Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
On the determination of cement content and type in hardened concrete using laser induced breakdown spectroscopy
The composition of concrete is a critical factor for the durability and safety of infrastructures. Accurate knowledge of the concrete composition is essential to assess the quality of the concrete, assessing potential structural damage, and formulating appropriate maintenance strategies. However, the composition of concrete in many existing structures is often undocumented, requiring retrospective analysis. Traditional analysis methods have several limitations, including their dependence on known chemical composition and solubility, elaborate sample preparation, time-consuming and labor-intensive procedures, and the need for either complete or partial destruction of the samples. Furthermore, their applicability in field situations is often limited. This thesis proposes the development of an alternative method using laser-induced breakdown spectroscopy (LIBS) for the identification of cement types and the quantification of cement content in hardened concrete. Two innovative methods for cement type identification are presented. The first method combines LIBS spectral features with supervised machine learning to develop a classifier model. This model is shown to be effective from pure cement paste to heterogeneous concrete. It successfully identified 14 out of 15 cement types in tests, although it requires suitable reference samples for training. The second method uses calibration-free LIBS (CF-LIBS), which bypasses the need for reference samples by comparing estimated chemical compositions with known cement types. While CF-LIBS offers the potential for rapid and accurate quantitative analysis in accordance with theoretical models, relative quantification errors of about 15 % are found on experimental spectra, resulting in the correct identification of only 2 out of 15 cement types. Therefore, CF-LIBS is presently considered inadequate for cement type determination. In order to estimate the cement content, a high spatial resolution probing method is developed that analyzes the spectra obtained from concrete samples in conjunction with stereology. This method is validated through tests conducted on both synthetic mesoscale models and actual concrete samples, taking into account variations in cement content and aggregate size distribution. The results confirm the effectiveness of the method, with an average relative error in cement content estimation of approximately 8 %. The thesis comprehensively discusses the advantages and limitations of these methods, including their practical applicability under field conditions. The methods developed in this research offer significant potential for improving infrastructure maintenance and safety by providing a deeper insight into the material composition of concrete.
On the determination of cement content and type in hardened concrete using laser induced breakdown spectroscopy
The composition of concrete is a critical factor for the durability and safety of infrastructures. Accurate knowledge of the concrete composition is essential to assess the quality of the concrete, assessing potential structural damage, and formulating appropriate maintenance strategies. However, the composition of concrete in many existing structures is often undocumented, requiring retrospective analysis. Traditional analysis methods have several limitations, including their dependence on known chemical composition and solubility, elaborate sample preparation, time-consuming and labor-intensive procedures, and the need for either complete or partial destruction of the samples. Furthermore, their applicability in field situations is often limited. This thesis proposes the development of an alternative method using laser-induced breakdown spectroscopy (LIBS) for the identification of cement types and the quantification of cement content in hardened concrete. Two innovative methods for cement type identification are presented. The first method combines LIBS spectral features with supervised machine learning to develop a classifier model. This model is shown to be effective from pure cement paste to heterogeneous concrete. It successfully identified 14 out of 15 cement types in tests, although it requires suitable reference samples for training. The second method uses calibration-free LIBS (CF-LIBS), which bypasses the need for reference samples by comparing estimated chemical compositions with known cement types. While CF-LIBS offers the potential for rapid and accurate quantitative analysis in accordance with theoretical models, relative quantification errors of about 15 % are found on experimental spectra, resulting in the correct identification of only 2 out of 15 cement types. Therefore, CF-LIBS is presently considered inadequate for cement type determination. In order to estimate the cement content, a high spatial resolution probing method is developed that analyzes the spectra obtained from concrete samples in conjunction with stereology. This method is validated through tests conducted on both synthetic mesoscale models and actual concrete samples, taking into account variations in cement content and aggregate size distribution. The results confirm the effectiveness of the method, with an average relative error in cement content estimation of approximately 8 %. The thesis comprehensively discusses the advantages and limitations of these methods, including their practical applicability under field conditions. The methods developed in this research offer significant potential for improving infrastructure maintenance and safety by providing a deeper insight into the material composition of concrete.
On the determination of cement content and type in hardened concrete using laser induced breakdown spectroscopy
Zur Bestimmung des Zementgehalt und -art in Festbeton mittels der laserinduzierten Plasmaspektroskopie
Völker, Tobias Alexander Matthias (Autor:in) / Technische Universität Berlin (Gastgebende Institution)
2024
Sonstige
Elektronische Ressource
Englisch
Zementart , LIBS , NDT , Zementgehalt , Spektroskopie LIBS , NDT , cement content , cement type , spectroscopy
DDC:
500
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Cement content determination through selective stain in hardened concrete
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Cement content determination through selective stain in hardened concrete
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