A sensitivity study for the visualisation of bacterial weathering of concrete and stone with computerised X-ray microtomography

• Published in: The Science of the total environment Vol. 341; no. 1; pp. 173 - 183
• Main Authors: De Graef, B., Cnudde, V., Dick, J., De Belie, N., Jacobs, P., Verstraete, W.
• Format: Journal Article
• Language: English
• Published: Shannon Elsevier B.V 01.04.2005; Elsevier Science
• Subjects: Applied sciences; Biodegradation, Environmental; Biological weathering; Building failures (cracks, physical changes, etc.); Building stone; Buildings. Public works; Calcium Carbonate; Computerised X-ray microtomography (μCT); Concrete; Concretes. Mortars. Grouts; Construction Materials; Durability. Pathology. Repairing. Maintenance; Exact sciences and technology; General (composition, classification, performance, standards, patents, etc.); Materials; Microradiography; Microscopy, Electron, Scanning; Natural stones; Quartz; Thiobacillus - metabolism; Tomography, X-Ray Computed - methods; Building stone; Concrete; Biological weathering; Computerised X-ray microtomography (μCT); Scanning electron microscopy; Sensitivity analysis; Aging test; Construction materials; X ray diffraction; Stone; Biological activity; Image analysis; Failure analysis; Computerized processing; Tomography; Weathering; Bacteria; Porosity
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2004.09.035

Geologists and engineers recently have adopted computerised X-ray microtomography (μCT), a radiological imaging technique, for geological and petrophysical applications such as the assessment of sediment characteristics, CT-measurement of compressibility and compaction, multiphase flow studies, measurement of bulk density and moisture content, and of porosity and permeability. This study focuses on another application: the monitoring of biological weathering of natural building stones and concrete. Microbial activity as a determining factor in the deterioration process of building materials has a major economic impact. Because of its non-destructive character, μCT could be the ideal monitoring technique. With this technique, three-dimensional (3D) images of the entire inner structure of the material can be obtained, together with quantitative data. In depth changes of porosity of concrete and stone specimens due to bacterial weathering were assessed in this work. Also, porosity was visualised based on 3D data with homemade software. Scanning electron microscopy (SEM) images provided additional information and supported conclusions drawn from the X-ray μCT data. Resolution improvement will make the study of petrophysical aspects of physical weathering and/or biological deterioration processes of natural building stones and concrete a promising subject for further μCT-application.