Aplicación de residuos en la fabricación de morteros industriales

La presente Tesis Doctoral estudia el uso de la fracción fina de los residuos de construcción y demolición (RCD) en la fabricación de morteros de albañilería. El principal uso de los áridos reciclados de RCD es la construcción de rellenos o firmes de carreteras, aunque su uso como áridos para la fabricación de hormigones o morteros le daría un mayor valor añadido. A nivel internacional existen numerosos estudios sobre la utilización de la fracción gruesa de los áridos reciclados de RCD en la fabricación de hormigones. Sin embargo son escasos los trabajos llevados a cabo para valorizar la fracción fina. Actualmente en España la fracción fina de los áridos reciclados de RCD está infrautilizada y en la mayoría de los casos depositada sin uso en los vertederos de las Plantas de reciclaje. En este trabajo se han utilizado dos tipos de áridos reciclados, uno procedente de residuos de hormigón (FRCA) y otro de residuos mixtos de tabiquería con un alto porcentaje de ladrillo rojo cerámico (FMRA). Todos los materiales han sido caracterizados desde un punto de vista físico, químico y mineralógico para justificar el efecto de su incorporación a la fabricación de morteros industriales de albañilería. En una primera fase se estudiaron las propiedades del mortero fresco y endurecido fabricado con FRCA y cinco niveles de sustitución volumétrica de arena natural y FRCA: 0%, 5%, 10%, 20% y 40%.Se utilizó un cemento puzolánico tipo CEM-IV y se evaluaron las propiedades a corto y largo plazo de morteros de baja resistencia (M5) En una segunda fase, se utilizó un cemento tipo CEM-II y se fabricaron morteros de mayor resistencia (M-10) utilizando FRMA. En esta etapa se llevaron a cabo sustituciones de arena natural por arena reciclada de 0%, 25%, 50%, 75% y 100%. El residuo fue evaluado medioambientalmente mediante el test de conformidad antes y después de ser ligado con cemento (lixiviación). Los resultados fueron completados con estudios de durabilidad. Con el objetivo de completar los estudios anteriores, se llevó a cabo una tercera fase, donde se sustituyó hasta un 100% de arena natural por FRCA, utilizando un cemento tipo CEM-II para fabricar un mortero tipo M-10, dosificado de manera similar al empleado en la segunda fase de este trabajo. Como conclusión general de esta tesis, se puede decir que pueden admitirse tasas de sustitución de hasta un 50% de arena natural por árido reciclado en morteros industriales de albañilería para usos de interior sin que sus propiedades puedan verse afectadas significativamente. Los resultados obtenidos contribuyen a reducir la extracción de arena natural de canteras y ríos, minimizar el consumo de energía y emisiones de CO2, mitigar el calentamiento global y evitar el depósito en vertedero de la fracción fina de RCD.

Estudo da incorporação da cal em composições binárias de solo-cimento para produção de tijolos maciços

The use of binders in the soil for the production of solid bricks is an old construction technique that has been used by several civilizations over time. At the same time, the need for environmental preservation and the tendency of scarcity of natural resources make the construction invest in researching new concepts, methods and materials for building systems for the sustainability of their economic activities. Thus arises the need to obtain building materials with low power consumption, capable of reducing the growing housing shortage of rural and urban population. Currently, research has been conducted on this topic to better understand the cementitious and pozzolanic reactions that occur in the formation of the microstructure of the soil-cement when added to other materials such as, for example, lime, and the relationship between microstructure and formed interfaces with the physical, mechanical and chemical analysis in compounds made from these ternary compositions. In this context, this study aimed to analyze the results of the influence of the incorporation of lime to the soil-cement to form a ternary mixture to produce soil-cement bricks and mortar without structural purposes. From the inclusion of contents of 6 %, 8 %, 10% and 12% lime to the soil, and soil-cement mixes in amounts of 2 %, 3 %, 4 % and 5 % were shaped-bodies of -cylindrical specimens to determine the optimum moisture content and maximum dry apparent specific weight. Then they were cured, and subjected to the tests of compressive strength, absorption and durability modified. Compositions obtained the best results in the tests performed on the bodies-of-proof cylindrical served as a parameter for molding of solid bricks, which underwent the same experimental methodology previously cited. The raw materials used, as well as compositions in which the bricks were molded solid, were characterized by physical and chemical tests, X-ray diffraction and scanning electron microscopy. The results obtained in the study indicate that the compositions studied, that showed the best results in terms of compressive strength, water absorption and durability ternary composition was soil, 10 % cement and 2 % lime

Síntese, aplicação e avaliação do efeito do teor de fósforo da celulose fosfatada em argamassa de alvenaria com aditivo comercial a base de hidroxi-etil-metil celulose (HEMC)

Generally, cellulose ethers improves mortar properties such as water retention, workability and setting time, along with adherence to the substrate. However, a major disadvantage of the addition of cellulose ethers in mortars is the delay in hydration of the cement. In this paper a cellulose phosphate (Cp) was synthesized water soluble and has been evaluated the effect of their incorporation into mortar based on Portland cement. Cellulose phosphate obtained was characterized by spectrophotometry Fourier transform infrared (FTIR), X-ray diffraction (XRD), elemental analysis and scanning electron microscopy (SEM). Mortar compositions were formulated with varying phosphorus content in cellulose and cellulose phosphate concentrations, when used in partial or total replacement of the commercial additive based hydroxyethyl methyl cellulose (HEMC). The mortars formulated with additives were prepared and characterized by: testing in the fresh state (consistency index, water retention, bulk density and air content incorporated) and in the hardened state (absorption by capillarity, density, flexural and compression strength). In mixtures the proportion of sand:cement of 1:5 (v / v) and factor a / c = 1.31 and water were held constant. Overall, the results showed that the celluloses phosphates employed in mortars added acted significantly when partially substituting the commercial additive. With regard to consistency index, water retention and bulk density in the fresh state and absorption by capillarity and bulk density apparent in the hardened state, showed no appreciable differences as compared to the commercial additive. The incorporated air content in the fresh state reduced markedly, but did not affect other properties. The mortars with cellulose phosphate, partially replacing the commercial additive showed an improvement of the properties of flexural strength and compressive strength

Bivalves marinhos do miocénio superior (Tortoniano superior) de Cacela (Algarve, Portugal)

Dissertação de mestrado em Estudos Marinhos e Costeiros, Unidade de Ciências e Tecnologias dos Recursos Aquáticos, Univ. do Algarve, 2000

Bioactive compounds of citrus as health promoters

Citrus are a group of fruit species, quite heterogeneous in many aspects, including chemical composition of the fruit. Since ancient times, some citrus fruits were used to prevent and cure human diseases. In the recent decades, it has been demonstrated that fruits can actually help prevent and cure some diseases and above all, they are essential in a balanced diet. Citrus fruits, as one of the groups of fruit species, with greater importance in the world, have been studied for their effects on human health. Some species of citrus were referred as potential antioxidant based therapy for heart disease, cancer and inflammation. Fruit peels and seeds have also high antioxidant activity. The health benefits of citrus fruit have mainly been attributed to the high level of bioactive compounds, such as phenols (e.g., flavanone glycosides, hydroxycinnamic acids), carotenoids and vitamin C. These compounds are present in the fruit pulp and hence in the juice. But some bioactive compounds can be found in parts of the fruit which usually are not used for human food. The content of bioactive compounds depends on the species and cultivar, but also depends on the production system followed in the orchard. Citrus fruits, their derivatives and their by-products (peel, pulp and oil) are reach in different bioactive compounds and its maturity, postharvest and agroindustry processes influence their composition and concentration. The aim of this chapter was to review the main bioactive compounds of the different components of citrus and their relationship to health.

Tiro de Artilharia vs. Tiro de Morteiro : Procedimentos

A presente investigação tem como objetivo identificar as diferenças existentes entre os procedimentos técnicos relativos ao tiro de Artilharia de Campanha e ao tiro de Morteiro. Tem por finalidade estudar a possibilidade de uniformização dos procedimentos, no que respeita aos procedimentos de Pontaria, cálculo dos Elementos de Tiro, Pedido e Regulação de Tiro e à Segurança, utilizados pelas unidades de tiro de Artilharia de Campanha e de Morteiro. O trabalho estuda cada tipo de procedimento, começando por enunciá-los e explicar os seus métodos, finalidade e determinação, tanto para o tiro de Artilharia de Campanha como para o tiro de Morteiro. Os procedimentos são comparados através de tabelas e sínteses, com o objetivo de analisar o porquê de serem executados da maneira prevista na doutrina, remetendo dessa forma para o estudo da sua possível padronização. Como método de recolha de dados foram submetidos inquéritos livres a oficiais subalternos de diversas unidades de formação e operacionais relacionadas com a instrução e execução do tiro de Artilharia de Campanha e de Morteiro, de forma a recolher a sua opinião sobre a viabilidade de adoção dos procedimentos e esclarecimento de dúvidas. Foram depois realizadas análises comparativas para verificar quais os procedimentos que apresentam possibilidade de uniformização. No final os procedimentos padronizáveis foram identificados e comparados com os procedimentos executados pelo Grupo de Artilharia de Campanha da Brigada de Reação Rápida, à qual pertence uma Bateria integrada na NATO Response Force 16. Sendo a única unidade orgânica a nível nacional que opera com meios de tiro de Artilharia de Campanha e de Morteiro, a sua análise foi crucial para a investigação. Dado que a finalidade do trabalho é estudar a possibilidade de adoção de procedimentos comuns, as conclusões tiveram a sua origem na análise comparativa com os procedimentos desta unidade. Verificou-se assim que os procedimentos são padronizáveis, mas que são necessárias algumas condições para que possam ser aplicados, devido às diferenças na orgânica e tática entre as unidades de tiro de Artilharia de Campanha e de Morteiro, à diferença técnica das armas e dos meios auxiliares de cálculo dos Elementos de Tiro e técnica dos dois tipos de tiro.

Optimización del pelado de maíz con cal a utilizarse como estrategia de descontaminación de fumonisinas

Objetivo: En este estudio, el proceso de pelado de maíz con cal(PPC) fue documentado y sus parámetros optimizados mediante un diseño experimental, con el fin de conseguir un pelado completo del maíz con el mínimo grado de contaminación con fumonisinas. La presencia de fumonisina B1 (FB1) en el maíz fue analizada mediante HPLC-RP-FLD. Metodología: Los experimentos se realizaron a partir de un lote de maíz en grano seco conformado por submuestras provistas por agricultores seleccionados del cantón Nabón de la provincia del Azuay en base a un trabajo de investigación previo realizado por el proyecto VLIR-IUC, “Nutrición, Alimentación y Salud”. El diseño experimental fue divido en tres etapas: la caracterización de proceso, el mismo que se realizó mediante encuestas y observaciones in situ; pruebas de agotamiento de cal para el PPC, las que se realizaron partiendo de los datos recogidos en la primera etapa, y las pruebas de evaluación del PPC en la reducción de fumonisinas B1. Resultados y conclusiones: Se observó que, independiente de la concentración de cal utilizada, la etapa de pelado produjo una reducción de 8.73 veces la concentración de FB1 del maíz crudo (P=0.030), y que el maíz pelado y cocinado presentó una reducción de 9.14 veces (P=0.019). Recomendaciones: Se recomienda continuar con la experimentación para elucidar si la reducción de FB1se debió al proceso mecánico de remoción de la cáscara, o a la transformación química en su forma hidrolizada, por lo que este trabajo podría considerarse como un estudio explorativo preliminar.

Impact of HydroPolymers on the soil biological components in mediterranean drylands

Soil degradation affects more than 52 million ha of land in counties of the European Union. This problem is particularly serious in Mediterranean areas, where the effects of anthropogenic activities (tillage on slopes, deforestation, and pasture production) add to problems caused by prolonged periods of drought and intense and irregular rainfall. Soil microbiota can be used as an indicator of the soil healthy in degraded areas. This is because soil microbiota participates in the cycle elements and in the organic matter decomposition. All this helps to the young plants establishment and in long term protect the soils against the erosion. During dry periods in the Mediterranean areas, the lack of water entering the soil matrix leads to a loss of soil microbiological activity and it turns into a lower soil production capabilities. Under these conditions, the aim of this study was to evaluate the positive effect on soil biological components produced by an hydro absorbent polymer (Terracottem). The aim of the experiment was to evaluate the impact assessment of an hydropolymer (Terracottem) on the soil biological components. An experimental flowerpot layout was established in June 2015 and 12 variants with different amount of Terracottem were applied as follow: i) 3.0 kg.m3 ; ii) 1.5 kg.m3 and; iii) 0 kg.m3. In all the variants were tested the further additives: a) 1% of glucose, b) 50 kg N.ha-1 of Mineral nitrogen, c) 1% of Glucose + 50 kg N.ha-1 of Mineral nitrogen d) control (no additive). According to natural conditions, humidity have been kept at 15% in all the variants. During four weeks, mineral nitrogen leaching and soil respiration have been measured in each flowerplot. Respiration has been quantified four times every time while moistening containers and alkaline soda lime has been used as a sorbent. The amount of CO 2 increase has been measured with the sorbent. Leaching of mineral nitrogen has been quantified by ion exchange resins (IER). IER pouches have been placed on the bottom of each container, and after completion of the experiment mineral nitrogen leaching has been evaluated by distillation and titration method. Results from respiration have shown statistically significant differences between the variants. According to control, soil with polymers have shown significant difference when comparing respiration with independence of the additive used. CO 2 production in the first week has exceeded the sum of the outputs of the following weeks. Mineral nitrogen leaching measurement has shown statistically significant differences. The lowest leaching has been occurred in control variant, while the highest in variant containing only the addition of mineral nitrogen. Research results may conclude that the biological part of the test soil is not limited by a lack of components, the only thing that suppresses its activity is the lack of moisture. After moistening it leads to a rapid growth of soil activity, without causing the nutrients loss. Besides, Terracottem has affected soil activity neither positively nor negatively, but it considers being a suitable tool for reducing the drought impact in arid and semi-arid areas.

Influência da adição de cinza do bagaço de cana calcinada em sistemas de pastas para cimentação de poços petrolíferos

Cementing operation is one of the most important stages in the oil well drilling processes and has main function to form hydraulic seal between the various permeable zones traversed by the well. However, several problems may occur with the cement sheath, either during primary cementing or during the well production period. Cements low resistance can cause fissures in the cement sheath and compromise the mechanical integrity of the annular, resulting in contamination of groundwater and producing zones. Several researches show that biomass ash, in particular, those generated by the sugarcane industry have pozzolanic activity and can be added in the composition of the cementing slurries in diverse applications, providing improvements in mechanical properties, revenue and cement durability. Due to the importance of a low cost additive that increases the mechanical properties in a well cementing operations, this study aimed to potentiate the use of sugarcane bagasse ash as pozzolanic material, evaluate the mechanisms of action of this one on cement pastes properties and apply this material in systems slurries aimed to cementing a well with 800 m depth and geothermal gradient of 1.7 °F/100 ft, as much primary cementing operations as squeeze. To do this, the ash beneficiation methods were realized through the processes of grinding, sifting and reburning (calcination) and then characterization by X-ray fluorescence, XRD, TG / DTG, specific surface area, particle size distribution by laser diffraction and mass specific. Moreover, the ash pozzolanic activity added to the cement at concentrations of 0%, 20% and 40% BWOC was evaluated by pozzolanic activity index with lime and with Portland cement. The evaluation of the pozzolanic activity by XRD, TG / DTG and compressive strength confirmed the ash reactivity and indicated that the addition of 20% in the composition of cement slurries produces improvement 34% in the mechanical properties of the slurry cured. Cement slurries properties evaluated by rheological measurements, fluid loss, free fluid, slurry sedimentation, thickening time and sonic strength (UCA) were satisfactory and showed the viability of using the sugarcane ash in cement slurries composition for well cementing

Arsenic Geochemitry in Warm Spring Ponds: New Field and Experimental Results

Silver Bow Creek (SBC) flows into the Warm Springs Ponds Operable Unit (WSPOU), where various containment cells are used to precipitate copper and other metals (e.g., Cd, Cu, Mn, Pb, Zn). Lime is added seasonally to increase the pH and assist in removal of metals from the water column. Although the WSPOU is effective at removing copper and other cationic trace metals, concentrations of dissolved arsenic exiting the facility are often above the site specific standard, 20 20 ug/L, during low-flow periods each summer and fall. This thesis is a continuation of arsenic geochemistry studies by Montana Tech in the WSPOU. Field work focused on Pond 3, the largest and first in the series of treatment ponds. Shallow groundwater was sampled from 8 PVC piezometers located near the south end of Pond 3. Three sediment pore-water diffusion samplers (“peepers”) were also deployed at the south end of Pond 3 to examine vertical gradients in chemistry in the top 25 cm of the pond sediment. In general, the pH and Eh values of the shallow groundwater and sediment pore-water were less than in the pond water. Concentrations of arsenic were generally higher in subsurface water, and tended to pass through a maximum (up to 530 g/L) about 10 cm below the sediment-water interface. In the peeper cells, there was a strong positive correlation between dissolved As and dissolved Fe, and an inverse correlation with sulfate. Therefore, the zone of arsenic release corresponds to a zone of bacterial Fe and sulfate reduction in the shallow, organic-rich sediment. Redox speciation of arsenic shows that arsenate (As(V)) is dominant in the pond, and arsenite (As(III)) is dominant in the subsurface water. A series of laboratory experiments with pH adjustment were completed using SBC water collected near the inlet to the WSPOU as well as water and shallow sediment collected from Pond 3. Water ± sediment mesocosms were set up in 1-L Nalgene bottles (closed system) or a 20-L aquarium (open system), both with continuous stirring. The pH of the mesocosm was adjusted by addition of NaOH or HNO3 acid. The closed system provided better pH control since the water was not in contact with the atmosphere, which prevented exchange of carbon dioxide. In both the closed and open systems, dissolved arsenic concentrations either decreased or stayed roughly the same with increase in pH to values > 11. Therefore, the release of dissolved As into the treatment ponds in low-flow periods is not due to changes in pH alone. All of these results support the hypothesis that the arsenic release in WSPOU is linked to microbial reduction of ferric oxide minerals in the organic-rich sediment. Upwards diffusion of dissolved As from the sediment pore-water into the pond water is the most likely explanation for the increase in As concentration of the WSPOU in low-flow periods.

An Investigation of Waste Glass-Based Geopolymers Supplemented with Alumina

An increased consideration of sustainability throughout society has resulted in a surge of research investigating sustainable alternatives to existing construction materials. A new binder system, called a geopolymer, is being investigated to supplement ordinary portland cement (OPC) concrete, which has come under scrutiny because of the CO2 emissions inherent in its production. Geopolymers are produced from the alkali activation of a powdered aluminosilicate source by an alkaline solution, which results in a dense three-dimensional matrix of tetrahedrally linked aluminosilicates. Geopolymers have shown great potential as a building construction material, offering similar mechanical and durability properties to OPC. Additionally, geopolymers have the added value of a considerably smaller carbon footprint than OPC. This research considered the compressive strength, microstructure and composition of geopolymers made from two types of waste glass with varying aluminum contents. Waste glass shows great potential for mainstream use in geopolymers due to its chemical and physical homogeneity as well as its high content of amorphous silica, which could eliminate the need for sodium silicate. However, the lack of aluminum is thought to negatively affect the mechanical performance and alkali stability of the geopolymer system. Mortars were designed using various combinations of glass and metakaolin or fly ash to supplement the aluminum in the system. Mortar made from the high-Al glass (12% Al2O3) reached over 10,000 psi at six months. Mortar made from the low-Al glass (<1% Al2O3) did not perform as well and remained sticky even after several weeks of curing, most likely due to the lack of Al which is believed to cause hardening in geopolymers. A moderate metakaolin replacement (25-38% by mass) was found to positively affect the compressive strength of mortars made with either type of glass. Though the microstructure of the mortar was quite indicative of mechanical performance, composition was also found to be important. The initial stoichiometry of the bulk mixture was maintained fairly closely, especially in mixtures made with fine glass. This research has shown that glass has great potential for use in geopolymers, when care is given to consider the compositional and physical properties of the glass in mixture design.

Influência de polímeros superabsorventes na retracção de argamassas

Hoje em dia, o desenvolvimento dos superplastificantes permite a produção de betões com menor razão água/cimento. Ao usar razões água/cimento mais baixas, os materiais científicos apresentam maior tendência para fissurar devido à retracção autogénea. Este trabalho apresenta um estudo sobre a utilização de polímeros superabsorventes (SAP) no controlo da retracção. O uso de SAPs em materiais comentícios atenua a retracção autogénea pois estes produtos permitem o fornecimento interno de água. Estes produtos podem também afectar outras propriedades, afectando as características mecânicas e a trabalhabilidade. Para análise do efeito dos SAP foram estudadas argamassas com várias concentrações deste produto, tendo como referência argamassas semelhantes sem SAP, determinando-se as retracções autogénea e total, a resistência à compressão e o módulo de elasticidade. Além de SAP, foi também utilizado um agregado leve, um outro tipo de introdutor de água, para comparação com os polímeros em estudo. /ABSTRACT: This work presents a study on the use of superabsorbent polymers (SAP) in the control of shrinkage. The use of SAPs in cementitious materials reduces the autogenous shrinkage because these products enable the internal supply of water. These materials can also affect other properties such as mechanical properties and workability. To analyze the effect of SAP, mortars containing various concentrations of this product were studied, in comparison with reference mortars without SAP. The tests performed were autogenous and total shrinkage, compressive strength and modulus of elasticity. Besides SAP, it was also used a lightweight aggregate, another type of internal supply of water, for comparison with the polymers under study.

Novos desenvolvimentos para a deteção de leveduras e bactérias presentes em argamassas

The development of simple and rapid new approaches for analysing microbial communities colonising Cultural Heritage materials is pivotal for its safeguard. Fluorescence in situ hybridisation technique using ribosomal RNA directed probes (RNA-FISH) has demonstrated a great potential for this purpose. A protocol for analysing filamentous fungi in mortars has been already developed in previous studies. In this work this protocol has been adapted for detecting bacteria and yeasts. Good results have been obtained for the analysis of suspensions of isolates. In this way, the optimized protocol was applied in microsamples from synthetic mortar artificially inoculated with yeast and bacterial isolates. Promising results have been obtained for the ex situ analysis of yeast and bacteria thriving in mortar microsamples.

Lacunae Infills for in Situ Treatment of Historic Glazed Tiles

Knowledge of current conservation materials and methods together with those adopted in the past is essential to aid research and improve or develop better conservation options. The infill and painting of tile lacunae are subjected to special requirements mainly when used in outdoor settings. A selection of the most commonly used materials was undertaken and performed based on inquiries to practitioners working in the field. The infill pastes comprised organic (epoxy, polyester), inorganic (slaked lime,hydraulic lime and zinc hydroxychloride) and mixed organic–inorganic (slaked lime mixed with a vinylic resin)binders. The selected aggregates were those most commonly used or those already present in the commercially formulated products. The infill pastes were characterised by SEM, MIP, open porosity, water absorption by capillarity, water vapour permeability, thermal and hydric expansibilities and adhesion to the ceramic body. Their performance was assessed after curing, artificial ageing (salt ageing and UV–Temp–RH cycles) and natural ageing. The results were interpreted in terms of their significance as indicators of effectiveness, compatibility and durability