https://repositorio.ufpb.br/jspui/handle/tede/5433 PPGECAM 2026-09-11T05:07:00Z https://repositorio.ufpb.br/jspui/handle/123456789/38817 Título: Estudo do potencial piezoresistivo de argamassas de cal e metacaulim utilizando o pó de grafite Autor(es): Monteiro, Héllykan Berliet Dos Santos Orientador: Nóbrega, Aline Figueiredo da Abstract: Lime has been widely used as a construction material since ancient times across the world. Currently, lime- and pozzolan-based materials are frequently employed in the repair of historical structures. In recent years, research has emphasized the importance of continuous monitoring of ancient buildings to assess structural health. In this context, the incorporation of conductive fillers, such as carbon fibers or nanotubes, graphite, carbon black, or graphene oxide, has enabled the development of concrete with self-sensing capabilities. By means of electrical resistivity measurements, it becomes possible to monitor the material's integrity, allowing for the detection of damage and crack formation. Furthermore, these composites often exhibit piezoresistive behavior, a property that correlates variations in electrical resistivity with their state of stress and strain. However, these materials are not fully compatible with heritage structures, and studies on restoration lime mortars reinforced with piezoresistive materials remain in an early stage, with several knowledge gaps still to be addressed. The present work aims to investigate lime–pozzolan mortars incorporating graphite powder with respect to their piezoresistive properties for application in historical constructions. Lime–metakaolin pastes were produced with graphite powder contents of 0%, 1%, 5%, and 10% to evaluate physical, mechanical, and piezoresistive properties. Based on the results, the compositions that exhibited the most promising piezoresistive behavior were identified. Among these, mixtures containing 70% and 80% lime were selected for mortar production with a binder-to-sand ratio of 1:3 by mass. Subsequently, mechanical and electrical resistivity tests were carried out. The results revealed a relationship between density and electrical resistivity, with resistivity increasing as moisture content decreased. Regarding compressive strength, higher metakaolin content led to improved mechanical performance. In terms of piezoresistive behavior, mortars with graphite powder additions demonstrated promising performance, exhibiting increasing linearity and sensitivity with higher applied stress levels. Overall, the findings indicate that incorporating graphite powder significantly enhances the piezoresistive properties of lime-based mortars while maintaining mechanical and chemical compatibility with historical structures, thus offering strong potential for applications in restoration and structural health monitoring. Editor: Universidade Federal da Paraíba Tipo: Tese 2025-08-28T00:00:00Z https://repositorio.ufpb.br/jspui/handle/123456789/38539 Título: Concreto permeável contendo resíduos de caulim e metacaulim: propriedades físicas, hidráulicas, mecânicas e adsortivas Autor(es): Bezerra, Diego de Paiva Orientador: Nóbrega, Aline Figueirêdo da Abstract: The intensification of urban soil impermeabilization has aggravated problems related to drainage and stormwater quality, requiring construction techniques capable of simultaneously performing hydraulic, structural, and environmental functions. In this context, the concept of multifunctional performance of pervious concrete stands out, being associated with the ability to combine hydraulic permeability, mechanical strength, and adsorptive capacity within a single material. From this perspective, kaolin residues, both in the fine fraction (FKR) and coarse fraction (CKR), present potential for application in pervious concrete mixtures, since kaolin-based materials are recognized for their adsorptive capacity. In addition, it is estimated that, for every ton of processed kaolin, approximately 80% becomes waste. This scenario represents a significant environmental liability due to the occupation of large disposal areas and the environmental degradation associated with mining activities, causing impacts on soils and adjacent water bodies. Given this context, this study evaluated the multifunctional performance of pervious concretes containing metakaolin, FKR, and CKR through an integrated experimental approach, including mechanical, hydraulic, and adsorption analyses of metallic ions (Al³⁺ and Fe²⁺) present in simulated contaminated stormwater. Initially, the chemical, mineralogical, physical, and morphological characterization of the materials was performed. Subsequently, the study was developed based on a preliminary analysis of cement pastes containing metakaolin replacements and additions (10% and 20%) relative to cement mass. The cement pastes with the best mechanical performance were later investigated in reference pervious concrete mixtures composed of natural aggregate and 10% and 20% metakaolin replacements relative to cement mass. Thereafter, concrete mixtures containing 10% metakaolin replacement relative to cement mass and additions of FKR and CKR at contents of 10%, 20%, 30%, and 40% relative to natural aggregate mass were analyzed. The pervious concretes were evaluated in both fresh and hardened states. Physical characterization included void ratio tests, two-dimensional image analysis obtained through Python programming, three-dimensional analysis using X-ray micro-computed tomography (micro-CT), texture analysis, and permeability tests. Mechanical properties were determined through compressive strength, flexural tensile strength, and abrasion mass loss tests. Additionally, durability against carbonation was evaluated. To integrate the different investigated properties, a multicriteria analysis based on dimensionless normalization was employed, allowing the identification of mixtures FKR10 and CKR10 as those presenting the best overall performance by balancing permeability, mechanical strength, and adsorptive capacity. The results demonstrated that additions of 10% FKR and CKR promoted moderate refinement of the paste–aggregate matrix, increased mechanical strength, and maintained permeability at adequate levels for pavements subjected to light traffic loads. In contrast, higher CKR contents (30% and 40%) resulted in mixtures with greater internal heterogeneity, less cohesive interfaces, and higher abrasion mass loss. The mixtures containing residues exhibited significant adsorptive performance during the initial hours of testing (First Flush), with Al³⁺ and Fe²⁺ removal efficiencies ranging from 25% to 48%. Therefore, based on the obtained results, it was possible to highlight that 10% contents of FKR and CKR may be considered the most technically viable for application in pervious concrete. Thus, the use of these residues may contribute to the circular economy, constituting a technically feasible and sustainable solution. Editor: Universidade Federal da Paraíba Tipo: Tese 2026-06-26T00:00:00Z https://repositorio.ufpb.br/jspui/handle/123456789/38244 Título: Modelagem da evapotranspiração usando balanço de energia e imagens de aeronaves remotamente pilotadas Autor(es): Oliveira Júnior, Marcos Elias de Orientador: Melo, Davi de Carvalho Diniz Abstract: Evapotranspiration (ET) encompasses both soil water evaporation and plant transpiration and is a key process in maintaining the water and energy balance at the Earth's surface. It is divided into three components: soil evaporation, canopy transpiration, and interception of water retained by the canopy. The Priestley-Taylor Jet Propulsion Laboratory (PT-JPL) model is widely used for ET estimation; however, it does not include a robust method for integrating thermal data obtained by UAVs. This study aims to map ET using meteorological data and aerial images acquired by UAVs in a sugarcane cultivation area in the northern coastal region of Paraíba, Northeast Brazil. Additionally, it proposes to evaluate how the QGIS plugin QWaterModel can be integrated into models such as PT- JPL to improve the accuracy of evapotranspiration estimates. To achieve this, a performance analysis was conducted comparing the ET simulated by the models (QWater and PT-JPL) with observed ET values from a flux tower installed in a sugarcane field in the coastal region of Paraíba between October 2022 and August 2023. By combining PT- JPL with QWaterModel, this study seeks to enhance ET estimation accuracy, particularly in an agricultural context such as a sugarcane field. Editor: Universidade Federal da Paraíba Tipo: Dissertação 2024-09-30T00:00:00Z https://repositorio.ufpb.br/jspui/handle/123456789/38099 Título: Estudo analítico-numérico de placas submetidas a ações pontuais e distribuídas em linha Autor(es): Siqueira, Ana Clara Ferreira Orientador: Mendonça, Ângelo Vieira Abstract: This work aims to discuss aspects of obtaining analytical and numerical solutions for plate problems, with or without elastic foundation support, subjected to point loads and/or line-distributed loads, using Kirchhoff and Mindlin plate theories. The analytical solutions for these problems were derived by manipulating the Dirac delta function (δ) for concentrated loads and the Heaviside function (H) for line distributions. Additionally, the strategies for obtaining the analytical solutions were based on the Levy and Navier methods. To enable numerical solutions for the plate problems, stiffness matrices associated with Winkler and Pasternak foundations were derived through mathematical manipulations compatible with the finite element formulations of DKT (Discrete Kirchhoff Triangle) and DST (Discrete Shear Triangle) elements, combined with linear or pseudo-consistent interpolations of transverse displacements within the element domain. Several analyzes were carried out involving different properties, boundary conditions and loading, the results of which were validated with analytical and/or numerical responses Editor: Universidade Federal da Paraíba Tipo: Dissertação 2025-07-31T00:00:00Z