The current study therefore aims to provide a comprehensive characterisation of weathered dry disposed ash cores, to reveal mobility patterns of chemical species as a function of depth and age of ash, with a view to assessing the potential environmental impacts. Fifty-nine samples were taken from 3 drilled cores obtained respectively from the 1 year, 8 year and 20-year-old sections of sequentially dumped, weathered, dry disposed ash in an ash dump site at Tutuka - a South African coal burning power station.

The Western Australian (WA) mining industry directly employs approximately 56,000 people. Almost half work Fly-in/Fly-out commute arrangements (FIFO, e.g. employees living in a city are flown to a remote worksite where they live and work during their work roster) and approximately half work more than 50 hours per week, on average. There are many anecdotal claims that FIFO has negative impacts on WA mining employees, leading to an elevated risk of high stress levels, depression, binge drinking, recreational drug use and relationship break-ups. Previous studies found FIFO can be stressful, and have negative impacts on WA employees 'and partners' lifestyles and relationships. This project investigated the long-term (Study One) and short-term (Study Two) impacts of FIFO and extended working hours on a representative sample of WA FIFO mining employees and partners. In Study One, a total of 222 FIFO and Daily Commute (DC) mining employees and partners completed an anonymous questionnaire investigating long-term impacts on work satisfaction, lifestyle, relationships and health. A subgroup of 32 Study One FIFO employees and partners also participated in Study Two; a detailed study of the short-term impacts of FIFO and extended working hours and how these impacts fluctuate in intensity during the mining roster. Study Two participants completed a diary and provided saliva samples each day throughout a complete mining roster. The main findings of the study were that FIFO and extended working hours had negative impacts on employees work satisfaction and FIFO was frequently reported to be disruptive to employees 'and partners' lifestyle, in the long-term. However, FIFO and extended working hours did not lead to poor quality relationships, high stress levels or poor health, on average in the long-term; there were generally no significant differences in these characteristics between FIFO and DC employees, or between the FIFO sample and the wider community. There were minor differences between FIFO and DC employees in long-term health characteristics, and Study One employees had similar, or in some cases poorer health outcomes than other community samples.

Philosophiae Doctor - PhD / The management and disposal of huge volumes of coal combustion by products such as fly ash has constituted a major challenge to the environment. In most cases due to the inadequate alternative use of coal fly ash, the discarded waste is stored in holding ponds, slag heaps, or stock piled in ash dumps. This practice has raised concerns on the prospect of inorganic metals release to the surface and groundwater in the vicinity of the ash dump. Acceptable scientific studies are lacking to determine the best ash disposal practices. Moreover, knowledge about the mobility patterns of inorganic species as a function of mineralogical association or pH susceptibility of the dry disposed ash dump under natural weathering conditions are scarce in the literature. Fundamental understanding of chemical interactions of dry disposed ash with ingressed CO2 from atmosphere, percolating rain water and brine irrigation within ash disposal sites were seen as key areas requiring investigation. The mineralogical association of inorganic species in the dry disposed ash cores can be identified and quantified. This would provide a basis for understanding of chemical weathering, mineralogical transformations or mobility patterns of these inorganic species in the dry ash disposal scenario. The current study therefore aims to provide a comprehensive characterisation of weathered dry disposed ash cores, to reveal mobility patterns of chemical species as a function of depth and age of ash, with a view to assessing the potential environmental impacts. Fifty-nine samples were taken from 3 drilled cores obtained respectively from the 1 year, 8 year and 20-year-old sections of sequentially dumped, weathered, dry disposed ash in an ash dump site at Tutuka - a South African coal burning power station. The core samples were characterized using standard analytical procedures viz: X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier transforms infrared (FTIR) techniques, Scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) and Acid neutralisation capacity (ANC) test. A modified sequential extraction (SE) method was used in this study. The chemical partitioning, mobility and weathering patterns in 1 year, 8 year and 20-year-old sections of the ash dump were respectively investigated using this modified sequential extraction scheme. The sequence of the extractions was as follows: (1) water soluble, (2) exchangeable, (3) carbonate, (4) iron and manganese and (5) residual. The results obtained from the 5 steps sequential extraction scheme were validated with the total metal content of the original sample using mass balance method. The distribution of major and trace elements in the different liquid fractions obtained after each step of sequential extraction of the 59 drilled core samples was determined by inductively coupled plasma mass spectrometry (ICPMS). The data generated for various ash core samples were explored for the systematic analysis of mineralogical transformation and change in ash chemistry with ageing of the ash. Furthermore, the data was analyzed to reveal the impact of ingressed CO2 from atmosphere, infiltrating rain water and brine irrigation on the chemistry of ash core samples. Major mineral phases in original ash core samples prior to extraction are quartz (SiO2) and mullite (Al2O3·2SiO2). Other minor mineral phases identified were hematite (Fe2O3), calcite (CaCO3), lime (CaO), anorthite (CaAl2Si2O8), mica (Ca (Mg, Al)3 (Al3Si) O10 (OH)2), and enstatite (Mg2Si2O6). X-ray diffraction results show significant loss of crystallinity in the older ash cores. The presence of minor phases of calcite and mica in dry disposed ash cores are attributed to reduction in the pore water pH due to hydration, carbonation and pozzolanic reactions. The X-ray diffraction technique was unable to detect Fe-oxyhydroxide phase and morealuminosilicate phases in ash core samples due to their low abundance and amorphous character. X-ray fluorescence results of the original ash core samples showed the presence of major oxides, such as SiO2, Al2O3, Fe2O3, while CaO, K2O, TiO2, Na2O, MnO, MgO, P2O5, and SO3 occur in minor concentrations. The ratio of SiO2/Al2O3 classified the original core samples prior to extraction as a silico-aluminate class F fly ash. The ternary plot of major elements in 1-year-old ash core samples was both sialic and ferrocalsialic but 8 year and 20-year-old ash core samples were sialic in chemical composition. It is noteworthy that the mass % of SiO2 varies through the depth of the core with an increase of nearly 3 %, to 58 mass % of SiO2 at a depth of 6 m in the 1-year-old core whereas in the case of the 8-year-old core a 2 % increase of SiO2 to a level of 57.5 mass % can be observed at levels between 4-8 m, showing dissolution of major components in the matrix of older ash cores.. The Na2O content of the Tutuka ash cores was low and varied between 0.6-1.1 mass % for 1-year-old ash cores to around 0.6-0.8 mass % for 8-year-old ash cores. Sodium levels were higher in 1-year-old ash cores compared to 8 year and 20-year-old ashcores. Observed trends indicate that quick weathering of the ash (within a year) leached out Na+ from the ash dump. No evidence of Na+ encapsulation even though the ash dump was brine irrigated. Thus the dry disposal ash placement method does not result in a sustainable salt sink for Na-containing species over time. The total content of each of the elements in 1 year and 20-year-old ash cores was normalised with their total content in fresh ash from same power station to show enrichment and depletion factor. Major elements such as K+, Mn showed enrichment in 1-year-old ash cores whereas Al, Si, Na+, Ti, Ca, Mg, S and Fe showed depletion due to over time erosion. Trace elements such as Cr, Sr, P, Ba, Pb, V and Zn showed enrichment but Ni, Y, Zr showed depletion attributed to over time erosion. In 20-year-old ash cores, major elements such as Al, Na+ and Mn showed enrichment while Si, K+, Fe, Mg and Ca showed depletion highlighting their mobility. Trends indicated intensive flushing of major soluble components such as buffering constituents (CaO) by percolating rain water. The 1-year-old and 20-year-old coal ash cores showed a lower pH and greater loss/depletion of the soluble buffering constituents than the 2-week-old placed ash, indicating significant chemical weathering within a year. Based on ANC results the leaching behaviours of Ca, Mg, Na+, K+, Se, Cr, and Sr were found to be controlled by the pH of the leachant indicating high mobility of major soluble species in the ash cores when in contact with slightly acid rain water. Other investigated toxic metals such as As, Mo and Pb showed amphoteric behaviour with respect to the pH of the leachant. Chemical alterations and formation of transient minor secondary mineral phases was found to have a significant effect on the acid susceptibility and depletion pattern of chemical species in the core ash samples when compared to fresh ash. These ANC results correlated well with the data generated from the sequential extraction scheme. Based on sequential extraction results elements, showed noticeable mobility in the water soluble, exchangeable and carbonate fractions due to adsorption and desorption caused by variations in the pore water pH. In contrast, slight mobility of elements in the Fe and Mn, and residual fractions of dry disposed fly ashes are attributed to the co-precipitation and dissolution of minor amount of less soluble secondary phase overtime. The 1-year-old dry disposed ash cores were the least weathered among the 3 drilled ash cores. Therefore low concentration of toxic metals in older ash cores were ascribed to extensive weathering with slower release from residual mineral phases over time. Elements were found to associate with different mineral phases depending on the age or depth of the core samples showing greater heterogeneity in dispersion. For instance the average amount of total calcium in different mineral associations of 1-year-old ash cores is as follows; water soluble (10.2 %), exchangeable (37.04 %), carbonate (37.9 %), Fe and Mn (7.1 %) and residual (2.97 %). The amount of total Na+ in different mineral phases of 1-year-old ash cores followed this trend: water soluble (21 %), exchangeable (11.26 %), carbonate (2.6 %), Fe and Mn (4.7 %) and residual (53.9 %). The non-leachable portion of the total Na+ content (namely that contained in the residual fraction) in the 1-year-old ash core samples under conditions found in nature ranged between 5-91 %. This non-leachable portion of the Na+ showed the metastability of the mineral phases with which residual Na+ associates. Results showed older ash cores are enriched in toxic elements. Toxic elements such as As, B, Cr, Mo and Pb are enriched in the residual fraction of older ash cores. For instance As concentration in the residual fraction varied between 0.0003- 0.00043 mg kg-1 for 1-year-old ash cores to around 0.0003-0.0015 mg kg-1 for 20-year-old ash cores. This suggests that the older ash is enriched in toxic elements hence dust from the ash dump would be toxic to human health. The knowledge of mobility and ecotoxicological significance of coal fly ash is needed when considering its disposal or reuse in the environment. The mobility and ecotoxicology of inorganic metals in coal fly ash are determined by (i) mineralogical associations of inorganic species (ii) in-homogeneity in the ash dumps (iii) long and short term exposure to ingress CO2 and percolating rain water. Management issues such as inconsistent placement of ash in the dumps, poor choice of ash dump site, in-homogeneity in brine irrigation, no record of salt load put on the ash dumps and lack of proper monitoring requires improvement. The thesis provides justification for the use of the modified sequential extraction scheme as a predictive tool and could be employed in a similar research work. This thesis also proved that the dry ash disposal method was not environmental friendly in terms of overall leaching potential after significant chemical weathering. Moreover the study proved that the practice of brine co-disposal or irrigation on ash dumps is not sustainable as the ash dump did not act as a salt sink. / South Africa

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

The disses thesis is focused on usage of secondary raw materials from the electric power industry, specifically fly ash as a component for the building industry, concentrated on concrete. Two main streams are covered, environmental and economical. Reasons, which led to focus on the selected subject are coming mainly from the scarcity and availability of high-quality mineral resources, environmental pressure for usage of industry byproduct, reducing emissions and economical pressure to reduce production cost, especially raw materials. The main purpose of the work was to verify the possibility of increasing the usability of fly ash as a mineral additive in the technology of concrete production with materials retrieved from coal fired power plants and applying mechanical activation of fly ash. The main goal of the experimental part of work was to demonstrate improvement of fresh and hardened concrete properties as a main condition to support economic efficiency of mechanical activated fly ash. Base on previous facts the methodology was covering two main areas, the experimental and the assessment. Relatively large sets of tests were performed, using a wide range of tested high temperature fly ash and fluidized bed combustion fly ash granulometrically treated, by mixing and grinding. Results of the testing confirmed focused parameters for concrete and mortar mechanical properties, total economical efficiency of the targeted solution and the subject of the dissertation. In the experiment section has been retrieved valuable findings contributing to the overall knowledge of the faculty, also for the practical application. The results of the tests confirmed the achievement of the planned target parameters, both in terms of physical and mechanical properties of experienced mortars and concretes, as well as the overall economic efficiency of the proposed design and the topic of the disses thesis. Within the experimental work, valuable professional knowledge and benefits w

Thesis (MScAgric (Soil Science))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: Acidic soils are a major limitation to agriculture worldwide. The Highveld in South Africa has many acidic soils and several coal burning power stations. These coal burning power stations generate alkaline fly ash as a waste material and it can thus serve as an ameliorant to the surrounding acidic soils. A two year field trial was undertaken to compare fly ash and other calcium ameliorants to alleviate the effects of subsoil acidity on maize root development. The field trail was established on Beestepan Farm in Middelburg, Mpumalanga. It consisted of 24 treatments, each done in triplicate, rendering a total of 72 plots. The materials used were unweathered fly ash (CCE 10%), calcitic lime (CCE 77%) and Calmasil (a calcium silicate slag, CCE 99%). Calmasil and lime were applied at rates of 0-, 1-, 2-, and 4t/ha, while fly ash was applied at 0-, 7-, 14- and 28t/ha. These treatments were applied to an acidic sandy loam soils in the presence or absence of 4t/ha gypsum. Beans were harvested after the first season following the application of amendments and maize was harvested in the second season. Yield, root length, leaf and soil analysis was undertaken to evaluate the effectiveness of the different liming materials. The effect of the treatments on fertility indicators such as pH, exchangeable acidity, Ca and Mg was investigated. Results indicated that all liming materials increased topsoil pH, soil nutrient and base status and crop yield in both seasons. Calmasil was the superior liming material in all respects. Fly ash increased pH minimally but reduced exchangeable acidity by 12% and 24% in the first and second seasons, respectively. Fly ash increased topsoil Ca levels from 74 to 102mg/kg and subsoil Ca from 61 to 114mg/kg. Topsoil Mg levels were increased from 7.3 to 16mg/kg and subsoil Mg was increased from 9.4 to 13mg/kg. The consequence of these increased nutrients was the subsequent increased foliar uptake of Ca and Mg. The substantial increase in bean yield from 958 to 1724kg/ha and maize yield from 5569 to 7553kg/ha following ash application compared well with results obtained from lime and Calmasil application. This may partly be due to the presence of additional plant nutrients such as P and K in the fly ash. Dissolution behaviour of fly ash indicates that upon exposure to acidity the release of micronutrients like B, Co, Cu, Fe, Mo, Mn and Zn occurs, and preliminary data shows that there is comparatively little concern regarding heavy metal accumulation in crops. The application of 4t/ha gypsum had no effect on pH and decreased subsoil acidity only minimally however, subsoil Ca status and acid saturation levels were considerably improved which would possibly account for the overall beneficial effect on maize yield, increasing by an average of 1071kg/ha. It was not possible to make any conclusions relating treatment application and maize root length. This field trial has confirmed that fly ash can be used as an efficient liming material and that it compares well with traditional liming materials. / AFRIKAANSE OPSOMMING: Suurgronde is ‘n groot beperking tot landbou wêreldwyd. Die Suid Afrikaanse Hoëveld het menigte suurgronde en verskeie steenkool-aangedrewe kragstasies. Hiedie kragstasies produseer alkaliese vliegas as ‘n afvalproduk. Hierdie vliegas kan dus dien as ‘n grondverbeteringsmiddel vir die aangrensende suurgronde. ‘n Tweejarige veldproef was onderneem om vliegas met ander kalsium-bevattende grondverbetereringsmiddels te vergelyk om die effek van ondergrondse suurheid op mielies op te hef. Hierdie veldproef was opgeset te Beestepan plaas in Middelburg, Mpumalanga. Dit het bestaan uit 24 behandelings wat drie keer herhaal was en lewer dus ‘n totaal van 72 persele. Die kalkmateriale wat gebruik was, is onverweerde vliegas (KKE 10%), kalsitiese kalk (KKE 77%) en Calmasil (‘n kalsium silikaat slak, KKE 99%). Calmasil en kalk was toegedien teen 0-, 1-, 2-, en 4t/ha, en vliegas teen 0-, 7-, 14- en 28t/ha. Hierdie behandelinge was toegedien tot ‘n suur leemsand met of sonder gips. Gips was toegedien teen 4t/ha. Een jaar nadat behandelinge toegedien was, is boontjies geoes en mieles was die daaropvolgende jaar geoes. Opbrengs, wortel lengte blaar- en grondontledings was uitgevoer om effektiwiteit te evalueer. Die effek van die behandelinge op indikatore van grondvrugbaarheid soos pH, uitruilbare suurheid, Ca en Mg was ondersoek. Resultate dui daarop dat alle kalkmateriale die grond se voedingstof- en basisstatus, bogrond pH asook gewasopbreng verhoog het. Calmasil was die beste kalkmateriaal in alle opsigte. Vliegas het die pH minimaal verhoog, terwyl dit die uitruilbare suurheid verminder het met 12% en 24% in die eerste en tweede jaar onderskeidelik. Vliegas het bogrond Ca vlakke vanaf 74 tot 102mg/kg vermeer, sowel as ondergrond Ca vanaf 61 tot 114mg/kg. Bogrond Mg was vermeer vanaf 7.3 tot 16mg/kg, asook ondergrond Mg vanaf 9.4 tot 13 mg/kg. Die gevolg van hierdie verhoogde voedingstowwe was die toename van Ca en Mg in die blare van die gewasse. Die beduidende toename in opbrengste van boontjies vanaf 958 tot 1724mg/kg en mielies vanaf 5569 tot 7553kg/ha na die toediening van vliegas vergelyk goed met die resultate van kalk en Calmasil. Dit is gedeeltelik toe te skryf aan die teenwoordigheid van addisionele plantvoedingstowwe soos P en K in vliegas. Oplossingstudies van vliegas dui op die teenwoordigheid van mikrovoedingstowwe soos B, Co, Cu, Fe, Mo, Mn en Zn. Aanvanklike data wys dat daar relatief min kommer oor swaarmetaal akkumulasie in gewasse is. Alhoewel 4t/ha gips geen effek op pH gehad het nie, en ondergondrondse suurheid minimaal verminder het, het ondergrondse Ca en gevolglik suurversadiging heelwat verbeter. Dit mag moontlik as verduideliking dien vir die oorhoofse voordelige effek van gips op mielie opbrengste, wat verhoog het met ‘n gemiddelde 1071kg/ha. Oorvleuende omstandighede het daartoe gelei dat geen konkrete afleidings gemaak kon word oor die wortel lengte van die mielies nie. Hierdie veldproef bevestig dat vliegas as ‘n effektiewe kalkmateriaal gebruik kan word en goed vergelyk met tradisionele kalkmateriale.

Des recherches d'extensions ont été entreprises sur les anciens travaux (10e siècle) du gisement D'imiter (Djebel Sarho - Anti Atlas - Maroc). Les minéralisations s'inscrivent dans deux séries précambriennes. (1) Une série du P II de type flysh à caractère de turbidites distales avec bancs de schistes pyriteux et coulées andésitiques interstratifiées, affectée d'un plissement isoclinal N 80° - 800N, et légèrement métamorphisée par l'intrusion de deux massifs granodioritiques tardi P II. (2) Une série du P II-III de type f lysh grossier débutant par 15 mètres de tufs et reposant en discordance sur la série précédente (N 50° 30°N). Des dykes de roches filoniennes (keratophyres et andésites) recoupent les séries P II et P II-III. Un complexe volcanique P III se trouve en contact faillé avec le P II et le P II -III au Nord du domaine minier. Les corps minéralisés à faciès en stockwerks, alignés sur des directions E-W montrent un contrôle structural net par deux directions EW et NS. Dans les schistes du P II, les bancs pyriteux exercent un contrôle chimique de type fahlbande sur l'enrichissement de colonnes minéralisées. Les principaux minéraux de la paragénèse sont : Sidérite, quartz, dolomite, oxydes de fer, wads, galène, blende, pyrite, chalcopyrite, mispickel, argent natif amalgamé à du mercure, freibergite, tétraédrite, cérusite, argentite. Les caractères d'oxydation et de cémentation ressortent. Une étude géochimique statistique montre l'existence d'une zonalité et d'associations entre éléments accompagnateurs relevant de processus hypogènes ou supergènes. Aucune hypothèse génétique (lien avec la granodiorite, avec les dykes, reconcentrations à partir des sédiments) ne s'applique au gisement que l'on rattachera au type II de Monsieur Pelissonnier, avec éventuel passage à la Bi, Co, Ni, et au type 12.

[pt] A gestão dos Resíduos Sólidos Urbanos (RSU) e seu consequente reaproveitamento ou não é um problema existente no Brasil e no mundo. No Brasil, a produção de energia mediante incineração de RSU ainda está na sua etapa inicial, como por exemplo, com a implantação da Usina Verde no campus da UFRJ, com a consequente produção de subprodutos, como as cinzas volante e de fundo. Este estudo apresenta o comportamento de um solo coluvionar argiloso estabilizado com cinzas de RSU sob carregamento estático, tendo como principal objetivo avaliar a influência destas cinzas misturadas com o solo para possíveis aplicações em obras geotécnicas. Para isso foram realizados ensaios de caracterização física, química e mecânica, como ensaios de compactação Proctor Normal e ensaios triaxiais consolidados isotropicamente drenados (CID), para o solo puro e misturas solo-cinza. Foram avaliadas as influências do teor de cinzas (20 por cento, 30 por cento e 40 por cento de cinza volante e de cinza de fundo), bem como do tempo de cura (30 e 60 dias). Os resultados mostram que todas as misturas solo-cinza apresentam melhores parâmetros de resistência, em comparação do solo puro, onde as misturas solo-cinza volante apresentaram melhores resultados quando comparadas às misturas solo-cinza de fundo. A variação de teor de cinza adicionado ao solo, sem cura, mostra que para maiores teores de cinza volante a coesão diminui e ocorre o contrário com a cinza de fundo. Com relação ao tempo de cura, na maioria dos casos houve melhora do comportamento das misturas solo-cinza em comparação ao obtido sem cura. O teor de cinza (volante ou de fundo), tempo de cura e a tensão de confinamento influenciam na deformação volumétrica das misturas solo-cinza, apresentando menores deformações volumétricas para maiores teores de cinza e maiores tempos de cura. As misturas com 40 por cento de cinza volante e 30 por cento de cinza de fundo apresentaram as melhores características de resistência e poderiam ser utilizadas como estabilizante no solo estudado, cumprindo exigências geotécnicas e ambientais, além de rebaixar os custos de obra e dar um destino mais nobre para as cinzas de RSU. / [en] Management of Municipal Solid Waste (MSW) and its subsequent reuse or not is an existing problem in Brazil and the world. In Brazil, the production of energy through incineration of MSW is still in its initial stage, for example, with the implementation of Usina Verde on campus at UFRJ, with the consequent production of byproducts, such as fly and bottom ashes. This study presents the behavior of a colluvial clayey soil stabilized with ashes from MSW under static load, with the main objective to evaluate the influence of these ashes mixed with the soil for possible applications in geotechnical works. For this characterization were performed physical, chemical and mechanical tests, as Proctor compaction tests Normal isotropically consolidated and drained triaxial (CID) for the pure and soil-ash mixtures. Were evaluated the influence of the ash content (20 per cent, 30 per cent and 40 per cent fly ash and botton ash) and of curing time (30 and 60 days). The results show that all mixtures soil-ash have better shear strength compared to the pure soil, where the soil- fly ash mixtures showed better results compared to mixtures of soil- bottom ash. The variation of the ash content added to the soil, without curing, shows that higher levels of ash the cohesion decrease and the opposite occurs with the bottom ash. Respect to the curing time, in most cases there was as improvement of the behavior of mixtures soil-ash compared to that obtained without curing. The ash content (fly or bottom), curing time and confinement stress influence the volumetric deformation to soil-ash mixtures, showed lower volumetric deformations to higher concentrations of ash and longer curing times. The mixtures with 40 per cent fly ash and 30 per cent bottom ash, showed the best characteristics of strength and could be used as stabilizer in the studied soil, compliance requirements geotechnical and environmental, in addition to lower labor costs and give a nobler destiny for the ashes of MSW.

The work is focused on the possibilities of using FBC fly ash for composite cements, monitoring their hydration processes, especially the creation of AFt phase. The possibility of preparing synthetic ettringite and thaumasite and their detection.

[pt] Este estudo apresenta o comportamento de um solo arenoso estabilizado com cinzas obtidas através da incineração de Resíduo Sólido Urbano (RSU) e cal. Através de um estudo experimental, objetiva-se avaliar a aplicabilidade de misturas solo-cinza e solo-cinza volante-cal em obras geotécnicas como, por exemplo, camadas de aterros sanitários, aterros sobre solos moles e estabilização de taludes. Para isso, foram realizados ensaios de caracterização física, química e mecânica (ensaios triaxiais CID) para os materiais envolvidos. Para as misturas solo-cinza volante-cal, adicionou-se 3 porcento de cal em substituição ao peso seco das cinzas. Foram avaliadas as influências do teor de cinza (30 e 40 porcento) e tipo de cinza (volante - CV e fundo - CF), bem como o tempo de cura (0, 60 e 90 dias) para misturas com cinza volante e cal. Os resultados mostram que tanto as misturas com CV, como CF, apresentam resultados satisfatórios. Para ambas as cinzas, as porcentagens de 30 e 40 porcento apresentaram resultados similares, podendo-se adotar o valor de 40 porcento como teor ótimo, uma vez que proporciona a utilização de uma maior quantidade de resíduo. Comparando-se as cinzas, a CF apresentou resultados mais satisfatórios que a CV. Para as misturas com cura, observou-se que no tempo de 60 dias o material sofreu um maior ganho de resistência. Foram utilizados dois métodos de moldagem de corpo de prova para o ensaio com cura, obtendo-se melhor resultado para o método onde a cura era realizada em um corpo de prova pré-moldado. Portanto o uso das cinzas de RSU em mistura com este tipo de solo se mostra satisfatório, uma vez que apresentou um bom comportamento, contribui com o menor consumo de material natural e proporciona uma destinação ambientalmente correta deste resíduo. / [en] This study presents the behavior of a sandy soil stabilized with municipal solid waste ash, and lime. In order to evaluate the applicability of mixtures soil-ash and soil-fly ash-lime for using in geotechnical projects as layers of landfills, embankment on soft soils and slope stability, an experimental campaign is presented. Thus, physical, chemical and mechanical (isotropically consolidated-drained triaxial test) characterization tests were performed for each material and mixtures. It was used 3 percent of lime in the mixtures soil- fly ash-lime, being added in replacement to the dry weight of fly ash. Were evaluated the influence of ash content (30 and 40 percent), type of ash (fly ash and bottom ash) and curing time (0, 60 and 90 days) for mixtures containing fly ash and lime. The results have shown that mixtures with both kinds of ashes present a satisfactory behavior, increasing or maintaining the shear strength parameters similar to the pure material. For both kinds of ashes the variation of the content has not provided significant changes in the strength parameters, therefore, 40 percent can be considered as best content, once it provides a bigger destination of the residue. Comparing fly and bottom ash, the last has presented better results than fly ash. For mixtures with lime and cure, it has been observed better results for 60 days of cure, with greater gain of strength. Two molding methods have been used for preparing the mixture specimen, being obtained a better result with pre modeled specimen. Therefore, the use of municipal solid waste ash for stabilizing this kind of soil for using in the cited works, could minimize the current problems of waste disposal, contribute with the reduction of consumption of natural resources and give a noble use for this material.