@misc{ThielGehlenFoestl, author = {Thiel, Charlotte and Gehlen, Christoph and F{\"o}stl, Florian}, title = {Service life prediction of concrete under freeze-thaw deicing salt attack with intermittent dry periodst}, series = {The Sixth International Symposium on Life-Cycle Civil Engineering : IALCCE 2018,28 -31.10.2018, Ghent}, journal = {The Sixth International Symposium on Life-Cycle Civil Engineering : IALCCE 2018,28 -31.10.2018, Ghent}, language = {en} } @misc{GehlenThiel, author = {Gehlen, Christoph and Thiel, Charlotte}, title = {Schnellpr{\"u}fverfahren zur Bestimmung des Karbonatisierungswiderstandes}, series = {Proceedings, 59. BetonTage : Betone der Zukunft, Neu-Ulm, 24.-26.02.2015}, journal = {Proceedings, 59. BetonTage : Betone der Zukunft, Neu-Ulm, 24.-26.02.2015}, publisher = {Bauverl.}, language = {de} } @article{ThielKratzerGrimmetal., author = {Thiel, Charlotte and Kratzer, Johanna and Grimm, Benedikt and Kr{\"a}nkel, Thomas and Gehlen, Christoph}, title = {Effect of Internal Moisture and Outer Relative Humidity on Concrete Carbonation}, series = {CivilEng}, volume = {4}, journal = {CivilEng}, number = {3}, publisher = {MDPI}, address = {Basel}, doi = {10.3390/civileng3040058}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-56091}, pages = {1039 -- 1052}, abstract = {With steadily rising CO2 concentrations in the ambient air and fast-changing concretecompositions with reduced clinker contents, the availability of reliable and accelerated concrete car-bonation tests is of crucial importance to design durable structures. This paper focuses on the effectsof moisture under accelerated conditions and the effects of different CO2 exposure conditions. Mor-tar prisms incorporating three different cement types were cured and stored at either 50\% or 65\%relative humidity (RH). Afterwards, the prisms were carbonated at different ambient humidities(50, 57 and 65\%), different CO2 concentrations (0.04, 1 and 3 vol.\%) and complemented by a seriesof tests at increased gas pressure (2 barg). High-resolution test methods were used to explain theunderlying carbonation mechanisms. The results show that pre-conditioning for two weeks—ascurrently suggested by the European Standard—seems to be too short because the initial inner mois-ture content severely affects the carbonation rate. Relative humidity during carbonation of 57\% ledto higher carbonation rates compared to 50\% and 65\%. In addition, climate data needs to be period-ically (preferably permanently) recorded in research experiments and in laboratory testing to ensurefair interpretation of experimental results.}, language = {en} } @article{AlbrechtHellerbrandWeiningeretal., author = {Albrecht, Sophie Viktoria and Hellerbrand, Stefan and Weininger, Florian and Thiel, Charlotte}, title = {Strategies for Minimizing Environmental Impact in Construction: A Case Study of a Cementitious 3D Printed Lost Formwork for a Staircase}, series = {materials}, volume = {18}, journal = {materials}, publisher = {MDPI}, doi = {10.3390/ma18040825}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:898-opus4-79236}, pages = {18}, abstract = {The construction industry faces significant challenges, including environmental sustainability, rising material costs, and a shortage of skilled labor. Digital fabrication technologies offer innovative solutions to address these issues by reducing raw material consumption and waste generation. Among these, 3D printing technologies offer distinct advantages over traditional construction methods, particularly in handling complex geometries. However, the significant environmental impact of cement in 3D printed concrete, due to its high rheological and printability requirements, remains a concern. This study introduces a novel application of 3D printed permanent formwork in the construction of a winder staircase, assessed through an Environmental Life Cycle Assessment (LCA) from cradle to gate. By comparing the environmental impacts of various construction materials and processes, this study highlights the comparative advantages and disadvantages of conventional methods versus 3D printing. The LCA results reveal that traditional production methods, particularly those using plywood formwork, exhibit higher environmental impacts. In contrast, timber formwork performs better than most 3D printed mixtures in terms of Global Warming Potential (GWP), Acidification Potential (AP), and abiotic depletion potential (ADP). The findings of this study underscore the potential of additive manufacturing for sustainable construction, particularly through the use of low-clinker cement in 3D printed formwork, offering a promising pathway towards reducing the environmental footprint of construction activities}, language = {en} } @inproceedings{ThielHaynackGeyeretal., author = {Thiel, Charlotte and Haynack, Alexander and Geyer, Sebastian and Gehlen, Christoph and Braun, Alexander}, title = {CarboDB-Open Access Database for Concrete Carbonation}, series = {Proceedings of the 3rd RILEM Spring Convention and Conference (RSCC 2020), Volume 1: Strategies for a Resilient Built Environment, March 9-14, 2020, Guimar{\~a}es, Portugal}, booktitle = {Proceedings of the 3rd RILEM Spring Convention and Conference (RSCC 2020), Volume 1: Strategies for a Resilient Built Environment, March 9-14, 2020, Guimar{\~a}es, Portugal}, editor = {Pereira, Eduardo B. and Barros, Joaquim A. O. and Figueiredo, Fabio P.}, publisher = {Springer International Publishing}, address = {Cham}, isbn = {978-3-030-76547-7}, doi = {10.1007/978-3-030-76547-7_8}, pages = {79 -- 90}, abstract = {Sustainable service life design of reinforced concrete structures relies on accurate input values. However, in the field of carbonation induced corrosion some input parameters and statistical distributions still need to be validated for worldwide climate conditions. Furthermore, many well-published literature data is not considered due to different storage conditions. At the suggestion of CEN/TC 104/SC1/WG1 the database "CarboDB" was created providing open access to extensive information on concrete carbonation under different storage conditions. The natural carbonation coefficient as well as the minimum concrete cover can be calculated for chosen situations. CarboDB provides reliable data on concrete carbonation in order to increase existing knowledge on concrete carbonation. The database is available online at http://carbodb.bgu.tum.de//. By registration further contribution is possible and appreciated. New insights can be gained by merging several sources. For natural carbonation, testing only up to 140 days underestimates the carbonation progress of concretes with limestone fillers and high amount of ground granulated blast furnace slag.}, language = {en} } @incollection{LatasteThielFranzoni, author = {Lataste, Jean-Fran{\c{c}}ois and Thiel, Charlotte and Franzoni, Elisa}, title = {Electrical Resistance}, series = {Methods of Measuring Moisture in Building Materials and Structures}, booktitle = {Methods of Measuring Moisture in Building Materials and Structures}, publisher = {Springer}, doi = {10.1007/978-3-319-74231-1_8}, pages = {55 -- 66}, abstract = {Electrical resistance is the ability for a material to impede the flow of electrical current. The resistance (R) is expressed in ohm (Ohm), its inverse is the conductance (C) is expressed in siemens (S). The resistance is function of geometry of tested body and measurement device. So one generally prefers the resistivity (ρΩ) expressed in ohm-meter (Ohm·m), or its inverse the conductivity (σ) in siemens per meter (S/m), representing the intrinsic material's property.}, language = {en} } @incollection{GehlenMayerThieletal., author = {Gehlen, Christoph and Mayer, Till Felix and Thiel, Charlotte and Fischer, Christian}, title = {Lebensdauerbemessung}, series = {Beton Kalender 2021 : Fertigteile, Integrale Bauwerke}, volume = {110}, booktitle = {Beton Kalender 2021 : Fertigteile, Integrale Bauwerke}, publisher = {Wilhelm Ernst \& Sohn}, doi = {10.1002/9783433610206.ch1}, pages = {1 -- 57}, abstract = {Christoph Gehlen, Till Felix Mayer, Charlotte Thiel und Christian Fischer beschreiben die Lebensdauerbemessung von Beton. Umfassend werden Transport- und Sch{\"a}digungsmodelle vorgestellt, die die Mechanismen der Carbonatisierung, der Chlorideindringung, der Korrosion und der korrosionsinduzierten Rissbildung im Stahlbeton beschreiben. Die damit einhergehende Verbundthematik wird erl{\"a}utert. Auch wird auf alle Mechanismen der Betonkorrosion eingegangen. Die Bemessung in Bezug auf die Dauerhaftigkeit und damit Absch{\"a}tzungen f{\"u}r die Lebensdauer von Beton wird in drei unterschiedlich genauen Formaten gef{\"u}hrt. Neben dem vollprobabilistischen Format wird beschrieben, wie Bemessungen auch auf Grundlage von Nachweisen basierend auf Teilsicherheitsbeiwerten durchgef{\"u}hrt werden k{\"o}nnen. Daran anschließend wird aufgezeigt, welche deskriptiven Bemessungsans{\"a}tze sich daraus ableiten lassen. An einigen exemplarisch herausgegriffenen Objektbeispielen wird die Lebensdauerbemessung konkret vorgef{\"u}hrt.}, language = {de} } @article{VanoutriveAldereteDeBelieetal., author = {Vanoutrive, Hanne and Alderete, Natalia and De Belie, Nele and Etxeberria, Miren and Grengg, Cyrill and Ignjatović, Ivan and Ling, Tung-Chai and Liu, Zhiyuan and Garcia-Lodeiro, In{\´e}s and Medina Mart{\´i}nez, C{\´e}sar and Sanchez, Javier and Palomo, Angel and Rebolledo, Nuria and Sakoparnig, Marlene and Sideris, Kosmas and Thiel, Charlotte and Van den Heede, Philip and Vollpracht, Anya and von Greve-Dierfeld, Stefanie and Wei, Jinxin and Zając, Maciej and Gruyaert, Elke}, title = {Report of RILEM TC 281-CCC: outcomes of a round robin on the resistance to natural carbonation of Portland, Portland-fly ash and blast-furnace cements and its relation to accelerated carbonation}, series = {Materials and Structures}, volume = {57}, journal = {Materials and Structures}, number = {9}, publisher = {Springer Science and Business Media}, issn = {1359-5997}, doi = {10.1617/s11527-024-02464-1}, abstract = {Numerous (inter)national standards are in place for assessing the resistance to carbonation of mortar and concrete. Within the framework of RILEM TC 281-CCC 'Carbonation of Concrete with SCMs,' an extensive interlaboratory test campaign (ILT) involving twenty-two participating laboratories worldwide was initiated to compare natural carbonation of concrete and mortar with three different cement types (Portland cement (CEM I), Portland-fly ash cement (CEM II/B-V) and blast-furnace cement (CEM III/B)) and investigate its relation to accelerated carbonation as reported in Vanoutrive et al. (Mater Struct 55:1-29, 2022). It could be concluded that ranking of cement types was analogous between accelerated and natural carbonation methods. Environmental parameters have an important effect on the carbonation rate, however, differences between the mean carbonation rates originating from indoor and sheltered outdoor natural exposure with different exposure conditions and curing regimes were insignificant for each considered cement type. This is caused by the scatter related to carbonation testing among different laboratories. Nevertheless, results showed that a natural exposure period of at least one year is essential to reach a constant carbonation rate over time. For both natural and accelerated carbonation, the carbonation rate increased by 18\% when the aggregate-to-cement ratio increased by 1.79 (concrete versus mortar). This correlation seems insensitive to binder type and exposure method. Finally, the best correlation between natural and accelerated carbonation was found for EN 12390-10 (specifically natural indoor exposure) and EN 12390-12 (accelerated exposure) when only test methods performed by more than one laboratory were considered.}, language = {en} } @article{BernalDhandapaniElakneswaranetal., author = {Bernal, Susan A. and Dhandapani, Yuvaraj and Elakneswaran, Yogarajah and Gluth, Gregor J. G. and Gruyaert, Elke and Juenger, Maria C. G. and Lothenbach, Barbara and Olonade, Kolawole Adisa and Sakoparnig, Marlene and Shi, Zhenguo and Thiel, Charlotte and van den Heede, Philip and Vanoutrive, Hanne and Von Greve-Dierfeld, Stefanie and De Belie, Nele and Provis, John L.}, title = {Report of RILEM TC 281-CCC: A critical review of the standardised testing methods to determine carbonation resistance of concrete}, series = {Materials and Structures}, volume = {57}, journal = {Materials and Structures}, number = {8}, publisher = {Springer}, issn = {0025-5432}, doi = {10.1617/s11527-024-02424-9}, pages = {31}, abstract = {The chemical reaction between CO2 and a blended Portland cement concrete, referred to as carbonation, can lead to reduced performance, particularly when concrete is exposed to elevated levels of CO2 (i.e., accelerated carbonation conditions). When slight changes in concrete mix designs or testing conditions are adopted, conflicting carbonation results are often reported. The RILEM TC 281-CCC 'Carbonation of Concrete with Supplementary Cementitious Materials' has conducted a critical analysis of the standardised testing methodologies that are currently applied to determine carbonation resistance of concrete in different regions. There are at least 17 different standards or recommendations being actively used for this purpose, with significant differences in sample curing, pre-conditioning, carbonation exposure conditions, and methods used for determination of carbonation depth after exposure. These differences strongly influence the carbonation depths recorded and the carbonation coefficient values calculated. Considering the importance of accurately determining carbonation potential of concrete, not just for predicting their durability performance, but also for determining the amount of CO2 that concrete can re-absorb during or after its service life, it is imperative to recognise the applicability and limitations of the results obtained from different tests. This will enable researchers and practitioners to adopt the most appropriate testing methodologies to evaluate carbonation resistance, depending on the purpose of the conclusions derived from such testing (e. g. materials selection, service life prediction, CO2 capture potential).}, language = {en} } @article{HaynackSekandarJithenderetal., author = {Haynack, Alexander and Sekandar, Zadran and Jithender, J. Timothy and Gambarelli, Serena and Kr{\"a}nkel, Thomas and Thiel, Charlotte and Ozbolt, Josko and Gehlen, Christoph}, title = {Can a Hend-Held 3D Scanner Capture Temperature-Induced Strain of Mortar Samples? Comparison between Experimental Measurements and Numerical Simulations}, series = {mathematics}, volume = {11}, journal = {mathematics}, number = {17}, publisher = {MDPI}, address = {Basel}, doi = {10.3390/math11173672}, abstract = {The expected lifespan of cement-based materials, particularly concrete, is at least 50 years. Changes in the pore structure of the material need to be considered due to external influences and associated transport processes. The expansion behaviour of concrete and mortar during freeze-thaw attacks, combined with de-icing salt agents, is crucial for both internal and external damage. It is essential to determine and simulate the expansion behaviour of these materials in the laboratory, as well as detect the slow, long-term expansion in real structures. This study measures the expansion of mortar samples during freeze-thaw loading using a high-resolution hand-held 3D laser scanner. The specimens are prepared with fully or partially saturated pore structures through water storage or drying. During freeze-thaw experiments, the specimens are exposed to pure water or a 3\% sodium chloride solution (NaCl). Results show contraction during freezing and subsequent expansion during thawing. Both test solutions exhibit similar expansion behaviour, with differences primarily due to saturation levels. Further investigations are required to explore the changing expansion behaviour caused by increasing microcracking resulting from continuous freeze-thaw cycles. A numerical analysis using a 3D coupled hygro-thermo-mechanical (HTM) model is conducted to examine the freeze-thaw behaviour of the mortar. The model accurately represents the freezing deformation during the freeze-thaw cycle.}, language = {en} } @inproceedings{ThielGehlen, author = {Thiel, Charlotte and Gehlen, Christoph}, title = {On the determination of carbonation in cementitious materials}, series = {Challenges in Design and Management of Structures. Proceedings of the International Conference on Sustainable Materials Systems and Structures (SMSS2019) Durability, Monitoring and Repair of Structures, 18.-22.03.2019, Rovinja, Croatio}, booktitle = {Challenges in Design and Management of Structures. Proceedings of the International Conference on Sustainable Materials Systems and Structures (SMSS2019) Durability, Monitoring and Repair of Structures, 18.-22.03.2019, Rovinja, Croatio}, publisher = {RILEM}, isbn = {978-2-35158-217-6}, pages = {373 -- 380}, abstract = {For material testing, qualification and subsequent assessment fast, simple, reliable and economic methods are needed. This paper provides an overview of different techniques to determine the depth of carbonation in cementitious materials. The easiest and cheapest way is to remove a core or a fragment of concrete cover and spray a colour indicator on the fresh fractured surface (by splitting). Here, 1 \% phenolphthalein in 70 \% ethanol is most widely used. However, this only indicates in which area the concrete has a pH value below 8.2-10, but not the actual carbonation front which is on average about 20 \% higher. Since phenolphthalein is carcinogenic, alternative colour indicators were investigated in the laboratory. 0.5 \% Curcumin showed similar colour change to phenolphthalein. In addition, 0.1 \% thymolphthalein proved to be an alternative. Scattering within one measurement was lower than for phenolphthalein and the results were closer to the carbonation depths determined by different analytical methods (TGA and LA-ICP-MS). Furthermore, the transition pH-value of thymolphthalein is in the area of 9.3-10.5 which is closer to the actual carbonation front, allowing a more accurate assessment of the risk of reinforcement corrosion.}, language = {en} } @incollection{ThielStengelGehlen, author = {Thiel, Charlotte and Stengel, T. and Gehlen, Christoph}, title = {Life cycle assessment (LCA) of road pavement materials}, series = {Eco-efficient Construction and Building Materials}, booktitle = {Eco-efficient Construction and Building Materials}, publisher = {Woodhead Publishing}, doi = {10.1533/9780857097729.2.368}, pages = {368 -- 403}, abstract = {At present the choice of materials and techniques in road construction is dictated by structural requirements and economic aspects. However, ecological factors have gained in importance due to environmental considerations in politics and society. To evaluate the environmental impact of motorways, a life cycle assessment (LCA) according to ISO 14040 was carried out for different pavement types. By investigating different case scenarios, the reduction potential of environmental impact was quantified. The biggest reduction in air pollution can be achieved by improving pavement properties (e.g., texture, stiffness and flatness) which would significantly reduce the fuel consumption of vehicles.}, language = {en} } @article{ThielGoetzfriedGehlen, author = {Thiel, Charlotte and Goetzfried, Franz Xaver and Gehlen, Christoph}, title = {Physikalische und chemische Auswirkungen von tauenden Chloriden auf Betone von Verkehrsbauwerken}, series = {Straße und Autobahn}, volume = {64}, journal = {Straße und Autobahn}, number = {9}, publisher = {Kirschbaum}, pages = {684 -- 688}, abstract = {Zur Untersuchung des Einflusses von Loesungen der Tausalze Natriumchlorid, Calciumchlorid und Magnesiumchlorid auf die Dauerhaftigkeit von Beton wurden unter praxisnahen Bedingungen im Labor Betonprobekoerper, mit typischen Qualitaeten fuer Verkehrsbauwerke, unterschiedlichen Belastungszyklen unterzogen. Auch bei extremer Belastung durch wiederholte Nass- und Trockenphasen mit anschliessenden zyklischen Frost-Tau-Wechseln waren die physikalischen und chemischen Auswirkungen auf die Betone gering. Die festgestellten Unterschiede der verschiedenen Tausalze im Schaedigungsverhalten sind fuer die Praxis vernachlaessigbar. Fuer die Winterdienstpraxis laesst sich die Schlussfolgerung ziehen, dass zur Herstellung von Feuchtsalz im Hinblick auf die Dauerhaftigkeit von Strassenbeton und XF4-Beton die Loesungen der Chloride von Natrium, Calcium und Magnesium gleichermassen geeignet sind. Auch bei vorbeugender Fluessigstreuung mit NaCl-Sole ist auf Fahrbahnen mit normkonform zusammengesetztem Beton lediglich ein extrem geringer Angriff zu erwarten. (A) ABSTRACT IN ENGLISH: To investigate the influence of solutions of the de-icing salts sodium chloride, calcium chloride and magnesium chloride onto the durability of concrete, concrete specimens, with typical qualities for roads and bridges, were subjected to different load cycles under practical conditions. Also in the case of extreme load through repeated wet and dry phases with subsequent cyclical freeze-thaw-attack the physical and chemical effects on the concrete were low. The found differences of the different de-icing salts in the damage behaviour are negligible for the practice. The results prove that for the generation of pre-wetted salt, the solutions of the chlorides of sodium, calcium and magnesium are equally suitable with regard to the durability of concrete used in road construction and of XF4 concrete. Also in the case of preventive liquid spraying with NaCI-brine only an extremely small attack is to be expected on roads constructed with concrete conform to the current standards.}, language = {de} } @article{KesslerThielGrosseetal., author = {Kessler, Sylvia and Thiel, Charlotte and Grosse, Christian U. and Gehlen, Christoph}, title = {Effect of freeze-thaw damage on chloride ingress into concrete}, series = {Materials and Structures}, volume = {50}, journal = {Materials and Structures}, number = {2}, publisher = {Springer}, doi = {10.1617/s11527-016-0984-4}, abstract = {In cold climates, reinforced concrete structures (RCSs) are frequently and severely damaged by freeze-thaw (FT) and deicing-salt attack during winter periods. FT action can also cause additional water uptake known as frost suction. If a critical degree of water saturation is exceeded, severe deterioration of the microstructure of the concrete is likely, enhancing chloride ingress and increasing the probability of corrosion of its reinforcement. We present herein a test method to characterize the resistance of concrete to FT and chloride ingress. Chloride migration tests were performed on concretes with different degrees of FT deterioration, with and without deicing agents. The performance of RCSs is decisively affected under these combined actions. Quantitative description of the resulting FT damage is achieved using ultrasonic measurements and resonance frequency analysis. The test results confirm that the latter nondestructive test method provides more reliable evaluation of FT damage compared with usual ultrasonic pulse velocity measurements. Different concretes with supplementary cementitious materials and different degrees of FT deterioration with and without deicing agents were tested. While concrete made with air-entraining agents clearly showed the best FT resistance, concrete with ground-granulated blast-furnace slag showed superior resistance to both chloride migration and FT attack, both being positively affected by appropriate curing conditions.}, language = {en} } @article{OlssonAbdulWahidNilssonetal., author = {Olsson, Nilla and Abdul Wahid, Fatmawati and Nilsson, Lars-Olof and Thiel, Charlotte and Wong, Hong S. and Baroghel-Bouny, V{\´e}ronique}, title = {Wick action in mature mortars with binary cements containing slag or silica fume - The relation between chloride and moisture transport properties under non-saturated conditions}, series = {Cement and Concrete Research}, volume = {111}, journal = {Cement and Concrete Research}, number = {September}, publisher = {Elsevier}, doi = {10.1016/j.cemconres.2018.06.006}, pages = {94 -- 103}, abstract = {Moisture and ionic transport under non-saturated condition is an important, but poorly understood transport phenomena particularly for mature systems containing supplementary cementitious materials. This paper investigates the moisture and chloride profiles of 3-year old mortars containing Portland cement (OPC), slag and silica fume (SF) after long-term (30-48 months) wick action exposure in 1.09 M NaCl solution. Moisture profiles were measured with ¹H NMR relaxometry and chloride profiles with microXRF. The measured profiles were discussed in relation to moisture dependent material properties such as chloride diffusion coefficients, moisture diffusion coefficients, and desorption isotherms. Results show that the combination of different cementitious materials, e.g. the cementitious binder, is the key factor affecting chloride penetration depth. The cementitious binder also strongly affects chloride diffusion coefficient, moisture diffusion coefficient and chloride binding properties, which are all important parameters for the prediction of chloride ingress.}, language = {en} } @article{VandenHeedeThielDeBelie, author = {Van den Heede, Philip and Thiel, Charlotte and De Belie, Nele}, title = {Natural and accelerated carbonation behaviour of high-volume fly ash (HVFA) mortar: Effects on internal moisture, microstructure and carbonated phase proportioning}, series = {Cement and Concrete Composites}, volume = {113}, journal = {Cement and Concrete Composites}, number = {October}, publisher = {Elsevier}, doi = {10.1016/j.cemconcomp.2020.103713}, abstract = {Binders with large portions of carbon-intensive Portland cement replaced by supplementary cementitious materials (e.g. fly ash) are more susceptible to carbonation mainly due to their lower CO2 buffering capacity. This conclusion is usually drawn from accelerated experiments at elevated CO2 levels involving processes that seriously differ from natural carbonation. The resulting presence of H2O reactant in the pore system and the carbonated microstructure itself may be very different. In this paper, these phenomena were investigated for High-Volume Fly Ash (HVFA) mortar via carbonation tests at ±0.04\% CO2 (natural carbonation), 1\% CO2 and 10\% CO2. Internal humidity sensor monitoring and 1H NMR relaxometry revealed the highest water vapour and liquid water contents after carbonation at 10\% CO2. Carbonation at 10\% CO2 results in a coarser pore structure than carbonation at 1\% CO2, and this probably due to a higher degree of C-S-H carbonation.}, language = {en} } @article{ThielSkarabisGehlenetal., author = {Thiel, Charlotte and Skarabis, Jens and Gehlen, Christoph and Goetzfried, Franz Xaver}, title = {Einfluss des Sulfatgehalts von Tausalzen auf den Frost-Tausalz-Widerstand von Betonen im Bereich der Bundesfernstraßen}, series = {Straße und Autobahn}, journal = {Straße und Autobahn}, number = {11}, publisher = {Kirschbaum}, pages = {811 -- 815}, language = {de} } @inproceedings{ThielHolmeErlacheretal., author = {Thiel, Charlotte and Holme, L. and Erlacher, L. and Gehlen, Christoph}, title = {Effect of real climatic conditions on freeze-thaw induced damage of concrete}, series = {Durable Concrete for Infrastructure under Severe Conditions : Smart admixtures, self-responsiveness and nano-additions, Proceedings 10-11 September 2019, Ghent, Belgium}, booktitle = {Durable Concrete for Infrastructure under Severe Conditions : Smart admixtures, self-responsiveness and nano-additions, Proceedings 10-11 September 2019, Ghent, Belgium}, editor = {Adelaide Ara{\´u}jo, Maria and Van Tittelboom, Kim}, isbn = {978-9-463-88638-3}, abstract = {The analysis of German weather data from 1996 to 2019 reveals a development in climate towards freeze-thaw exposure conditions which are detrimental to concrete durability. This trend may intensify freeze-thaw attack in future and lead to more internal and/or external damage in concrete structures. This contribution considers the inclusion of real climate conditions in laboratory simulations. Weather data were recorded and compared with depth-resolved measurements of humidity and temperature in concrete samples stored at the median site of an expressway. The strength of attack depends mainly on the amount of damaging freeze-thaw cycles (minimum temperature <-5°C in combination with moisture). In addition, the salt content of the contact water, minimum temperature and thickness of the ice layer on the concrete surface are decisive. Experiments show that internal and to a minor degree also external damage increase due to lower heating rates. The exposure of the sample itself (i.e. compass direction and removal of snow) affects the resulting damage evolution significantly. In order to save resources and enable the production of more sustainable concrete structures, current accelerated tests need to be adapted to real climatic conditions. 1. Introduction Adaptation to climate change and the associated extreme weather events represents a crucial challenge for our society. The durability of concrete, the most frequently used building material, is highly dependent on the local environment of concrete structures. In the case of a freeze-thaw de-icing salt attack, this is given by essentially the number of frost-thaw cycles (FTC) relevant to damage, the minimum temperature, the thickness of the ice layer, the moisture conditions and the concentration of salt. By investigating the interdependencies, the depth of scaling of the concrete surface per winter period can be predicted as a function of parameters accounting for the different effects of the concrete composition (air content, w/b ratio and binder type), curing time, carbonation and the duration and formation of damaging freeze-thaw cycles, [1, 2]. In order to quantify the individual effects and map them in an engineering model, a large number of laboratory tests are necessary. For this purpose, a known freeze-thaw cycle usually has to be modified. While it is already known that the cooling rate [3] and holding time at minimum temperature [4] affect scaling development, we investigated the effect of different heating rates on scaling on freeze-thaw de-icing salt attack.}, language = {en} } @incollection{ThielGehlen, author = {Thiel, Charlotte and Gehlen, Christoph}, title = {Nuclear Magnetic Resonance and Magnetic Resonance Imaging}, series = {Methods of Measuring Moisture in Building Materials and Structures}, booktitle = {Methods of Measuring Moisture in Building Materials and Structures}, publisher = {Springer}, doi = {10.1007/978-3-319-74231-1_13}, pages = {99 -- 108}, abstract = {Nuclear Magnetic Resonance (NMR) enables to quantify the hydrogen nuclei in a sample and thus indirectly the water content. Here, hydrogen nuclei are put in oscillation (resonance) by applying a magnetic field and additional irradiation with pulsed electromagnetic waves of certain frequencies. In case all hydrogen nuclei of a sample are exclusively bound in water molecules, the resulting initial amplitude of the detected NMR signal is directly proportional to the water content. The subsequent attenuation of the oscillation is caused by relaxation mechanisms and provides information on the mobility and thus the binding states of the hydrogen nuclei. Therefore even the pore size distribution can be determined in completely water-saturated samples. If the magnetic field is graded, images can be created based on spatially resolved nuclei density distributions (MRI). Depending on the research objective, tailored choice of equipment and settings can be used to qualitatively and mostly quantitatively analyze almost every moisture-related problem. The article gives an overview of the existing NMR methods, equipment, influencing parameters, calibration techniques, applications and limitations.}, language = {en} } @article{GehlenThielStengel, author = {Gehlen, Christoph and Thiel, Charlotte and Stengel, Thorsten}, title = {{\"O}kobilanz f{\"u}r die Herstellung und Nutzung eines Autobahnabschnitts}, series = {Griffig : Aktuelles {\"u}ber Verkehrsfl{\"a}chen aus Beton}, journal = {Griffig : Aktuelles {\"u}ber Verkehrsfl{\"a}chen aus Beton}, number = {1}, publisher = {G{\"u}tegemeinschaft Verkehrsfl{\"a}chen aus Beton e.V.}, pages = {16}, abstract = {Im Rahmen einer nachhaltigen Entwicklung hat sich u.a. Deutschland dazu verpflichtet, klimasch{\"a}digende Emissionen zu reduzieren. Luftschadstoffe werden zu erheblichen Teilen durch den Straßenverkehr verursacht. Die potentiellen Umweltwirkungen, die bei der Herstellung und Nutzung eines 1 km langen Autobahnabschnitts mit vier verschiedenen Oberbauarten wurden in einer {\"O}kobilanz ermittelt und miteinander verglichen. Durch Ber{\"u}cksichtigung der Verkehrsbelastung w{\"a}hrend einer dreißigj{\"a}hrigen Nutzungsdauer werden die Auswirkungen des Treibstoffverbrauchs verdeutlicht. M{\"o}gliche Einsparpotentiale werden dargelegt.}, language = {de} }