high turnover number. The products obtained from the metathesis of methyl oleate include the diester, 1,18-Octadecenedioate and an alkene, 9-Octadecene which can be used as monomer for polymer synthesis when reacted with other molecules. The reaction conditions such as temperature, reaction time, the promoter used were optimized to obtain high yield of products from the metathesis of methyl oleate. The catalyst 3% MTO/ZnCl2-Al2O3-meso with Al/Zn ratio of 8 at reaction temperature of 45°C for 60 min was found to be active for metathesis of methyl oleate. It was also found that the other halides and metal chlorides did not promote the reaction similar to ZnCl2. The enhancement of activity by addition of ZnCl2 to Al2O3-meso was found to be due to the Lewis acidic nature enhanced by addition of ZnCl2. The kinetic studies showed that the catalyst was highly active resulting in conversion> 80% within 30 min of reaction between 25°C to 60°C. The catalytic activity at room temperature was also promising proving it to be a very efficient catalyst for self metathesis of methyl oleate. The conditions optimized for methyl oleate metathesis was extended for the application of triolein, the abundant triglyceride present in the high oleic sunflower oil and other vegetable oils. The catalyst was found to be active with formation of the alkene 9-Octadecene and the dimers and trimers of triolein as desired metathesis products. The MTO based catalyst was active in forming the desired metathesis product and the undesired product namely the cross-linked polymer formed with the homogeneously catalyzed reaction was avoided. The promising results for the metathesis of triolein prove that the catalyst 3% MTO/ZnCl2-Al2O3-meso can be used for the metathesis of vegetable oils such as high-oleic sunflower oil which contains triolein as its major component.

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37

Guénette, Maryse. "Wood blocks as a carrier for Saccharomyces cerevisiae cells used in the production of fructose and ethanol." Thesis, University of Ottawa (Canada), 1993. http://hdl.handle.net/10393/6479.

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Saccharmoyces cerevisiae ATCC 39859 was immobilized onto small cubes of wood in order to produce very enriched fructose syrup from synthetic glucose/fructose mixtures, through the selective fermentation of glucose. The kinetics of growth and ethanol production rates were measured. Several tests to assess the influence of substrate and product concentration on the production rates were carried out and appropriate rate equations were proposed as a design basis for continuous immobilized reactors. The growth and ethanol production rates were found to be inhibited linearly by both substrate and product concentrations. A maximum ethanol productivity of 21.9 g/Lh was attained from a feed containing 10% (w/v) glucose and 10% (w/v) fructose. The ethanol concentration was 29.6 g/L, the glucose conversion was 78% and a fructose yield of 99% was obtained. This resulted in a fructose/glucose ratio of 2.7. At lower ethanol productivity levels the fructose/glucose ratio increases, as does the ethanol concentration in the effluent. The addition of oleic acid, which is known as an anaerobic growth factor, increased the productivity by 13%. The effect of reactor temperature on production rate was studied. Ethanol productivity peaked at 32.6$\sp\circ$C and approached zero near 44$\sp\circ$C. Batch fermentations were carried out using the reactor effluent in an attempt to enhance the ethanol concentration in the effluent from the reactor. The productivity of these processes was not very high due to the low biomass concentration leaving the reactor. The addition of yeast extract or active biomass increased the productivity substantially. The immobilized cell bioreactor was also used to produce sorbitol continuously from fructose. Sorbitol is a polyol which is used as a sweetening agent for diabetics. It is also used in pharmaceutical, foods and chemical industry. A maximum productivity of 3.25 g/Lh was attained from a 133.8 g/L fructose feed, with a fructose conversion of 44%. (Abstract shortened by UMI.)

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38

Tatli, Emre. "Pretreatment Of Peanut Shells For Co-production Of Glucose And Concrete Admixture." Master's thesis, METU, 2013. http://etd.lib.metu.edu.tr/upload/12615535/index.pdf.

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This thesis work aims the ionic liquid pretreatment of peanut shells for co-production of glucose as fermentable sugar and lignin, considering a multi product perspective. The effects of ionic liquid type and pretreatment time period on the sugar and lignin yields were investigated, as the particle size and temperature parameters were determined in the preliminary studies. Peanut shells were pretreated at constant temperature, 150 oC, for 5, 15 and 30 minutes with 1-ethyl-3-methylimidazolium acetate and for 15, 30 and 60 minutes with 1-ethyl-3-methylimidazolium chloride. The pretreated peanut shells were then subjected to enzymatic hydrolysis in order to produce fermentable sugars, mostly, glucose. The solid residue obtained upon enzymatic hydrolysis was analyzed in terms of lignin quantity. 1-ethyl-3-methylimidazolium acetate pretreatment for 15 minutes resulted in the maximum reducing sugar and lignin yields
28 g of reducing sugar and 20 g of solid residue with 70% lignin were obtained per 100 g of peanut shells. Higher pretreatment time resulted in lower yields. Moreover, no optimal time period for 1-ethyl-3- methylimidazolium chloride pretreatment was obtained, since reducing sugar and lignin yields increased as the time period increased. Also all reducing sugar and lignin yields were lower than that obtained with 1-ethyl-3-methylimidazolium acetate. Lignin obtained upon enzymatic hydrolysis of 1-ethyl-3-methylimidazolium acetate pretreated peanut shells were characterized by SEM, FTIR, TGA and XRD analyses, which also showed the morphological and structural effects of pretreatment and enzymatic hydrolysis on peanut shells
and used as concrete admixture, which increased the flow of the concrete by 6%.

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39

Bouxin, Florent. "Solvolyse des lignines : production de synthons aromatiques de faibles masses." Thesis, Reims, 2011. http://www.theses.fr/2011REIMS004/document.

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Les lignines ne sont pas suffisamment considérées dans les procédés de bioraffinerie. Pourtant, elles sont une source abondante de synthons aromatiques, et éléments essentiels de la rentabilité de transformation des lignocelluloses. A ce jour, les perspectives de production de synthons à partir des lignines se heurtent aux réactions de condensations des lignines, limitant leurs conversions en produits de faibles masses. Cette étude nous a permis de cerner les conditions propices à l’hydrolyse et/ou aux condensations grâce à l’étude de différentes lignines modèles soumises aux conditions d’acidolyse. D’une part, les conditions propices à l’hydrolyse des liaisons -O-4 sont l’utilisation d’une catalyse homogène (HCl), pour des températures comprises entre 120 et 140°C et une acidité de l’ordre de 0.05 M. A l’inverse, l’emploi d’une catalyse hétérogène (Montmorillonite K10) est peu efficace car elle doit s’affranchir des phénomènes d’adsorption du substrat tout en lui permettant d’accéder à ses sites actifs. D’autre part, les réactions de condensation secondaires sont exacerbées par l’emploi de l’argile de Montmorillonite, mais aussi par l’augmentation de l’acidité et de la température, elles mêmes nécessaires pour une bonne hydrolyse. La substitution de l’alcool coniférylique par le coniféraldéhyde permet de minimiser ces condensations secondaires du fait de sa forte stabilité dans les conditions d’acidolyse. Toutefois, l’incorporation de ce type de précurseur dans les lignines provoque une diminution de la fréquence des liaisons -O-4. Cette réduction du potentiel d’hydrolyse des lignines est compensée par l’exacerbation des réactions de rétroaldolisation. Pour les condensations primaires, l’acidolyse des lignines pures -O-4 nous permet d’affirmer que celles-ci, constantes face à l’augmentation de la concentration en acide et en nucléophiles aromatiques, seraient plutôt de type intramoléculaire
Lignins are not sufficiently considered in the biorefinery processes. However, they are a rich source of aromatic building blocks, and essential elements of lignocellulose processing viability. Although the production prospects of building blocks from lignins exist, their strong affinities for condensation reactions limit the conversion into low molecular weight products. This study allowed us to identify hydrolysis or condensation suitable conditions by studying different models lignins subjected to acidolysis conditions. On the one hand, suitable conditions for the -O-4 bonds hydrolysis are the use of homogeneous catalysis (HCl), for temperatures and HCl concentration ranged from 120 to 140 ° C and from 0.05 M to 0.1M. In contrast, the use of heterogeneous catalysis (Montmorillonite K10) is inefficient because it has to overcome the substrate adsorption and allow an access to its active sites. On the other hand, secondary condensation reactions are exacerbated by the use of Montmorillonite clay, but also by acidity and temperature increases, themselves necessary for an efficient hydrolysis.The substitution of coniferyl alcohol by coniferaldehyde minimizes these condensation reactions due to its high stability in acid conditions. However, the incorporation of this precursor in lignin leads to a decrease of -O-4 bond frequency. This reduction of lignin hydrolysis potential is compensated for the exacerbation of retroaldolisation reactions. About primary condensations, pure -O-4 lignins acidolysis allows us to claim that this kind of reactions, unchanged at the hand of acid or aromatic nuclei concentration increase, are intramolecular

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Bravo, Rafael Segantini [UNESP]. "Análise de blocos de concreto com resíduo de borracha de pneu e metacaulim." Universidade Estadual Paulista (UNESP), 2014. http://hdl.handle.net/11449/124467.

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Made available in DSpace on 2015-07-13T12:10:20Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-08-01. Added 1 bitstream(s) on 2015-07-13T12:25:23Z : No. of bitstreams: 1 000837029.pdf: 2125746 bytes, checksum: 3c7acd4bd3c47790e571b23a516ef2d6 (MD5)
Vários segmentos da sociedade têm se voltado para os conceitos da sustentabilidade, pesquisando alternativas para minimizar os impactos causados pelo consumo, muitas vezes, indiscriminado de matéria-prima e pelo grande volume de resíduos gerados, entre os quais se incluem os resíduos de borracha. Neste sentido, diversos trabalhos de engenharia têm indicado que a adição de resíduos de borracha de pneu têm potencial para promover a redução da massa específica de matrizes cimentícias. Deste modo, objetivou-se neste trabalho avaliar a aplicação de resíduos de borracha de pneu na confecção de concretos leves, com massa específica aparente inferior a 2000 kg/m3, tendo em vista a sua aplicação em blocos de concreto para alvenaria. Observou-se que houve uma diminuição da resistência à compressão do concreto, razão pela qual adotou-se o procedimento de substituir 10% de cimento por metacaulim (em massa). Objetivou-se ainda, neste trabalho, promover uma destinação apropriada para este resíduo e assim minimizar os possíveis impactos ambientais, muitas vezes causados pela sua destinação inadequada. Foram produzidos traços de concreto sem resíduo (concreto referência), com 9,2%, 18% e 26,8% de resíduo em substituição do agregado miúdo, em relação ao volume. Confeccionaram-se corpos de prova cilíndricos 10 cm x 20 cm e blocos de concreto 14 cm x 19 cm x 29 cm, os quais foram ensaiados visando a determinação da resistência à compressão simples. Os blocos de concreto foram também submetidos a ensaios de absorção. Constatou-se que entre os traços ensaiados, o resultado menos favorável foi obtido para os blocos produzidos com 26,8% de resíduo, os quais apresentaram resistência característica à compressão de 2,74 MPa e absorção de 6,96%, resultados que atendem às prescrições da NBR 6136 para a confecção de blocos vazados de concreto para alvenaria
Various segments of society have focused on the concepts of sustainability, researching alternatives to minimize the impacts caused by the often indiscriminate consumption of raw materials and the large volume of waste generated, among which include the waste rubber. Accordingly, many engineering studies have shown that the addition of waste rubber tire has the potential to promote the reduction of specific mass of cementitious matrices. Thus, the aim of this study was to evaluate the application of these wastes in the manufacture of lightweight concrete, with specific mass less than 2000 kg/m3, with a view to their application in concrete block masonry. It was observed that there was a decrease in compressive strength of the concrete, which is why we adopted the procedure of replacing 10% of metakaolin in cement (by mass). Still aim of this study, promote appropriate disposal for this waste and to minimize possible environmental impacts, often caused by their improper disposal. Ratio of concrete were produced without residue (reference concrete), with 9,2%, 18% and 26,8% of residue in substitution fine aggregate, in relative to the volume. Were produced cylindrical specimens 10 cm x 20 cm and concrete block 14 cm x 19 cm x 29 cm, which were tested in order to determine the compressive strenght. The concrete blocks were also tested for absorption. It was found that among the tested ratios, the less favorable result was obtained for the blocks produced with 26,8% of residue, which showed characteristic compressive strength of 2,74 MPa and absorption of 6,96%, results that meet the requirements of NBR 6136 for the manufacture of hollow concrete block mansory

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Bravo, Rafael Segantini. "Análise de blocos de concreto com resíduo de borracha de pneu e metacaulim /." Ilha Solteira, 2014. http://hdl.handle.net/11449/124467.

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Orientador: Jorge Luís Akasaki
Banca: Mauro Mitsuuchi Tashima
Banca: Lúcia Reig Cerdá
Resumo: Vários segmentos da sociedade têm se voltado para os conceitos da sustentabilidade, pesquisando alternativas para minimizar os impactos causados pelo consumo, muitas vezes, indiscriminado de matéria-prima e pelo grande volume de resíduos gerados, entre os quais se incluem os resíduos de borracha. Neste sentido, diversos trabalhos de engenharia têm indicado que a adição de resíduos de borracha de pneu têm potencial para promover a redução da massa específica de matrizes cimentícias. Deste modo, objetivou-se neste trabalho avaliar a aplicação de resíduos de borracha de pneu na confecção de concretos leves, com massa específica aparente inferior a 2000 kg/m3, tendo em vista a sua aplicação em blocos de concreto para alvenaria. Observou-se que houve uma diminuição da resistência à compressão do concreto, razão pela qual adotou-se o procedimento de substituir 10% de cimento por metacaulim (em massa). Objetivou-se ainda, neste trabalho, promover uma destinação apropriada para este resíduo e assim minimizar os possíveis impactos ambientais, muitas vezes causados pela sua destinação inadequada. Foram produzidos traços de concreto sem resíduo (concreto referência), com 9,2%, 18% e 26,8% de resíduo em substituição do agregado miúdo, em relação ao volume. Confeccionaram-se corpos de prova cilíndricos 10 cm x 20 cm e blocos de concreto 14 cm x 19 cm x 29 cm, os quais foram ensaiados visando a determinação da resistência à compressão simples. Os blocos de concreto foram também submetidos a ensaios de absorção. Constatou-se que entre os traços ensaiados, o resultado menos favorável foi obtido para os blocos produzidos com 26,8% de resíduo, os quais apresentaram resistência característica à compressão de 2,74 MPa e absorção de 6,96%, resultados que atendem às prescrições da NBR 6136 para a confecção de blocos vazados de concreto para alvenaria
Abstract: Various segments of society have focused on the concepts of sustainability, researching alternatives to minimize the impacts caused by the often indiscriminate consumption of raw materials and the large volume of waste generated, among which include the waste rubber. Accordingly, many engineering studies have shown that the addition of waste rubber tire has the potential to promote the reduction of specific mass of cementitious matrices. Thus, the aim of this study was to evaluate the application of these wastes in the manufacture of lightweight concrete, with specific mass less than 2000 kg/m3, with a view to their application in concrete block masonry. It was observed that there was a decrease in compressive strength of the concrete, which is why we adopted the procedure of replacing 10% of metakaolin in cement (by mass). Still aim of this study, promote appropriate disposal for this waste and to minimize possible environmental impacts, often caused by their improper disposal. Ratio of concrete were produced without residue (reference concrete), with 9,2%, 18% and 26,8% of residue in substitution fine aggregate, in relative to the volume. Were produced cylindrical specimens 10 cm x 20 cm and concrete block 14 cm x 19 cm x 29 cm, which were tested in order to determine the compressive strenght. The concrete blocks were also tested for absorption. It was found that among the tested ratios, the less favorable result was obtained for the blocks produced with 26,8% of residue, which showed characteristic compressive strength of 2,74 MPa and absorption of 6,96%, results that meet the requirements of NBR 6136 for the manufacture of hollow concrete block mansory
Mestre

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Metzner, Richard Rondang Bonar [Verfasser]. "Chemoenzymatic syntheses for the production of Rosuvastatin and other enantiomerically pure pharmaceutical building blocks / Richard Rondang Bonar Metzner." Bielefeld : Universitätsbibliothek Bielefeld, 2014. http://d-nb.info/1060824299/34.

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Alam, Nazki Aiman. "Elucidating the spatial organization and control of information processing in cell signalling networks : from network and enzymatic building blocks to concrete systems." Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/29945.

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Cells function and survive by making decisions in response to dynamic environments. The core controllers of decision-making are highly complex intracellular networks of proteins and genes, which harbour sophisticated information processing capabilities. The effect of spatial organization and control of signaling networks is typically ignored. However, the role of space in signalling networks is being increasingly recognized. While there are some experimental and modelling efforts that incorporate spatial aspects in specific cellular contexts, the role of spatial regulation of signalling across different cell networks remains largely unexplored. In this thesis, we utilize a combination of mathematical modeling, systems engineering and in silico synthetic approaches to understand the spatial organization and control of signaling networks at multiple levels. We examine spatial effects in representative networks and enzymatic building blocks, including typical network modules, covalent modification cycles and enzymatic modification cascades and pathways. We complement these studies by dissecting the role of spatial regulation in the concrete context of the Caulobacter cell cycle, which involves specific combinations of these building blocks. In another investigation, we examine the organization of spatially regulated signaling networks underlying chemotaxis. We explicitly examine the effects of diffusion and its interplay with spatially varying signals and localization/compartmentalization of signalling entities and gain key insights into the interplay of these factors. At the network level, examining typical network modules reveals how introduction of diffusion/global entities may significantly distort temporal characteristics and introduce new types of signal transduction characteristics. At the enzymatic level, dissecting spatial regulation in enzymatic modules highlights the subtle effect and new facets that arise due to the interweaving of cycle kinetics and diffusion. The various ways in which spatial compartmentalization affects pathway behaviour is revealed in the study of various types of signaling pathways. The study of spatial regulation of these enzymatic/network building blocks provides a systematic basis for understanding how spatial control can affect the spatiotemporal interactions driving Caulobacter cell cycle and we use an in-silico synthetic approach to create a platform for further understanding the functioning of the networks controlling this process. In a different study, we use a design approach to shed light on different signalling configurations of chemotactic networks that allow cells to exhibit both attractive and repulsive behaviour, in light of known signalling characteristics seen in cells. Our results uncover the various capabilities, constraints and trade-offs associated with the spatial control of information processing in signalling networks, which come to the surface only if spatial factors are explicitly considered. Overall, using a focused multipronged approach reveals different facets of spatial regulation of signalling at multiple levels and in different contexts. Combining mathematical modelling, systems engineering and synthetic design approaches creates a powerful framework, which may be used to elucidate spatial control of information processing in multiple contexts and design synthetic systems that could fruitfully exploit spatial organization and regulation.

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Maas, Celso Ricardo. "Resistencia a compressão de paredes de alvenaria estrutural, com blocos assentados com argamassa plena e longitudinal." [s.n.], 2004. http://repositorio.unicamp.br/jspui/handle/REPOSIP/257679.

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Orientador: Newton de Oliveira Pinto Junior
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo
Made available in DSpace on 2018-08-04T00:14:58Z (GMT). No. of bitstreams: 1 Maas_CelsoRicardo_M.pdf: 5291856 bytes, checksum: eb48c5e46eeba69d2c7fae64e7014aea (MD5) Previous issue date: 2004
Resumo: Os dois objetivos principais deste trabalho são verificar e analisar a redução da carga de ruptura de paredes de alvenaria estrutural, quando os blocos são assentados com argamassa apenas nas suas paredinhas longitudinais (argamassa longitudinal). Estas verificações e análises se fazem necessárias porque a NBR 8798 (1985) ainda especifica a colocação de argamassa em todas as paredes dos blocos (argamassa plena), embora o que mais se tem observado nas nossas construções é a colocação de argamassa apenas nas paredinhas longitudinais. Além disso, essas verificações se tornam mais necessárias quando se sabe que esse tipo de assentamento é o mais usado nos países mais ricos e desenvolvidos do mundo. Para a determinação do valor dessa redução, bem como para melhor compreender a ruptura das paredes com esses dois tipos de assentamento, foram ensaiados corpos-de-prova de blocos, prismas e paredes de 1,00 m de altura, na idade de 14 dias, com argamassa plena e longitudinal. Todos os ensaios foram feitos com blocos de concreto e com blocos cerâmicos. Finalizando, após evidenciar as deficiências dos atuais modelos de prismas, principalmente dos prismas com argamassa longitudinal, este trabalho tem como um último objetivo propor novos modelos de prismas para ensaios, em conformidade com os tipos de assentamento
Abstract: The two main aims of this work are to verify and analyze the reduction of the compressive strength of structural masonry walls, when the blocks are laid with mortar only in the outside faces of the block (face shell bedding). These verifications and analysis are important because, although the Brazilian code NBR 8798 (1985) still specifies that the entire block surface must be bonded (full mortar bedding), in Brazil the most used type of bedding is the face shell bedding. Besides, these verifications are important because we notice that the face shell bedding is used in the richest countries. In order to find the magnitude of this reduction and to understand the collapse of the two types of bedding, 14 days old specimens of blocks, prisms and wallettes of one meter height were tested, with face shell and full mortar bedding. All the tests were carried out with concrete and ceramic structural blocks. After realize the handicaps of the Brazilian prisms, mainly that ones bonded whit face shell bedding, the last aim of this work is to propose a new model of prisms, to be used in laboratory tests
Mestrado
Edificações
Mestre em Engenharia Civil

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Bezy, Susana Elizabeth. "A life-cycle assessment of concrete in Hong Kong : the consumption and disposal of concrete materials and the environmental criteria and factors regarding its production, use and disposal /." Hong Kong : University of Hong Kong, 1995. http://sunzi.lib.hku.hk/hkuto/record.jsp?B14038705.

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NASCIMENTO, Maria Victória Leal de Almeida. "Estudo de blocos intertravados de concreto para pavimentação de resíduo do polimento do porcelanato." Universidade Federal de Pernambuco, 2016. https://repositorio.ufpe.br/handle/123456789/17151.

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A utilização de resíduos em materiais cimentícios, tem sido desenvolvida para melhorar a qualidade ambiental, diminuindo os resíduos gerados. O RPP é um resíduo industrial produzido em grande escala pela indústria cerâmica, ele foi utilizado nesse trabalho sendo incorporado em blocos intertravados de concreto. Os blocos intertravados de concreto foram escolhidos dentre os materiais cimentícios, por não ter sua trabalhabilidade comprometida, quando se trata de adicionar um material pulverulento, pois é produzido por vibro-compressão. Foi realizada a otimização do empacotamento dos agregados, para a produção dos blocos intertravados de concreto, através de método matemático. Também foi otimizada, através de método experimental a relação água/cimento. O traço de referência, encontrado após as otimizações, foi 1: 2,68: 2,32 (cimento: areia: pedrisco), com relação água/cimento de 0,45, atendeu as especificações da NBR 9781 (ABNT, 2013), com relação a resistência à compressão. A partir do traço de referência foi realizado o empacotamento matemático para a incorporação do RPP. O resíduo foi considerado como agregado no empacotamento, ele foi incorporado nas seguintes porcentagens: 3% de RPP, 6% de RPP, 9% de RPP, e 12% de RPP, afim de avaliar a influência do resíduo nos blocos intertravados de concreto, nas propriedades do estado endurecido. A presença do RPP, reduziu a absorção de água tendendo a trazer para o admitido pela NBR 9781 (ABNT, 2013), manteve a resistência a abrasão de acordo com as especificações da NBR 9781 (ABNT, 2013), embora tenha prejudicado a resistência a compressão, sendo promissor a sua utilização, em blocos intertravados de concreto, em situações onde não há tráfego de veículos, como em: passeios públicos, praças, parques infantis, áreas que necessitem de drenagem. O traço com a incorporação do resíduo, que de uma forma geral obteve os resultados mais satisfatórios foi o traço 2 (3% RPP), que apesar da resistência à compressão média ter sido de 14,26 MPa menor que o especificado pela norma, apresentou uma taxa de absorção média de 6,60%, e em relação a resistência à abrasão apresentou uma cavidade média de 17,50 mm.
To incorporate residues in cimentitious materials has been developed to improve the environmental quality, reducing the amount of disposed residues. The ceramic porcelain industry generates a large amount of porcelain tile polishing residue. This work proposes to incorporate this tile polishing residue in concrete interlocking blocks. The concrete interlocking blocks were chosen due to the addition of a powder material not prejudice their workability, once they are molded by vibrocompression. It was determined the best packaging by a mathematical method. The water-cement ratio was also optimized by the experimental method. The achieved reference mix proportion after all optimizations was 1:2.68:2.32 (cement: sand: gravel) with ratio water-cement ratio 0.45. The compressive strength of the reference mix proportion is according to the NBR 9781 (ABNT, 2013). In the sequence, based on this reference mix, the incorporation of the residue was also mathematically optimized. The residue was considered as an aggregate on the packaging method. The residue was incorporated at the following percentages: 3%, 6%, 9% and 12% in order to evaluate its influence on the hardened state properties of the concrete interlocking blocks. The presence of the tile polishing residue reduces the water absorption, tending to bring the values to the admitted one by the NBR 9781. The abrasion resistance was in agreement with the NBR 9781 (ABNT, 2013). However, the compressive resistance was reduced, limiting the applications of the concrete interlocking blocks with the addition of tile polishing residue where there is no vehicle traffic, as in public footpaths, parks, playgrounds or areas requiring drainage. In a general way, the most satisfactory result among the evaluated mixes incorporating tile polishing residue was to the mix 2 (3% of residue). Despite the average compressive strength was 14.26 MPa lower than the specified by the standard, this mix presented the average absorption of 6.60% and 17.50 mm as a medium cavity liner in the abrasion resistance test.

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Mitzithra, Maria Eleni. "Detection of corrosion of reinforced concrete on cooling towers of energy production sites." Toulouse 3, 2013. http://thesesups.ups-tlse.fr/2135/.

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Cette thèse a été financée par Electricité de France-Recherche et Développement (EDF R&D). L'objectif est le développement d'une méthodologie pour une meilleure estimation de l'état de corrosion des armatures du béton des aéroréfrigérants, soumis à la carbonatation atmosphérique, sur la base d'une double approche: le radar géophysique (GPR) et la mesure de la résistance de polarisation1. Le GPR peut être utilisé pour la détection rapide des zones présentant un risque élevé de corrosion (détection des contrastes de permittivité). En plus, le GPR est utilisé pour la localisation des armatures d'acier et l'estimation de l'épaisseur d'enrobage. Cette dernière application est très importante pour cette étude. Dans les zones identifiées comme potentiellement corrodées par le GPR, il est proposé d'utiliser la mesure de la résistance de polarisation pour quantifier l'activité de corrosion. Cette étude propose une méthode opérationnelle et originale, adaptée seulement à cette problématique. Après une analyse critique des dispositifs existants pour la mesure sur site de la résistance de polarisation, un nouveau dispositif est proposé. Un modèle numérique de ce dispositif est développé. Sur la base des résultats du modèle, des abaques sont construites afin de remonter aux propriétés électrochimiques de l'acier (potentiel et courant) à partir des valeurs qui sont mesurées à la surface du béton. Le rôle des paramètres influents, physiques (courant injecté, résistivité), géométriques (enrobage, position de la sonde) et électrochimiques (état de l'acier), est examiné en détail. Ensuite, la méthode d'inversion proposée est testée en laboratoire, sur des corps d'épreuve reproduisant les conditions du site2. La fiabilité et l'efficacité du modèle dans son domaine de définition sont démontrées. Les limites et l'incertitude du protocole de mesure sont également abordées. Enfin, un premier protocole opérationnel pour l'utilisation sur site de la technique est proposé
The current thesis is the result of a study funded by Electricité de France -Research and Development (EDF R&D). It aims to develop an original methodology for a better estimation of the state of corrosion of steel reinforced concrete of cooling towers, due to atmospheric carbonation, based on a double approach: the Ground Penetrating Radar (GPR) and the electrochemical measurement of polarization resistance1. GPR can be used for detecting zones with a high risk of corrosion (detection of contrasts of permittivity). In addition, GPR is used for the location of steel rebars and the estimation of concrete cover thickness. On the zones identified by GPR with high risk of corrosion, it is proposed to use the polarization resistance measurement to define quantitatively the corrosion activity. This study proposes an original simple operative measurement mode, adapted only for this particular context. After a critical analysis of the existing devices of the polarization resistance measurement, a novel probe is proposed. A numerical model of this probe is developed. Based on the results of the model, abacuses are built in order to gather the real electrochemical proprieties of the steel reinforcement (potential and current) from those values measured on the concrete surface. The role of the influencing factors i. E. Physical (injected current, resistivity), geometric (concrete cover, probe's position) and electrochemical (state of the reinforcement), are fully investigated. The proposed model is applied in a laboratory environment, by reproducing the real site conditions2. The experimental work proves its feasibility, efficiency and effectiveness (within certain limits) by confirming its theoretical principles and indicating some uncertainties during its application. Finally, a primary operational protocol for the on site utilization of the technique is proposed

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Marchioni, Mariana Lobo. "Desenvolvimento de técnicas para caracterização de concreto seco utilizado na fabricação de peças de concreto para pavimentação intertravada." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/3/3146/tde-18072013-150832/.

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O concreto seco, também chamado de concreto sem abatimento (no-slump) é utilizado na produção de artefatos de cimento, como por exemplo em peças de concreto para pavimentação, blocos para alvenaria e tubos de concreto e ainda como camada de subbase de pavimentos com a técnica de concreto compactado a rolo. A técnica de conformar concretos com reduzido teor de umidade através de equipamentos que aplicam simultaneamente compressão e vibração é amplamente utilizada na produção de artefatos de concreto, como as peças de concreto para pavimentação intertravada. Para as peças de concreto o desafio é ainda maior, pois as especificações de resistência característica à compressão podem chegar a 50 MPa. A principal característica do concreto seco é o baixo teor de água e elevada coesão, necessitando de energia de compactação e vibração para a eliminação de vazios e o concreto assumir a forma desejada. Esta técnica permite a desfôrma imediata, que garante elevada produtividade e consequente diminuição dos custos de produção. Já a compactação permite obter componentes de concreto com menor consumo de cimento se comparados ao concreto plástico. Diferentemente de toda literatura e metodologias de dosagem encontradas para o concreto plástico, o concreto seco encontra barreiras técnicas para a aplicação de metodologias que otimizem sua dosagem, em formulações empíricas que não levam em conta de forma adequada as características dos agregados, características estas diretamente ligadas à compacidade das peças, que por sua vez tem grande influência nas características do produto final. Além disto, há poucos estudos do comportamento reológico do concreto seco, que influenciam a fluidez e coesão da do concreto e que irão determinar a produtividade e qualidade da produção. Dessa forma, neste trabalho é apresentado uma metodologia para caracterização do concreto seco nos estados fresco e endurecido que permite o desenvolvimento sistemático de formulações com maior facilidade de compactação e que também resulte na melhoria do desempenho das peças e diminuindo a necessidade de testes em escala real. O método se baseia em produzir em laboratório um corpo de prova que reproduz as condições de moldagem de uma vibroprensa, eliminando-se a variável da vibração e padronizando as condições de compressão. Nos corpos-de-prova são avaliadas características nos estados fresco e endurecido, além de aspectos do comportamento reológico do concreto, através de técnicas de reologia compressiva. Para aferir a metodologia foram utilizadas amostras de referência produzidas em uma fábrica de peças de concreto. Com a metodologia proposta, foi possível atingir 90% da resistência mecânica das peças produzidas em uma vibroprensa de alta compactação. Sendo assim esta metodologia poderá ser utilizada em estudos de dosagem de concreto seco, portanto o trabalho desenvolvido é indicado na utilização de dosagens de concreto seco, obtendo-se maior ecoeficiência, a medida que otimiza o consumo de cimento da mistura e facilita o estudo de dosagem de materiais alternativos em substituição aos agregados convencionais.
The dry concrete, also known as earth moist concrete or no-slump concrete, is most used to manufacture precast concrete products, as paving blocks, masonry blocks and concrete tubes, and also in rolled compacted concrete pavement. Its most important property is the low water content, and it requires mechanical equipment for its compactation. Paving blocks are normally manufactured using vibrocompression equipment, which at the same time applies both compaction and vibration resulting in paving blocks with high durability and mechanical resistance. Even though this technique is highly used it still lacks studies on some important steps of the manufacturing process. The mix design techniques are mostly empirical and dont deeply consider the aggregate characteristics, that are connected with its compacity and, by that, the characteristics of the paving block. Also, there are only a few studies of the rheology characteristics of dry concrete, which relates with de manufacturing process and the easiness that the mix is compacted. So, the object of this study is to develop a dry concrete characterization methodology that allows the systematic development of mix designs that are easily compacted and also improves the performance of the paving blocks.

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Yakub, H. I. "Influences on durability and leaching behaviour of concrete : new technologies in fly ash production." Thesis, University of Dundee, 2016. https://discovery.dundee.ac.uk/en/studentTheses/4c6f0d6a-6b22-4ae0-9209-07fd509e4e5d.

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This report describes a 3 year study carried out to determine the effects of modern coal power generation technologies on the properties of fly ash and how these may affect the use of the material in concrete. A total of 18 fly ashes, from 11 different sources, produced under a range of conditions and technologies were investigated. These primarily included co-combustion, low NOx, supercritical and oxy-fuel technologies, although other available materials (run-of-station, air-classified, processed and stockpiled fly ashes) were included for comparison. The initial experimental work involved physical and chemical characterization of the fly ash samples. Thereafter, tests covering fresh properties, strength development and durability were carried out on selected concretes. A fly ash level of 30% was used with w/c ratios covering the practical range considered (0.35 to 0.65). Equal strength comparisons were also made where appropriate. Finally, granular (unbound fly ash) and monolithic (fly ash concrete) leaching tests were carried out to assess the environmental implications of using the fly ashes. The results from the physical and chemical characterization tests suggest that modern technologies used for coal fired power generation can have an influence on the properties of fly ash produced. The co-combustion, oxy-fuel and in-combustion low NOx fly ashes had reduced fineness and greater LOI, which had a negative effect on foam index and water requirement of the materials. However reactivity was largely unaffected. The post-combustion low NOx and supercritical fly ashes appeared to be unaffected by their production methods compared to that produced by conventional/establish means. Tests on fresh concrete properties showed that fly ashes with high LOI and low fineness required higher SP doses than the reference PC concrete. However, fly ashes with high fineness and low surface area were found to require a lower SP dose than the PC concrete. The concrete compressive strength tests indicate that, in general, finer fly ash concretes tended to have higher strengths than those containing coarser material. However, there did not appear to be any significant difference in performance between fly ash concretes, which suggests that, although modern technologies can have an impact on fly ash properties, if account is taken of these they should not have any significant influence on strength development. Comparison with an earlier study from the 1990s considering BS EN 450-1 fly ashes showed general agreement between the data. The durability study showed that finer, low LOI fly ashes had higher chloride resistance and at equal strength fly ash concretes performed better than those with PC. Equal strength fly ash concretes covering the modern technologies were found to have similar levels of durability for sulfate attack, abrasion and carbonation. High alkali concrete (following the BS 812-123 method) gave similar expansion levels and good resistance with respect to AAR. With air-entrainment, it was found that the fly ash concretes required high doses of AEA (relative to the PC concrete), with high LOI/BET fly ashes requiring greatest quantities. At equal strength, the fly ash concretes had poorer freeze-thaw scaling resistance than PC concrete. However, the majority of the fly ashes did manage to achieve acceptable scaling resistance according to the Swedish criteria. In general, the findings of the durability study are in agreement with the earlier study from the 1990s. Overall, no effect of production technology on the durability of concrete was observed. The leaching studies showed that, in general, in both granular and concrete form, modern fly ashes met the non-hazardous waste requirements in the WAC for all components tested except chromium. For the granular test, there were instances where elevated chromium levels were observed. Similarly, the fly ash concretes failed to meet the non-hazardous limit for chromium. However, chromium from the cement may have contributed to this, since the PC reference also failed to meet this requirement. Based on the results, there is no effect of production technology on the leaching characteristics of fly ash or concrete and the materials do not appear to pose a significant environmental risk. The practical implications of the study have been considered and overall, it has been shown that modern fly ashes behave in much the same way as traditional materials, and therefore, if these materials meet the requirements of BS EN 450-1, and their properties are taken into account in the proportioning of concrete, they should give satisfactory performance.

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Wieschalka, Stefan [Verfasser]. "Engineering Corynebacterium glutamicum as a designer-bug for the bio-based production of chemical building blocks and biofuel / Stefan Wieschalka." Ulm : Universität Ulm. Fakultät für Naturwissenschaften, 2012. http://d-nb.info/1029295816/34.

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