Estudo das técnicas de tomografia ultrassônica e radar de penetração com contribuição em metodologia de inspeção de obras de concreto

• Autor(a) principal: Leonel, Antônio Carlos Assis
• Data de Publicação: 2022
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFG
• Texto Completo: http://repositorio.bc.ufg.br/tede/handle/tede/12843
• topic: Inspeções; Ensaios não destrutivos; Concreto; Tomografia ultrassônica; Radar GPR; Inspections; Non-destructive testing; Concrete; Ultrasonic tomography; GPR radar; ENGENHARIAS::ENGENHARIA CIVIL::CONSTRUCAO CIVIL::PROCESSOS CONSTRUTIVOS

Periodic inspection programs are essential for planning preventive and corrective maintenance in a timely manner, making financial contributions and hiring technical and engineering staff, and avoiding structure collapses, huge monetary losses and social disturbances. Allied to these needs for maintenance actions, modern non-destructive testing methods are important tools for monitoring the integrity of these structures, offering quantitative and qualitative parameters that help the inspector's analysis. Given this context, this work proposes to evaluate the applicability of non-destructive tests for detecting damage in concrete structures, mainly ultrasonic tomography and GPR radar tests and, based on quali-quantitative parameters, propose the improvement of a methodology pre-existing infrastructure dedicated to large Brazilian infrastructure works such as dams, hydroelectric plants and wind farms, considering their degree of deterioration. The proposed experimental program foresees the laboratory production and molding of two structural concretes used in infrastructure works, with strength classes C25 and C45, under two curing conditions: air and humid. In these concretes, the basic characterization of the constituent materials and physical and mechanical characterization were carried out with the use of tests of compressive strength, modulus ofelasticity, water absorption by immersion and voids index and non-destructive tests (rebound hammer, ultrasonic wave velocity and surface electrical resistivity and volumetric) from 1 to 28 days. The potential use of ultrasonic tomography and GPR radar tests was also verified to identify bars and tubes inside blocks, analysis of defects generated in plates and cracking in slabs. As a result, it was possible to obtain good correlations between destructive and non- destructive tests, with coefficients of determination R 2 , mostly above 0.9. The smallest correlations obtained (on the order of 0.7 to 0.79) refer to the results of electrical resistivity of concrete submitted to dry curing in air. Regarding the verification of defects and damages in the C25 and C45 concretes, the GPR radar proved to be efficient to locate reinforcement and defects of greater magnitude. The use of ultrasonic tomography, on the other hand, proved to be useful to analyze different homogeneities, detect internal voids in small and medium-sized concrete structures, in addition to being able to act in the detection of reinforcement. However, none of the techniques could be able to accurately identify concrete cold joints. Thus, each situation in which these cutting-edge techniques are used must be precisely analyzed, depending on the test conditions and the expected results, since on many occasions it is up to the operator to interpret what is presented to him by the images generated by the radar and tomography. Finally, a proposal has been presented to change the GDE UNB methodology, with the recommendation of inserting some non-destructive tests, as well as the addition of new weighting and intensity factors to be considered, in order to compose a methodology focused on the damage analysis adapted to the situations of large infrastructure works.