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Avaliação de características físicas e mecânicas de diversos materiais através de ensaios não destrutivos
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A garantia da segurança estrutural e da eficiência econômica na construção civil impulsiona a adoção de Ensaios Não Destrutivos (NDT) para a monitorização e avaliação da homogeneidade de componentes sem comprometer a sua integridade. O presente estudo tem como objetivo principal avaliar a aplicabilidade da técnica de Velocidade de Pulso Ultrassônico (UPV), recorrendo a transdutores de 54 kHz e transdutor tipo scanner, dotado da tecnologia de pulso eco, na caracterização física e mecânica de três materiais distintos: betão, madeira e rocha granítica. A campanha experimental combinou medições ultrassônicas, unindo resultados de transmissões diretas, semidiretas e indiretas, com esclerometria, ensaios de arrancamento e estimativa de fendas, sendo todos os provetes submetidos à rutura por compressão axial para validação dos modelos. No betão, a transmissão direta revelou uma elevada fiabilidade preditiva, com R² = 0,9408 para regressões polinomiais, e o método SonReb obteve um erro médio de estimativa para 6,64%, demonstrando a eficácia da combinação de dois métodos não destrutivos na predição da resistência à compressão do betão. Relativamente à madeira, mapeou-se o seu comportamento anisotrópico através de varreduras triaxiais. Por fim, a caracterização do granito evidenciou as limitações dos NDT perante a influência da orientação dos cristais, registando coeficientes de determinação menores que 0,3 na relação entre UPV e fc, e erro médio de 13,97% na metodologia SonReb.
The assurance of structural safety and economic efficiency in civil construction has encouraged the adoption of Non-Destructive Testing (NDT) techniques for the monitoring and assessment of material homogeneity without compromising their integrity. The main objective of this study is to evaluate the applicability of the Ultrasonic Pulse Velocity (UPV) technique, using 54 kHz transducers and a scanner-type transducer equipped with pulse-echo technology, for the physical and mechanical characterization of three distinct materials: concrete, wood, and granite rock. The experimental campaign combined ultrasonic measurements, including direct, semi-direct, and indirect transmission methods, with rebound hammer testing, pull-out tests, and crack depth estimation. All specimens were subsequently subjected to axial compression failure tests in order to validate the proposed models. For concrete, direct transmission demonstrated high predictive reliability, with an R² = 0.9408 for polynomial regressions, while the SonReb method achieved an average estimation error of 6.64%, demonstrating the effectiveness of combining two non-destructive techniques in predicting the compressive strength of concrete. Regarding wood, its anisotropic behavior was mapped through triaxial scanning procedures. Finally, the characterization of granite highlighted the limitations of NDT techniques due to the influence of crystal orientation, with coefficients of determination lower than 0.3 in the relationship between UPV and compressive strength, and an average error of 13,97% for the SonReb methodology.
The assurance of structural safety and economic efficiency in civil construction has encouraged the adoption of Non-Destructive Testing (NDT) techniques for the monitoring and assessment of material homogeneity without compromising their integrity. The main objective of this study is to evaluate the applicability of the Ultrasonic Pulse Velocity (UPV) technique, using 54 kHz transducers and a scanner-type transducer equipped with pulse-echo technology, for the physical and mechanical characterization of three distinct materials: concrete, wood, and granite rock. The experimental campaign combined ultrasonic measurements, including direct, semi-direct, and indirect transmission methods, with rebound hammer testing, pull-out tests, and crack depth estimation. All specimens were subsequently subjected to axial compression failure tests in order to validate the proposed models. For concrete, direct transmission demonstrated high predictive reliability, with an R² = 0.9408 for polynomial regressions, while the SonReb method achieved an average estimation error of 6.64%, demonstrating the effectiveness of combining two non-destructive techniques in predicting the compressive strength of concrete. Regarding wood, its anisotropic behavior was mapped through triaxial scanning procedures. Finally, the characterization of granite highlighted the limitations of NDT techniques due to the influence of crystal orientation, with coefficients of determination lower than 0.3 in the relationship between UPV and compressive strength, and an average error of 13,97% for the SonReb methodology.
Descrição
Mestrado de dupla diplomação com a UTFPR - Universidade Tecnológica Federal do Paraná
Palavras-chave
Ensaios não destrutivos Velocidade de pulso ultrassônico Betão Madeira Granito