Ingenieurwissenschaften und zugeordnete Tätigkeiten
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- 2023 (2) (entfernen)
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- Zeitschriftenartikel (1)
- Vortrag (1)
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- Englisch (2)
Schlagworte
- Capillary suction (1)
- Capillary transport coefficient (1)
- Cement hydration (1)
- Concrete (1)
- Fire spalling (1)
- Frost salt attack (1)
- Moisture transport (1)
- NMR relaxometry (1)
- Sensitivity (1)
- Supplementary cementitous materials (1)
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Eingeladener Vortrag
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To evaluate the durability of new alternative cement compositions, it is important to examine the internal transport of moisture through these materials. For this purpose, mortars were prepared from different types of cement and capillary suction experiments were carried out. The moisture transport was studied with an NMR tomograph and compared with weight easurements. With the tomograph, the total moisture input could be determined, as well as the moisture content within the samples non-destructively and spatially resolved. This allows precise observation of the moisture fronts. The tomograph was also used to determine the capillary transport
coefficient.
NMR is becoming increasingly popular for the investigation of building materials as it is a non-invasive technology that does not require any sample preparation nor causes damage to the material. Depending on the specific application it can offer insights into properties like porosity and spatial saturation degree as well as pore structure. Moreover it enables the determination of moisture transport properties and the (re-)distribution of internal moisture into different reservoirs or chemical phases upon damage and curing. However, as yet most investigations were carried out using devices originally either designed for geophysical applications or the analysis of rather homogeneous small scale (< 10 mL) samples. This paper describes the capabilities of an NMR tomograph, which has been specifically optimized for the investigation of larger, heterogeneous building material samples (diameters of up to 72 mm, length of up to 700 mm) with a high flexibility due to interchangeable coils allowing for a high SNR and short echo times (50 - 80 m s).