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Dissertations/Thesis

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2025

	Dissertations
1	JOSÉ ARTHUR DO NASCIMENTO RAMALHO POTENTIAL FOR SURFACE RUNAGE, ACCELERATED EROSION AND DIFFUSE POLLUTION IN THE POTENGI RIVER WATERBASIN - RN Advisor : CARLOS WILMER COSTA COMMITTEE MEMBERS : CARLOS WILMER COSTA OLAVO FRANCISCO DOS SANTOS JUNIOR KARINA PATRICIA VIEIRA DA CUNHA JOSÉ AUGUSTO DI LOLLO Data: Jan 24, 2025 Show Abstract This study aimed to characterize the surface runoff potential and accelerated erosion risk in the Potengi River Basin (BHRP), located in Rio Grande do Norte, Brazil, using multicriteria analysis in a GIS environment. The methodology integrated 14 geoenvironmental variables, including lithology, slope, genesis and thickness of unconsolidated materials, permeability, drainage density, surface storage features, landforms, rainfall, land use and cover, erodibility, and soil proportions of clay and sand. Primary and secondary data were used, notably the collection of 110 soil samples and satellite imagery, resulting in two main cartographic products: the Surface Runoff Potential Map and the Accelerated Erosion Risk Map. The results indicated that the BHRP is predominantly characterized by low to moderate surface runoff potential (95% of the area with values equal to or less than 5). However, approximately 32.85% of the area presents a high risk of accelerated erosion (classes 7 and 8), attributed to factors such as crystalline basement, steep slopes, highly erodible sandy soils, and intensive anthropogenic activities, including land conversion for pasture and urbanization. The most vulnerable areas include the upper course of the basin, marked by steeper slopes, friable soils, and reduced vegetation cover, along with smaller patches in the central, northeastern, and exutory regions. The analyses highlight the importance of implementing sustainable soil management actions, such as restoring native vegetation and controlling inappropriate land use, particularly in critical areas, to mitigate erosion impacts and promote environmental sustainability.
2	PHILLIPY JOHNY LINDOLFO DA SILVA ANALYSIS OF THE MECHANICAL BEHAVIOR OF LATERITIC SOIL MIXTURES WITH ASPHALT WASTE FOR USE IN PAVEMENT LAYERS Advisor : ENIO FERNANDES AMORIM COMMITTEE MEMBERS : ENIO FERNANDES AMORIM JOHN KENNEDY GUEDES RODRIGUES OSVALDO DE FREITAS NETO SILVANA FAVA MARCHEZINI Data: Feb 26, 2025 Show Abstract The analysis of the mechanical behavior of soils and alternative materials for pavements has been widely studied due to the need for sustainable and economically viable solutions in transportation engineering. This study investigates the feasibility of using Reclaimed Asphalt Pavement (RAP), a byproduct of asphalt concrete production, in the stabilization of lateritic granular soils from Rio Grande do Norte for application in base and sub-base layers of flexible pavements. The samples were classified according to the MCT (Miniature, Compacted, Tropical) system and the Universal Methodology for Lateritic Soil Classification. The mechanical characterization involved repeated load triaxial tests to determine the resilient modulus (MR) and permanent deformation (PD), considering natural soils and mixtures with 10% and 20% RAP, as well as chemical stabilization with 2% cement. The results indicated that the incorporation of RAP improved the resilient response, increasing structural stiffness and reducing the accumulation of plastic deformations. Cement stabilization enhanced these effects, doubling the MR values and mitigating progressive deformations. The influence of confining stress was crucial in increasing the stiffness of the stabilized mixtures, while deviator stress significantly influenced the progression of permanent deformation, indicating higher structural resistance in mixtures with 10% RAP and cement, evaluated after seven days of curing. The applied models showed determination coefficients (R²) above 0.90, demonstrating a strong correlation between mechanical parameters and the obtained adjustments. Computational analyses performed using the MeDiNa software confirmed the structural feasibility of the evaluated mixtures under different traffic conditions, highlighting improvements in fatigue resistance and lower susceptibility to permanent deformation accumulation over time. The results contribute to a better understanding of the influence of lateritic granular soil stabilization with asphalt residues, providing guidelines for future applications in road infrastructure. It is concluded that the combination of RAP and chemical stabilization represents a sustainable and efficient alternative for pavement construction, reducing the need for natural aggregate extraction and promoting the reuse of asphalt industry residues.
3	AFRÂNIO PEREIRA DE OLIVEIRA JÚNIOR Assessment of the potential for using salt production residue (carago) as a stabilizing agent for expansive soil Advisor : OSVALDO DE FREITAS NETO COMMITTEE MEMBERS : OLAVO FRANCISCO DOS SANTOS JUNIOR OSVALDO DE FREITAS NETO RICARDO NASCIMENTO FLORES SEVERO Data: Feb 27, 2025 Ata de defesa assinada: Show Abstract Expansive soils are present in several parts of the world. Its main characteristic is the volumetric variation based on the variation in moisture content. This is due to the presence of expansive clay minerals in the clay fraction of the soil, such as Montmorillonite. These volume variations cause damage to engineering works, which can range from small cracks to total damage to the structure. These soils can be stabilized by adding materials that react with the clay and reduce or eliminate expansion. This research aimed to evaluate the potential of using a by-product of salt production, called Carago, for stabilizing expansive soil present in the city of Mossoro, in the state of Rio Grande do Norte (RN). To this end, characterization, compaction, free expansion, expansion stress and direct shear tests were carried out on soil mixtures with 5% and 10% carago contents. Based on the results, it was possible to conclude that the addition of 10% carago to the soil reduced free expansion by 20% and that there was an increase in cohesion in all mixtures with carago.
4	GERALDO BRAZ SILVA SANTOS PROPOSAL FOR MAPPING PRIORITY AREAS FOR SOUND PRESSURE MONITORING IN WIND FARMS Advisor : HÉRIKA CAVALCANTE DANTAS DA SILVA COMMITTEE MEMBERS : CARLOS ALBERTO NASCIMENTO DA ROCHA JUNIOR HÉRIKA CAVALCANTE DANTAS DA SILVA RODRIGO GUIMARÃES DE CARVALHO SANDRA RUFINO SANTOS Data: Mar 7, 2025 Ata de defesa assinada: Show Abstract The noise from the operation of wind farms is one of the main concerns of surrounding populations, potentially causing adverse impacts on health and well-being. The noise impact depends on several variables, such as the distance to the receptor area, the characteristics of the turbine, and the speed and direction of the wind. In Brazil, the lack of legislation defining a minimum distance between populated areas and wind turbines may contribute to the exposure of inhabited areas to the noise from wind farm operations. With the large number of wind farms in operation, it is necessary to develop methodologies that identify, quantify, and assess which areas have the greatest need for monitoring potential noise impacts. Therefore, the objective of this study is to propose an index for mapping priority areas for monitoring noise pressure from wind farms. Using spatial analysis techniques, data on the exposure of potential receptors to noise from operating wind farms was obtained. The proposed index was built from seven individual indicators that, when weighted, allowed for the classification of areas according to their level of criticality. The results indicated that 10% of the operating wind turbines have receptors within the adopted noise influence area (400m), with a total of 1,882 receptors. Regarding monitoring priority classes, 23 turbines were classified as “Very High,” 86 as “High,” 127 as “Medium,” and 81 as “Low.” The proposed index proved to be an effective tool for socio-environmental management.
5	MARIA DENISE BARBOSA GOMES Phosphorus sorption by oxidic soil: Strategies for mitigating eutrophic waters in the Brazilian semiarid region Advisor : VANESSA BECKER COMMITTEE MEMBERS : VANESSA BECKER KARINA PATRICIA VIEIRA DA CUNHA FERNANDA MONICELLI CÂMARA BRITO NATÁLIA PESSOA NOYMA Data: Apr 2, 2025 Show Abstract Eutrophication compromises the water quality of lakes and reservoirs, impacting aquatic biota and ecosystem services. Mitigation involves everything from reducing external sources to blocking internal fertilization. Geoengineering is a technique that can be used to mitigate eutrophic waters by using materials with phosphate adsorption affinity. Natural adsorbents, such as soils, bauxites, and zeolites, emerge as viable alternatives to commercial and more sustainable products. Among them, oxidic soils, rich in Fe and Al oxides, stand out for their high degree of weathering and sorption capacity. This study investigated the potential for P sorption by a tropical oxidic soil to mitigate the eutrophication of aquatic ecosystems in the semiarid region of northeastern Brazil. The experiment was carried out with water from three eutrophic reservoirs (Gargalheiras, Boqueirão de Parelhas and Dourado), using 0.1 g of Dystroferric Red Nitosol, collected at the base and top of a toposequence in the Cabo Basin/PE. After application of the soil (sorbent), the samples were shaken at 200 rpm for 24 hours. The concentrations of phosphate and humic substances, as well as the pH, were evaluated. The tested soils showed P sorption potential, especially at initial concentrations up to 2.5 mg L-1, with P removals reaching above 90% in Gargalheiras and Boqueirão at the initial concentration. The maximum capacity was 3.38 Base and 4.13 mg g⁻¹ Top (Gargalheiras), 2.08 Base and 2.34 mg g⁻¹ Top (Boqueirão) and 1.74 Base and 1.24 mg g⁻¹ Top (Dourado). The sorptive behavior can be attributed to Fe and Al oxides and soil characteristics, such as low pH and organic matter content and high clay fraction. In addition, water properties can also influence sorption, even favoring precipitation. Humic substances reduced after the experiment; however, pH exerted a greater influence on sorption compared to them. Sorbents appear to be a promising strategy for mitigating eutrophic waters, especially in the semiarid region, since both were able to remove P under conditions close to those found in reservoirs.
6	SANDRO RICARDO DA SILVA ANDRADE Analysis of the incorporation of Diatomite in the properties of historical lime mortar. Advisor : MARIA DAS VITORIAS VIEIRA ALMEIDA DE SA COMMITTEE MEMBERS : MARIA DAS VITORIAS VIEIRA ALMEIDA DE SA KLEBER CAVALCANTI CABRAL PAULO ALYSSON BRILHANTE FAHEINA DE SOUZA ADLA KELLEN DIONISIO SOUSA Data: Apr 4, 2025 Show Abstract In recent years, the demand for intervention services for the conservation and rehabilitation of historic buildings has increased significantly. This is necessary because the preservation of historical heritage represents an important action to safeguard the culture of a people, their identity and their memories, as a living document. These interventions are often carried out by changing materials and construction processes that have not always contributed to improving the state of conservation of historic buildings. So, in order to make a more effective contribution to the restoration of historic buildings, the aim of this study was to develop a research project using lime mortars, a new material that could provide a again in resistance at the first ages and increase the useful life of the masonry cladding, in order to guarantee the compatibility of the restoration mortar with the pre-existing mortar in the historic building. To this end, 4 (four) types of lime and sand mortar were selected (1:2, 1:4, 1:6 and 1:8), which are the most commonly found in historic buildings in Brazil. And then, diatomite was added, replacing the hydrated lime in percentages of 10% and 20% in each of them. The physical-mechanical characterization of historical mortar specimens aged 28 and 90 days was carried out. The results of the tests carried out showed an increase in the mechanical performance of the mortars with the incorporation of diatomite, reaching a 16.6% increase in the tensile strength in flexion in the mixture richest in binder (1:2). And in axial compression, the mixes with 20% incorporation reached an average increase of 3 times more in relation to the resistance values of the reference mixes.
7	IRANILTON FERREIRA DE SOUSA APPLICATION OF CALCIUM HYDROXIDE AS A TECHNIQUE FOR MITIGATION OF EUTROPHICATION IN RESERVOIRS IN THE BRAZILIAN SEMI-ARID REGION Advisor : JOSE LUIZ DE ATTAYDE COMMITTEE MEMBERS : JOSE LUIZ DE ATTAYDE FABIANA OLIVEIRA DE ARAUJO FERNANDA MONICELLI CÂMARA BRITO JOSÉ NEUCIANO PINHEIRO DE OLIVEIRA Data: Apr 9, 2025 Show Abstract Eutrophication is a process of increased primary production caused by increased input of limiting nutrients and represents a serious threat to aquatic ecosystems. This study investigated the potential of hydrated lime used in construction as a phosphorus sorbent using water from four reservoirs in the Brazilian semiarid region. Through microscale experiments in the laboratory, the sorption capacity of hydrated lime in natural water samples was evaluated. The results demonstrated that hydrated lime presented a high capacity for phosphorus removal in natural waters through P sorption and calcium phosphate precipitation, with maximum sorption capacity (qmax) of 176.1 mg.P.g-1 (Dourado), 160.6 mg.P.g-1 (Gargalheiras), 130.3 mg.P.g-1 (Boqueirão) and 111.5 mg.P.g-1 (Armando Ribeiro Gonçalves). Furthermore, hydrated lime was shown to be effective in removing humic substances, contributing to improving water quality. Linear regression analyses showed that increased hardness and humic substances help to increase the qmax of the sorbent material, while the presence of sulfate ions reduces the qmax. Furthermore, the application of lime increased the pH of the medium, a phenomenon that helps in the main sorption mechanism of the material and cancels out the inhibitory effects of calcium phosphate precipitation caused by humic substances. However, this fact requires attention when applying this compound to natural waters. It is concluded that hydrated lime used in civil construction presents itself as a promising and low-cost alternative for controlling eutrophication in reservoirs.
8	AMANDA BEATRIZ PINHEIRO DE SOUSA EFFECTS OF LAND USE ON RIPARIAN SOIL QUALITY AND ON THE POTENTIAL CONTRIBUTION OF DIFFUSE POLLUTION FROM TROPICAL RESERVOIRS Advisor : VANESSA BECKER COMMITTEE MEMBERS : VANESSA BECKER KARINA PATRICIA VIEIRA DA CUNHA RONALDO ANGELINI JOSÉ NEUCIANO PINHEIRO DE OLIVEIRA Data: Apr 11, 2025 Show Abstract Permanent Preservation Areas are essential for the conservation of ecosystems and themaintenance of soil and surface water quality. This study evaluated the effects of differentland uses on riparian soil quality and its influence on diffuse pollution in the Dourado andCruzeta reservoirs in the Brazilian semi-arid region. The hypothesis is that anthropogenic usesdegrade soil quality and enhance its capacity to contribute to diffuse pollution in water bodies.Soils under vegetation, livestock, agriculture, and exposed land were analyzed, selected fromland use mapping within a 100-meter strip around the reservoirs. The soil attributes assessedincluded sand, silt, clay content, soil density, pH, electrical conductivity, organic mattercontent, and available phosphorus. Water quality was analyzed through limnological variablessuch as temperature, pH, turbidity, electrical conductivity, total phosphorus and nitrogen,organic and inorganic carbon, total suspended solids, organic and inorganic solids, andchlorophyll-a. Statistical analysis involved descriptive statistics, Kruskal-Wallis test, andPrincipal Component Analysis. The results indicate that the water and riparian soil quality ofboth reservoirs are degraded, regardless of land use. Even areas mapped as natural cover havevegetation incapable of functioning as an ecological filter, compromised by anthropogenicfactors such as livestock access for grazing, highlighting the need to improve theclassification system for this region. Soil attributes such as sand, silt, and pH, and waterquality variables, such as temperature, electrical conductivity, inorganic and organic carbon,total phosphorus, organic suspended solids, and chlorophyll-a, showed statistical differencesbetween the reservoirs, reflecting environmental variations influenced by the characteristics ofthe predominant soils. In Dourado, the Neossolo Litólico is shallow and highly susceptible toerosion. In Cruzeta, the Luvissolo Crômico, although more structured, has an abrupt texturalchange and also exhibits vulnerability to erosion. Thus, anthropogenic uses enhance the soils’ability to contribute solids and nutrients to the reservoirs. However, while in Dourado theexcess of nutrients favors the growth of cyanobacteria, in Cruzeta, the high turbidity restrictsaquatic biomass but maintains the eutrophic condition of the water. In light of this scenario,strategies such as reforestation with native species, sustainable agricultural practices, andgrazing control are essential for the recovery of the PPAs, reduction of diffuse pollution, andensuring the sustainability of water resources in the semi-arid region.

2024

	Dissertations
1	LEANDRO DOS SANTOS Nonlinear analysis of plane frames considering hyperelastic models through the finite element positional method Advisor : DANIEL NELSON MACIEL COMMITTEE MEMBERS : DANIEL NELSON MACIEL JOEL ARAUJO DO NASCIMENTO NETO MARCELO GRECO RODRIGO BARROS Data: Mar 22, 2024 Ata de defesa assinada: Show Abstract Computational mechanics, particularly the Finite Element Method, has become an essential tool for engineers to simulate the behavior of structures under various conditions. Additionally, hyperelastic models are commonly used to represent the behavior of highly deformable materials, such as elastomers and polymers, which are increasingly utilized in engineering applications. The use of hyperelastic models is suitable for capturing nonlinear stress-strain relationships of materials, but the accuracy of these models may vary depending on material properties and deformation regimes. Therefore, it is important to select an appropriate model for specific conditions of interest. In this context, hyperelastic models including Mooney-Rivlin, Neo-Hookean, Ogden, and Yeoh were implemented in a computational code in FORTRAN using the Finite Element Positional Method along with Reissner's kinematics and the Newton-Raphson method for nonlinear analysis of plane frames with samples of elastomers containing varying percentages of carbon black. Subsequently, the Method of Least Squares was employed to determine the constitutive coefficients of hyperelastic models. The performance of each model was then evaluated by comparing the force vs. displacement curve of the material under study. Ultimately, it was concluded that the Yeoh and Ogden models exhibited consistent values, while the Neo-Hookean and Mooney-Rivlin models deviated. This observation was attributed to the number of constants in the formulation of these models. Furthermore, it can be stated that the use of the positional finite element method for nonlinear analysis of plane frames with hyperelastic models performs well, especially after the modifications proposed in this work to the formulations of hyperelastic models. These modifications consisted of adding the first invariant of deformation from the simple shear formulation to include the consideration of distortion in the specific energy of deformation of hyperelastic models.
2	MURILO DE LIMA RODRIGUES EVALUATION OF THE SUPPORT CAPACITY OF SOIL MIXTURES WITH GRADED CRUSHED ASPHALT (BGA) FOR USE IN BASE AND SUB-BASE LAYERS OF FLEXIBLE PAVEMENTS Advisor : ENIO FERNANDES AMORIM COMMITTEE MEMBERS : ENIO FERNANDES AMORIM OSVALDO DE FREITAS NETO SILVANA FAVA MARCHEZINI Data: Mar 25, 2024 Ata de defesa assinada: Show Abstract The road transport system plays a fundamental role in Brazil, being responsible for the movement of cargo and passengers. In 2023, more than 22 million passengers were transported, decreasing an increase of 18.75% compared to the previous year. In 2022, this means of transport represented approximately 64.7% of the cargo transport matrix. The growing increase in demand highlights the urgency of investing in new projects and maintaining existing roads. As road construction requires a large amount of natural materials, the extraction of which causes considerable environmental liabilities, alternative materials are seen as a solution to minimize damage. Given this need, this work evaluated the support capacity of mixtures of different types of soil in the State of Rio Grande do Norte, associated with waste from an asphalt plant called Graded Brita Asphalt (BGA), with percentages of 10% and 20%, by mass. The work methodology was carried out through characterization, compression, California Bearing Ratio (CBR), X-ray Fluorescence (XRF,) and X-ray Diffraction (XRD) tests, with musical purposes for the use of layered mixtures of subgrade and grade of flexible road pavements. At the end of the study, it was found that four samples with high percentages of sand, in their granulometric composition, in the pure soil condition, and the soil mixture with 20% BGA, all at modified compaction energy, with reuse of material, we obtained considerable gains in support capacity, enabling its use in the base and sub-base structural layers of flexible pavements.
3	MAISA DANTAS SILVEIRA CRUZ CHARACTERIZATION AND STUDY OF THE HISTORIC MORTARS EXISTING IN THE RUINS OF THE CHURCH OF SANTA RITA DE CÁSSIA IN PEDRO VELHO/RN – BRAZIL Advisor : KLEBER CAVALCANTI CABRAL COMMITTEE MEMBERS : KLEBER CAVALCANTI CABRAL MARIA DAS VITORIAS VIEIRA ALMEIDA DE SA ERICA NATASCHE DE MEDEIROS GURGEL PINTO LEONETE CRISTINA DE ARAUJO FERREIRA MEDEIROS SILVA Data: Mar 25, 2024 Ata de defesa assinada: Show Abstract In an increasingly evident and fundamental way is the search for the conservation of cultural heritage, as a way of maintaining and preserving the identity of a society. Historic buildings are an integral part of this heritage and the best way to conserve and safeguard them is to analyze and understand the materials and methods used during the period of their construction, in order to carry out a more harmonious and efficient restoration, with materials similar to the originals. In this context, this work aims to characterize and study the mortar covering the ruins of the Church of Santa Rita de Cássia, in the city of Pedro Velho/RN - Brazil. To this end, on-site visits were carried out for visual observations and photographic records of the historic building, collecting a total of 30 (thirty) samples of coating mortar for subsequent physical-chemical characterization through visual, tactile analysis and analytical techniques carried out in the laboratory, FRX, DRX, mortar content (binder:aggregate) tests by acid attack and granulometric analysis were developed. From these analyzes it was found that the mortars analyzed are rich in lime, with a binder of a calcitic nature and sand of siliceous origin, as aggregate, with the presence of clay in their composition, presenting different binder:aggregate ratios in almost all cases. mortars, ranging from 1:3 to 1:13, proving their production without any technological control. Therefore, for possible future restoration, it must be done with mortar made of lime and sand with different traits.
4	KAREN ANDREZA MARCELINO Parametric analysis of the distribution of internal forces due to moving loads in widened decks of skewed girder bridges Advisor : DANIEL NELSON MACIEL COMMITTEE MEMBERS : DANIEL NELSON MACIEL JOSE NERES DA SILVA FILHO LEANDRO MOUTA TRAUTWEIN RODRIGO BARROS Data: Mar 26, 2024 Ata de defesa assinada: Show Abstract The road system participates significantly in the Brazilian transport matrix, with bridges being essential elements for the full implementation of the road network. Currently, Brazil is witnessing an increase in road traffic demand from larger, heavier and more numerous vehicles. Furthermore, the requirements necessary for the design of road bridges, present in the relevant guidelines, have undergone several adjustments over the last few years, which has led to old bridges not meeting the new design specifications, needing to be subjected to interventions, among which the widening of decks. Bridges that are subjected to the widening procedure begin to present a new distribution of internal forces, this distribution being more complex in the case of skewed bridges, due to their structural configuration. However, the expansion of existing skewed bridges is still little investigated in the scientific community. The objective of this research is, therefore, to evaluate the distribution of internal forces (due to moving loads) in widened skewed bridge decks through a parametric analysis, considering the variation in deck stiffness. To this end, analytical and numerical models were be developed – via the Finite Element Method (FEM) – of skewed bridges, which had variable quantities of girders and skew angles, in order to denote the behavior of such bridges in relation to different structural models and, thus, making it possible to analyze the influence of widening on the transversal distribution of moving loads, in addition to the influence of the compressive strength of the concrete in the widened region. The internal stress distribution analysis carried out can be applied by structural designers in the safe and economical design of widened span bridges.
5	NAYARA TALASSA DAMASCENO INÁCIO Numerical analysis of the influence of complementary reinforcements in blocks on two piles with embedded cup and interfaces with shear key. Advisor : OSVALDO DE FREITAS NETO COMMITTEE MEMBERS : MARCELA NOVISCHI KATAOKA HIDELBRANDO JOSE FARKAT DIOGENES OSVALDO DE FREITAS NETO RODRIGO BARROS Data: Mar 27, 2024 Ata de defesa assinada: Show Abstract This research aimed to analyze the behavior of a reinforced concrete two pile caps with embedded socket and shear keys in the presence of additional reinforcement. A numerical model was developed in the ABAQUS software, based on the finite element method. The numerical models were calibrated and validated based on experimental tests by Barros (2013).A parametric analysis of the models was carried out in two stages, which also included the variation in the compressive strength of the concrete of the pile caps. The first step consisted of varying the steel area and arrangements of the additional reinforcement proposed by Barros (2013). The second stage included the variation in angle and configuration of the additional reinforcement. It was observed throughout the parametric analyzes that the compressive strength of the pile caps was the parameter that most influenced the load capacity of the models by providing greater resistance to the compression struts, since the models' collapse occurred due to the crushing of the concrete in the struts in the connection region. The results of the first stage showed that the additional reinforcement, originally proposed by Barros (2013), does not influence the load capacity of the pile caps and crack control. The analyzes of the second stage showed that the new proposed configurations A1, A2 and A1+A2 enabled better control of the cracking of the pile caps. Reinforcement A1 acted to control diagonal cracking of the pile caps strut, resulting in an increase in load capacity between 0.94% and 2.55%, varying according to the pile caps’ compressive strength. The A2 model was more efficient, controlling central cracking and diagonal cracking of the pile caps struts, resulting in an increase in load capacity between 5.31% and 10.19%. The A1+A2 model presented practically a superposition of effects, controlling both diagonal cracking and central cracking. It was the arrangement that provided the greatest increases in load capacity, which varied between 6.77% and 12.48%. Thus, the importance of reinforcement for controlling cracking in pile caps with embedded socket with shear keys is demonstrated. Since, in addition to resulting in better behavior in service and greater durability of the structural element, they can also act by delaying the collapse mechanisms of the pile caps and, thus, increasing their load capacity, as was observed more significantly on models A2 and A1+A2.
6	ANA CAROLINA LIRA DE LIMA LABORATORY EQUIPMENT FOR STUDYING THE RESPONSE OF THE BACKFILL SOIL OF INTEGRAL BRIDGE ABUTMENTS SUBJECT TO CYCLIC LATERAL MOVEMENTS Advisor : YURI DANIEL JATOBA COSTA COMMITTEE MEMBERS : YURI DANIEL JATOBA COSTA CARINA MAIA LINS COSTA FERNANDO LUIZ LAVOIE SILVIA CRISTINA JUSTO FERNANDES NOBRE DE ARAUJO Data: Mar 27, 2024 Ata de defesa assinada: Show Abstract The backfill soil next to integral bridge abutments is subjected to cyclic loading, due to thermal variations of the structure, which may induce the increase of the lateral earth pressures in the abutment wall face and the buildup of permanent deformations (ratcheting) in the soil mass. Although a large number of integral bridges have been built in North America, Europe and in some other places so far, its accessibility still faces uncertainties about understanding the soil-structure interaction involved. However, experimental studies with reduced-scale physical models can help clarify the mechanisms that cause the detrimental effects in the backfill near the abutment in the long term. This work aims at presenting and discussing the development and validation of a laboratory equipment designed to model the response of soil subjected to cyclic lateral displacements. A steel testing box, instrumented with pressure and displacement transducers, was developed with the capacity to contain a volume of soil of 300 x 300 x 350 mm. The data generated by the transducers are collected by a low-cost data acquisition system built with open-source hardware and software. One of the walls of the testing box can apply cyclic rotational or translational displacements in the soil mass, as to simulate the behavior of the backfill soil of an integral bridge abutment when the structure is subjected to temperature fluctuations. Settlements on the soil surface and deformation fields within the soil mass were captured by a digital image correlation technique. The images were acquired from a transparent side wall of the testing box and were processed using the Ncorr algorithm via Matlab. A series of experiments were conducted to validate the testing apparatus and the data acquisition system, as well as to evaluate the general behavior of the soil upon cyclic loading. The results showed a good performance of the equipment for rotational movements around the base. The low-cost data acquisition system was also found to meet operational requirements. The findings from the physical models revealed a noticeable increase of the passive lateral earth pressure with cycling and the early appearance of ratcheting in the early cycles of imposed lateral displacements.
7	GUILHERME ADLER ACIOLE MEDEIROS USE OF NATURAL ORGANIC COAGULANTS IN THE MITIGATION OF EUTROPHICATION AND IN THE TREATMENT OF WATER FROM SEMI-ARID RESERVOIRS Advisor : VANESSA BECKER COMMITTEE MEMBERS : HELIO RODRIGUES DOS SANTOS HÉRIKA CAVALCANTE DANTAS DA SILVA JOSÉ CAPELO NETO VANESSA BECKER Data: May 3, 2024 Ata de defesa assinada: Show Abstract The coagulation process involves the destabilization of colloidal particles (including microorganisms) and suspended matter in water, for subsequent removal in separation units, through the addition of coagulants. Coagulation is one of the tools used in the mitigation of eutrophication, capable of removing algal biomass from water bodies. Additionally, coagulation plays a fundamental role in water treatment for supply, being an essential step in removing suspended particles and impurities, thus ensuring the quality and safety of the drinking water provided to the population. Therefore, this dissertation aimed to evaluate the use of organic coagulants of plant origin in the mitigation of eutrophication and the treatment of water from eutrophicated sources in the Brazilian semiarid region. The first chapter focused on eutrophication mitigation, evaluating the use of three organic plant-based coagulants in the Floc & Sink technique, which involves the coagulation and sedimentation of algal biomass and has been used as a means to mitigate the effects of eutrophication. The three tested coagulants are composed of extracted tannins, chemically modified through the cationization process, from the bark of three different trees: cashew (Anacardium occidentale), black jurema (Mimosa tenuiflora), and Tanfloc SG, obtained from black wattle (Acacia mearnsii). Three different doses of each coagulant (50, 100, and 200 mg.L-1) were applied to water samples from four reservoirs in the tropical semiarid region. The results showed that all treatments were capable of removing algal biomass and turbidity, except for the 50mg/L dose of cashew. Increased doses of coagulants resulted in greater removal of biomass and turbidity. Tannin-based coagulants were able to approach the zeta potential to the isoelectric point (0 mV), favoring the neutralization of surface charges of suspended particles. Additionally, no significant changes in water pH were observed after the application of coagulants. Thus, plant-based coagulants emerge as promising alternatives to inorganic coagulants in the Floc & Sink technique, aiming to mitigate the effects of eutrophication in the semiarid region. They represent a potentially more sustainable solution for removing algal biomass in future large-scale applications. The second chapter aimed to evaluate the use of natural tannins as an alternative to metallic coagulants in the treatment of water from eutrophicated reservoirs in the semiarid region for supply. In this chapter, jar test assays were performed with water samples from two semiarid reservoirs. The assays were conducted with 3 tannin-based coagulants: from cashew (Anacardium occidentale), black jurema (Mimosa tenuiflora), and Tanfloc SG, obtained from black wattle (Acacia mearnsii). Four doses (10, 25, 50, and 100 mg.L-1) of each coagulant were used. All analyzed coagulants demonstrated a reduction in both turbidity and chlorophyll-a. As the doses of coagulants increased, greater removal of algal biomass and turbidity was observed. The approximation of the zeta potential to the isoelectric point (0 mV) favored the tannins' ability to neutralize the surface charges of suspended particles. Overall, tannins did not cause significant changes in water pH. Although tannin-based coagulants removed algal biomass and turbidity from water, they failed to remove color satisfactorily, making them less promising alternatives for the treatment of water from the studied reservoirs. Our study demonstrated that the tested tannin-based coagulants are potential products for the mitigation of eutrophication in semiarid reservoirs due to their high capacity for removing algal biomass and turbidity. However, their use in water treatment plants for supply is compromised due to their low capacity for color removal.
8	UESLEI SILVA NUNES THE IMPACT OF THE METAKAOLIN/LIMESTONE RATIO ON THE PRINTABILITY OF LC³-BASED CEMENTITIOUS COMPOSITES Advisor : ANA CECILIA VIEIRA DA NOBREGA COMMITTEE MEMBERS : ANA CECILIA VIEIRA DA NOBREGA ANTONIO EDUARDO MARTINELLI PAULO ALYSSON BRILHANTE FAHEINA DE SOUZA ALINE FIGUEIRÊDO NÓBREGA DE AZERÊDO RÍSIA AMARAL ARAÚJO Data: May 24, 2024 Ata de defesa assinada: Show Abstract This research aimed to investigate the effect of metakaolin and limestone filler contents on the printability of LC3 mixtures for 3D printing of concrete (3DCP). The study focused on mixtures with high cement replacement in different proportions (ranging from 35% to 45%) and a ratio of 1:3 for metakaolin to limestone filler. The study employed a statistical approach based on optimized experimental planning of mixtures. A water-to-binder ratio of 0.33 and a sand-to-binder ratio of 1.0 were used for all the mixes, and a mix with 100% cement was used as the reference. Printability was evaluated by analyzing extrudability, constructability, pumpability, shape retention, open time, compressive strength, and microstructure.
9	FERNANDA MORAIS LIMA Evaluation of a soil for 3D printing on earth stabilized with cement, metakaolin and filler Advisor : MARCOS ALYSSANDRO SOARES DOS ANJOS COMMITTEE MEMBERS : MARCOS ALYSSANDRO SOARES DOS ANJOS MARIA DAS VITORIAS VIEIRA ALMEIDA DE SA NORMANDO PERAZZO BARBOSA Data: May 29, 2024 Ata de defesa assinada: Show Abstract Earth construction is one of the oldest and most widespread vernacular building techniques, as it is an ecological, sustainable, affordable material, which reduces the impact of greenhouse gases for the house-building industry. The aim of this work is to analyse a soil classified as sandy-silt and see if it is compatible with the 3D printing process, stabilizing it with Portland Cement using chemical additives to provide the pumpability required for printing, partially replacing the cement with mineral additions (metakaolin and limestone filler), so that the 3D printing mixture in cement-stabilized soil (3DTC) has a paste volume suitable for the printing system, but with low Portland Cement contents. The experimental program began with an empirical analysis of the mixtures, starting with the 1:1 cement:soil mixture, known as the reference (REF), in order to obtain a 3DTC mixture with a consistency compatible with the extrusion method of the 3D printer available at UFRN, in order to establish the chemical additive contents and the water/dry material ratio compatible with the printing speed and nozzle height conditions. From this mixture, the reduction in cement consumption of the REF mixture was analyzed, in two mixtures called T15%C and T20%C with proportions of 0.15:0.85:1 and 0.2:0.80:1 (cement:mineral additions:sand). The number of possible layers for printing 3DTC blocks to be built continuously and without crumbling was then determined using a constant printing speed of 80 mm/s with a deposition height of 1 cm. With these printing conditions established, 6 3DTC blocks were printed, of each composition, with dimensions of 14 cm x 14 cm in cross section and 16 cm in height, where 3 blocks were subjected to dimensional analysis and then the axial compressive strength was determined, and 3 blocks were used to extract small pieces (40x40x160 mm) to carry out compressive strength and flexural tensile strength tests. With the mixtures analyzed, it was possible to build 3DTC blocks with cement consumption in the T15%C -113.60 kg/m³ and T20%C - 152.78 kg/m³ mixtures and make them printable with cement reduction levels of 87% and 82%, respectively, compared to the reference mixture (REF), which used only cement and soil in a 1:1 ratio by mass. The reference 3DTC block had the highest compressive strength (19.8 MPa) of the three mixes evaluated, due to the high cement content in the mix. The T15%C and T20%C mixtures had block strengths of 3.1 MPa and 3.0 MPa, respectively, making them suitable for masonry construction.
10	LILIAN ALAIDE SOUZA SANTOS Prediction of optimal constituent ranges of LC3 for oilwell cementing pastes based on response surface method (RSM) Advisor : ANA CECILIA VIEIRA DA NOBREGA COMMITTEE MEMBERS : ANA CECILIA VIEIRA DA NOBREGA EDGAR PERIN MORAES JÚLIO CÉZAR DE OLIVEIRA FREITAS RODRIGO CESAR SANTIAGO GLAUCO SOARES BRAGA Data: May 31, 2024 Ata de defesa assinada: Show Abstract This study focuses on the ideal mix of constituents (cement, calcinated clay, limestone, and gypsum) of LC3 (Limestone Calcinated Clay Cement) for oilwell cementing pastes based on the response surface method (RSM). Slurries with a density of 14.2 lb/gal (1.66 g/cm³) were prepared for the first cementing phase, and their consistency, rheology at 27 °C and 52 °C, and thickening time were investigated. Compressive strength, permeability, and ultrasound resistance were measured on the hardened pastes after 8 hours, 24 hours, and 7 days. The evolution of the hydrated phases over time was also studied using X-ray diffraction, thermal analysis, and scanning electron microscopy.
11	MATHEUS NATAN FERREIRA ALVES DE SOUSA Determination of areas vulnerable to erosion and priority areas for recovery in the watershed of Potengi river - RN. Advisor : CARLOS WILMER COSTA COMMITTEE MEMBERS : CARLOS WILMER COSTA JOSE LUIZ DE ATTAYDE IANA ALEXANDRA ALVES RUFINO JOSÉ AUGUSTO DI LOLLO Data: Jun 26, 2024 Ata de defesa assinada: Show Abstract Purpose: The study aims to identify areas vulnerable to soil loss in the Potengi River hydrographic basin (BHRP) in Rio Grande do Norte, through a multicriteria analysis involving various geo-environmental attributes, in order to guide efforts towards efficient actions for the Recovery of Degraded Areas (RAD). Methodology: Data on geology, climate, geomorphology, pedology, hydrographic network, and interpretation of land cover and land use were collected. Through map algebra, it was possible to model the landscape of the basin and locate the areas most vulnerable to soil loss. Originality/Relevance: After the investigation using geoprocessing, the results generated in the form of cartographic products were evaluated and validated through field inspections to verify all situations identified as critical and assess the accuracy of the method used. It is important to note that in other studies conducted in BHRP, there was no specific objective of evaluating and validating the reality. Results: It was found that approximately 76% of the 4,170 km² area of the basin is moderately vulnerable to erosion, with nine critical areas of very high vulnerability identified, which need to reduce soil loss to avoid future effects such as drainage siltation and transport of soil nutrients. Social/Managerial contributions: Mapping the current state of land cover, land use, and preservation areas is essential to develop protection and monitoring measures. This allows for the implementation of initiatives such as Payment for Environmental Services (PSA) and the creation of a bank of priority areas, aiming to preserve water resources, especially in the semiarid region of Northeast Brazil.
12	EMANUELLA SILVA PEREIRA DE MACÊDO COASTAL VULNERABILITY ON AN URBAN BEACH ON THE EAST COAST OF RIO GRANDE DO NORTE, EQUATORIAL ATLANTIC SECTOR Advisor : VENERANDO EUSTAQUIO AMARO COMMITTEE MEMBERS : ADA CRISTINA SCUDELARI LÍVIAN RAFAELY DE SANTANA GOMES PINHEIRO MARIA DEL PILAR DURANTE INGUNZA MICHAEL VANDESTEEN SILVA SOUTO VENERANDO EUSTAQUIO AMARO Data: Sep 30, 2024 Show Abstract Coastal erosion and flooding are processes that directly affect cities near thecoastline and are responsible for causing a series of significant damages in the economicand socio-environmental spheres. Some impacts include the loss of land and coastalinfrastructure, the loss of habitats and biodiversity, impacts on the economy and tourism, and risks to safety and health. The study area is located on the coast of Rio Grande do Norte - RN, in the municipaly of Maxaranguape. The city stands out for its tourism and development of economic activities along the coast. However, due to the development of the region and the migration of the population to the coastal zone without prior planning, the safety of the region has been compromised ad the situation is expected to worsen over the years. In order to analyze coastal Vulnerability and propose mitigation measutes for areas with high associated risk, geoprocessing and numerical modeling tools were used to forecast future scenarios thet can serve as decison-making material for public authorities. The InVEST Costal Vulnerability module was used to perform the costal Vulnerability analysis based on the classification of the area into five distinct categories,ranked from low to high Vulnerability classes. This classification was determined by acomprehensive analysis of several factors, including wave exposure, natural habitatcharacteristics, geomorphology, relief and sea level changes. The studies revealed asignificant variation in the sediment balance profile over the period between 1984 and2023. On a short-term and high-resolution scale, an emerging trend was observed,highlighting specific areas that are particularly vulnerable to the erosion process, notablythose close to the river mouth.
13	PEDRO HENRIQUE SILVA DE CAMPOS Geotechnical characterization of residual gabbroic soil for dam application. Advisor : OLAVO FRANCISCO DOS SANTOS JUNIOR COMMITTEE MEMBERS : OLAVO FRANCISCO DOS SANTOS JUNIOR OSVALDO DE FREITAS NETO RICARDO NASCIMENTO FLORES SEVERO Data: Sep 30, 2024 Show Abstract Com base na análise das propriedades geotécnicas de corpos gabróicos visando a aplicação em construções de barragens e infraestruturas correlatas, este estudo evidencia resultados significativos que contribuem para a viabilidade desses materiais em contextos de engenharia civil. Os corpos gabróicos examinados demonstraram possuir propriedades favoráveis, como baixa permeabilidade e adequada resistência ao cisalhamento, que os qualificam para uso em barragens de terra. Entretanto, a amostra A41, afetada por processos de intemperismo e lixiviação, apresentou uma textura mais arenosa, destacando-se pela sua potencial aplicabilidade como material de filtro, um achado relevante para o desenho e a otimização de estruturas de barragens. Além disso, a avaliação dos índices de compressão sugeriu que, embora todas as amostras possam ser consideradas para uso em barragens, em situações onde a minimização do assentamento é crítica, materiais com coeficientes de compressão mais baixos seriam preferíveis. A amostra A41, em particular, mostrou-se excepcionalmente adequada para uso como subleito em sistemas rodoviários, uma aplicação que destaca sua versatilidade e amplia o escopo de uso desses materiais. Este estudo, ao identificar e caracterizar as propriedades geotécnicas de corpos gabróicos, fornece uma base sólida para futuras aplicações em engenharia, ressaltando a necessidade de uma análise detalhada que inclua não apenas propriedades físicas, mas também critérios como disponibilidade local e impacto ambiental, para assegurar a sustentabilidade e a eficácia de projetos de infraestrutura hídrica.
14	RAABI INARAIR FERREIRA BRAZ BEHAVIOR OF EXPANSIVE SOIL STABILIZED WITH ORNAMENTAL STONE PROCESSING WASTE Advisor : MARIA DEL PILAR DURANTE INGUNZA COMMITTEE MEMBERS : FAGNER ALEXANDRE NUNES DE FRANCA JOHN ELOI BEZERRA MARIA DEL PILAR DURANTE INGUNZA RICARDO NASCIMENTO FLORES SEVERO Data: Sep 30, 2024 Ata de defesa assinada: Show Abstract Expansive soils present volumetric instability when experiencing moisture variations. It is important to understand this expansion mechanism and the stabilization techniques for this type of soil, aiming to minimize losses in civil construction. Among the possibilities of techniques for improving expansive soil, the following research highlights chemical stabilization, commonly carried out with the addition of portland cement or hydrated lime. The costs and environmental impact of producing these materials have encouraged researchers to use solid waste as stabilizers, as they are produced abundantly in industries and in most cases are disposed of irregularly. This work aims to analyze the stabilization of an expansive soil with ornamental rock processing residue, observing the improvement of mechanical, hydraulic and deformability properties of the soil. For this, the expansive soil will be collected in mossoró-rn and stabilized with additions of processing residue of 10%, 20% and 30%. The soil, ornamental rock processing residue and soil-residue mixtures will be analyzed, initially, by preliminary tests: granulometric analysis by sieving and sedimentation, atterberg limits and real grain density, later the chemical characterization tests will be carried out: fluorescence of x-ray (xrf), x-ray diffraction (xrd) and energy dispersive x-ray spectroscopy (eds) integrated with the scanning electron microscope (sem) and finally the mechanical characterization tests: simple compression, free expansion and compression triaxial.
15	FÁBIO PEREIRA ANTI-RETROGRESSION EFFECT OF ALTERNATIVE SILICAS COMPARED TO CRYSTALLINE SILICA IN HIGH TEMPERATURE AND HIGH-PRESSURE OILWELL CEMENTING Advisor : ANA CECILIA VIEIRA DA NOBREGA COMMITTEE MEMBERS : ANA CECILIA VIEIRA DA NOBREGA BRUNO LEONARDO DE SENA COSTA GLAUCO SOARES BRAGA Data: Oct 25, 2024 Show Abstract Oil well cementing in high-temperature scenarios is critical for constructing wells under high temperature and pressure gradients. In high-temperature environments, challenges increase significantly, as the cement must withstand elevated temperatures without compromising its stability and mechanical properties. Temperatures above 110°C trigger chemical changes in the cement hydration products, converting semicrystalline Calcium Silicate Hydrate (C-S-H) into crystalline phases (conversion of hydrated calcium silicate into lime-rich phases), such as Alpha-Dicalcium Silicate Hydrate (α-C2SH). Quartz-based (SiO2) materials are generally added to the cementitious pastes to mitigate strength regression at high temperatures. The main contribution of these materials to cementitious systems exposed to high-temperature conditions is the formation of semicrystalline calcium silicate hydrate-rich phases, mainly Xonotlite in systems where only crystalline silica (SiO2 with a minimum purity of 97%) is added, and Tobermorite in systems where mineral sources are primarily used, which, in addition to SiO2, contain aluminum. These two crystalline phases are responsible for combating strength regression. This study aimed to evaluate the contribution of different substitution percentages in the combined use of two silica-rich (SiO2) residues derived from industrial mortar production and thermal treatment of biomass in cement pastes. Specimens were molded according to international standards and cured directly in a curing chamber at a temperature of 180°C for 7, 14, and 28 days. After these curing periods, the specimens were subjected to uniaxial compressive strength tests to evaluate their mechanical strength. Samples were collected for microstructural analyses, including X-ray diffraction (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM), in addition to qualitative analyses by energy-dispersive spectroscopy (EDS). The results showed that the reference paste with 35% crystalline silica substitution predominantly formed the Xonotlite phase at all three curing ages. On the other hand, the ternary pastes, with 50% combined substitution of residues from industrial mortar production and biomass thermal treatment, predominantly formed the Tobermorite phase at all three curing ages. These findings can provide a solid foundation for optimizing formulations used in wells.

2023

	Dissertations
1	GABRIELLY DA MOTA NUNES Evaluation of the mechanical behavior of 3DCP mixtures with partial replacement of cement by limestone filer and metakaolin in comparison with materials for structural masonry Advisor : MARCOS ALYSSANDRO SOARES DOS ANJOS COMMITTEE MEMBERS : MARCOS ALYSSANDRO SOARES DOS ANJOS KLEBER CAVALCANTI CABRAL ARNALDO MANOEL PEREIRA CARNEIRO ULISSES TARGINO BEZERRA Data: Feb 10, 2023 Ata de defesa assinada: Show Abstract 3D printing has generated changes in traditional processes, ensuring greater freedom of design with complex geometries and the possibility of using various materials. However, the cementitious mixtures 3D printing on concrete (3DCP) have high Portland cement contents to meet the printing parameters, so, in order to satisfy the more sustainable construction aspect, an alternative is to partially replace cement by supplementary cementitious materials (SCMs). As also, in view of the similarity of the 3D printing system with that of structural masonry, a comparative evaluation between the aforementioned methods is of importance. Based on this, the present study aims to develop 3DCP blocks, prisms and mini-walls with limestone filler and metakaolin in partial replacement of Portland cement, aiming to evaluate the mechanical behavior of these 3DCP elements in comparison to the structural masonry system; in addition to analyzing their performance in the fresh and hardened state. The results show that the lime filler increases the fluidity and the open time of the mixture, while the metakaolin increases the viscosity of the mixture. It was also found that the geometry of the 3DCP containing an internal lattice ensured greater stability to the material, being favorable to the buildability of the 3DCP. As well as, it was possible to prove the similarity of the mechanical behavior of the structural masonry system with 3DCP, with respect to the brittle failure mode and the compressive strength.
2	TATIANE MILENE DE ARAÚJO STUDY OF THE POTENTIALITY OF ARISCO IN THE PRODUCTION OF SOLID BRICKS STABILIZED WITH PORTLAND CEMENT AND CONTENT OF CARAGO, HYDRATED LIME AND METAKAOLIN. Advisor : WILSON ACCHAR COMMITTEE MEMBERS : OSVALDO DE FREITAS NETO VAMBERTO MONTEIRO DA SILVA WENDELL ROSSINE MEDEIROS DE SOUZA WILSON ACCHAR Data: May 17, 2023 Show Abstract The civil construction represents one of the sectors of the economy that most contributes to the degradation of the environment, however, it also has a high potential for the application of new materials that add parameters of sustainable development, such as functionality and sustainability. For this reason, this research seeks to produce an ecological material, that is, a solid brick of arisco, predominantly sandy soil with little clay fraction, with cement contents and the incorporation of other components, aiming at the partial replacement of Portland cement, high energy cost input and carbon dioxide generator, by salinization residue, such as carago or binder such as hydrated lime, or pozzolanic additive such as metakaolin. 32 bricks were produced with variations of substitutions between the materials mentioned above. In the initial stage, the characterization of the arisco was carried out, in addition to DRX and FRX tests of the raw materials and thermogravimetric analysis of the carago. After manufacturing the brick, the physical and mechanical properties were evaluated, through resistance to resistance, water absorption and durability. Once this step was completed, samples taken from the collapse of the bricks were subjected to microstructural tests such as XRD and SEM, seeking out to understand the interaction mechanism between the constituents of the hidden mixtures. Finally, it was found that the reference composition reached the highest mechanical strength, while the mixture that used only carago showed the highest water absorption and the one that included carago and metakaolin had the highest mass loss. The mixtures behaved within the requirements of Brazilian technical standards and can be used in non-structural masonry.
3	ALEX ARMANDO DA SILVA TECHNICAL EVALUATION OF THE USE OF WASTE FROM AN ASPHALT PLANT IN HOT MACHINED ASPHALT CONCRETE MIXTURES Advisor : ENIO FERNANDES AMORIM COMMITTEE MEMBERS : ENIO FERNANDES AMORIM OLAVO FRANCISCO DOS SANTOS JUNIOR FAGNER ALEXANDRE NUNES DE FRANCA MARCONDES MENDES DE SOUZA Data: May 18, 2023 Ata de defesa assinada: Show Abstract Road transport in Brazil is the main means of movement of goods, services and people nowadays. Given this situation, with population growth, it is necessary to carry out maintenance and construction of highways in the country, which leads to the exploitation of natural resources and the generation of waste that cause major environmental problems. In this segment, it's important mentioning that in the production process of Hot-Machined Asphaltic Concrete (HMAC) a residue called Brita Graduate with Asphalt (BGA) is generated, a noble material, composed of coarse aggregates, small aggregates and Petroleum Asphalt Cement (PAC). Thus, the present study analyzed the technical feasibility of using BGA in proportions of 0%, 2%, 4%, 6% and 8%, by mass, in relation to new hot-machined asphalt mixtures for application in of road works. For this, chemical characterization analysis by X-Ray Fluorescence (XRF), mineralogical analysis by X-Ray Diffraction (XRD) and physics of BGA and natural aggregates were carried out. Asphalt mixtures with the incorporation of BGA were produced based on Marshall dosing procedures, embodied in the National Department of Transport Infrastructure (NDTI) standards. At the end of the work, it was verified that the mixes of concrete with 2% and 8% of BGA presented the best values for the volumetric parameters and Marshall stability, so that they were superior to those recommended by the Brazilian technical standards. In addition, the results of the physical, chemical and mineralogical characterization revealed values compatible with the natural aggregates used in paving works in the country. Thus, it is concluded that the use of BGA presents itself as an alternative material to be used in the composition of (HMAC), meeting the technical criteria required by Brazilian agencies, in addition to providing advantages from an economic and environmental point of view.
4	LORENA KARLA SOARES PEIXOTO Evaluation of durability parameters against attack by chloride ions in self-compacting concrete using recycled aggregates from civil construction waste Advisor : MARCOS ALYSSANDRO SOARES DOS ANJOS COMMITTEE MEMBERS : ALINE FIGUEIRÊDO NÓBREGA DE AZERÊDO LUCIANA DE FIGUEIREDO LOPES LUCENA MARCOS ALYSSANDRO SOARES DOS ANJOS MARIA DAS VITORIAS VIEIRA ALMEIDA DE SA Data: May 18, 2023 Ata de defesa assinada: Show Abstract As economic development drives the accelerated pace of construction, it is known that it projects a global environmental crisis as a result of the waste of natural resources from non-renewable sources, thus arousing the search for alternatives for reuse of construction and demolition waste (CDW). In this study, the influence of incorporating recycled aggregates of CDW, sand and gravel, on the durability parameters in mixtures of self-compacting concrete (SCC), with and without the addition of metakaolin, submitted to two exposure conditions: in open air and in chloride ion attack cycles, was verified. Five mixtures were produced: (1) reference SCC, with natural sand and gravel; (2) SCC with recycled sand and gravel; (3) SCC with recycled sand and gravel and addition of 10% MK; (4) SCC with recycled sand, natural gravel and addition of 10% MK and (5) SCC with natural sand, recycled gravel and addition of 10% MK. The water/cementitious material ratio was kept constant for all mixtures and the additive dosage was adjusted according to the variation in the use of aggregates. The evaluation of mechanical properties and durability was performed from tests of axial compressive strength, ultrasonic pulse velocity, chloride penetration, chloride ion diffusion, electrical resistivity and corrosion potential. The results showed that the SCC properties were reduced with the use of recycled CDW aggregates. However, for some durability indicators, SCC with recycled aggregate behaved similarly to SCC with natural aggregates. The addition of metakaolin compensated for the decrease in quality of the SCC with the use of recycled aggregates. The SCC mixture with recycled sand and metakaolin stood out positively in relation to the others, with better results than the reference mixture.
5	ISLA LICELY RODRIGUES BATISTA Influence of the hydroxypropylmethylcellulose content on the mechanical and thermal properties of coating mortars Advisor : KLEBER CAVALCANTI CABRAL COMMITTEE MEMBERS : ERICA NATASCHE DE MEDEIROS GURGEL PINTO KLEBER CAVALCANTI CABRAL MARCOS ALYSSANDRO SOARES DOS ANJOS WENDELL ROSSINE MEDEIROS DE SOUZA Data: May 26, 2023 Ata de defesa assinada: Show Abstract The approach to the thermal performance of buildings has been a recurring theme in the space of scientific research after the development of the performance standard, NBR 15575 (ABNT, 2013). It seeks to improve the thermal performance of buildings mainly through the use of passive cooling techniques in the envelope through cementitious materials that acquire insulating properties with the use of additives that directly or indirectly allow the incorporation of air. Therefore, the present study aims to observe the influence of the use of hydroxypropylmethylcellulose (HPMC) on the thermal and mechanical properties of coating mortars with the addition of 0%, 0.015%, 0.030%, 0.045%, 0.060%, 0.090% of HPMC . To determine the properties of the fresh and hardened state of the mortars, tests were carried out on compressive strength, flexural strength, water absorption by immersion, mass density, modulus of elasticity and water loss by evaporation. The results indicate that the addition of HPMC causes an increase in the void index of the material, resulting in a reduction in the mechanical strength and modulus of elasticity. It is also noted that the incorporation of the additive produces a mortar with lower mass density, resulting in a lighter material and possibly with better thermal properties.
6	RAYANE DIAS DA SILVA POTENTIAL FOR PHOSPHORUS RELEASE FROM SEDIMENT DUE TO WIND-INDUCED RESUSPENSION: EXPERIMENTAL STUDY WITH SEMI-ARID TROPICAL RESERVOIR Advisor : HÉRIKA CAVALCANTE DANTAS DA SILVA COMMITTEE MEMBERS : FABIANA OLIVEIRA DE ARAUJO HÉRIKA CAVALCANTE DANTAS DA SILVA JOSÉ NEUCIANO PINHEIRO DE OLIVEIRA VANESSA BECKER Data: May 26, 2023 Show Abstract High concentrations of nutrients, mainly phosphorus, trigger the eutrophication of lentic water sources. Thus, the reduction of external sources does not reduce eutrophication efficiently, since the nutrients accumulated in the sediment can be released into the water column, depending on the physical and chemical conditions of the system, favoring internal fertilization. Linked to this, the tropical semi-arid region of Brazil presents reduced precipitation and high temperatures, conditions that result in high evaporation and decrease in the water level of reservoirs used for supply, thus favoring resuspension by the wind. This, in turn, intensifies internal fertilization and the eutrophication process. Thus, this work will analyze the influence of wind resuspension on the release of phosphorus from the sediment to the water column, on a laboratory scale, using material from a shallow reservoir in the Brazilian tropical semi-arid region. In this study, resuspension simulations will be performed in microcosms to evaluate the release of phosphorus at the water-sediment interface. Based on the water-soluble reactive phosphorus concentrations of the microcosms, it will be possible to calculate the rate of P release from the sediment to the water column before and after resuspension events.
7	TEREZA CATRINA FERREIRA FERNANDES CÂMARA EROSIVE PROCESS AND COASTAL DEFENSES OF THE BEACHES OF PONTA NEGRA AND VIA COSTEIRA, NATAL/RN: A STRUCTURAL AND ENVIRONMENTAL ANALYSIS Advisor : VENERANDO EUSTAQUIO AMARO COMMITTEE MEMBERS : ANDRE LUIS SILVA DOS SANTOS MARIA DEL PILAR DURANTE INGUNZA VENERANDO EUSTAQUIO AMARO Data: May 31, 2023 Ata de defesa assinada: Show Abstract Coastal agents such as waves, nearshore currents, winds and tides are capable of transporting sediments from one place to another, to generate a positive or negative sediment balance in coastal areas. Ponta Negra beach and part of Via Costeira in Natal/RN suffer erosion and their sediment supply is compromised due to disorderly urbanization from the 1990s onwards. Several problems were installed on the beach caused by the energy of the waves, which no longer had space to dissipate, since urbanization advanced on the beaches and solidified an environment that was still part of a dynamic process. As it is one of the biggest tourist places in the city of Natal, the region attracted the government's attention to the elaboration of a beach recovery plan with the implementation of new coastal defense works: sediments replacement, containment structure and adequacy of the rainwater drainage system that flows into the beach face. This work analyzes the coastal erosion status and evaluates the coastal defense works implemented and in planning at Ponta Negra beach and Via Costeira. Making use of satellite images, LANDSAT and Sentinel-2, and geoprocessing tools such as CASSIE and QGIS, it was possible to perform the automatic extraction of shorelines and verify the sedimentary balance in area in the long (last 30 years) and medium term (last 06 years) area. The study also analyzes the pathologies of the coastal protection works installed since 2012 and the weaknesses that they will cause to the process of fattening the beach. With geoprocessing, Ponta Negra Beach faces continuous erosion and the Via Costeira is still a region considered stable. About beach recovery projects, there is a lack of integration and harmony between them, which favors the emergence of flaws in the definition of relevant points for the proper functioning of the recovery work.
8	ROMÁRIO STÉFFANO AMARO DA SILVA Geotechnical analysis of platforms for large crane operation Advisor : OLAVO FRANCISCO DOS SANTOS JUNIOR COMMITTEE MEMBERS : ENIO FERNANDES AMORIM OLAVO FRANCISCO DOS SANTOS JUNIOR OSVALDO DE FREITAS NETO RAIMUNDO LEIDIMAR BEZERRA Data: Jun 9, 2023 Show Abstract The use of large crawler cranes in engineering projects introduces several complexities to the scope of the projects. In this context, the preparation of operational platforms capable of providing the necessary safety and functionality for the equipment to perform its activities stands out. These platforms must be constructed based on specific geotechnical analyses. International practice demonstrates that such analyses are developed by considering the crane's load on soil layers as similar to the case of direct foundations resting on the surface of a terrain. Thus, geotechnical investigation and design methods are adapted from foundation engineering. However, in Brazil, projects of this nature are usually developed from a perspective derived from highway engineering, which is not the most suitable for this type of situation. In this context, this thesis presents a discussion about the main aspects associated with international and national practices regarding the design and execution of platforms for operating large crawler cranes. It particularly focuses on the most commonly used geotechnical investigation and design methods. Based on these discussions, a methodology is proposed for the development of geotechnical investigation plans and design methods applicable to operational platforms for large crawler cranes, specifically adapted to the Brazilian context. Additionally, two examples of design sequences are presented using the proposed methodology. These examples illustrate how aspects such as the magnitude of the load and the geometry of the support elements influences the analyses.
9	ALLAN BENÍCIO SILVA DE MEDEIROS Stability of dams for water accumulation in Brazil subjected to seismic loads: case study of Armando Ribeiro Gonçalves dam Advisor : OSVALDO DE FREITAS NETO COMMITTEE MEMBERS : FRANCISCO CHAGAS DA SILVA FILHO OLAVO FRANCISCO DOS SANTOS JUNIOR OSVALDO DE FREITAS NETO RICARDO NASCIMENTO FLORES SEVERO Data: Jun 9, 2023 Show Abstract Dams are extremely important, and it is necessary to guarantee their integrity and stability in adverse conditions, exemplified by earthquakes. The seismic evaluation can be carried out by several methods, highlighting the pseudo-static methodology. The applicability of this method depends on the ability to define representative horizontal and vertical reference levels. In Brazil, the ANA allows the application of fixed coefficients, defined disregarding seismic regionality. The northeast region of Brazil presents a relevant seismic risk, having the Açu dam as one of its most important dams. Pseudo-statics were analyzed with the Açu dam, adopting determination decisions in different ways. When inclined to those suggested by ANA, the dam showed stability, with FS close to 1.4. However, when applied the methodology proposed by Cruz et al. (2021), the dam has evaluable stability considering return times of 475 and 975 years, and evaluable instability considering return times of 2,475 and 10,000 years. It was noticed that verification by the ANA is capable of representing smaller scale events, which may not guarantee an adequate level of safety depending on the location in Brazil, suggesting the use of other methodologies to define these homologation coefficients in dams.
10	FRANCISCO SOARES ROQUE INFLUENCE OF BASIN TRANSPOSITION ON THE OPERATION OF WATER SYSTEMS IN SEMI-ARID REGIONS Advisor : JOANA DARC FREIRE DE MEDEIROS COMMITTEE MEMBERS : JOANA DARC FREIRE DE MEDEIROS ADELENA GONCALVES MAIA ALEX PINHEIRO FEITOSA Data: Aug 2, 2023 Ata de defesa assinada: Show Abstract Water scarcity is a recurring problem in semi-arid regions, mainly due to the low incidence of precipitation and high evapotranspiration, which result in reduced water availability and low reliability for the supply of water demands. In this scenario, water transposition projects between hydrographic basins are an important solution to guarantee access to water for the population of these regions. The present work aims to define technical criteria for the operation of water systems that receive water from transposition projects, in semi-arid regions, in order to achieve greater guarantee in meeting the demands for water with the lowest input of exogenous waters. For this, the hydrological states of the reservoirs that make up the water system under study and that trigger the need for water transfer will be defined, in addition to optimizing the transferred volumes that result in the greatest synergistic gain in the use of water resources in the system. This research will be developed in a stretch of the Apodi-Mossoró river, between the water delivery portal of the São Francisco River Integration Project (PISF) and the Santa Cruz do Apodi dam, in the state of Rio Grande do Norte. Different scenarios of operation of the reservoirs that make up this water system will be simulated, adopting the operating rule of the Guide Curve method based on zones. Thus, it is expected with this research to define operating rules that best suit the proposed scenarios for the water system, in order to enable the minimization of deficits in meeting the demands requested in this region, as well as the reduction of losses due to overflow and evaporation. in the reservoirs, generating benefits in terms of access to water in this semi-arid region.
11	IGOR JOSÉ NASCIMENTO DE MEDEIROS ANALYSIS OF THE EFFICIENCY OF RAINWATER ACCUMULATION SYSTEMS CONSIDERING THE VARIABILITY OF RAINFALL REGIMS IN RIO GRANDE DO NORTE AND EXTERNAL WATER SUPPLY SCENARIOS Advisor : LUCIO FLAVIO FERREIRA MOREIRA COMMITTEE MEMBERS : LUCIO FLAVIO FERREIRA MOREIRA ADELENA GONCALVES MAIA José Anderson do Nascimento Batista LUCIANA PEIXOTO AMARAL Data: Aug 24, 2023 Ata de defesa assinada: Show Abstract The Brazilian semi-arid region suffers from water scarcity in much of its territory. In this way, it is necessary to use several alternatives of water sources so that there is a balance between demand and water supply, in addition to seeking to increase its availability. The use of Rainwater Storage Systems (SAAC) has been widely adopted to increase water supply, especially in regions with high water shortages and irregularities in the distribution of precipitation. The study will be implemented for several locations inserted in regions with homogeneous rainfall regimes in the State of Rio Grande do Norte. Thus, taking these factors into account, the present work aims to analyze the temporal characteristics of the rain that occurs in each homogeneous area and to verify the efficiency of the water storage system for different combinations of demand, water catchment area and volume of water. reservoir. In addition, an analysis will be made for different rules of water supplementation by an external source supplied by water trucks in dry periods and, thus, seek to propose measures to increase the efficiency of the rainwater storage system (SAAC) characterized by the cistern. In this way, it will be possible to verify the influence between the factors of reservoir volume, roof area, water demand for human consumption and frequency of water supply from the water truck, on the efficiency of the system.
12	MARIA DE LOURDES XAVIER DE FRANÇA NETA ALVES PHYSICAL AND MECHANICAL CHARACTERIZATION OF WOOD SPECIES FROM THE CAATINGA FOR USE IN CIVIL CONSTRUCTION Advisor : KLEBER CAVALCANTI CABRAL COMMITTEE MEMBERS : EDNA MOURA PINTO KLEBER CAVALCANTI CABRAL MARCOS ALYSSANDRO SOARES DOS ANJOS WENDELL ROSSINE MEDEIROS DE SOUZA Data: Aug 25, 2023 Show Abstract The civil construction sector has continuously sought materials that have a lower impact on the built environment, for this reason the use of wood has become attractive because it is a natural and renewable material. Knowledge of physical and mechanical properties is essential to classify new species and indicate their constructive component use. In the Northeast region of Brazil, the Caatinga biome stands out for its biodiversity as the only fully national biome. However, the physical and mechanical properties of the local species are little known and investigated and therefore their application becomes limited, being commonly used for energy purposes. With this, the study seeks to characterize the species Mimosa Tenuiflora and Aspidosperma Piryfolium native to the Caatinga biome and indicate potential uses in civil construction. Physical tests were performed to determine moisture (U), density ( ), apparent density ( ), dimensional stability ( , ΔV) and thermal conductivity; mechanical tests of compression parallel to the fibers (fc0), parallel and perpendicular shearing (fv0, fv90), traction parallel and perpendicular to the fibers (ft0, ft90), Janka hardness parallel and perpendicular (fH0, fH90), static bending (fM0) and elastic modulus test by non-destructive methods by ultrasound, stress waves and longitudinal and flexural excitation. The Shapiro-Wilk test and the Pearson correlation between physical and mechanical properties were used. The indication of applications of the species was carried out through the classification proposed by the IPT (2013) and IPT/SUDAM (1981), using the criteria of Nahuz (1974) and Nogueira (1991). The results show the species Mimosa Tenuiflora with 13 correlations and Aspidosperma Piryfolium with 19 representative correlations between physical and mechanical properties. Both species have equivalent properties to the commercialized species for constructive use, Aspidosperma Piryfolium can be used in light civil construction. Meanwhile, Mimosa Tenuiflora can be used in light and heavy civil construction.
13	WILKER FERNANDES SOARES ANALYSIS OF THE UNCERTAINTIES OF THE EFFICIENCY OF RAINWATER USE SYSTEMS: climate changes, demand, cistern capacity and catchment area Advisor : ADELENA GONCALVES MAIA COMMITTEE MEMBERS : ADELENA GONCALVES MAIA JONATHAN MOTA DA SILVA LUCIO FLAVIO FERREIRA MOREIRA LUIS CÉSAR DE AQUINO LEMOS FILHO Data: Aug 28, 2023 Ata de defesa assinada: Show Abstract The use of rainwater in homes is used as an attenuator of the problems of low water demand, especially in semi-arid or remote regions. This research has the general objective of analyzing the effects of epistemic uncertainties on the water balance of cisterns located in the Brazilian semi-arid region. Thus, to achieve this objective, the Monte Carlo Simulation method was applied, having as input variables the reservoir volume, water demand, catchment area and rainfall, under the effects of climate change, and as a variable output, the performance index called volumetric cistern reliability. For the consideration of climate change, two distinct periods were considered: the recent climate (1979 – 2005) and the future climate (2023 – 2052), using three Global Climate Models, under two radiative forcing scenarios (RCP 4.5 and CPR 8.5). The obtained results indicate low volumetric reliabilities in all simulations, however, even with all the uncertainties, both in the recent climate and in the future climate, the highest efficiency indexes are obtained with the observed precipitation data. The highest frequency of simulations that reached a reliability of 90% occurred for the recent climate, with the observed data, and the lowest frequency happened for the future climate with one of the models under RCP 4.5, however, greater differences are found for lower efficiencies .
14	ISABELLA LEANDRO SOARES PEREIRA Comparison of direct downward filtration with double filtration in the removal of humic substances from the water of a tropical coastal lagoon. Advisor : SILVÂNIA LUCAS DOS SANTOS COMMITTEE MEMBERS : ANDRE LUIS CALADO ARAUJO HELIO RODRIGUES DOS SANTOS PAULO EDUARDO VIEIRA CUNHA SILVÂNIA LUCAS DOS SANTOS Data: Aug 30, 2023 Ata de defesa assinada: Show Abstract The presence of natural organic matter (NOM) in water sources used for public supply influences the performance of water treatment units (oxidation, coagulation and adsorption). The quantity, characteristics and properties of NOM vary among waters from different sources and depend on the biogeochemical cycles of the surrounding environments. Water sources such as Brazilian coastal lagoons typically have low turbidity, so NOM is a determining factor in the coagulant dose. In these water sources, water treatment in a complete cycle is generally not efficient, as the flocs produced in the coagulation/flocculation are light, and the technologies of downflow direct filtration or upflow direct filtration are more suitable. Despite this, some tropical coastal lagoons may have high turbidity (and color) values, due to intense tropical rains and the anthropic degradation of the basin of these water sources, so the use of double filtration can be advantageous, as it can provide greater capacity to retain particles and NOM, increasing the robustness of the treatment system. However, the operation of more filtration units implies higher operational demand, higher consumption of washing water, electricity, etc., which may result in higher treatment costs. In this research, laboratory-scale and pilot-scale treatability tests of downflow direct filtration and double filtration with water from a tropical coastal lagoon will be carried out, with the objective of comparing these two systems for water treatment with emphasis on the NOM removal.
15	MÔNICA KASSIANE DE ALMADA OLIVEIRA MODELING SOIL CONSERVATION PRACTICES IN A SEMI-ARID WATER BASIN VULNERABLE TO DESERTIFICATION Advisor : JONATHAN MOTA DA SILVA COMMITTEE MEMBERS : JONATHAN MOTA DA SILVA ADELENA GONCALVES MAIA DAVI RODRIGUES RABELO SANDRA ISAY SAAD Data: Aug 30, 2023 Ata de defesa assinada: Show Abstract Water erosion is a natural phenomenon that can separate the soil into smaller particles, being transported by surface runoff to deposition in more flattened areas. Soil use and management based on conservation practices reduce the effects of water erosion and can be evaluated using hydrosedimentological modeling. Studies in this area are essential to analyze impacts of change and land use and/or desertification, which expands significantly in the Brazilian semi-arid region. In this sense, the objective of this work was to evaluate the effects of two widely used conservationist practices, terracing and dams, in the containment of erosion and sediment production in the hydrographic basin of the Seridó river. The tool used in this analysis was hydrosedimentological modeling, where three numerical experiments were carried out: (1) control (CNTRL), where natural soil cover and long-term desertification were represented; and scenarios of soil conservation practices: (2) terracing (TERR) and (3) dams (BARR). In general, dams (BARR) showed greater efficiency in reducing erosion and sediment production compared to the efficiency of terraces (TERR), 47% more effective, where sediment production, respectively, was equal to 0, 8 ton/ha/year and 1.2 ton/ha/year, compared to the control scenario (CONTRL), where it was 3.2 ton/ha/year. Terracing and dams considerably reduced soil loss in a watershed undergoing desertification. These practices should also be evaluated in the field, experimentally, in order to assess their applicability in the process of mitigating soil loss due to desertification, as well as calibrating and validating hydrosedimentological models. Advances in this area can help guarantee food security and water quality in the Brazilian semi-arid region.
16	THÂMARA DAYANE BATISTA ALVES APPLICABILITY OF LOW IMPACT URBAN DEVICES IN TROPICAL URBAN BASINS. Advisor : ADA CRISTINA SCUDELARI COMMITTEE MEMBERS : ADA CRISTINA SCUDELARI JEAN LEITE TAVARES JOANA DARC FREIRE DE MEDEIROS Data: Aug 30, 2023 Show Abstract Os sistemas de drenagem urbana convencionais não são construídos para acompanhar a urbanização rápida e descontrolada, tornando-se ineficientes na coleta e descarga do escoamento produzido por eventos de chuvas intensas, fazendo com que ocorram inundações. Além disso, as chuvas intensas provavelmente sofrerão interferências das mudanças climáticas em longo prazo, de modo que existe a necessidade de revisão dos critérios de projeto para sistemas de drenagem urbana de acordo com os cenários climáticos esperados. A fim de mitigar as falhas nos dispositivos de drenagem convencionais e garantir uma maior resiliência da drenagem urbana frente às mudanças climáticas vem-se empregando uma concepção descentralizada de infraestrutura de drenagem urbana: os dispositivos urbanos de baixo impacto (Low Impact Development – LID) como telhados verdes, pavimentos permeáveis, trincheiras de infiltração e micro reservatórios, que objetivam simular o comportamento hidrológico natural da bacia para controlar as vazões de pico no escoamento superficial. Embora os benefícios hidrológicos dos LIDs tenham sido amplamente documentados, os potenciais impactos das mudanças climáticas no desempenho desses dispositivos, permanecem desconhecidos nas modelagens, gerando conclusões parciais e isoladas sobre o comportamento futuro de dispositivos da drenagem urbana. Dessa forma, este trabalho tem como objetivo avaliar a aplicabilidade da associação dos LIDs aos sistemas de drenagem convencionais em mitigar inundações em bacias urbanas tropicais.
17	THALITA DAYANE DE MELO MENDES SABINO Evaluation of physical-chemical, mechanical and thermal properties of LC³ mortars with low Portland cement contents. Advisor : ANA CECILIA VIEIRA DA NOBREGA COMMITTEE MEMBERS : ANA CECILIA VIEIRA DA NOBREGA MARIA DAS VITORIAS VIEIRA ALMEIDA DE SA ANTONIO EDUARDO MARTINELLI ERIKA PINTO MARINHO Data: Aug 31, 2023 Ata de defesa assinada: Show Abstract LC3 (Limestone Calcined Clay Cement) mortars with different Portland cement contents (PC) (100%, 55%, 50%, 45%, and 40%) and a combination of metakaolin (MK) and limestone filler (LS) (0%, 45%, 50%, 55%, and 60%) in a 2:1 ratio were evaluated regarding their fresh, hygroscopic, mechanical, and thermal properties. LC3 mortars with as low as 40% Portland cement contents satisfied the normative requirements for applying on walls and ceilings. In addition, the incorporation of MK and LS for reducing PC consumption generated mortars with lower densities, reflecting in lighter materials with improved thermal insulation capacity with a reduction up to 4 ºC of the equilibrium plateau temperature for mortars LC3 – 55, LC3 – 50, LC3 - 45, and 2.5 ºC for the mortar with the lowest PC content (LC3 - 40).
18	JOSÉ AILTON DA COSTA FERREIRA Multicriteria dam safety risk assessment model based on fuzzy logic Advisor : OSVALDO DE FREITAS NETO COMMITTEE MEMBERS : FAGNER ALEXANDRE NUNES DE FRANCA OLAVO FRANCISCO DOS SANTOS JUNIOR OSVALDO DE FREITAS NETO ROGÉRIO DE ABREU MENESCAL Data: Nov 29, 2023 Ata de defesa assinada: Show Abstract Dams are water structures that contribute to the socioeconomic development of a region. However, the absence of adequate safety procedures increases the risk of failures with the potential to cause significant impacts to downstream areas. This work developed a fuzzy safety risk assessment methodology for water accumulation dams located in the semi-arid region of Brazil. The fuzzy hierarchical analytical process (FAHP) was used to obtain the weight of the indicators and the aggregated scores corresponding to the vulnerability and potential harm criteria. In the fuzzy inference phase, the system was divided into two stages to obtain a more representative model. In the first step, vulnerability was estimated using conditional IF-THEN statements to estimate the combined effect of technical characteristics, conservation status, and security plan. Then, the defuzzified vulnerability values were combined with the potential harm to estimate the resulting potential risk. When comparing the results obtained by the proposed model with the CNRH classification regarding the CRI, it was observed that the studied dams were categorized into equivalent classes. As for the periodicity, deadlines and frequency based on the proposed danger scale, they were more rigorous than those of the ANA and allowed the establishment of priorities for safety procedures, such as monitoring and sensing, appropriate to the situations encountered in the field. Therefore, the proposed model allowed incorporating the uncertainties of the specialists' subjective judgments into the decision-making process and can be inserted as an improvement in the normative assessment to estimate the risk of dams with similar characteristics.
19	PAULA DE MOURA ESTEVAO PEROBA Mechanical Behavior of Compacted Gabbroic Residual Soil Advisor : OLAVO FRANCISCO DOS SANTOS JUNIOR COMMITTEE MEMBERS : OLAVO FRANCISCO DOS SANTOS JUNIOR MARIA DEL PILAR DURANTE INGUNZA OSVALDO DE FREITAS NETO LEONARDO FLAMARION MARQUES CHAVES RICARDO NASCIMENTO FLORES SEVERO Data: Nov 29, 2023 Ata de defesa assinada: Show Abstract The mechanical behavior of a saprolitic soil, originating from gabroic rock formations covering an area of approximately 31 km² in a semi-arid region of Brazil, was investigated. The study involved the collection of data from petrographic, chemical (XRF), and mineralogical (XRD) analyses, as well as a series of physical (geotechnical characterization and compaction), hydraulic (permeability), and mechanical (triaxial and consolidation) tests. The results indicated that the soil originates from a gabronorite and exhibits non-plastic behavior, low permeability and low compressibility, with SUCS classification of SW-SM. During compaction tests, the soil displayed a propensity for grain breakage; however, it was not possible to fully characterize this phenomenon within the scope of the conducted tests. The mechanical tests revealed that the yield stress imposed by compaction made the soil's behavior resemble that of an overconsolidated soil. This led to the generation of negative pore pressures, increasing the soil's strength in undrained tests, and a dilatant behavior in drained tests, where the dilatant tendency decreased as the effective confining stress increased. Under higher confinement stresses, the behavior shifted to a contractive state, and reaching peak strength was followed by a significant reduction in strength due to the continuous increase in positive pore pressure – an unfavorable trend for certain geotechnical applications, as it indicates a predisposition to static soil liquefaction under confining stresses exceeding the critical threshold.
20	NICOLLE REGINA CRISTINO BELFORT GUERRA MIXTURE OF SOIL AND ASH FROM INCINERATION OF WASTE SERVICESHEALTH FOR USE IN FINAL COVERAGE OF LANDFILLS Advisor : MARIA DEL PILAR DURANTE INGUNZA COMMITTEE MEMBERS : MARIA DEL PILAR DURANTE INGUNZA OSVALDO DE FREITAS NETO FAGNER ALEXANDRE NUNES DE FRANCA RICARDO NASCIMENTO FLORES SEVERO Data: Nov 30, 2023 Ata de defesa assinada: Show Abstract In accordance with recent changes in Brazilian legislation, all production processes are now required to account for the byproducts resulting from their operations and consider potential alternatives for appropriate disposal before resorting to sanitary landfills. Under this principle, the current study has delved into examining the properties of incineration bottom ashes from Healthcare Waste in a facility located in Paraíba. The aim is to assess the viability of utilizing these ashes in the impermeable barrier layers of the final cover of sanitary landfills. To achieve this objective, geotechnical and chemical-mineralogical composition tests were conducted to determine whether the material meets the necessary criteria for the proposed application. Mixtures were prepared using the soil typically used for the final cover of sanitary landfills, incorporating varying mass proportions of HMW ashes. Notably, all these mixtures displayed a saturated permeability coefficient in the order of 10^-7 m/s, approximating the hydraulic conductivity values to those recommended in the existing literature.
21	MARIA ELIZABETH TEIXEIRA SANTANA PRAXEDES EVALUATION OF THE ELECTRICAL PROPERTIES OF CONVENTIONAL MASONRY WALLS IN THE MICROWAVE RANGE BY A NON-DESTRUCTIVE METHOD Advisor : KLEBER CAVALCANTI CABRAL COMMITTEE MEMBERS : CRISTHIANNE DE FATIMA LINHARES DE VASCONCELOS ERICA NATASCHE DE MEDEIROS GURGEL PINTO KLEBER CAVALCANTI CABRAL WENDELL ROSSINE MEDEIROS DE SOUZA Data: Dec 15, 2023 Ata de defesa assinada: Show Abstract The propagation characteristics of microwave signals, such as power loss and speed, in buildings significantly determine the operational performance of mobile devices inside buildings. These characteristics are determined by the electrical properties of the walls that make up the masonry of these buildings. Most current communication is carried out through signals that propagate wirelessly and can suffer interference in environments built with different materials, which is a relevant problem, especially in smart buildings. Therefore, evaluating the power loss caused by the main materials used in masonry, as well as the electrical properties of these materials, is fundamental for the design of indoor wireless communication links. In this sense, this research aims to evaluate the attenuation of microwave signals and the electrical properties of different materials used in building masonry (ceramic blocks, concrete blocks and plaster walls). Three wall samples were produced from each of these materials for characterization purposes regarding their structure, microstructural organization and electrical properties. The attenuation in the wireless signal caused by each type of material, and the electrical properties such as electrical permittivity, shielding efficiency and electrical conductivity were determined using an experimental measurement scheme proposed in this work. Average values for attenuation coefficients as a function of frequency for the operating range of the main 5G and Internet of Things (IoT) services were obtained. Furthermore, the dependence of wireless signal attenuation on the type of material and its composition and the influence of the type of wall covering on signal attenuation were evaluated. The results indicated that walls made of ceramic blocks caused the greatest attenuation of the signal, among all types of masonry analyzed; while plaster walls were those that caused the least attenuation. When comparing non-structural block masonry, it appears that cement block walls showed lower attenuation when compared to ceramic block walls. After analyzing the micrographs of the ceramic and cement blocks, it can be stated that the higher the void index and the porosity of the material the wall was manufactured from, the lower the value of its electrical permittivity and consequently the lower the attenuation caused in the wireless signals in today's commercial service bands.