TY - CHAP A1 - Lataste, Jean-François A1 - Hansen, Kurt Kielsgaard A1 - Nilsson, Lars-Olof A1 - Thiel, Charlotte A1 - Schießl-Pecka, Angelika A1 - Göller, Arndt A1 - Gehlen, Christoph T1 - Spatial Distributions T2 - Methods of Measuring Moisture in Building Materials and Structures N2 - In many applications moisture measurements are made to estimate the moisture differences between different points in a structure. Here, it is often more important to use a “simple” method that is easy and rapid to use in many points instead of necessarily obtain the exact moisture level in each point. The objective with “moisture indications” like that could very well be to select points where more accurate moisture measurements are to be made. The measuring principle to apply is of course a trade-off between accuracy and simplicity. Y1 - 2018 U6 - https://doi.org/10.1007/978-3-319-74231-1_19 SP - 173 EP - 190 PB - Springer ER - TY - CHAP A1 - Gehlen, Christoph A1 - Thiel, Charlotte T1 - Specification of building materials for in service durability T2 - Proceedings ICSBM 2019: 2nd international conference of sustainable building materials, 2019, Eindhoven N2 - To assess whether a structural element made of a given building material can withstand the expected mechanical load and environmental exposure in service, designers need information on the material resistances and loads as well as the local conditions. The durability of a building material in the structure can only be assessed if these factors are taken into account. Usually, the material resistances are obtained from laboratory tests. However, the performance of materials under standardized laboratory conditions differs from those occurring in the field. This paper considers this assessment problem and develops a solution strategy based on carbonation-induced corrosion as an example. Y1 - 2019 SN - 978-90-386-4898-9 SP - 31 EP - 40 PB - Technische Universiteit Eindhoven CY - Eindhoven ER - TY - CHAP A1 - Hansen, Kurt Kielsgaard A1 - Lataste, Jean-François A1 - Thiel, Charlotte T1 - ND-Methods - From a Surface T2 - Methods of Measuring Moisture in Building Materials and Structures N2 - A complicated application is to measure a moisture distribution with depth from a surface non-destructively. Only a few methods are suitable for such a case. KW - Complicated Applications KW - Electrical Resistivity Tomography KW - Gray Straight Line KW - Integral Moisture Content KW - Resistivity Distribution Model Y1 - 2018 U6 - https://doi.org/10.1007/978-3-319-74231-1_21 SP - 193 EP - 198 PB - Springer ER - TY - CHAP A1 - Nilsson, Lars-Olof A1 - Agostini, Franck A1 - Thiel, Charlotte T1 - Installation of Probes T2 - Methods of Measuring Moisture in Building Materials and Structures KW - Evaporable Water Content KW - Large Moisture Gradient KW - Mortar Coupling KW - Roof Park KW - Wooden Rings Y1 - 2016 U6 - https://doi.org/10.1007/978-3-319-74231-1_23 SP - 207 EP - 219 PB - Springer ER - TY - CHAP A1 - Thiel, Charlotte A1 - Schoen, Alex A1 - Gehlen, Christoph T1 - Einfluss der CO2-Permeation auf die Carbonatisierung zementgebundener Baustoffe T2 - Tagungsbericht: Ibausil, 20. Internationale Baustofftagung, 12.-14. September 2018, Weimar Y1 - 2018 SP - 153 EP - 161 PB - Bauhaus-Universität Weimar ER - TY - CHAP A1 - Thiel, Charlotte A1 - Lowke, Dirk A1 - Gehlen, Christoph T1 - Effect of minimum temperature, salt and moisture content on concrete under freeze-thaw deicing salt attack T2 - ICDC 2012 : International Congress on Durability of Concrete; Trondheim, Norway, 18-21 June 2012 N2 - While in the field of reinforcement corrosion service life prediction is well-established, there is still need for a user-friendly design model in the field of freeze-thaw deicing salt attack. This attack is one of the major causes of damage to concrete structures in cold climates. The degree of moisture during the first freeze-thaw-cycles exceeds moisture saturation by capillary suction and diffusion. When a critical degree of saturation is reached before freezing damage occurs immediately. As a consequence, depending on the concrete resistance (e.g. pore structure of the concrete) and the severeness of the freeze-thaw load (e.g. minimum temperature, moisture offer and salt concentration), a certain number of freeze-thaw cycles is needed before damage occurs (initial phase). The main exposure parameters influencing the initial phase as well as the subsequent evolution of damage (deterioration phase) are the minimum temperature as well as the salt and moisture content. These factors were determined by single-sided NMR, gravimetry and mercury intrusion porosimetry respectively. Three different concrete compositions were exposed to freeze-thaw deicing salt load at different minimum temperatures. To investigate the influence of the initial moisture content concrete specimens were continuously exposed to freeze-thaw load while other specimens from the same batch were exposed to alternating freeze-thaw exposure with intermediate dry periods. It was found that the minimum temperature and intermediate dry periods had a significant influence on the initial phase as well as on the degradation phase. In addition, higher chloride content in the near-surface concrete reduced the scaling rate. The chloride content under freeze-thaw exposure with 3% NaCl solution in laboratory significantly exceeded typical contents due to capillary suction and diffusion. Increasing the minimum temperature increased the chloride content. The investigations form the basis for service life prediction of concrete towards freeze-thaw deicing salt attack. KW - freeze-thaw deicing salt attack KW - moisture movement Y1 - 2012 U6 - https://doi.org/10.13140/2.1.3243.9367 PB - Norwegian Concrete Association ER - TY - CHAP A1 - Thiel, Charlotte A1 - Beddoe, Robin E. A1 - Lowke, Dirk A1 - Gehlen, Christoph T1 - Accelerated carbonation: changes in water transport, porosity and phases of mortar due to different CO 2 pressures T2 - Proceedings of the 10th fib International PhD Symposium in Civil Engineering, July 21 to 23, 2014, Québec, Canada N2 - Currently, the carbonation resistance of concrete is assessed on the basis of accelerated tests performed with high (unrealistic) CO2 concentrations. It remains unclear whether these high concentrations reflect the processes occurring under natural conditions and enable the accurate prediction of field behaviour. To develop future test procedures with higher reliability, it is necessary to deepen the knowledge on the mechanisms of carbonation. Thin slices of mortar were stored in a gaseous mixture of 2 % CO2 and 98 % N2 at atmospheric pressure or 5 bar. IH-NMR equipment was used to detennine moisture profiles with aresolution of 0.2 mm. At 5 bar a drying front at the near-surface region of the mortar discs severely inhibited the progression of the carbonation reactions. This effect was prevented by exposure to altemating cycles of pressure and storage at atmospheric pressure (65%RH) which significantly increased the rate of carbonation, but was too severe to resolve the effect of cement type on carbonation resistance. Furthermore , the evolution of water beyond the carbonation front of mortar sampies under accelerated concentration and at atmospheric pressure was clearly visible. This may lead to an overestimation of carbonation resistance of sampies tested under accelerated conditions at the optimal relative humidity for natural carbonation (50-70% RH). Y1 - 2014 UR - https://mediatum.ub.tum.de/doc/1230854/1230854.pdf SP - 217 EP - 221 ER - TY - CHAP A1 - Thiel, Charlotte A1 - Beddoe, Robin E. T1 - Investigating the role of moisture on concrete carbonation using single-sided H-NMR T2 - International RILEM Conference on Materials, Systems and Structures in Civil Engineering 2016 - Conference segment on Moisture in Materials and Structures, 22-24 August 2016, Lyngby, Denmark N2 - Accelerated test methods are commonly used in order to predict concrete carbonation in natural concentrations. Here, specimens are carbonated at high CO 2 concentrations at a specified temperature and relative humidity. However, the transfer of laboratory results to field behaviour remains difficult because CO 2 transport is affected by the original moisture content of the specimens and additional moisture formed by the carbonation reaction. Therefore knowledge on moisture transport and content during carbonation is required. Specimens made with Ordinary Portland cement and a water/cement ratio 0.50 were exposed to 0.05, 2 and 10 vol.% CO 2 for 28 days. Single-sided NMR moisture profiles were determined before, during and after carbonation. It is shown that moisture content increases due to carbonation at high CO 2 10 %) in the beginning of the exposure. An increase in capillary pore water in front and behind the carbonation front could be observed even after 28d. During natural carbonation moisture changes are mainly due to the change in porosity produced by the carbonation reactions. It is shown that changes in phase composition and thus porosity dominate the carbonation process in cement-based materials. Therefore, the suitability of high CO 2 concentrations is limited for an accelerated test that reflects field condition. Single-sided 1 H NMR proved to be a valuable tool to investigate moisture transport in concrete non-destructively. Y1 - 2016 SN - 978-2-35158-171-1 SP - 261 EP - 268 PB - RILEM Publications S.A.R.L. ER - TY - CHAP A1 - Thiel, Charlotte A1 - Lowke, Dirk A1 - Gehlen, Christoph T1 - Detection of Transport Processes during Freeze-Thaw Deicing Salt Attack Using Single-Sided NMR T2 - Microstructural-related durability of cementitious composites : Second International Conference on Microstructural-related Durability of Cementitious Composites, 11 - 13 April 2012, Amsterdam N2 - Damage of concrete structures exposed to a combined freeze-thaw deicing salt attack (FTDSA) is one of the major deterioration mechanisms in cold climates. Before damage occurs, concrete structures subjected to freeze-thaw cycles (FTC) in the presence of water or deicing salt solution exhibit fast moisture uptake known as frost suction. There is still need for research in describing and modelling the mechanisms that lead to freeze-thaw induced surface scaling of concrete. Therefore, the moisture transport under FTDSA was investigated using single-sided 1 H NMR. The technique enables the observation of dynamic transport processes of water inside the sample non-destructively. Furthermore, porosity and pore size distribution of water saturated samples can be determined. The method also provides information on the mobility of water, i.e. water in capillaries or in gel pores. Water redistribution in pores as well as changes in the pore structure inside the near surface concrete sample under FTDSA were observed with single-sided 1 H NMR. The measurements confirmed the additional saturation of gel pores during thawing previously described by the micro ice lens model. The results are discussed within the context of the mechanisms of freeze-thaw deicing salt attack of concrete and contribute to a deeper understanding of the mechanisms that lead to freeze-thaw deterioration of concrete. Y1 - 2012 PB - RILEM ER - TY - CHAP A1 - Thiel, Charlotte A1 - Keßler, Sylvia A1 - Chillé, R. A1 - Gehlen, Christoph T1 - Effect of internal freeze-thaw deterioration on chloride migration in concrete T2 - Life-Cycle and Sustainability of Civil Infrastructure Systems : proceedings of the third International Symposium on Life-Cycle Civil Engineering, Vienna, Austria, 3 - 6 October 2012 N2 - Depending on the specific exposure conditions, reinforced concrete structures (RCS) are simultaneously subjected to different physical and chemical loads. While in the field of reinforcement corrosion, service life prediction based on full-probabilistic models is well-established, the consequences of combined attack have been neglected until now. The most frequent “load” combination on RCS in cold climates are freeze-thaw attack which can lead to inner or outer damage and chloride ingress which can lead to reinforcement corrosion. In an experimental study four different concrete compositions are exposed either to a defined freeze-thaw attack or stored in moist environment. Afterwards, the chloride migration coefficient of the specimens which were both exposed to freeze-thaw-cycles and not, was determined with a modified rapid chloride migration test. The results clearly show an influence of freeze-thaw-induced internal damage on chloride ingress depending on concrete composition. Y1 - 2012 PB - CRC Press ER -