@incollection{HansenLatasteNilssonetal., author = {Hansen, Kurt Kielsgaard and Lataste, Jean-Fran{\c{c}}ois and Nilsson, Lars-Olof and Thiel, Charlotte and Michel, Alexander}, title = {Specimen or Core; In the Laboratory}, series = {Methods of Measuring Moisture in Building Materials and Structures : State-of-the-Art Report of the RILEM Technical Committee 248-MMB}, booktitle = {Methods of Measuring Moisture in Building Materials and Structures : State-of-the-Art Report of the RILEM Technical Committee 248-MMB}, publisher = {Springer}, doi = {10.1007/978-3-319-74231-1_24}, pages = {221 -- 228}, abstract = {When also the sides, of a specimen or a core from a structure, are available during the moisture measurement procedure numerous techniques are applicable compared with when only the exposed surface is available.}, language = {en} } @article{VanoutrivevandenHeedeAldereteetal., author = {Vanoutrive, Hanne and van den Heede, Philip and Alderete, Natalia and Andrade, Carmen and Bansal, Tushar and Cam{\~o}es, Aires and Cizer, {\"O}zlem and de Belie, Nele and Ducman, Vilma and Etxeberria, Miren and Frederickx, Lander and Grengg, Cyrill and Ignjatović, Ivan and Ling, Tung-Chai and Liu, Zhiyuan and Garcia-Lodeiro, In{\´e}s and Lothenbach, Barbara and Medina Martinez, C{\´e}sar and Sanchez-Montero, Javier and Olonade, Kolawole and Palomo, Angel and Phung, Quoc Tri and Rebolledo, Nuria and Sakoparnig, Marlene and Sideris, Kosmas and Thiel, Charlotte and Visalakshi, Talakokula and Vollpracht, Anya and von Greve-Dierfeld, Stefanie and Wei, Jinxin and Wu, Bei and Zając, Maciej and Zhao, Zengfeng and Gruyaert, Elke}, title = {Report of RILEM TC 281-CCC: outcomes of a round robin on the resistance to accelerated carbonation of Portland, Portland-fly ash and blast-furnace blended cements}, series = {Materials and Structures}, volume = {55}, journal = {Materials and Structures}, number = {3}, publisher = {Springer}, doi = {10.1617/s11527-022-01927-7}, pages = {1 -- 29}, abstract = {Many (inter)national standards exist to evaluate the resistance of mortar and concrete to carbonation. When a carbonation coefficient is used for performance comparison of mixtures or service life prediction, the applied boundary conditions during curing, preconditioning and carbonation play a crucial role, specifically when using latent hydraulic or pozzolanic supplementary cementitious materials (SCMs). An extensive interlaboratory test (ILT) with twenty two participating laboratories was set up in the framework of RILEM TC 281-CCC 'Carbonation of Concrete with SCMs'. The carbonation depths and coefficients determined by following several (inter)national standards for three cement types (CEM I, CEM II/B-V, CEM III/B) both on mortar and concrete scale were statistically compared. The outcomes of this study showed that the carbonation rate based on the carbonation depths after 91 days exposure, compared to 56 days or less exposure duration, best approximates the slope of the linear regression and those 91 days carbonation depths can therefore be considered as a good estimate of the potential resistance to carbonation. All standards evaluated in this study ranked the three cement types in the same order of carbonation resistance. Unfortunately, large variations within and between laboratories complicate to draw clear conclusions regarding the effect of sample pre-conditioning and carbonation exposure conditions on the carbonation performance of the specimens tested. Nevertheless, it was identified that fresh and hardened state properties alone cannot be used to infer carbonation resistance of the mortars or concretes tested. It was also found that sealed curing results in larger carbonation depths compared to water curing. However, when water curing was reduced from 28 to 3 or 7 days, higher carbonation depths compared to sealed curing were observed. This increase is more pronounced for CEM I compared to CEM III mixes. The variation between laboratories is larger than the potential effect of raising the CO2 concentration from 1 to 4\%. Finally, concrete, for which the aggregate-to-cement factor was increased by 1.79 in comparison with mortar, had a carbonation coefficient 1.18 times the one of mortar. Supplementary Information The online version contains supplementary material available at 10.1617/s11527-022-01927-7.}, 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} } @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{HansenLatasteThiel, author = {Hansen, Kurt Kielsgaard and Lataste, Jean-Fran{\c{c}}ois and Thiel, Charlotte}, title = {ND-Methods - From a Surface}, 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_21}, pages = {193 -- 198}, abstract = {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.}, language = {en} } @inproceedings{ThielBeddoe, author = {Thiel, Charlotte and Beddoe, Robin E.}, title = {Investigating the role of moisture on concrete carbonation using single-sided H-NMR}, series = {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}, booktitle = {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}, publisher = {RILEM Publications S.A.R.L.}, isbn = {978-2-35158-171-1}, pages = {261 -- 268}, abstract = {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.}, language = {en} } @inproceedings{ThielStengel, author = {Thiel, Charlotte and Stengel, Thorsten}, title = {Nachhaltigkeitsaspekte von Oberbauweisen aus Asphalt und Beton}, series = {10. M{\"u}nchener Baustoffseminar GRIFFIG - LEISE - DAUERHAFT, Asphalt und Beton im Straßenbau, 10, 2012, M{\"u}nchen}, booktitle = {10. M{\"u}nchener Baustoffseminar GRIFFIG - LEISE - DAUERHAFT, Asphalt und Beton im Straßenbau, 10, 2012, M{\"u}nchen}, language = {de} } @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} } @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} } @inproceedings{ThielLowkeGehlen, author = {Thiel, Charlotte and Lowke, Dirk and Gehlen, Christoph}, title = {Effect of minimum temperature, salt and moisture content on concrete under freeze-thaw deicing salt attack}, series = {ICDC 2012 : International Congress on Durability of Concrete; Trondheim, Norway, 18-21 June 2012}, booktitle = {ICDC 2012 : International Congress on Durability of Concrete; Trondheim, Norway, 18-21 June 2012}, publisher = {Norwegian Concrete Association}, doi = {10.13140/2.1.3243.9367}, abstract = {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.}, 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{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{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} } @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} } @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} } @inproceedings{ThielLowkeGehlen, author = {Thiel, Charlotte and Lowke, Dirk and Gehlen, Christoph}, title = {Praxisgerechte Modellierung des Sch{\"a}digungsverlaufs von Betonen unter Frost-Tausalz-Angriff -Einfluss der Austrocknung}, series = {Tagungsbericht / IBAUSIL, 18. Internationale Baustofftagung : 12.-15. September 2012, Weimar, Band 2}, booktitle = {Tagungsbericht / IBAUSIL, 18. Internationale Baustofftagung : 12.-15. September 2012, Weimar, Band 2}, publisher = {Bauhaus-Univ.}, isbn = {978-3-00-034075-8}, language = {de} } @inproceedings{GrimmMuenchmeyerKraenkeletal., author = {Grimm, Benedikt and M{\"u}nchmeyer, Sebastian and Kr{\"a}nkel, Thomas and Gehlen, Christoph and Thiel, Charlotte}, title = {Developing a New Rapid, Relevant, and Reliable (R3) Method for Accelerated Measurement of Carbonation Progress at Gas Overpressure}, series = {International RILEM Conference on Synergising expertise towards sustainability and robustness of CBMs and concrete structures, SynerCrete'23 - Volume 1}, booktitle = {International RILEM Conference on Synergising expertise towards sustainability and robustness of CBMs and concrete structures, SynerCrete'23 - Volume 1}, publisher = {Springer}, doi = {10.1007/978-3-031-33211-1_30}, pages = {336 -- 346}, abstract = {The determination of durability-relevant material resistances of concrete is of great importance. They serve as input to engineering models to predict the durability of structures under real environmental conditions. The natural resistances have to be determined in time-consuming experiments, since the processes in nature are very slow. This is particularly important for new materials where long-term experience is not yet available. Thus, accelerated testing is required. Only that way new materials can be evaluated regarding their durability and subsequently be used in practical applications. For carbonation, a new R3 accelerated test method is presented in this contribution. An automated carbonation pressure chamber was developed. It consists of a pressure vessel, automated in such a way that it can apply gas overpressure of various intensities up to 8 bar to mortar and concrete samples. Simultaneously, it can control and regulate the ambient CO2 concentration from 0 to 99.5\% in a fully automated and continuously variable procedure. Experiments were carried out with varying combinations of gas overpressure at CO2 concentrations of 3 vol.-\% to achieve the most time-efficient carbonation of mortars and concretes. Mortars with different material compositions were used to evaluate the general suitability of the test procedure with the developed equipment. The automated carbonation pressure chamber enables reliable carbonation testing with a total duration under accelerated conditions of only 7 days.}, language = {en} } @inproceedings{ThielSchoenGehlen, author = {Thiel, Charlotte and Schoen, Alex and Gehlen, Christoph}, title = {Einfluss der CO2-Permeation auf die Carbonatisierung zementgebundener Baustoffe}, series = {Tagungsbericht: Ibausil, 20. Internationale Baustofftagung, 12.-14. September 2018, Weimar}, booktitle = {Tagungsbericht: Ibausil, 20. Internationale Baustofftagung, 12.-14. September 2018, Weimar}, publisher = {Bauhaus-Universit{\"a}t Weimar}, pages = {153 -- 161}, language = {de} } @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} } @inproceedings{FrankeThielDuranetal., author = {Franke, Wolfram and Thiel, Charlotte and Duran, F. and Gehlen, Christoph}, title = {Effect of Calcium Nitrate on the freeze-thaw-resistance of concrete}, series = {Proceedings of the 2nd International Congress on Concrete Durability, 2, 2014, New Delhi}, booktitle = {Proceedings of the 2nd International Congress on Concrete Durability, 2, 2014, New Delhi}, abstract = {Concrete in cold climates is not only exposed to cold weather while concreting but also to freeze-thaw cycles during its lifetime. Thus not only the concrete production needs to be adjusted to the environmental conditions but also the mixture has to be durable and resist the environmental impacts. Commonly an air entraining agent is used to interrupt the capillary pore system and to provide further space for the freezing water to expand. The downside of this approach is a loss in compressive strength. Within this paper the effect of simultaneous use of air entraining agent and calcium nitrate is discussed. It is shown that calcium nitrate can counteract strength loss due to the air entraining agent without reducing the durability gain in the same extent. A certain combination of calcium nitrate and air entraining agent can also be used to increase the freeze-thaw-resistance.}, 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{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{ThielBeddoeLowkeetal., author = {Thiel, Charlotte and Beddoe, Robin E. and Lowke, Dirk and Gehlen, Christoph}, title = {Accelerated carbonation: changes in water transport, porosity and phases of mortar due to different CO 2 pressures}, series = {Proceedings of the 10th fib International PhD Symposium in Civil Engineering, July 21 to 23, 2014, Qu{\´e}bec, Canada}, booktitle = {Proceedings of the 10th fib International PhD Symposium in Civil Engineering, July 21 to 23, 2014, Qu{\´e}bec, Canada}, organization = {F{\´e}d{\´e}ration International du B{\´e}ton (fib)}, pages = {217 -- 221}, abstract = {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).}, language = {en} } @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} } @inproceedings{ThielKesslerChilleetal., author = {Thiel, Charlotte and Keßler, Sylvia and Chill{\´e}, R. and Gehlen, Christoph}, title = {Effect of internal freeze-thaw deterioration on chloride migration in concrete}, series = {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}, booktitle = {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}, publisher = {CRC Press}, abstract = {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.}, language = {en} } @incollection{LatasteHansenNilssonetal., author = {Lataste, Jean-Fran{\c{c}}ois and Hansen, Kurt Kielsgaard and Nilsson, Lars-Olof and Thiel, Charlotte and Schießl-Pecka, Angelika and G{\"o}ller, Arndt and Gehlen, Christoph}, title = {Spatial Distributions}, 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_19}, pages = {173 -- 190}, abstract = {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.}, language = {en} } @inproceedings{ThielGehlen, author = {Thiel, Charlotte and Gehlen, Christoph}, title = {Compliance testing for probabilistic durability design purposes}, series = {Proceedings of the Sixth International Symposium on Life-Cycle Civil Engineering (IALCCE 2018), 28-31 October 2018, Ghent, Belgium}, booktitle = {Proceedings of the Sixth International Symposium on Life-Cycle Civil Engineering (IALCCE 2018), 28-31 October 2018, Ghent, Belgium}, publisher = {Taylor \& Francis}, language = {en} } @inproceedings{ThielLowkeGehlen, author = {Thiel, Charlotte and Lowke, Dirk and Gehlen, Christoph}, title = {Detection of Transport Processes during Freeze-Thaw Deicing Salt Attack Using Single-Sided NMR}, series = {Microstructural-related durability of cementitious composites : Second International Conference on Microstructural-related Durability of Cementitious Composites, 11 - 13 April 2012, Amsterdam}, booktitle = {Microstructural-related durability of cementitious composites : Second International Conference on Microstructural-related Durability of Cementitious Composites, 11 - 13 April 2012, Amsterdam}, publisher = {RILEM}, abstract = {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.}, 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} } @inproceedings{GehlenThiel, author = {Gehlen, Christoph and Thiel, Charlotte}, title = {Specification of building materials for in service durability}, series = {Proceedings ICSBM 2019: 2nd international conference of sustainable building materials, 2019, Eindhoven}, booktitle = {Proceedings ICSBM 2019: 2nd international conference of sustainable building materials, 2019, Eindhoven}, publisher = {Technische Universiteit Eindhoven}, address = {Eindhoven}, isbn = {978-90-386-4898-9}, pages = {31 -- 40}, abstract = {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.}, 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} } @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} } @inproceedings{HaynackSchneiderTimothyetal., author = {Haynack, Alexander and Schneider, Alexander and Timothy, Jithender J. and Kr{\"a}nkel, Thomas and Gehlen, Christoph and Thiel, Charlotte}, title = {Effect of Chloride Concentration on the Freeze-Thaw Resistance of Concrete}, series = {International RILEM Conference on Synergising expertise towards sustainability and robustness of CBMs and concrete structures, SynerCrete'23 - Volume 2}, booktitle = {International RILEM Conference on Synergising expertise towards sustainability and robustness of CBMs and concrete structures, SynerCrete'23 - Volume 2}, publisher = {Springer}, address = {Cham}, doi = {10.1007/978-3-031-33187-9_83}, pages = {911 -- 921}, abstract = {Performance test methods intend to provide a fast, accurate and precise determination of a particular building material property and thus determine the associated material performance. In concrete, various performance tests are used to classify existing or to approve new materials, to compare concrete compositions or to determine causes of damage in existing structures. The challenge of such test methods is to accelerate natural (very slow) mechanisms to determine the material performance precisely within a short time. However, the attack on the material must not be unrealistically intensive, but must represent reality, just in fast motion. The performance tests used to demonstrate the freeze-thaw resistance of concrete employ a 3\% NaCl solution, with literature data ranging from 1\% to 10\% showing that low concentrations can result in higher surface scaling. In this paper, mortar and concrete specimens are tested at 0, 1, 3, 6, and 9\% NaCl solution following the CDF procedure (DIN CEN/TS 12390-9:2017-05). The results are discussed against the background of the existing literature and show that the damage is critically dependent on the pore system and thus also on the effect of the micro-ice lens pump. With increasing freeze-thaw exposition, the pessimum in the external damage shifts towards a de-icing salt concentration of 6\%. Furthermore, a novel test methodology based on 3D-laserscanning is presented to determine scaling accurately by eliminating side effects that are typically present in current standards.}, 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} } @incollection{NilssonAgostiniThiel, author = {Nilsson, Lars-Olof and Agostini, Franck and Thiel, Charlotte}, title = {Installation of Probes}, 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_23}, pages = {207 -- 219}, language = {en} } @article{HaynackTimothyKraenkeletal., author = {Haynack, Alexander and Timothy, Jithender J. and Kr{\"a}nkel, Thomas and Gehlen, Christoph and Thiel, Charlotte}, title = {Analyse des Frost-Tausalz-Widerstands zementgebundener Baustoffe mittels 3D-Laserscanning}, series = {ce/papers: Proceedings in Civil Engineering}, volume = {6}, journal = {ce/papers: Proceedings in Civil Engineering}, number = {6}, publisher = {Ernst \& Sohn}, issn = {2509-7075}, doi = {10.1002/cepa.2951}, pages = {1189 -- 1196}, abstract = {Eine Herausforderung performancebasierter Pr{\"u}fverfahren zur Bewertung der Dauerhaftigkeit ist die Beschleunigung nat{\"u}rlicher Mechanismen. Dies ist notwendig, um innerhalb kurzer Zeit die Langzeit-Leistungsf{\"a}higkeit ermitteln zu k{\"o}nnen. Die Bestimmung der Frost-Tausalzbest{\"a}ndigkeit von Beton kann durch den CDF-Test erfolgen, welcher f{\"u}r Betone mit ausreichendem Frost-Tausalz-Widerstand sehr gut funktioniert. Bei Proben mit einer unzureichenden bzw. unbekannten Performance k{\"o}nnen erh{\"o}hte Randabwitterungen auftreten, welche durch das Abl{\"o}sen des seitlichen Abdichtbands entstehen. Der zunehmende Randeinfluss f{\"u}hrt so zu einer Verf{\"a}lschung der Ergebnisse und zu einer Untersch{\"a}tzung der tats{\"a}chlichen Performance des Bauteils. In diesem Beitrag werden M{\"o}rtel- und Betonprobek{\"o}rper mit unterschiedlichen Abwitterungsraten in Anlehnung an das CDF-Verfahren untersucht. Zus{\"a}tzlich wird die Oberfl{\"a}chensch{\"a}digung der Proben anhand einer neuartigen Messmethode mittels hochaufl{\"o}sendem 3D-Laserscanning ausgewertet. Die Ergebnisse zeigen, dass die Randeffekte mit der Laserscan-Methode umgangen und vergleichbare Ergebnisse zu den CDF-Untersuchungen erzielt werden k{\"o}nnen. Somit k{\"o}nnen Betone ohne Randeinfl{\"u}sse charakterisiert und eine pr{\"a}zise Prognose der Langzeitbest{\"a}ndigkeit getroffen werden.}, language = {de} } @article{GrimmThielKraenkeletal., author = {Grimm, Benedikt and Thiel, Charlotte and Kr{\"a}nkel, Thomas and Gehlen, Christoph}, title = {Einfluss der Permeation auf die Carbonatisierung von Beton}, series = {ce/papers: Proceedings in Civil Engineering}, volume = {6}, journal = {ce/papers: Proceedings in Civil Engineering}, number = {6}, publisher = {Ernst \& Sohn}, address = {Berlin}, issn = {2509-7075}, doi = {10.1002/cepa.3005}, pages = {1348 -- 1357}, abstract = {Die Carbonatisierung von Beton kann einerseits zu Sch{\"a}den bei Stahlbetonbauwerken f{\"u}hren, andererseits kann der Beton so CO2 speichern und damit seinen CO2-Fußabdruck verringern. In diesem Beitrag wird dargestellt, wie eine effiziente Beschleunigung der Carbonatisierung durch Anlegen eines geringen {\"a}ußeren Drucks erreicht werden kann. Damit wird neben der Diffusion der wesentlich schneller ablaufende Transportmechanismus der Permeation ausgenutzt, der das CO2 tiefer in das Probeninnere transportiert und damit in kurzer Zeit die Bestimmung des Carbonatisierungswiderstand zementgebundener Materialien erm{\"o}glicht. Hierzu wurde eine Pr{\"u}feinrichtung entwickelt, die es erm{\"o}glicht, die CO2-Konzentration und in gewissen Grenzen auch relative Luftfeuchte sowie die Temperatur gezielt einzustellen und zu steuern, um so M{\"o}rtel- und Betonproben schnell und pr{\"a}zise zu carbonatisieren. Der Einfluss verschiedener Druckstufen und Wechselzyklen wird dargelegt und die resultierenden chemischen und physikalischen Ver{\"a}nderungen der Proben bestimmt. Als besonders effizient und gleichzeitig realit{\"a}tsnah erwies sich die konstante CO2-Beaufschlagung mit 3 Vol.-\% CO2 mit zus{\"a}tzlichem, moderatem Gasdruck. Das hier entwickelte Verfahren kann daher genutzt werden, um Betone schnell und effizient in zeitraffenden Materialtests hinsichtlich Carbonatisierungswiderstand zu charakterisieren.}, language = {en} } @article{vonGreveDierfeldLothenbachVollprachtetal., author = {von Greve-Dierfeld, Stefanie and Lothenbach, Barbara and Vollpracht, Anya and Wu, Bei and Huet, Bruno and Andrade, Carmen and Medina, C{\´e}sar and Thiel, Charlotte and Gruyaert, Elke and Vanoutrive, Hanne and Del Sa{\´e}z Bosque, Isabel F. and Ignjatovic, Ivan and Elsen, Jan and Provis, John L. and Scrivener, Karen and Thienel, Karl-Christian and Sideris, Kosmas and Zajac, Maciej and Alderete, Natalia and Cizer, {\"O}zlem and van den Heede, Philip and Hooton, Robert Douglas and Kamali-Bernard, Siham and Bernal, Susan A. and Zhao, Zengfeng and Shi, Zhenguo and de Belie, Nele}, title = {Understanding the carbonation of concrete with supplementary cementitious materials}, series = {Materials and Structures}, volume = {53}, journal = {Materials and Structures}, publisher = {Springer Nature}, doi = {10.1617/s11527-020-01558-w}, pages = {1 -- 34}, abstract = {Blended cements, where Portland cement clinker is partially replaced by supplementary cementitious materials (SCMs), provide the most feasible route for reducing carbon dioxide emissions associated with concrete production. However, lowering the clinker content can lead to an increasing risk of neutralisation of the concrete pore solution and potential reinforcement corrosion due to carbonation. carbonation of concrete with SCMs differs from carbonation of concrete solely based on Portland cement (PC). This is a consequence of the differences in the hydrate phase assemblage and pore solution chemistry, as well as the pore structure and transport properties, when varying the binder composition, age and curing conditions of the concretes. The carbonation mechanism and kinetics also depend on the saturation degree of the concrete and CO2 partial pressure which in turn depends on exposure conditions (e.g. relative humidity, volume, and duration of water in contact with the concrete surface and temperature conditions). This in turn influence the microstructural changes identified upon carbonation. This literature review, prepared by members of RILEM technical committee 281-CCC carbonation of concrete with supplementary cementitious materials, working groups 1 and 2, elucidates the effect of numerous SCM characteristics, exposure environments and curing conditions on the carbonation mechanism, kinetics and structural alterations in cementitious systems containing SCMs.}, language = {en} } @article{ThielStrasserObergriesseretal., author = {Thiel, Charlotte and Strasser, Juliane and Obergrießer, Mathias and Linner, Thomas}, title = {Strategien zur Implementierung der Kreislaufwirtschaft beim Bauen mit Beton}, series = {Beton- und Stahlbetonbau}, volume = {118}, journal = {Beton- und Stahlbetonbau}, publisher = {Ernst \& Sohn, a Wiley Brand}, address = {Berlin}, doi = {DOI: 10.1002/best.202200118}, abstract = {Beton ist das am meisten verwendete Baumaterial weltweit. CO2-Emissionen, die bei der Zement- und Betonherstellung an-fallen, m{\"u}ssen reduziert, Produktionsmethoden verbessert und Betonzusammensetzungen angepasst werden. Zudem steigt die Nachfrage nach Beton, w{\"a}hrend fossile Brennstoffreserven und die Verf{\"u}gbarkeit von mineralischen Rohstoffen abnehmen. Hinzu kommt, dass bei der Betonherstellung neue mineralogi-sche Phasen entstehen, was ein echtes Recycling erschwert. Die Implementierung kreislaufkonformer Strategien wie der Verl{\"a}ngerung der Nutzungsphase ist ein wichtiger Hebel, um Umweltwirkungen im Bauwesen zu reduzieren, und erfordert die ganzheitliche Betrachtung des Bauwerks. Besonders großes Potenzial liefern hier die digital vernetzte und modellba-sierte Planung sowie die darauf aufbauende robotergest{\"u}tzte Fertigung der Bauteile, mit der sich leicht l{\"o}sbare Verbindun-gen, einfach r{\"u}ckbaubare, multifunktionale, flexible sowie bzgl. Dauerhaftigkeit optimierte Strukturen {\"o}kologisch und kosten-effizient generieren lassen. Technisch w{\"a}ren bereits viele Pro-jekte in der Praxis umsetzbar, allerdings m{\"u}ssen hierzu die rechtlichen Rahmenbedingungen verbessert und b{\"u}rokratische H{\"u}rden abgebaut werden. Dieser Beitrag hat das Ziel, das Be-wusstsein f{\"u}r den n{\"o}tigen Wechsel von der Linear- zur Kreis-laufwirtschaft im Betonbau und den korrespondierenden Daten zu erh{\"o}hen und dem Planer einfache Grunds{\"a}tze f{\"u}r den Ent-wurf, die Ausschreibung und Umsetzung mitzugeben, um jetzt schon einen wichtigen Beitrag zum verantwortungsvollen Um-gang mit immer knapper werdenden Ressourcen zu leisten.}, language = {de} } @unpublished{VollprachtGluthRogiersetal., author = {Vollpracht, Anya and Gluth, Gregor J. G. and Rogiers, Bart and Uwanuakwa, Ikenna D. and Phung, Quoc Tri and Zaccardi, Yury Villagran and Thiel, Charlotte and Vanoutrive, Hanne and Etcheverry, Juan Manuel and Gruyaert, Elke and Kamali-Bernard, Siham and Kanellopoulos, Antonios and Zhao, Zengfeng and Martins, Isabel Milagre and Rathnarajan, Sundar and De Belie, Nele}, title = {Report of RILEM TC 281-CCC: Insights into factors affecting the carbonation rate of concrete with SCMs revealed from data mining and machine learning approaches}, publisher = {Research Square Platform LLC}, doi = {10.21203/rs.3.rs-4169492/v1}, abstract = {The RILEM TC 281-CCC ''Carbonation of concrete with supplementary cementitious materials'' conducted a study on the effects of supplementary cementitious materials (SCMs) on the carbonation rate of blended cement concretes and mortars. In this context, a comprehensive database has been established, consisting of 1044 concrete and mortar mixes with their associated carbonation depth data over time. The dataset comprises mix designs with a large variety of binders with up to 94\% SCMs, collected from the literature as well as unpublished testing reports. The data includes chemical composition and physical properties of the raw materials, mix-designs, compressive strengths, curing and carbonation testing conditions. Natural carbonation was recorded for several years in many cases with both indoor and outdoor results. The database has been analysed to investigate the effects of binder composition and mix design, curing and preconditioning, and relative humidity on the carbonation rate. Furthermore, the accuracy of accelerated carbonation testing as well as possible correlations between compressive strength and carbonation resistance were evaluated. The analysis revealed that the w/CaOreactive ratio is a decisive factor for carbonation resistance, while curing and exposure conditions also influence carbonation. Under natural exposure conditions, the carbonation data exhibit significant variations. Nevertheless, probabilistic inference suggests that both accelerated and natural carbonation processes follow a square-root-of-time behavior, though accelerated and natural carbonation cannot be converted into each other without corrections. Additionally, a machine learning technique was employed to assess the influence of parameters governing the carbonation progress in concretes.}, language = {en} }