Programa de Pós-Graduação em Engenharia Civil
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Master Thesis Propriedades de concretos leves autoadensáveis com agregados leves artificiais produzidos a partir da calcinação de resíduos agroindustrial e de mineração(Universidade Federal do Rio Grande do Norte, 2020-10-29) Sousa, Jemima Tabita Ferreira de; Anjos, Marcos Alyssandro Soares dos; ; http://lattes.cnpq.br/3904325866154130; ; http://lattes.cnpq.br/4264366967034668; Amorim, Enio Fernandes; ; http://lattes.cnpq.br/3436413268425331; Gomes, Valtencir Lúcio de Lima; ; http://lattes.cnpq.br/3252979522453088Self-compacting concrete (SCC) is an important example of new technology and alternative to the use of conventional concrete. The rheological parameters demonstrated by this type of concrete, provide high fluidity and cohesion that results in the ability to fill and resistance to segregation, as well as optimize concrete processes and reducing labor costs. Currently, due to the lack of resistant soil to support loads of buildings in urban agglomerations, studies have been carried out in search of possibilities that result in a lower weight for the structure, as well as ease of transportation, execution and thermoacoustic properties. The self-compacting lightweight concrete (SCLC) then emerges as a possible alternative for grouping the benefits of SCC and structural lightweight concrete (SLC). In the production of these concretes, the lightweight aggregate most used in the world and in Brazil is still an expanded clay, with its national production concentrated in the Southeast Region. In this context, studies carried out by Leal de Souza (2019) and Souza (2019), verified the viability of producing lightweight aggregates from the sintering of industrial residues and regional raw materials (Rio Grande do Norte/Brazil), as waste from sugar cane biomass ash (SCBA), scheelite residue (RPS) and local clays. In view of the above, the present study listed some of the lightweight aggregates that were developed by Leal de Souza (2019) and Souza (2019), and analyzed their influence on the composition of self-compacting lightweight concretes, investigating their efficiency and behavior in comparison with SCLC produced with commercial lightweight aggregate. The concretes were subjected to characterization tests in the fresh state, where the properties of fluidity, apparent viscosity, visual stability and passing ability were evaluated, through slump flow tests, flow time (t500), visual stability index and J-ring, respectively, and measurement of fresh density. In the hardened state, tests were performed to determine the mechanical properties, with the compressive strength test at 7 and 28 days, with the measurement of the dry density for each age, and the durability parameters through the diffusion of chloride ions. The results obtained showed the viability of producing selfcompacting lightweight concrete with unconventional lightweight aggregates. Both in the fresh and in the hardened state, all mixtures met the requirements established in the standard, with final density ranging between 1.94 to 2.03 g/cm³ and compressive strength at 28 days between 36.72 to 26.11 MPa. The mixtures with lightweight aggregates of SCBA showed a constant performance and similar to the performance of concrete with commercial lightweight aggregate, demonstrating to be a promising material for use in self-compacting lightweight concretes. Still, it was found that the physical properties of the lightweight aggregates influenced the results obtained in the fresh and hardened state, making the lightweight aggregate the main responsible for limiting and influencing the properties of the concretes.Master Thesis Avaliação da degradação de um geotêxtil tecido submetido ao intemperismo do ambiente costeiro em Natal/RN(Universidade Federal do Rio Grande do Norte, 2020-10-30) Santos, Ewerton Weynemi Cavalcante dos; França, Fagner Alexandre Nunes de; Medeiros, José Ivan de; ; http://lattes.cnpq.br/0875521131771417; ; http://lattes.cnpq.br/6854485206744906; ; http://lattes.cnpq.br/4802317754099845; Amorim, Enio Fernandes; ; http://lattes.cnpq.br/3436413268425331; Portelinha, Fernando Henrique Martins; ; http://lattes.cnpq.br/0791082339645058The number of cases of maritime works and coastal protection using geosynthetics has increased. Systems that use geosynthetic materials in conjunction with filler materials, usually sand, are often used to prevent and control coastal erosion. The type of geosynthetic most used in these systems is geotextile. The coastal environment has as main aggressive agents UV radiation and salinity of sea water. The durability and properties of the material, after exposure to weathering in oceanic environments, need to be known for more accurate designing. In hydraulic works, tensile strength is one of the most important properties to be guaranteed. This research analyzed the degradation of a woven geotextile submitted to the weathering of the coastal environment in Natal / RN comparing values of tensile tests before and after exposure. The samples were exposure for a period of up to three months. The samples were exposed in four different situations and interactions: on a wooden plate, on sand, on sand immersed in sea water, and only immersed in sea water. In order to assess the effects of degradation, the geotextile samples were subjected to breaking force and elongation of textile fabrics test, according to ASTM D5035. The analysis of the results consisted of comparing the values of tensile strength and deformation at break obtained from the virgin samples and the exposed samples, considering the mean value and the time of exposure. The results found show that, for the analyzed period, there was no significant degradation of the polypropylene woven geotextile and that the different exposure situations did not present great divergences in the results.Master Thesis Efeitos das elevadas temperaturas em concretos autoadensáveis com altos teores de resíduo da biomassa da cana-de-açúcar e metacaulim(2019-07-29) Mello, Larissa Cavalcante de Araújo; Anjos, Marcos Alyssandro Soares dos; Almeida, Maria das Vitorias Vieira; ; ; ; Lucena, Luciana de Figueiredo Lopes; ; Souza, Wendell Rossine Medeiros de;The fines added to the self-compacting concrete (SCC) as an alternative to lower the high content of cement contribute to make the SCC a sustainable composite in order to minimize the production of CO2 by the cement industry. Furthermore, mineral additions can provide improvements in the mechanical properties and durability of the concrete. One of the parameters of durability is the behavior of the material in extreme situations such as when subjected to high temperatures, similar to those reached in a fire. In this situation, the decrease of the resistance and modulus of elasticity, changes in color and porosity, besides the spalling effect, can occur in the concrete due to the loss of water and microstructural changes. In this context, the present study aims to evaluate the behavior at high temperatures of self-compacting concrete with high levels of residues sugarcane biomass (SBA) and metakaolin (MK). For this, cement was substituted for 30% to 50% by mineral additions. In the fresh state, the properties were evaluated proving the workability of the concretes made. In the hardened state, the samples were evaluated at room temperature, 200 °C, 400 °C, 600 °C and 800 °C and analyzed by visual and tactile inspection, mass loss, compressive strength, ultrasonic pulse velocity, absorption by immersion, void index, specific mass, absorption by capillarity and X-ray diffraction. The results showed that SCCs with up to 40% of mineral additions are less sensitive to high temperatures and that higher metakolin insertion makes them more sensitive to high temperatures. Moreover, phase changes are visualized and the high content of mineral additions consumes Ca(OH)2 from the medium, forming gismondine and margarite.Master Thesis Avaliação da durabilidade frente ao ataque de CO2 e CI- em concretos autodensáveis com elevadores teores de resíduo da biomassa da cana-de-açúcar e metacaulim(2019-03-28) Farias, Evilane Cassia de; Anjos, Marcos Alyssandro Soares dos; Almeida, Maria das Vitorias Vieira; ; ; ; Lucena, Luciana de Figueiredo Lopes; ; Nóbrega, Ana Cecilia Vieira da; ; Azeredo, Givanildo Alves de;Master Thesis Potencial de substituição do cimento pela cal em tijolos de solo-cimento com incorporação de resíduo cerâmico(2018-03-26) Fonsêca, Nayara Jhéssica Marques da; Acchar, Wilson; ; ; Silva, Jaqueligia Brito da; ; Nobrega, Andreza Kelly Costa; ; Silva, Vamberto Monteiro da;Civil construction is an important industry in the economic system in which it is inserted. In addition to generating employment and income, the sector also contributes by modifying the natural landscape to guarantee society housing, security and well-being. However, the high indices of natural resources used by the construction, as well as the large amounts of waste generated by it, raise great concern about the negative environmental impact generated and the serious consequences. Considering the high energy consumption in the cement manufacturing process, the large amounts of CO2 emitted during clinker firing, the availability of hydrated lime in the Northeast region of Brazil, and also the high loss rate involving the ceramic blocks used in sealing masonry, this work evaluated the potential of cement substitution by lime in soil-cement bricks with ceramic residue (RC) incorporation. Ternary compositions of soil + 12% cement + 4% CR, soil + 12% hydrated lime + 4% CR, quaternary soil + 6% cement + 6% hydrated lime + 4% CR were developed. The compositions were also formulated without addition of RC to serve as reference and enable the analysis of the influence of the residue on the behavior of the bricks produced. After the pressing and curing processes of the bricks, they were submitted to tests of mechanical resistance, water absorption and modified durability. Then, the microstructure of these materials was analyzed through Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD) of the fracture surfaces. Given the silica and alumina contents present in both the used soil and the finely ground ceramic residue, the so-called pozzolanic reaction occurs, that contribute to the improvement of the physical and mechanical properties of the compositions studied. It was observed that the bricks produced presented good conditions of resistance to simple compression, water absorption and durability in accordance with the recommendations of the current Standards for bricks in nonstructural application. The experimental results showed that the ternary composition soil + 12% cement + 4% CR showed more significant values, exceeding 2 MPa of simple compression strength, after 150 days of cure. Among the quaternary mixtures, the soil formulation + 6% cement + 6% lime and 4% CR showed the best performance, exceeding the minimum compression strength of 2 MPa recommended by Norma, after 120 days of cure. Based on the results obtained, it is possible to conclude that, from a technical and economic point of view, the replacement of cement by lime in soil-cement bricks is viable, with the benefits of incorporating RC and observing the necessary for the effective hydration of the binders and the pozzolanic reactions.Master Thesis Estudo de concretos autoadensáveis com reduzidos teores de cimento e elevados teores de adições minerais(2016-05-06) Medeiros, Fernanda Karolline de; Anjos, Marcos Alyssandro Soares dos; Almeida, Maria das Vitorias Vieira; ; ; ; Nóbrega, Andreza Kelly Costa; ; Barbosa, Normando Perazzo;The concrete production process generates a significant environmental impact as one of the largest consumers of raw materials, like sand, stone and water. However, the greatest impact is caused by the production of Portland cement, an essential material to the concrete. Materials such as sugarcane bagasse ashes (RBC), silica from rice husk (PCA), metakaolin (MK) and silica fume, are mineral additions that play an important role in resistance and durability properties, when used in combination with Portland cement and, under certain conditions, can perfectly replace high cement content in mixtures, given to them in addition to the known benefits that cement reduction entails, like significant increase in durability. The use of self-compacting concrete (SCC) has grown significantly by its high fluidity characteristics and cohesiveness and the possibility of forming in situ without vibration, forming a fault and void-free product which has also flowability by its own weight completely filling the molds and reaching compaction even in heavily armed structures. Based on these, this study aimed to evaluate the rheological, physical, mechanical and durability properties of self-compacting eco-concrete with the high percentage incorporation of sugarcane biomass ashes, silica from rice husk and metakaolin. Based on these, this study evaluated the rheological properties, physical, mechanical and durability freight to attack by chloride ions of self-compacting ecoconcrete with the incorporation of high content of ash biomass sugarcane, rice husk silica and metakaolin. For this, a self-compacting concrete with conventional materials without mineral admixtures for use as a reference and four concrete incorporating 40% and 50% additions were analyzed using gray bagasse from sugarcane, pozzolan rice husk and metakaolin. The results showed that the resulting synergy of developed mixtures revealed mechanical and durability performance, freight to attack by chloride ions, above the reference SCC. When compared to the reference concrete, concrete with additions showed an increase of up to 13.4% of the compressive strength at 28 days and reducing to 87% the penetration of chloride ions to 91 days. The results of the study also showed that incorporating high volumes of mineral additions in the SCC causes a reduction of the environmental impact generated by the anthropogenic emissions of CO2, the energy consumed and the consumption of natural materials, thus confirming the relevance of the research. It is possible to produce self-compacting concrete with promising performances, using high RBC levels, PCA and MK, with a significant reduction in cement consumption to levels of about 220 kg / m3, thus contributing to the sustainability of the construction industry, minimizing energy released and compression.Master Thesis Análise de durabilidade da ponte do Rio do Carmo utilizando ensaios não destrutivos, norma DNIT e a metodologia GDE/UNB(Universidade Federal do Rio Grande do Norte, 2015-08-28) Medeiros, Alisson Gadelha de; Almeida, Maria das Vitórias Vieira; Silva Filho, José Neres da; ; http://lattes.cnpq.br/0915972389480304; ; http://lattes.cnpq.br/7590200701773198; ; http://lattes.cnpq.br/5804393691816726; Pereira, Alexandre da Costa; ; http://lattes.cnpq.br/5259454403464034; Anjos, Marcos Alyssandro Soares dos; ; http://lattes.cnpq.br/3904325866154130The durability of reinforced concrete structures has motivated many researches, considering the high cost of repairs in many situations, such as bridges, as well as the damage caused by the need to ban regarding recovery services. Thus, this study aims to assess the conditions of durability of the bridge over the Carmo River with 90.90 meters long. This was built in 1976 and is located at km 36 of the BR-110 highway, between the municipalities of Areia Branca/RN and Mossoró/RN, in environmentally high aggression region. For this study, non-destructive tests were done on that proved to be good homogeneity of the concrete before the rebound hammer testing. For ultrasound measures the quality of the concrete was identified as "regular" and enabled the estimation of the dynamic modulus of elasticity and strength of 13.51 MPa and 17.60 GPa, respectively. The carbonation depth assay gave values in steps of 0.00 to 19.00 mm and the testing of the presence of chlorides, there were larger dimensions, most of them being equal to 22.80 mm. However, both did not reach the depth of the steel, 30 mm. The corrosion potential of the test, most of the measurement concentrated in a range of -150 to -250 mV which indicates probabilities of 10 to 90% corrosion. Pathological present manifestations were identified using inspection methods: a standard DNIT 010/2004 and GDE / UnB. With this, from them, it was observed that the highest incidence of injuries suffered were in the superstructure, the mesostructure and other auxiliary elements such as the facade beams. Furthermore, according to this lifting, it was possible to quantify the deterioration of the structure; so that was obtained technical score equal to 3 in accordance with standard DNIT 010/2004, characterizing it as a work "potentially problematic", and overall degree of deterioration of the structure (Gd) equal to 64.03 classifying the level "High". In comparison between both methodologies, the GDE/UnB resulted in greater accuracy, due to richness of detail in your analysis. All these results indicate that the bridge study, needs repairs in the elements studied in this research and allies for more specific inspections, will be able to plan the most appropriate solution in relation to safety aspects and economics.