Na produção de concreto estrutural, apesar dos avanços tecnológicos, ainda se utilizam de materiais in natura, o que vem ocasionando problemas ambientais e econômicos a cadeia produtiva. Um dos problemas está associado à extração de areia do leito de rios, motivo pelo quais os profissionais envolvidos com a tecnologia do concreto vêm buscando alternativas ao uso dessa areia na produção de concreto estrutural. Uma alternativa que vem sendo estudada, pela grande disponibilidade, é o uso de uma areia produzida a partir da cominuição de rochas, chamada de areia de britagem. Na região de Caxias do Sul existem grandes reservas de rochas de origem basáltica (Riodacitos), a partir das quais é possível se produzir esse tipo de areia. Neste trabalho foi avaliada a viabilidade de se substituir à areia natural por areia de britagem de rochas basálticas produzidas em cinco empresas mineradoras localizadas na região de Caxias do Sul. O estudo foi desenvolvido em três etapas: na primeira foram avaliadas as características das areias decorrentes da mineralogia e petrografia das rochas e do processo de fabricação nas mineradoras; na segunda etapa foram avaliadas as propriedades do concreto através do método de dosagem EPUSP/IPT; na terceira etapa, para comprovar a eficiência do método de dosagem, foram produzidos traços específicos para cada tipo de areia. Os resultados de caracterização demonstraram que as areias de britagem possuem características diferentes das da areia natural e que apenas duas das cinco areias avaliadas apresentam propriedades que permitem a sua utilização em concreto estrutural. As propriedades decorrentes do processo de fabricação, como a presença de material pulverulento, forma e textura dos grãos provocaram um aumento no teor de argamassa, o que influenciou diretamente no proporcionamento dos materiais constituintes. Os resultados para a avaliação das propriedades do concreto demonstraram que, para um mesmo traço, a resistência a compressão axial e o módulo de elasticidade são menores nos concretos produzidos com areias de britagem. Corrigindo-se os teores de argamassa e produzindo-se traços específicos para cada tipo de areia é possível produzir concretos com resistências desejadas. Apesar das diferenças encontradas nas propriedades das areias foi comprovado que as areias de britagem estudadas podem ser utilizadas na produção de concreto estrutural de cimento Portland, substituindo totalmente à areia natural. / Submitted by Marcelo Teixeira (mvteixeira@ucs.br) on 2014-06-03T20:43:28Z No. of bitstreams: 1 Dissertacao Edison Humberto Viero.pdf: 1978943 bytes, checksum: fab5a6668b1624ae95d901331299a4d3 (MD5) / Made available in DSpace on 2014-06-03T20:43:28Z (GMT). No. of bitstreams: 1 Dissertacao Edison Humberto Viero.pdf: 1978943 bytes, checksum: fab5a6668b1624ae95d901331299a4d3 (MD5) / Despite the technological advances on the structural concrete production, in natura materials are still used. This fact has been causing environmental and economic problems to the manufacturing chain. One of the problems is related to the sand extraction from riverbeds, this is the reason why professionals involved with concrete technology are searching for alternatives to the use of this type of sand in the structural concrete manufacturing. One alternative that is being studied in various parts of the country, because its large availability is a sand produced from the rocks´ comminution, called crushing sand. In the Caxias do Sul region there are large reservations of basaltic rocks origin (Riodacitos), from which it is possible to produce this type of sand. In this work, it was evaluated the feasibility of substitute natural sand for crushing sand from basaltic rocks produced in five mining companies located at Caxias do Sul region. The study was developed in three stages: on the first one, the features of the sand that arises from rocks´ mineralogy and petrography and from the mining manufacturing process were evaluated; on the second the concrete properties through the EPUSP/IPT dosage method were evaluated; on the third they were produced specific trace to each type of sand in order to verify the efficiency of the dosage method. The characterization results established that the crushing sand have different features IF compared with natural sand and that Just two out of Five evaluated sands presented properties that allow its use in structural concrete. The properties arising from the fabrication process, for example the presence of powder material, the grains´ shape and texture caused the raise of the plaster content, which influenced directly on the constituents materials proportioning. The results of the concrete properties evaluation showed that, for the same trace, the resistance to axial compression and the elasticity module are smaller in the concretes produced with crushing sand. If the plaster content is corrected and the specific traces are produced for each type of sand it is possible to produce concretes with desired resistance. In spite of the differences found on the sand properties it was proven that the crushing sand produced at the Caxias do Sul region can be used on the portland cement structural concrete production, replacing totally the natural sand used.

Na produção de concreto estrutural, apesar dos avanços tecnológicos, ainda se utilizam de materiais in natura, o que vem ocasionando problemas ambientais e econômicos a cadeia produtiva. Um dos problemas está associado à extração de areia do leito de rios, motivo pelo quais os profissionais envolvidos com a tecnologia do concreto vêm buscando alternativas ao uso dessa areia na produção de concreto estrutural. Uma alternativa que vem sendo estudada, pela grande disponibilidade, é o uso de uma areia produzida a partir da cominuição de rochas, chamada de areia de britagem. Na região de Caxias do Sul existem grandes reservas de rochas de origem basáltica (Riodacitos), a partir das quais é possível se produzir esse tipo de areia. Neste trabalho foi avaliada a viabilidade de se substituir à areia natural por areia de britagem de rochas basálticas produzidas em cinco empresas mineradoras localizadas na região de Caxias do Sul. O estudo foi desenvolvido em três etapas: na primeira foram avaliadas as características das areias decorrentes da mineralogia e petrografia das rochas e do processo de fabricação nas mineradoras; na segunda etapa foram avaliadas as propriedades do concreto através do método de dosagem EPUSP/IPT; na terceira etapa, para comprovar a eficiência do método de dosagem, foram produzidos traços específicos para cada tipo de areia. Os resultados de caracterização demonstraram que as areias de britagem possuem características diferentes das da areia natural e que apenas duas das cinco areias avaliadas apresentam propriedades que permitem a sua utilização em concreto estrutural. As propriedades decorrentes do processo de fabricação, como a presença de material pulverulento, forma e textura dos grãos provocaram um aumento no teor de argamassa, o que influenciou diretamente no proporcionamento dos materiais constituintes. Os resultados para a avaliação das propriedades do concreto demonstraram que, para um mesmo traço, a resistência a compressão axial e o módulo de elasticidade são menores nos concretos produzidos com areias de britagem. Corrigindo-se os teores de argamassa e produzindo-se traços específicos para cada tipo de areia é possível produzir concretos com resistências desejadas. Apesar das diferenças encontradas nas propriedades das areias foi comprovado que as areias de britagem estudadas podem ser utilizadas na produção de concreto estrutural de cimento Portland, substituindo totalmente à areia natural. / Despite the technological advances on the structural concrete production, in natura materials are still used. This fact has been causing environmental and economic problems to the manufacturing chain. One of the problems is related to the sand extraction from riverbeds, this is the reason why professionals involved with concrete technology are searching for alternatives to the use of this type of sand in the structural concrete manufacturing. One alternative that is being studied in various parts of the country, because its large availability is a sand produced from the rocks´ comminution, called crushing sand. In the Caxias do Sul region there are large reservations of basaltic rocks origin (Riodacitos), from which it is possible to produce this type of sand. In this work, it was evaluated the feasibility of substitute natural sand for crushing sand from basaltic rocks produced in five mining companies located at Caxias do Sul region. The study was developed in three stages: on the first one, the features of the sand that arises from rocks´ mineralogy and petrography and from the mining manufacturing process were evaluated; on the second the concrete properties through the EPUSP/IPT dosage method were evaluated; on the third they were produced specific trace to each type of sand in order to verify the efficiency of the dosage method. The characterization results established that the crushing sand have different features IF compared with natural sand and that Just two out of Five evaluated sands presented properties that allow its use in structural concrete. The properties arising from the fabrication process, for example the presence of powder material, the grains´ shape and texture caused the raise of the plaster content, which influenced directly on the constituents materials proportioning. The results of the concrete properties evaluation showed that, for the same trace, the resistance to axial compression and the elasticity module are smaller in the concretes produced with crushing sand. If the plaster content is corrected and the specific traces are produced for each type of sand it is possible to produce concretes with desired resistance. In spite of the differences found on the sand properties it was proven that the crushing sand produced at the Caxias do Sul region can be used on the portland cement structural concrete production, replacing totally the natural sand used.

Thesis (MEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Sedimentation and the effects it has on turbine blades was the primary problem identified in run-of-river (RoR) hydropower schemes. Sedimentation in RoR hydropower schemes also increases trash rack blockage and reduces energy output in the long-term. Damage occurs to all underwater parts that come into contact with sediment. The main concern is sediment passing through the hydropower intake and causing turbine damage. The reason for the abrasion and cavitation of turbine blades is increased sediment loads in river channels. This problem can be overcome in two ways. The first is the use of existing lakes or reservoir storage upstream as natural sand traps, and the second is by investigating the three features associated with river bend diversion, which are: the optimum diversion location in a river bend to minimise the abstraction of sediment, the optimum diversion structure angle to limit coarse sediment diversion, and the sediment load diverted through the intake. The first objective of the research was investigated by construction of a physical model of a curved river channel to determine the location of the deepest scour forming on the outside of the bend. The second objective was to test the diversion orientation to maximize the local scour and thereby limiting sediment diversion at the intake. A third objective was to compare mathematical 2D model simulated scour results with the findings of the laboratory tests to evaluate the reliability of the numerical model predictions. Finally different diverted discharge ratios were tested with different intake setups in the physical model, to evaluate the sediment load diverted. . The first experiment in the curved laboratory channel was to predict where the deepest scour takes place without a diversion structure. This was then followed by placing a diversion structure at the maximum scour position, retrieved from experiment one, and by angling the structure with reference to the flow direction. The flow direction vector was placed as a tangent to the bend and orientated at angles of 0⁰, 30⁰, 45⁰ and 60⁰ into the bend direction. The optimum diversion location was found to be positioned on the outside of the bend, approximately 60⁰ into the channel bend. The final position of maximum scour in a 90⁰ bend corresponds with the Sediment Committee and the Chinese Hydraulic Engineering Societies (1992) prediction of 60⁰ into the bend. The optimal diversion had a 30⁰ angle to the flow direction, as this presented the most efficient and effective scouring in front of the model intake. Numerical simulations were performed with the CCHE 2D (hydrodynamics and sediment dynamics) modelling program. The numerical results were compared to the physical results to validate CCHE as a beneficial simulation tool. It was found that the numerical model predicted the scour depths at the intakes tested with an accuracy of 43.8%, which is within the accuracy range of the sediment transport equation used by the numerical model. The final experiment was the diversion of sediment with different intake level heights and discharges. It was evident from the results that low sediment diversion ratios were achieved with a diverted discharge ratio of 50% or less. The intake elevation highest above the channel bed diverted the least sediment. The interrelationship between Diverted Discharge Ratio (DDR), Diverted Froude number Ratio (DFrR) and Diverted Sediment load Ratio (SDR) was established in the study. It is recommended that RoR schemes have sand traps downstream of the diversion structures and that turbines are coated with HVOF to overcome the power loss arising due to the excessive erosion of hydro turbines. / AFRIKAANSE OPSOMMING: Sedimentasie en die invloed wat dit het op turbines was die primêre probleem geïdentifiseer in “run-of-river” (RoR) hidrokrag-skemas. Die sediment wat saam met die water uit ‟n rivier uitgekeer word beskadig die inlaatrooster en verlaag kragopwekking in die langtermyn. Skade word aangerig aan alle onderwatertoerusting en masjinerie wat aan sediment blootgestel word. Die grootste probleem tydens die uitkering van water is die growwe sediment wat daarmee deur die onttrekking inlaat gaan en turbineskade veroorsaak. Soos wat die sedimentlading in die rivier drasties toeneem, sal afslyting en kavitasie van turbinelemme meer gereeld voorkom. Dié probleem kan op twee maniere beperk word. Die een is die gebruik van bestaande opgaardamme stroomop, en die tweede is deur die ondersoek van drie kenmerke van rivierdraaie en uitkeringstrukture, bv. die optimale uitskurings posisie in 'n rivierdraai (sonder ʼn struktuur) om die diepste uitskuringposisie op die buitekant van die draai te bepaal, die optimale uitkeringsstruktuuroriëntasie wat maksimum uitskuring verseker en die sediment uitkering beperk, en die lading van sedimentonttrekking deur die inlaat. Die eerste doelwit van die navorsing is ondersoek deur ʼn fisiese model te bou van ʼn kronkelkanaal en te bepaal waar die diepste uitskring plaasvind op die buitekant van die draai. Die tweede doelwit van die studie was om die optimale uitkeringshoek te bepaal vir 'n uitkeringstruktuur sodat die uitskuring by die inlaat ʼn maksimum is om die uitkering van sediment te beperk. ʼn Derde doelwit was om die akkuraatheid van ʼn wiskundige model se uitskuring voorspelling te toets teen die waargenome laboratorium resultate. Die finale doelwit was om vir verskillende inlaatontwerpe, rivier- en uitkeervloeie die sedimentladings wat uitgekeer word te ondersoek. Die eerste eksperiment in die kronkelende kanaal was voorberei om die optimale uitskuring in die draai te bepaal. Dit is gevolg deur toetse met uitkeerstrukture by die maksimum uitskurings posisie te plaas en die hoek van die struktuur dan te verander met verwysing na die vloeirigting. Die vloeirigting vektor was as 'n raaklyn geplaas op die kanaal draai en georiënteer met hoeke: 0⁰, 30⁰, 45⁰ en 60⁰, in die rigting van die draai. Die optimale uitskurings posisie was aan die buiterand van die kanaal draai gevind, ongeveer 60⁰ in die draai in. Die maksimum uitskuur posisie van 'n 90⁰ kanaal draai stem ooreen met SC en CHES (1992) se resultaat van 60⁰ in die draai in. Daar was ook genoegsame bewyse dat 'n optimale uitkeerwerke oriëntasie van 30⁰ die doeltreffendste en effektiefste uitskuring sal gee. Numeriese simulasies is deur middel van 'n twee dimensionele wiskundige model CCHE 2D (hidro- en sedimentdinamika) uitgevoer. Die numeriese resultate was vergelyk met die laboratoriumresultate om die CCHE program te verifieer as 'n voordelige simulasie program. Daar is gevind dat die wiskundige model die uitskuurdieptes by die inlate met ʼn akkuraatheid van 43.8 % voorspel, wat binne die akkuraatheid is van die sedimentvervoervergelyking wat deur die numeriese model gebruik word. Die finale eksperiment was die uitkering van sediment met verskillende inlaathoogtes en uitkerings sedimentladings. Uit die toetse was dit duidelik dat 'n lae sediment uitkeerverhouding behaal kan word met 'n uitkeerverhouding van 50% en minder. Verdere waarnemings het ook gewys dat die inlaathoogte van die uitkeerstruktuur met die optimale resultate die hoogste bokant die rivierbedding was. Die verwantskap tussen die uitgekeerde deurstromingverhouding, die uitgekeerde Froude getal verhouding en die uitgekeerde sedimentlading is bepaal in die navorsing. Dit word aanbeveel dat sandvangkanale stroomaf van uitkeerwerke geplaas word en dat turbines met HVOF as bedekkingsmateriaal beskerm word om kragverliese as gevolg van buitensporige erosie van die turbines te voorkom.

Characterising the geochemistry and speciation of major contaminant radionuclides is crucial in order to understand their behaviour and migration in complex environmental systems. Organic complexing agents used in nuclear decontamination have been found to enhance migration of radionuclides at contaminated sites; however, the mechanisms of the interactions in complex environments are poorly understood. In this work, radionuclide speciation and sorption behaviour were investigated in order to identify interactions between four key radionuclides with different oxidation states (Cs(I) and Sr(II) as important fission products; Th(IV) and U(VI) as representative actinides), three anthropogenic organic complexing agents with different denticities (EDTA, NTA and picolinic acid as common co-contaminants), and natural sand (as simple environmental solid phase). A UV spectrophotometric and an IC method were developed to monitor the behaviour of EDTA, NTA and picolinic acid in the later experiments. The optimised methods were simple, applied widely-available instrumentation and achieved the necessary analytical figures of merit to allow a compound specific determination over variable background levels of DOC and in the presence of natural cations, anions and radionuclides. The effect of the ligands on the solubility of the radionuclides was studied using a natural sand matrix and pure silica for comparison of anions, cations and organic carbon. In the silica system, the presence of EDTA, NTA and, to a lesser extent, picolinic acid, showed a clear net effect of increasing Th and U solubility. Conversely, in the sand system, the sorption of Th and U was kinetically controlled and radionuclide complexation by the ligands enhanced the rate of sorption, by a mechanism identified as metal exchange with matrix metals. Experiments in which excess EDTA, NTA and picolinic acid (40 – 100 fold excess) were pre-equilibrated with Th and U prior to contact with the sand, to allow a greater degree of radionuclide complex formation, resulted in enhanced rates of sorption. This confirmed that the radionuclide complexes interacted with the sand surface more readily than uncomplexed Th or U. Overall this shows that Th and U mobility would be lowered in this natural sand by the presence of organic co-contaminants. In contrast, the complexation of Sr with the complexing agents was rapid and the effect of the ligands was observed as a net increase on Sr solubility (EDTA, picolinic acid) or sorption (NTA). As expected, Cs did not interact with the ligands, and showed rapid sorption kinetics. Finally, ESI-MS was used to study competitive interactions in the aqueous Th-Mn-ligand ternary system. Quantification presented a challenge, however, the careful approach taken to determine the signal correction allowed the competitive interactions between Mn and Th for EDTA to be studied semi-quantitatively. In an EDTA limited system, Th displaced Mn from the EDTA complex, even in the presence of a higher Mn concentration, which was consistent with the higher stability constant of the Th-EDTA complex.

Submitted by Mariana Dornelles Vargas (marianadv) on 2015-05-29T17:53:11Z No. of bitstreams: 1 analise_influencia.pdf: 4201896 bytes, checksum: 5bde8b1b65dd35cc811456f73f745be3 (MD5) / Made available in DSpace on 2015-05-29T17:53:11Z (GMT). No. of bitstreams: 1 analise_influencia.pdf: 4201896 bytes, checksum: 5bde8b1b65dd35cc811456f73f745be3 (MD5) Previous issue date: 2011-04-29 / FINEP - Financiadora de Estudos e Projetos / UNISINOS - Universidade do Vale do Rio dos Sinos / A construção civil é um setor industrial que provoca elevado impacto ambiental, devido ao grande consumo de matéria-prima. Em função da crescente restrição da extração de areias dos rios e a escassez de areias naturais, com conseqüente elevação de seu custo, a utilização de areia proveniente da britagem de rochas na construção civil tem se tornado cada vez mais comum nos grandes centros urbanos. A utilização deste tipo de areia, fazendo-se uso de procedimentos e equipamentos adequados, pode ser uma alternativa viável para substituição da areia proveniente dos depósitos aluvionares de rios na produção de argamassas de revestimento de alvenarias. Este estudo apresenta e discute as características tecnológicas de três tipos de agregados miúdos com diferentes formas de grãos: uma areia de leito de rio (areia aluvionar) e duas areias de britagem de rocha basáltica, produzidas através de diferentes britadores, e avalia o comportamento de argamassas produzidas com estas areias. As diferenças entre os processos de obtenção resultam em diferenças na distribuição granulométrica, forma e textura superficial dos grãos, alterando o comportamento de argamassas fabricadas com estes agregados. As propriedades de uma argamassa de cimento, cal e areia dosada para a areia de rio foram comparadas com argamassas com o mesmo traço, substituindo-se a areia de rio pelos outros agregados miúdos, e o mesmo procedimento foi realizado para diferentes teores de adição de fíler à argamassa. Utilizou-se cimento CP II Z? 32 e cal CH-I, sendo produzidas vinte misturas de argamassas, oito com areia de britagem passante pelo britador VSI, quatro com areia de britagem passante pelo britador de mandíbulas e oito com areia de rio, no traço de volume em cimento, cal e areia, 1:1:6, com índice de consistência fixado em 260mm + 5mm na mesa de consistência. As propriedades determinadas no estado fresco são o índice de consistência, a reologia (squezze flow e penetração de cone), o teor de ar incorporado, a retenção de água e a densidade de massa. Foram determinadas a densidade de massa, a resistência à compressão e à tração na flexão, a absorção de água por capilaridade, o coeficiente de capilaridade, a absorção de água total, o índice de vazios, a massa específica real, a retração linear e o módulo de elasticidade dinâmico no estado endurecido. Para os ensaios em revestimentos foram utilizados substratos com dois diferentes teores de absorção de água, sendo determinada a resistência de aderência do revestimento e o grau de fissuração. Observou-se diferenças expressivas no comportamento das argamassas confeccionadas com os diferentes agregados, como: perda de trabalhabilidade; perda de densidade de massa; redução da resistência à compressão e da resistência à tração na flexão; diminuição do módulo de elasticidade dinâmico; aumento da absorção de água por imersão; aumento do índice de vazios; e aumento da massa específica. Em função das diferenças morfológicas e das diferenças no teor de fíler na mistura. / The construction industry causes high environmental impact due to large consumption of raw materials. Due to the restriction of sand extraction and the reduction of natural sand, with a consequent increase in cost, the use of crushed fine aggregates in construction has become increasingly common in large urban centers. The use of crushed fine aggregates made with appropriate procedures and equipments can be an alternative to replace the sand extracted of rivers for the production of rendering mortars. This paper discusses the technical characteristics of three different aggregates with distinct morphologies: the natural sand (alluvial sand) and two basalt crushed fine aggregates, produced by different crushers, and evaluate the behavior of mortars produced from these sands. Differences in particle size, shape and surface texture of the grains changes the behavior of mortars made with this aggregates. The properties of a reference mortar made with river sand was compared with others, replacing the river sand aggregate by crushed aggregates, and the same procedure was performed for different levels of addition of fillers in the mortar. Brazilian CP II Z-32 cement and CH-I lime were used for production of twenty mortars: eight with VSI crushed aggregates, four with jaw crushed sand mortars and eight with natural sand. The 1: 1: 6 (cement, lime and sand by volume) proportion was adopted, with consistency index of 260mm±5mm on the consistency table. Properties measured in the fresh state were consistency index, workability (by squezze-flow and cone penetration), air content, water retention and density. On the hardened state, density, compressive strength, flexural strength, capillarity water absorption, water absorption, shrinkage and modulus of elasticity were determined. Rendering mortar were applied over two substrates with different water absorption, determining bond strength and cracking. There were observed significant differences in the behavior of mortars made with different aggregates, as loss of workability and of density, reduction of compressive and flexural strength, decreasing of modulus of elasticity, increasing of absorption and density.