TY - CONF A1 - Strangfeld, Christoph A1 - Johann, Sergej A1 - Müller, Maximilian A1 - Bartholmai, Matthias T1 - Moisture Measurements with RFID based Sensors in Screed and Concrete N2 - To quantify the moisture in concrete, RFID based humidity sensors are embedded. Passive high frequency, ultra-high frequency RFID tags as well as active Bluetooth sensors are tested. After concreting, all sensors measure the corresponding relative humidity to monitor the concrete moisture. Two case studies are performed, embedding in an existing construction, i.e. the duraBASt test bridge, and embedding in cement based mortar in the laboratory. As basis for robust and long-life sensors in alkaline concrete, different casing materials are tested. Furthermore, signal strength measurements and their sensitivity to different moisture levels are performed. T2 - 8th European Workshop On Structural Health Monitoring CY - Bilbao, Spain DA - 05.07.2016 KW - Humidity sensors KW - Moisture measurements KW - RFID based sensors KW - DuraBASt PY - 2016 SP - 1 EP - 10 AN - OPUS4-36817 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Strangfeld, Christoph A1 - Johann, Sergej A1 - Müller, Maximilian A1 - Bartholmai, Matthias T1 - Moisture Measurements with RFID based Sensors in Screed and Concrete N2 - To quantify the moisture in concrete, RFID based humidity sensors are embedded. Passive high frequency, ultra-high frequency RFID tags as well as active Bluetooth sensors are tested. After concreting, all sensors measure the corresponding relative humidity to monitor the concrete moisture. Two case studies are performed, embedding in an existing construction, i.e. the duraBASt test bridge, and embedding in cement based mortar in the laboratory. As basis for robust and long-life sensors in alkaline concrete, different casing materials are tested. Furthermore, signal strength measurements and their sensitivity to different moisture levels are performed. T2 - EWSHM 2016 CY - Bilbao, Spain DA - 05.07.2016 KW - Moisture measurements KW - RFID based sensors KW - DuraBASt KW - Humidity sensors KW - Long-life sensor casing PY - 2016 AN - OPUS4-36834 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Strangfeld, Christoph A1 - Kruschwitz, Sabine T1 - Monitoring of the absolute water content in porous materials based on embedded humidity sensors N2 - Moisture transport monitoring may indicate the onset of deterioration in porous building materials Prior to damage occurring. Most moisture measurement systems provide only qualitative values, require extensive calibration, or are destructive. Thus, non-destructive and calibration-free monitoring Systems are required. Our approach of moisture monitoring is to embed sensors that measure the relative humidity. In our experiment, screed samples are monitored during the Hydration and evaporation process. Every test sample is equipped with 10 embedded sensors which measure the relative humidity across the sample thickness. Based on Hillerborg’s approach, the relative humidity is converted into the corresponding pore saturation. In our study, the free water is computed without knowledge of the Sorption isotherm. The free water in the pore system is predicted and validated. The predicted weight decrease corresponds conclusively to gravimetrically measured weights. The embedded sensors yield the absolute liquid water content and enable an experimental, non-destructive monitoring of liquid water in porous materials. KW - Moisture measurements KW - Porous materials KW - Embedded sensors KW - Partial pore saturation KW - Sorption isotherm PY - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-453476 SN - 0950-0618 VL - 177 SP - 511 EP - 521 PB - Elsevier AN - OPUS4-45347 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Strangfeld, Christoph T1 - Feuchtemessverfahren N2 - Discussion and presentation of different methods for moisture measurements in civil Engineering. T2 - Vorlesung Diagnostik und Ertüchtigung von Bauwerken CY - TU Berlin, Germany DA - 16.05.2018 KW - Material moisture KW - Moisture measurements PY - 2018 AN - OPUS4-44944 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Strangfeld, Christoph T1 - Moisture testing and mapping N2 - Discussion and presentation of different methods for moisture measurements in civil engineering. T2 - NDT&E Advanced Training Workshop CY - Berlin, Germany DA - 05.07.2017 KW - Building materials KW - Moisture measurements KW - Concrete PY - 2017 SP - 87 EP - 107 CY - Berlin, Germany AN - OPUS4-42624 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Strangfeld, Christoph A1 - Kruschwitz, Sabine T1 - Validierung und Vergleich verschiedener Methoden zur Bestimmung von Flüssigwasser in Baustoffen N2 - Darstellung der aktuellen Feuchtemesstechnik im Bauwesen. Erklärung der Grundlagen über die Sorptionsisotherme und den Wasserdampfpartialdruck. Vorstellung der Ergebnisse der korrespondierenden relativen Luftfeuchtemessungen. T2 - Abteilungsseminar der Abteilung 8, BAM CY - BAM, Berlin, Germany DA - 06.11.2017 KW - Concrete KW - Material moisture KW - Moisture measurements KW - Moisture in civil engineering KW - Corresponding relative humidity PY - 2017 AN - OPUS4-42744 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Strangfeld, Christoph A1 - Kruschwitz, Sabine T1 - Moisture testing and mapping N2 - Eight different screed types are tested including two different sample heights of 35 and 70 mm. The moisture of the four cement based and four sulphate based screeds are monitored during hydration and evaporation. All samples are stored in a climatic chamber at 23° C and 50 % relative humidity. Embedded sensors like temperature arrays, humidity sensor arrays, and multi-ring electrodes are embedded in the samples to yield a detailed moisture evolution with high depth resolution. Furthermore, nuclear magnetic resonance is used to quantify the water content at different depths. This multi-sensor approach allows a comprehensive monitoring of the moisture and its gradient in the different screed samples. This yields a deeper insight into the hydration, moisture convection, and diffusion processes. T2 - 4. Autumn School - Moisture measurements in porous mineral materials CY - Karlsruhe, Germany DA - 18.09.2017 KW - Material moisture KW - Moisture measurements KW - Corresponding relative humidity KW - Sorption isotherme KW - Porous materials PY - 2017 AN - OPUS4-42096 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -