Efeitos do tratamento superficial da sílica ativa com soluções de ácidos nítrico e fosfórico em propriedades do concreto

The addition of active silica potentially improves the quality of concrete due to its high reactivity and pore refinement effect. The reactivity of silica is likely related to its charge density. Variations in surface charge alter the reactivity of the material consequently affecting the properties of concrete. The present study aimed at investigating variations in the charge density of silica as a function of acid treatments using nitric or phosphoric acid and different pH values (2.0, 4.0 and 6.0). Effects on concrete properties including slump, mechanical strength, permeability and chloride corrosion were evaluated. To that end, a statistical analysis was carried out and empirical models that correlate studied parameters (pH, acid and cement) with concrete properties were established. The quality of the models was tested by variance analysis. The results revealed that the addition of silica was efficiency in improving the properties of concrete, especially the electrochemical parameters. The addition of silica treated using nitric acid at pH = 4.0 displayed the best cement performance including highest strength, reduced permeability and lowest corrosion current

Efeito da adição de fibras da palma do licuri (syagrus coronata) no comportamento físico e mecânico de compósitos de matriz cimentícia

This research was motivated by the requirement of asbestos s replacement in building systems and the need to generate jobs and income in the country side of the state of Bahia, Brazil. The project aimed at using fibers from licuri leaves (syagrus coronata), an abundant palm in the region, to produce composites appropriate for the sustainable production of cement fibre reinforced products in small plants. The composites were produced in laboratory using Portland cement CP-II-F32, sand, water, licuri palm fiber contents of 1.0, 1.5 and 2.0% by weight of binder (two different fiber length) and metakaolin. The latter was chosen as an additional binder for its efficiency to reduce the alkalinity of cementitious matrixes therefore preventing the degradation of vegetable fibers. The characterization of the composite components was carried out by sieving and laser particle size analyses, thermal analysis, fluorescence and X-ray diffraction. The composites performance was evaluated by 3- point-bending tests, compressive strength, ultrasound module of elasticity, free and restrained shrinkage, water capillarity absorption and apparent specific gravity. It has been found that the addition of fibers increased the time to onset of cracking over 200.00% and a 25% reduction in cracks opening in the restrained shrinkage test. The capillary absorption reduced about 25% when compared to fiber-free composites. It was also observed with regard to flexural strength, compressive strength and specific gravity, that the addiction of fibers did not affect the composite performance presenting similar results for compounds with and without fibers. In general it can be stated that the reinforced composite fibers of palm licuri presents physical and mechanical characteristics which enable them to be used in the intended proposals of this research

Avaliação da incorporação combinada dos resíduos de cascalho de perfuração de poço de petróleo e de polimento do porcelanato em cerâmica vermelha

Among the industries, those that produce ceramic porcelain for use in construction industry and oil, during the exploration and production period, play an important role in the production of waste. Much research has been carried out both by academia and the productive sector, sometimes reintroducing them in the same production line that generated them, sometimes in areas unrelated to their generation, as in the production of concrete and mortar for the construction, for example, but each one in an isolated way. In this research, the aim is to study the combined incorporation of the waste drill cuttings of oil well and the residue of the polishing of porcelain, generated in the final stage of finishing of this product in a clay matrix, for the production of red pottery, specifically bricks, ceramic blocks and tiles. The clay comes from the municipality of São Gonçalo, RN, the drilling waste is from the Natal basin, in Rio Grande do Norte, and the residue of the polishing proceeds from a ceramic porcelain of the State of Paraíba. For this purpose, we used a mixture of a plastic clay with a non-plastic, in a ratio of 50% each, settling formulations with the addition of these two residues in this clay matrix. In the formulations, both residues were incorporated with a minimum percentage of 2.5% and maximum of 12.5%, varying from 2.5% each, in each formulation, which the sum of the waste be no more than 15%. It should be noted that the residue of the polishing of ceramic porcelain is a IIa class (not inert). The materials were characterized by XRF, XRD, TG, DTA, laser granulometry and the plasticity index. The technological properties of water absorption, apparent porosity, linear shrinkage of burning, flexural tensile strength and bulk density were evaluated after the sintering of the pieces to 850 °C, 950 °C and 1050 °C, with a burning time of 3 hr, 3 hr and 30 minutes, and 3 hr and 50 minutes, respectively, with a heating rate of 10 °C/minute, for all formulations and landing of 30 minutes. To better understand the influence of each residue and temperature on the evaluated properties, we used the factorial planning and its surfaces of response for the interpretation of the results. It was found that the temperature has no statistical significance at a 95% of reliability level in flexural tensile strength and that it decreases the water absorption and the porosity, but increases the shrinkage and the bulk density. The results showed the feasibility of the desired incorporation, but adjusting the temperature to each product and formulation, and that the temperatures of 850 °C and 950 °C were the one that responded to the largest number of formulations

Estudo do resíduo fosfogesso na formulação de uma pasta para revestimento interno de edifícios

Universidade Federal do Rio Grande do Norte

Influência da substituição de areia natural por pó de pedra no comportamento mecânico, microestrutural e eletroquímico de concretos

The construction industry is one of the largest consumers of natural raw materials, and concrete is considered today the most used material wide. This accentuated consumption of natural resources has generated concern with the preservation of the environment, and has motivated various studies related to the use of resid ues, which can partially or entirely substitute, with satisfactory performance, some materials such as the aggregate, and in so doing, decrease the impact on the environment caused by the produced residues. Research has been done to better understand and improve the microstructure of concrete, as well as to understand the mechanism of corrosion in reinforced steel. In this context, this work was developed aiming at discovering the influence of the substitution of natural sand by artificial sand, with rega rd to mechanical resistance, microstructure, and durability. To obtain the electrochemical parameters, an adaptation was made to the galvanostatic electrochemical method to study the corrosion in reinforced steel. Concretes of categories 20 MPa and 40 MPa were produced, containing natural sand, and concretes of the same categories were produced with artificial sand substituting the natural sand, and with the addition of sodium nitrate and sodium chloride. Due to the use of rock dust reject (artificial sand), an evaluation was made of its environmental risk. The results indicate that the concretes of category 20 MPa present a better performance than the concrete made with natural sand, thus making it a viable substitute. For the category 40 MPa, the better performance is from the concrete containing natural sand. The adaptation of the galvanostatic electrochemical technique to the study of the corrosion of reinforced steel within concrete proved to be valid for obtaining electrochemical parameters with a high degree of reliability, considering the number of degrees of freedom

Desenvolvimento de sistemas de aditivos químicos para aplicação em cimentações de poços de petróleo

The primary cementing is an important step in the oilwell drilling process, ensuring the mechanical stability of the well and the hydraulic isolation between casing and formation. For slurries to meet the requirements for application in a certain well, some care in the project should be taken into account to obtain a cement paste with the proper composition. In most cases, it is necessary to add chemicals to the cement to modify its properties, according to the operation conditions and thus obtain slurries that can move inside the jacket providing a good displacement to the interest area. New technologies of preparation and use of chemicals and modernization of technological standards in the construction industry have resulted in the development of new chemical additives for optimizing the properties of building materials. Products such as polycarboxylate superplasticizers provide improved fluidity and cohesion of the cement grains, in addition to improving the dispersion with respect to slurries without additives. This study aimed at adapting chemical additives used in civil construction to be used use in oilwell cement slurries systems, using Portland cement CPP-Special Class as the hydraulic binder. The chemical additives classified as defoamer, dispersant, fluid loss controller and retarder were characterized by infrared absorption spectroscopy, thermogravimetric analyses and technological tests set by the API (American Petroleum Institute). These additives showed satisfactory results for its application in cement slurries systems for oil wells. The silicone-based defoamer promoted the reduction of air bubbles incorporated during the stirring of the slurries. The dispersant significantly reduced the rheological parameters of the systems studied. The tests performed with the fluid loss controller and the retarder also resulted in suitable properties for application as chemical additives in cement slurries

Desenvolvimento de pastas cimentantes utilizando cimentos portland compostos para cimentação de poços petrolíferos

The Compound Portland cements are commonly used in construction, among them stand out the CPII-Z, CPII-F and CPIV. These types of cement have limited application on oil well cementing, having its compositional characteristics focused specifically to construction, as cement for use in oil wells has greater complexity and properties covering the specific needs for each well to be coated. For operations of oil wells cementing are used Portland cements designed specifically for this purpose. The American Petroleum Institute (API) classifies cements into classes designated by letters A to J. In the petroleum industry, often it is used Class G cement, which is cement that meets all requirements needed for cement from classes A to E. According to the scenario described above, this paper aims to present a credible alternative to apply the compound cements in the oil industry due to the large availability of this cement in relation to oil well cements. The cements were micro structurally characterized by XRF, XRD and SEM tests, both in its anhydrous and hydrated state. Later technological tests were conducted to determine the limits set by the NBR 9831. Among the compound cements studied, the CPII-Z showed satisfactory properties for use in primary and secondary operations of oil wells up to 1200 meters cementing

Efeito da adição de cargas minerais leves na resistência mecânica de grautes para cimentação de poços offshore

The preparation of cement slurries for offshore well cementing involves mixing all solid components to be added to the mixing water on the platform. The aim of this work was to study the formulation of pre-prepared dry mixtures, or grouts, for offshore oilwell cementing. The addition of mineral fillers in the strength of lightweight grouts applied for depths down to 400 m under water depths of 500 m was investigated. Lightweight materials and fine aggregates were selected. For the choice of starting materials, a study of the pozzolanic activity of low-cost fillers such as porcelain tile residue, microsilica and diatomaceous earth was carried out by X-ray diffraction and mechanical strength tests. Hardened grouts containing porcelain tile residue and microsilica depicted high strength at early ages. Based on such preliminary investigation, a study of the mechanical strength of grouts with density 1.74 g/cm3 (14.5 lb/gal) cured initially at 27 °C was performed using cement, microsilica, porcelain tile residue and an anti-foaming agent. The results showed that the mixture containing 7% of porcelain tile residue and 7% of microsilica was the one with the highest compressive strength after curing for 24 hours. This composition was chosen to be studied and adapted for offshore conditions based on testes performed at 4 °C. The grout containing cement, 7% of porcelain tile residue, 7% of active silica and admixtures (CaCl2), anti-foaming and dispersant resulted satisfactory rheology and mechanical strength after curing for 24 hours of curing

Educação tecnológica e pré-sal: necessidades e urgências

The purpose of this dissertation is whether the demand for manpower trained in technical school for the sector of Oil and Gas (O&G) is in balance with the offer of that training in the Brazilian education system. The methodology used to obtain such information was based on School Census 2000 and 2008 where data were worked out in order to clarify the numbers of enrollments in secondary technical level demanded by the sector of O&G. The demand for manpower with that qualification as a data source was the 2010-2014 Business Plan Program for Mobilization of the National Oil and Natural Gas (PROMINP). This Program identified the future demand for manpower for the Sector of the O&G until 2014 where the occupational categories are mapped prerequisite training and experience. In order to better understand the object of this study was dome a review of the literature with regard to technical education in Brazil but also the importance of the education to economic growth and the peculiarities of the oil economy in different countries possessors of those mines, or that is, developed and underdeveloped countries. Analysis showed that enrollment in technical education in Brazil had a significant increase between the dates 2000 and 2008. It also don´t bring balance with the characteristic of the dynamics of the productive sectors of the economy mainly due to heating of the economy before the global growth especially in the Construction Industry as well as in the Oil and Natural Gas Engineering and a Naval account of the discovery of oil in the Pre-Salt. Another important aspect is that one of the major problems of qualification of manpower in Brazil is due to a bad quality of the student´s school and high school which makes difficult a good performance in office work and also this ability to learn new functions. The rapprochement between the supply of the education system and the demand for manpower with training mid-level technical support for the sector O&G showed that most technical courses demanded or had no enrollment in 2008, had few enrollment in 15 states with demand expect to occur and those enrollment were unevenly distributed among states. The analysis therefore signalize the needed of a public policy that enables the adequacy of the education system (Secondary Technical Education) to Sector of O&G in terms of enrollment and its distribution between the oil producing states and in relation to technical expertise offered

Educação tecnológica e pré-sal: necessidades e urgências

O objetivo desta dissertação de mestrado é verificar se a demanda de mão-de-obra com formação no ensino médio técnico para o setor de Petróleo e Gás (P&G) está em consonância com a oferta daquela formação no sistema educacional brasileiro. A metodologia aplicada para obter tal informação foi baseada no Censo Escolar 2000 e 2008, em que os dados foram trabalhados de maneira a explicitar o número de matrículas nos cursos de nível médio técnico, demandados pelo setor de P&G. A demanda de mão-de-obra com aquela qualificação teve como fonte de dados o Plano de Negócios 2010-2014 do Programa de Mobilização da Indústria Nacional de Petróleo e Gás Natural (PROMINP). Este Programa identificou a demanda futura de mão-de-obra para o setor de P&G até 2014, onde as categorias ocupacionais mapeadas possuem pré-requisitos de formação e experiência. Com o intuito de entender melhor o objeto deste estudo foi feita uma revisão de literatura no que diz respeito ao ensino técnico no Brasil, como também a importância da educação para o crescimento econômico e as peculiaridades da economia do petróleo nos diferentes países possuidores daquelas jazidas, ou seja, países subdesenvolvidos e desenvolvidos. As análises demonstraram que as matrículas no ensino técnico no Brasil apresentaram um significativo aumento entre as datas de 2000 a 2008. Traz também como característica a desarmonia com a dinâmica dos setores produtivos da economia, devido principalmente ao aquecimento da economia antes da crise mundial de 2008, e a retomada recente do crescimento notadamente no Setor de Construção Civil, bem como no setor de Petróleo e Gás Natural e Engenharia Naval por conta da descoberta de petróleo na camada Pré-sal. Outro aspecto relevante é que um dos grandes problemas da qualificação de mão-de-obra no Brasil se deve a má qualidade do ensino fundamental e médio, que dificulta para o futuro profissional um bom desempenho nas suas funções laborais e na capacidade de aprender novas funções. A aproximação entre a oferta no sistema educacional e a demanda de mão-de-obra com a formação de nível médio técnico para o setor de P&G, demonstraram que a maioria dos cursos técnicos demandados não apresentava matrículas em 2008, ou possuíam poucas matrículas nos 15 estados com demanda prevista, e aquelas matrículas estavam mal distribuídas entre os estados. A análise aponta para a necessidade de uma política pública que possibilite a adequação do sistema educacional (Ensino Médio Técnico) ao setor de P&G, tanto no que se refere ao número de matrículas e a sua distribuição entre os estados produtores de petróleo quanto no que se refere à especialidade técnica oferecida

O Cariri cearense: da ocupação do território à institucionalização da região metropolitana do Cariri

Urbanization in their mearing simpler, the agglomeration of people, occurred from the time that the productive activities have to be based on trade. The first cities arose when the evolution of agriculture allowed the production and storage of surpluses. However, with industrialization was that urbanization becomes intense, according to Singer (1987), the industrial revolution was to stage, from the beginning, the urban area. It requires, in its proximity, the presence of a large number of workers. With respect to the Cariri cearense, the occupation of its territory is associated with the movement of agricultural surpluses produced and reproduced under the hegemony of merchant capital and due to the development of extensive cattle that promoted the territorial occupation of Ceará. From the 1960s, the region has undergone changes in its productive structure due to industrial planning policies of the government of Ceará. However it was in the 1990s that the region itself as economic and urban polo because policies to attract investments from the state government of Ceará. This policy led to boosting trade and services marking the predominance of tertiary activities in the region, especially the retail, wholesale , medical services and education. Investments also consolidated the industrial park area making it diverse, especially the footwear industries, mining, non-metallic minerals, transport equipment, pharmaceutical chemical, food and beverages, rubber and leather and construction. Thus, the aim of this study was to review the region of Cariri cearense occupation of its territory institutionalizing its metropolitan region, to understand what factors influenced the Cariri cearense become an important area in urban and economic terms in the interior of Ceará. In order to develop this research in that refers to the methodological perspective, research is guided by bibliographic studies and also makes use of secondary data analysis (population, GDP, urbanization rate, employment) of the main databases the country, as IBGE, IPEADATA and RAIS - MTE

Avaliação de concreto com adição de fibras de PET submetido a altas temperaturas

The concrete for centuries constituted an essential structural element in the construction industry due to its relative ease of forming, before the weather durability, low cost, its lower maintenance compared to other materials such as steel. However, when the concrete is exposed to high temperatures tends to lose its mechanical characteristics, and may even result in loss of section, which undermines the stability and mechanical strength of structural elements. The pathologies resulting from exposure to elevated temperatures ranging from cracks, pops up chipping explosives (spalling). Recently, the technology of concrete is closely related to the study of its microstructure. The use of fibers added to concrete has been revealed as a solution to increase the mechanical strength of the concrete, it acts directly on the distribution of efforts to act in the play within the microstructure. In this work we used recycled PET fibers embedded in concrete with 15x2mm fck = 30MPa, water/cement ratio of 0.46, in works made for verification of mechanical strength of this mixture submitted to high temperature. The specimens of concrete with addition of PET fibers were tested after exposure to temperatures: ambient (30ºC), 100°C, 200°C, 300°C, 400°C, 600°C and 900°C. It was found that the concrete loses significant strength when exposed to temperatures above 300°C, however the use of fiber PET may delay the risk of collapse of structures for the formation of a network of channels that facilitate the escape of vapor 'water, reducing the pore pressure inside the structural element

Avaliação do concreto de cimento portland com resíduo da produção de scheelita em substituição ao agregado miúdo

From the 70`s, with the publication of the Manifesto for Environment UN Conference, held in Stockholm, in Sweden (1972), defend and improve the environment became part of our daily lives. Thus, several studies have emerged in several segments in order to reuse the waste. Some examples of waste incorporated in portland cement concrete are: rice husk ash, bagasse ash of cane sugar, powder-stone, microsilica, tire rubber, among others. This research used the residue of the mining industry Scheelite, to evaluate the incorporation of the residue composition of Portland cement concrete, replacing the natural sand. The percentage of residue were incorporated from 0% to 100%, with a variation of 10%, 11 being produced concrete mix in the ratio 1:2:3:0.60, by mass. We evaluated the following characteristics of concrete: slump test, compressive strength, tensile strength by diametral compression, water absorption, porosity and density, based on the ABNT, through tests performed in the Laboratory of Civil Construction, UFRN. The trace with the addition of 60% scheelite residue was obtained which better performance. Therefore, the use of the waste from the production of Scheelite is feasible due to the durability parameters (water absorption and porosity), sustainability, and the good results of the resistance of the concrete

Estudo da viabilidade da utilização de cinza de lodo de esgoto como adição em argamassa de cimento Portland

The use of sewage sludge as a raw material falls within the waste recycling key in the current process model environmental sustainability .Waste recycling has been consolidated as a sustainable environmentally sound technical solution, and. Despite showing very variable composition and characteristics, sewage sludge, can be considered as a residue with a high recycling potential in the building sector. In this paper the feasibility of using sewage sludge ash was studied in addition to Portland cement mortar in 1:3 mass considered the standard dash. This gray additions were studied in proportions of 5%, 10 %, 15 %, 20 %, 25% and 30% by mass of cement. The methodology was focused on the characterization of materials by physical, chemical , mechanical , environmental and morphological followed by the production of mortar tests ,and finalized by the characterization tests of mortar in the fresh state, through the consistency index, content of entrained air, bulk density and water retention, and in the hardened state by bulk density, water absorption by capillarity capillarity coefficient, compressive strength, tensile strength in bending ,tensile bond strength and microstructural analysis for percentages of 0 to 20%. After comparing with the standard mortar mortars with addition of ash, it is concluded that the ash of sewage sludge did not impair the integrity and properties of mortars with addition, including increasing resistance to compression and tension, being 20% more indicated percentage. Thus, it becomes feasible the addition of sewage sludge ash in Portland cement mortar for the trait studied

Qualidade em obras públicas: um estudo comparativo entre as metodologias Seis Sigma, ISO 9000 e PBQP-H no RN

In Brazil the theme quality in public construction has been widely discussed in the early 1990s, with the creation of the Brazilian Program of Quality and Productivity for the Habitat (PBQP-H) which is strongly influenced by the wave of studies on issues of quality in the world, such as the ISO 9000. Over the years, other approaches have emerged and been consolidated, evolving from market and customer´s needs. An example is the Six Sigma methodology. This study aims to examine the Six Sigma, ISO 9000 and PBQP-H methodologies, noting the common elements, differences, gaps and how the methods are complementary, so that with the ongoing work, proposed initiatives can be developed to improve the quality that enables its application in public construction. Still aiming to optimize the deployment of the proposed initiatives, it was performed an analysis of ISO 9001 and PBPQ-H certifications in Brazil and in the state of Rio Grande do Norte, with respect to the construction industry and a case study to identify the factors that influence the adoption of initiatives to improve quality, and check if the selected construction company is prepared to implement the proposed initiatives. This research is characterized as exploratory and applied, with literature review and a case study. The data collection instrument was a questionnaire and the statistical analysis used a multidimensional scaling method. The conclusion is that the methodologies are compatible and complementary, and their integration could potentialize the goals set. It was identified that the state of Rio Grande do Norte has a few number of certifications in construction. Nine initiatives are proposed for implementation at construction companies. In the case study it was found that the studied company would be able to implement the suggestions proposed and the requirement for certification by clients and funding institutions influence the adoption of quality improvement initiatives. This result confirms the literature which states that top management support is crucial for the successful implementation of quality methodologies