TY - CONF A1 - Rogge, Andreas A1 - Thiele, Marc ED - Strauss, ED - Frangopol, ED - Bergmeister, T1 - Damage evolution in concrete under high compressive cyclic loadings N2 - The aim of this project is to get deeper insight into the fatigue behaviour of concrete under cyclic compressive loading. It focuses on the evaluation and modelling of the entire damage process during life-cycle by means of various non-destructive measuring techniques. In numerous tests on cylinders h/d = 30/10 cm under different cyclic loading conditions, the crack development and the damage evolution are monitored using acoustic emission analysis and ultrasonic velocity measurement. The final aim will be the definition of a damage descriptor D based on experimental observations, which can be implemented into a numerical model on a meso-mechanical level. T2 - IALCCE 2012 - 3rd International symposium on life-cycle civil engineering CY - Vienna, Austria DA - 03.10.2012 KW - Concrete KW - Cyclic loading KW - Fatigue KW - Damage PY - 2013 SN - 978-0-415-62126-7 SP - 1307 EP - 1313 PB - CRC Press CY - Boca Raton, Fla. AN - OPUS4-26845 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stohl, Leonie A1 - Manninger, Tanja A1 - von Werder, Julia A1 - Dehn, F. A1 - Gorbushina, Anna A1 - Meng, Birgit T1 - Bioreceptivity of concrete - A review N2 - Materials that support natural biodiversity on their surfaces can compensate for human activities that have a negative impact on nature and thus contribute to a carbon-neutral and nature-positive world. Specifically designing bioreceptive materials which favor the growth of biofilms on their surface is an approach complementing conventional, macroscopic green façades. But what exactly characterizes a bioreceptive substrate and how do biofilm and substrate interact? How and why does a spontaneous colonization and the formation of biofilms take place? What are biofilms and how can they be established in a laboratory setting? How can this existing knowledge be transferred to the artificial stone concrete so that this material can be tuned to increase (or decrease) its bioreceptivity? This review paper aims at summarizing the existing state of knowledge on bioreceptive concrete and pointing out inconsistencies and contradictions which can only be removed by more interdisciplinary research in the field. KW - Bioreceptivity KW - Biofilm KW - Green facades KW - Developing building materials KW - Surface interactions KW - Concrete PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-581685 DO - https://doi.org/10.1016/j.jobe.2023.107201 SN - 2352-7102 VL - 76 SP - 1 EP - 17 PB - Elsevier AN - OPUS4-58168 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stohl, Leonie A1 - Tonon, Chiara A1 - Cook, Jake A1 - Gorbushina, Anna A1 - Dehn, Frank A1 - von Werder, Julia T1 - Understanding bioreceptivity of concrete: realistic and accelerated weathering experiments with model subaerial biofilms N2 - Vertical greening systems are a promising solution to the increasing demand for urban green spaces, improving environmental quality and addressing biodiversity loss. This study facilitates the development microbially greened algal biofilm facades, which offer a low maintenance vertical green space. The study focuses on concrete as a widely used building material and explores how physical surface characteristics impact its bioreceptive properties. Concrete samples, produced from the same mix but differing in surface structure, were subjected to a laboratory weathering experiment to assess their bioreceptivity. A novel inoculation method was employed, involving a single initial inoculation with either alga ( Jaagichlorella sp.) alone, or a model biofilm consisting of a combination of the alga ( Jaagichlorella sp.) with a fungus ( Knufia petricola). The samples underwent four months of weathering in a dynamic laboratory setup irrigated with deionized water to observe subaerial biofilm attachment and growth. The formation of subaerial biofilms was monitored with high resolution surface imaging, colorimetric measurements and Imaging Pulse Amplitude Modulated Fluorometry (Imaging PAM-F), with Imaging PAM-F proving the most effective. Statistical analysis revealed that by impacting surface pH value and water retention capability, surface structures significantly influence microbial growth and that the concrete’s bioreceptivity can be influenced through thoughtful design of the materials surface. The inoculation of algae combined with a fungus facilitated the formation of a stable subaerial biofilm, enabling algae to colonize a surface structure that it could not colonize alone. This finding highlights the importance of modelling synergistic interactions present in natural biofilms. KW - Bioreceptivity KW - Concrete KW - Biofilm PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-653105 DO - https://doi.org/10.1617/s11527-025-02864-x SN - 1359-5997 VL - 59 IS - 2 SP - 1 EP - 18 PB - Springer Science and Business Media LLC AN - OPUS4-65310 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Epple, Niklas A1 - Sanchez Trujillo, Camila Andrea A1 - Hau, Julia A1 - Niederleithinger, Ernst A1 - Malm, F. T1 - Structural Monitoring in an Urban Underground Metro Station Using Cod N2 - Active ultrasonic monitoring with coda wave interferometry has demonstrated its potential for structural Health monitoring in concrete structures. This study investigates its application using ultrasonic transducers embedded in the ceiling of a subway station in Munich, Germany. We evaluate the impact of environmental conditions, specifically electromagnetic interference and temperature, on data quality, as well as the influence of regular loading from passing trams. Results indicate that electromagnetic interference significantly affects measurements, while temperature effects remain minimal due to the station’s stable thermal environment. Long-term measurements and a controlled load test show that both dynamic and static loading from trams induce ultrasonic velocity changes of only 0.01%–0.06%. Although the experiment demonstrates the capacity to detect structural responses and supports the feasibility of long-term monitoring, improved electromagnetic shielding and Hardware reliability are required for successful future applications. T2 - NDT-CE 2025 CY - Izmir, Turkey DA - 24.09.2025 KW - Coda Wave Interferometry (CWI) KW - Structural health monitoring (SHM) KW - Concrete KW - Ultrasonic testing KW - Urban infrastructure PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-654619 DO - https://doi.org/10.58286/31706 SN - 1435-4934 SP - 1 EP - 10 PB - e-Journal of Nondestructive Testing (eJNDT) AN - OPUS4-65461 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Niederleithinger, Ernst A1 - Wunderlich, Carolin ED - Meßinger, J. T1 - Temperature influence on ultrasonic velocity in concrete N2 - Ultrasonic methods are valuable tools for quality assessment and structural imaging of concrete. In such applications, accurate and reliable determination of ultrasonic wave velocities is essential, as they are affected by various experimental and environmental factors. In this research coda wave interferometry (CWI) was used to determine the influence of temperature (0 to 50 °C) on ultrasonic wave velocity in concrete samples. A resolution of better than 10-4 was achieved in the measurement of relative velocity changes. Reversibility and repeatability were taken into account. In additlon the benefit of newly developed permanently embedded sensors was evaluated. The presented results can be used to Interpret and refine data from ultrasonic monitoring Systems. T2 - 2nd Neustadt workshop CY - Neustadt a.d. Weinstraße DA - 11.11.2012 KW - Coda wave interferometry KW - Concrete KW - Temperature KW - Ultrasound KW - Velocity PY - 2012 SN - 0947-1944 VL - IV SP - 60 EP - 61 PB - Dt. Geophysikalische Ges. CY - Potsdam AN - OPUS4-27224 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram ED - Beushausen, Hans T1 - Application of a cusum control system for enhanced robustness of the flow properties of self-compacting concrete N2 - Control chart systems are used in quality management systems to keep production processes stable. In concrete production they are often applied for the control of the compressive strength. The most efficient control chart systems are cumulated sums (cusum), which help to observe deviations from a targeted value. Unlike alternative observation chart systems that focus on process data evaluation, cusum observations react very rapidly on systematic process changes in processes. Therefore, the cusum method is particularly suitable if immediate counteractions have to be taken, like in the case of fresh concrete properties of self-compacting concrete (SCC), which can have severe influences on the durability and mechanical strength of concrete. The rheology of SCC can be affected by an enormous variety of influencing factors, from raw material properties to handling or environmental temperature. The present study shows that regardless of the material based influencing parameter for a rheology change, a steady slump flow can be achieved only by adding supplementary superplasticizer in case of loss of flow and adding stabilising agent (ST) in case of increased flow if the respective V-mask indicates a systematic change. A reference SCC was artificially manipulated in order to achieve realistic experimental data for flowability and flowability changes due to changes in the raw material properties. The results point out that productions with applied cusum methods were capable of keeping the target slump flow deviation within approximately 1% only, while productions without applied cusum method deviated up to 14% and more from the target. T2 - fib Symposium 2016. Performance-Based Approaches for Concrete Structures. CY - Cape Town, South Africa DA - 21.11.2016 KW - Concrete KW - Self-compacting concrete KW - cusum KW - control chart KW - quality control KW - robustness PY - 2016 SN - 978-2-88394-121-2 SP - 106-1 EP - 106-10 PB - Fédération internationale du béton ( fib) CY - Lausanne, Switzerland AN - OPUS4-40976 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmidt, Wolfram A1 - Priebe, Nsesheye Susan A1 - Kühne, Hans-Carsten T1 - Optimising the rheology of concrete for sub-Saharan African boundary conditions / Optimierung der Rheologie von Beton für Rahmenbedingungen in Subsahara-Afrika N2 - Die Zement- und Betontechnologie in Afrika hat keine ähnlich lange Tradition wie viele Länder der nördlichen Hemisphäre. In vielen afrikanischen Ländern ist die Bauindustrie jedoch von Wachstum gekennzeichnet und hier werden Zement und Beton zukünftig zweifelsohne an Bedeutung gewinnen. KW - Africa KW - Cement KW - Concrete KW - Proficiency testing KW - Round robin PY - 2012 SN - 0373-4331 SN - 1865-6528 N1 - Sprachen: Deutsch/Englisch - Languages: German/English N1 - Geburtsname von Priebe, Nsesheye Susan: Msinjili, N. S. - Birth name of Priebe, Nsesheye Susan: Msinjili, N. S. VL - 78 IS - 09 SP - 60 EP - 67 PB - Bauverl. CY - Gütersloh AN - OPUS4-27338 LA - mul AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmidt, Wolfram A1 - Mota, Berta A1 - Ramirez Caro, Alejandra T1 - The action of aggregates on concrete rheology N2 - Most factors acting on concrete rheology work at an extremely small-scale level. Influencing factors in the millimetre or centimetre area are essentially restricted to sand and aggregates. The latter, however, make up 50 to 70% of the total volume of most concretes – a fact often ignored in research on controlling concrete processing properties. Whereas suitably chosen concrete admixtures and additives can influence rheology in a very targeted manner, sand and aggregates are less suitable for controlling rheology but nonetheless contribute to the rheology of the Overall system. The actions of sand and aggregate can impose themselves upon the actions of admixtures and additives and, in unfavourable circumstances, even render them redundant. For this reason, any results concerning the processability of binding agent systems can only be transferred to concrete with great care. It is important to better understand the action of sand and aggregates in order to be able to harmonise them in such a way that they complement the action of superplasticisers positively, instead of working against them. Savings on costs can also be made by this targeted fine-tuning. KW - Rheology KW - Aggregates KW - Viscosity KW - Yield stress KW - Concrete PY - 2018 VL - 3 SP - 42 EP - 49 PB - ad-media GmbH CY - Cologne AN - OPUS4-47045 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmidt, Wolfram A1 - Gluth, Gregor T1 - Knowledge transfer and quality assurance - key factors for the future prospects of building with cement in Africa / Wissentransfer und Qualitätssicherung - Schlüsselfaktoren für die Zukunftsperspektiven der Bauweise mit Zement in Afrika N2 - The SPIN Project included workshops for young academics and building materials laboratories of the cement and concrete sector. Within the framework of the SPIN Project, plans were discussed for the conference 'Advances in Cement and Concrete Technology in Africa' that will take place in January 2013. A lecture on application rules for shotcrete construction was given by Prof. Regina Stratmann-Albert who took part in the courses as guest speaker. A short lecture was given by Akindehinde Ayotunde on the use of starch in cement-bound systems. Renato Rajzer talked about standard regulations for quality assurance during site operation. A workshop for an interlaboratory comparison took place with participants from all regions of Africa to test cement according to the standard series EN 196. The Round Robin test comprises the determination of the tensile bending and compressive strengths according to EN 196-1, of the water demand, the initial and final set, and the soundness according to EN 196-3 as well as of the fineness according to EN 196-6. KW - Africa KW - Cement KW - Concrete KW - Proficiency testing KW - Round robin PY - 2012 SN - 0949-0205 N1 - Sprachen: Deutsch/Englisch - Languages: German/English VL - 65 IS - 9 SP - 34 EP - 38 PB - Bauverl. BV CY - Gütersloh AN - OPUS4-26535 LA - mul AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmidt, Wolfram T1 - Start of round-robin test for cement testing in Africa T1 - Start für Ringversuch zur Zementprüfung in Afrika N2 - Within the scope of the SPIN project (www.spin.bam.de), three staff members of the Federal Institute for Materials Research and Testing (BAM), Berlin, traveled to Tanzania on 30 June. There they, together with scientists from several other African countries, were to give a course of lectures for Masters and Ph.D. students as well as leading a kick-off workshop for an all-African round-robin test for cement testing. The first stop of the BAM staff was in Zanzibar, where they inspected an on-going a building reinstatement project and discussed plans for the conference “Advances in Cement and Concrete Technology in Africa” (www.accta2013.com) to be held in January 2013. At the international conference in Johannesburg, which is mainly organized by BAM and the University of the Witwatersrand, more than 300 visitors from over 40 nations will come together. KW - Africa KW - Cement KW - Concrete KW - Proficiency testing KW - Round robin PY - 2012 UR - http://www.bft-international.com/de/artikel/bft_2012-08_Start_fuer_Ringversuch_zur_Zementpruefung_in_Afrika_1468912.html SN - 0373-4331 SN - 1865-6528 N1 - Sprachen: Deutsch/Englisch - Languages: German/English VL - 08 SP - 54 EP - 55 PB - Bauverl. CY - Gütersloh AN - OPUS4-26429 LA - mul AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Priebe, Nsesheye Susan T1 - Obtaining optimum workability using RHA in a modified cementitious system N2 - In order to reduce CO2 emission in concrete and minimize the environmental impact, majority of research focuses on using supplementary cementitious materials (SCMs) such as Fly Ash (FA), blast furnace slag (GGBS) and Silica Fume (SF) or Microsilica as a replacement for ordinary Portland cement in concrete. However, in terms of sustainability, it is not economically feasible to use the above mentioned SCMs in countries where these materials are not readily available. In addition, when dealing with the carbon footprint of concrete, despite their positive influence in concrete, such SCMs cannot be said to be eco-friendly materials due to their high energy production process. In many developing countries in sub-Saharan Africa (SSA), agriculture is the leading economic sector. Generally, agricultural by-products are eco-friendly in terms of low energy in production, and they often have no further use for the environment. These by-products (baggase, cassava peels and rice husks) are mainly not the materials of discussion in this current day and age and especially in the northern hemisphere, where the majority of concrete technology originates. Hence, it is inevitable to consider other more sustainable resources in concrete for SSA. Nevertheless, optimization of these resources in concrete can only function with a clear understanding of the reactivity of the materials and its interaction and mechanism to adopt similar and workable properties as a normal performance cementitious system. This paper addresses rice husk ash (RHA) as a main SCM in various cementitious systems with added limestone filler (LSF) and observes its performance in mortar. Superplasticizers such as polycarboxylate-ethers (PCEs) and lignosulphonates (LS) are incorporated in the cementitious systems to improve workability. The interaction of RHA with the superplasticizers was investigated by means of zeta potential (ZP). According to the results presented, it is shown that RHA powder has a positive compatibility with the chosen superplasticizers and its performance in mortar with LSF also shows increase in strength and workability. T2 - International Concrete Sustainability Conference CY - Washington DC, USA DA - 15.05.2016 KW - Superplaticizers KW - Supplementary cementitious materials; KW - Sub-Saharan Africa KW - Rice husk ash KW - Cement KW - Concrete PY - 2016 N1 - Geburtsname von Priebe, Nsesheye Susan: Msinjili, N. S. - Birth name of Priebe, Nsesheye Susan: Msinjili, N. S. AN - OPUS4-41033 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmidt, Wolfram A1 - Kumaran, G.S. T1 - Clearing the way N2 - With a rapidly-expandingpopuiation plus enormous infrastructure and housing needs, Africa has vast potential for its domestic construction industry. Cement and concrete are expected to play a key role in the region's development but to be truly sustainable current productlon technology will need to be adapted to local boundary conditions. It is in this context that 11 African and European organisations created the Spearhead Network for Innovative, Ctean and Safe Cement and Concrete Technologies (SPIN) which aims to Support the development of concepts tailor-made for Africa. KW - Cement KW - Concrete KW - Africa KW - Research policy PY - 2012 SN - 0959-6038 IS - October SP - 86 EP - 88 PB - Holbrook & Son CY - Dorking AN - OPUS4-27177 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kruschwitz, Sabine A1 - Munsch, Sarah Mandy A1 - Telong, Melissa A1 - Schmidt, Wolfram A1 - Bintz, Thilo A1 - Fladt, Matthias A1 - Stelzner, Ludwig T1 - The NMR core analyzing TOMograph: A multi-functional tool for non-destructive testing of building materials N2 - NMR is becoming increasingly popular for the investigation of building materials as it is a non-invasive technology that does not require any sample preparation nor causes damage to the material. Depending on the specific application it can offer insights into properties like porosity and spatial saturation degree as well as pore structure. Moreover it enables the determination of moisture transport properties and the (re-)distribution of internal moisture into different reservoirs or chemical phases upon damage and curing. However, as yet most investigations were carried out using devices originally either designed for geophysical applications or the analysis of rather homogeneous small scale (< 10 mL) samples. This paper describes the capabilities of an NMR tomograph, which has been specifically optimized for the investigation of larger, heterogeneous building material samples (diameters of up to 72 mm, length of up to 700 mm) with a high flexibility due to interchangeable coils allowing for a high SNR and short echo times (50 - 80 m s). KW - Fire spalling KW - Moisture transport KW - Concrete KW - Cement hydration KW - Sensitivity KW - Supplementary cementitous materials KW - Frost salt attack PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-573755 DO - https://doi.org/10.1016/j.mrl.2023.03.004 SN - 2097-0048 VL - 3 IS - 3 SP - 207 EP - 219 PB - Elsevier B.V. AN - OPUS4-57375 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Vasiliou, Eleni A1 - Schmidt, Wolfram A1 - Stefanidou, Maria A1 - Kühne, Hans-Carsten A1 - Rogge, Andreas ED - Amziane, Sofiane ED - Sonebi, Mohammed ED - Charlet, Karine T1 - Effectiveness of starch ethers as rheology modifying admixtures for cement based systems N2 - Polysaccharides are important rheology modifying admixtures in the building material sector. The use of starch is becoming increasingly important, due to many ecological and economic advantages. In the construction sector, starch ethers are being used as thickeners and as means to increase the yield stress. The starch ethers that are available on the market differ in their behaviour, which can vary greatly depending upon the binder system and mortar composition, e.g. solid volume content, binder type, additional admixtures. In view of the limited knowledge about the influence of molecular modifications associated with cement based systems, some fundamental rheological functional mechanisms were analysed in this study. The differently modified starch ethers used were derived from potatoes. They varied in their charges and degrees of hydroxypropylation. The setting and the flow behaviour of all examined variations of starch ethers were analysed in cement pastes. In order to illustrate the effects of the starch ethers that were used, the water-cement ratio (w/c) was held constant in all the mixtures [Schmidt 2012]. The results indicated significant differences in setting and flow behaviour. T2 - Second International RILEM Conference on Bio-based Building Materials CY - Clermont-Ferrand, France DA - 21.06.2017 KW - Rheology KW - Polysaccharides KW - Cement KW - Concrete KW - Starch KW - Polycarboxylate PY - 2017 SN - 978-2-35158-192-6 SP - 81 EP - 85 PB - RILEM S.A.R.L CY - Paris, France AN - OPUS4-43548 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmidt, Wolfram A1 - Brouwers, H.J.H. A1 - Kühne, Hans-Carsten A1 - Meng, Birgit T1 - Interactions of polysaccharide stabilising agents with early cement hydration without and in the presence of superplasticizers N2 - Polysaccharides are incorporated into cement based Systems in order to modify the rheological properties. Typically, cellulose ethers, sphingan gums, guar gum or starch ethers are applied. Depending upon their chemistry, molecular architecture, and adsorption tendency, polysaccharides interact differently with the entire cementitious system. Some stabilising agents like diutan gum mainly affect the cementitious paste; other stabilising agents like starch tend to interact with the sand fraction and even with the coarse aggregates. Cellulose and guar gum shows more diverse performances. Typically stabilising admixtures like polysaccharides are used, when sophisticated rheological properties are adjusted. Therefore, polysaccharides are often used in combination with superplasticisers, which are added to reduce the yield stress of concrete. This can cause interactions, particularly when the stabilising Agent shows a strong tendency to adsorb on particle surfaces. Adsorptive stabilising agents may reduce the amount of adsorbed superplasticisers, thus affecting both viscosity and yield stress, while non-adsorptive stabilising agents mainly affect the plastic viscosity independently of the superplasticiser. Due to the strong influence of superplasticisers on the yield stress, influences of the stabilising agent on the yield stress retreat into the background, so that their major effect is an increase of the plastic viscosity. The paper provides a comprehensive overview of how different polysaccharide superplasticisers affect cementitious flowable systems and points out the challenges of the combined use of polysaccharides and superplasticisers. Based on rheometric experiments and observations of the hydration process, time dependent effects on the workability as well as of the hydration of cement are presented and discussed. KW - Concrete KW - Polysaccharides KW - Rheology KW - Stabilising agents KW - Starch KW - Sphingan PY - 2017 DO - https://doi.org/10.1016/j.conbuildmat.2016.11.022 SN - 0950-0618 SN - 1879-0526 VL - 139 SP - 584 EP - 593 PB - Elsevier AN - OPUS4-40597 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram A1 - Olonade, K. A. A1 - Mbugua, R. N. A1 - Lenz, F. J. A1 - Tchetgnia Ngassam, I. T1 - Bio-Based Rheology Modifiers for High Performance Concrete – Possible Modes of Actions and Case Study for Cassava Starch in West Africa N2 - Polymers that help tailoring rheological properties during the casting process have become inevitable constituents for all kinds of high-performance concrete technologies. Due to lacking industries, these typically crude-oil based admixtures are not readily available in many parts of the world, which limits the implementation of more sustainable high-performance construction technologies in these regions. Alternative polymers, which often demand for less processing, can be derived from local plant-based resources. The paper provides experimental data of flow tests of cement pastes with polysaccharides from Triumfetta pendrata A. Rich, acacia gum and cassava without and in the presence of polycarboxylate ether superplasticizer. The flow tests are amended by observations of the zeta potentials and the hydrodynamic diameters in the presence of and without calcium ions in the dispersion medium. The results show that in the presence of and without calcium ions all polysaccharides provide negative zeta potentials, yet, they affect flowability and thixotropy in different ways. Cassava starch, acacia gum, and the gum of Triumfetta pendrata A. Rich qualified well for robustness improvement, strong stiffening, and additive manufacturing, respectively. The reason for the different effects can be found in their average sizes and size distribution. Due to the promising results, a flow chart for local value chains is derived on the example of yet unused cassava wastes, which can be converted in parallel. T2 - 3rd International Conference on the Application of Superabsorbent Polymers CY - Skukuza, South Africa KW - Admixtures KW - Polysaccharides KW - Rheology KW - Thixotropy KW - Concrete PY - 2020 SN - 978-3-030-33341-6 SN - 978-3-030-33342-3 DO - https://doi.org/10.1007/978-3-030-33342-3_17 SP - 158 EP - 166 PB - Springer AN - OPUS4-58404 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram A1 - Kühne, Hans-Carsten A1 - Leinitz, Sarah ED - Diouri, A. ED - Boukhari, A. ED - Ait Brahim, L. ED - Bahi, L. ED - N., Khachani ED - Saadi, M ED - Aride, J. ED - Nounah, A. T1 - Concrete casting robustness improvement due to active rheology N2 - With ongoing innovation in process technology, the challenges of concrete technology are more and more focused on the rheological optimisation for these processes, since improper mixture stability or poor compaction ability negatively affect the concrete homogeneity and quality. However, along with the increasing complexity of today’s concrete mixture compositions, concrete becomes more prone to failure regarding the casting process. Variable properties of the raw materials typically cause changing workability. The reasons can be found among others in scattering water contents, physical or chemical properties of the cement or varying environmental temperatures. Robustness in the delicately adjusted rheology, however, is of utmost importance for modern and future process technology, from sprayed concrete over pumpable concrete towards 3D-printing, with regard to the long-term strength, the function and the durability. Typically, material induced changes cannot be identified easily due to the complex interactions of concrete constituents. Therefore, a precise and prompt counteraction is impossible. However, it is known that the yield stress can be controlled by addition of supplementary superplasticizer or stabilising agent. In combination with computerized process observation tools that can rapidly interpret and react on changes in the rheology, it is therefore thinkable, that only these two admixture types can adjust the rheology steadily and permanently, regardless of the actual root cause for observed macroscopic rheology change. The presentation will firstly give a comprehensive overview of effects at the interface between pore solution, particles and hydrates, which affect the rheology of fresh concrete. Secondly, ways are recommended how the rheology can be actively manipulated before eventually computerized methods are demonstrated that help to actively and rapidly assess and counteract performance scatter during steady casting processes. T2 - 2nd International Congress on Materials & Structural Stability (CMSS-2017) CY - Rabat, Morocco DA - 22.11.2017 KW - Cusum KW - Rheology KW - Control Chart KW - Concrete KW - Robustness PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-444317 DO - https://doi.org/10.1051/matecconf/201814901001 SN - 2261-236X VL - 149 SP - 01001-1 EP - 01001-7 PB - EDP Sciences CY - Les Ulis AN - OPUS4-44431 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram A1 - Tchetgnia Ngassam, I. L. A1 - Mbugua, R. A1 - Olonade, K. A. ED - Greim, M. ED - Kusterle, W. ED - Teubert, O. T1 - Natural rheology modifying admixtures for concrete N2 - The possibility to tailor the rheology of concrete eventually opened up the path to new technologies, where design criteria are no longer limited to the compressive strength. Thus, it can be concluded that the capability to control the rheology of concrete can be considered as catalyst for many of today’s concrete innovations. In the same way rheology modifying admixtures will be key to mastering the challenges of the next decades. In many regions of the Southern hemisphere, the effective use of chemical admixtures would significantly contribute to solve problems induced by the challenging climate, but particularly in Africa there is often a lack of local supply and supply infrastructure. In Africa, concrete admixtures are largely shipped or transported from outside the continent. The long distance transportation of chemicals is not very environmentally friendly and the economic consequences are dramatic: the agents are difficult to purchase, expensive, and there is no large variety of products available in the market. Due to the enormous relevance of rheology modifying admixtures, it is worthwhile to recollect that nature provides an enormous variety of chemicals that can be used readily or with low processing and without enormous transportation distances, since these plants are typically regionally abundantly available, cheap, and they are environmental friendly. The paper presents an overview of various options for rheology modifying admixtures, that can be found in Africa, and that may become a real alternative, once their interaction within the complex cementitious system is well understood. T2 - 26. Workshop und Kolloquium "Rheologische Messungen an Baustoffen" CY - Regensburg, Germany DA - 21.02.2017 KW - Concrete KW - Rheology PY - 2017 SN - 978-3-7439-0171-1 SP - 75 EP - 87 PB - tredition GmbH CY - Hamburg AN - OPUS4-40599 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Müller, Sabine A1 - Niederleithinger, Ernst A1 - Bohlen, T. T1 - Reverse time migration: a seismic imaging technique applied to synthetic ultrasonic data N2 - Ultrasonic echo testing is a more and more frequently used technique in civil engineering to investigate concrete building elements, to measure thickness as well as to locate and characterise built-in components or inhomogeneities. Currently the Synthetic Aperture Focusing Technique (SAFT), which is closely related to Kirchhoff migration, is used in most cases for imaging. However, this method is known to have difficulties to image steeply dipping interfaces as well as lower boundaries of tubes, voids or similar objects. We have transferred a processing technique from geophysics, the Reverse Time Migration (RTM) method, to improve the imaging of complicated geometries. By using the information from wide angle reflections as well as from multiple events there are fewer limitations compared to SAFT. As a drawback the required computing power is significantly higher compared to the techniques currently used. Synthetic experiments have been performed on polyamide and concrete specimens to show the improvements compared to SAFT. We have been able to image vertical interfaces of step-like structures as well as the lower boundaries of circular objects. It has been shown that RTM is a step forward for ultrasonic testing in civil engineering. KW - Beton KW - Ultraschall KW - Concrete KW - Imaging KW - Ultrasonics KW - Reverse time migration PY - 2012 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-262952 DO - https://doi.org/10.1155/2012/128465 SN - 1687-8868 SN - 1687-885X VL - 2012 IS - Article ID 128465 SP - 1 EP - 7 PB - Hindawi Publishing Corporation CY - New York, NY, USA AN - OPUS4-26295 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Priebe, Nsesheye Susan A1 - Schmidt, Wolfram A1 - Gluth, Gregor A1 - Florea, M.V.A. A1 - Kumaran, G.S. A1 - Akindahunsi, A. A. A1 - Uzoegbo, H.C. A1 - Oslakovic, I.S. ED - Alexander, M. G. ED - Beushausen, H.-D. ED - Dehn, F. ED - Moyo, P. T1 - Concrete knowledge improvement in sub-Saharan Africa N2 - The building situation in Africa is overwhelmed with high-priced materials and lack of adequate concrete technology, which provides a challenge in the concrete industry. Worldwide, cement and concrete experts are at the cutting-edge to sustainable, green and healthy but nonetheless high-performance concrete, which is more sustainable and safer than traditional methods of construction with clay and wood. Since concrete in Africa is rather a new construction material, this sustainability experience can offer the continent a unique opportunity to begin a constantly growing building sector with the newest state-of-the-art technology. This can be achieved without subordinating to existing standards by establishing a sustainable “African concrete technology”. The major challenge for most sub-Saharan countries is the deficiency of experts, which would be required to establish such state-of-the-art technology. Based on the examples of two African-European scientific networks—SPIN and LightSHIP—this paper presents possible solution strategies for the establishment of a scientific cooperation between Europe and Africa, with links to policy making bodies that can help accelerate the progress of cement and concrete industries in Africa. T2 - 3rd International conference on concrete repair, rehabilitation and retrofitting III CY - Cape Town, South Africa DA - 03.09.2012 KW - Education KW - Research sub-Sahara KW - Africa KW - Cement KW - Concrete PY - 2012 SN - 978-0-415-89952-9 N1 - Geburtsname von Priebe, Nsesheye Susan: Msinjili, N. S. - Birth name of Priebe, Nsesheye Susan: Msinjili, N. S. IS - Theme 5 SP - 1459 EP - 1465 PB - CRC Press CY - London, UK AN - OPUS4-26508 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Malaga, Katarina A1 - Lundahl, A. A1 - Müller, Urs T1 - Use of technical textiles to modify concrete surfaces N2 - To keep concrete building façades clean from dirt and algal growth intense maintenance is needed. A designaspiration for advanced building materials is that they should be easily cleanable when used in façades. Theapplication of technical textiles as a building material component has mainly focused on their use as a rein-forcement material for concrete or mortar. The goal of this study was to modify the concrete surface by cast-ing concrete in a textile mould, giving the surface a fine structured imprint, that subsequently was impreg-nated with hydrophobic agents to achieve the self-cleaning Lotus effect.The analysis of the surface properties was performed by means of contact angle measurements, laser scan-ning confocal microscopy and optical microscopy. Three different textiles, including one with nano-engi-neered surface, were used for moulding and imprinting. The results demonstrated significant variations inhydrophobicity and oleophobicity between the samples. Micro- and nano-structuring of the surface did notresult in hydrophobicity by itself; therefore a hydrophobic treatment was necessary to achieve water- andoleophobicity. After this treatment all samples became hydrophobic but not necessarily oleophobic. Onlysingle samples reached a superhydrophobic eff KW - Concrete KW - Textile imprint KW - Nano KW - Hydrophobicity KW - Oleophobicity KW - Beton KW - Textilien KW - Oberflächen KW - Wasserabweisend PY - 2012 SN - 1864-7251 SN - 0947-4498 VL - 18 IS - 1 SP - 23 EP - 30 PB - Aedificatio Publ. CY - Freiburg AN - OPUS4-25635 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kocherla, Amarteja A1 - Duddi, Murali A1 - Kolluru, Subramaniam T1 - Embedded PZT sensors for combined viboacoustic sensing of concrete structures N2 - Accurate assessment of damage in concrete structures requires monitoring techniques that can capture both global stiffness degradation and local cracking processes. Existing structural health monitoring approaches typically rely on separate sensors for vibration measurements and acoustic emission (AE) monitoring, while conventional surface-mounted devices often suffer from poor and variable coupling. This study presents an embedded piezoelectric (PZT) sensor developed for dual mode vibroacoustic monitoring in concrete structures. The sensor is cast within the concrete matrix to improve mechanical coupling and enable robust measurement of structural response during damage evolution. Dual-mode monitoring is achieved through sequential operation of the same embedded sensor in two distinct modes passive acoustic emission (AE) monitoring during fracture loading and impulse-excited vibration testing conducted before and after fracture test. Benchmarking experiments include comparison with commercial accelerometers and AE sensors, confirming that the embedded configuration enhances high-frequency sensitivity and coupling performance. The fracture process is interpreted by correlating AE activity with Digital Image Correlation (DIC)-based crack kinematics, enabling zone-wise understanding of crack development. The vibration response is interpreted using a stiffness-reduction framework consistent with hinge-type crack formation, explaining the observed modal-frequency reduction and in crease in damping. Electromechanical impedance measurements quantify sensor–matrix interaction, highlighting the role of epoxy-mediated impedance matching. Overall, the results demonstrate that the proposed embedded sensor provides a unified platform for validated AE-vibration sensing, offering a promising approach for integrated structural health monitoring of concrete infrastructure KW - Vibroacoustic sensor KW - Embedded PZT sensor KW - Crack dynamics KW - DIC KW - Concrete PY - 2026 DO - https://doi.org/10.1016/j.measurement.2026.120690 VL - 268 SP - 1 EP - 14 PB - Elsevier Ltd. CY - Amsterdam, Netherlands AN - OPUS4-65560 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Seifert, Lando T1 - Review: Steel‐Reinforced Concrete Str‐uctures: Assessment and Repair of Corrosion N2 - In 2019 CRC Press published the "Steel‐Reinforced Concrete Structures" as a paperback. This book does not vary in terms of content from the hardback publication of 2008. But it is first reviewed here in corrosion news. The book provides eight of nine chapters in which the author discusses technical aspects of assessment and repair of steel‐reinforced concrete structures. To sum up, this book is recommended for students and people involved with the assessment and repair of reinforced‐concrete structures, who want to get a quick introduction into the different aspects of the field. Readers also learn much about the economic interactions besides the topic. However, for experienced technicians and corrosion experts, this book may not be exact enough in both the electrochemical description of deterioration processes and the practical aspects of repair and control methods. Despite that, the discussions of the author are scientifically correct. KW - Concrete KW - Corrosion PY - 2020 DO - https://doi.org/10.1002/maco.202070084 SN - 1521-4176 SN - 0947-5117 VL - 71 IS - 8 SP - 1408 EP - 1409 PB - WILEY‐VCH Verlag GmbH & Co. KGaA CY - Weinheim AN - OPUS4-51075 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Seifert, Lando T1 - Review: Concrete Repair to EN 1504: Diagnosis, Design, Principles and Practice N2 - In 2019 CRC Press published the “Concrete Repair to EN 1504” as paperback. This issue does not differ in terms of content from the hardback publication of 2014. Like the previous version, the book covers both detailed background information on repair procedures of reinforced concrete structures and provides a reference work for technicians and people who are involved with the maintenance of these structures, according to EN 1504. The book presents a high number of figures and tables, i.e., approximately one illustration per page. For readers who prefer a more comfortable to handle paperback, the book is recommended; however, the hardback from 2014 is still up‐to‐date. KW - Corrosion KW - Concrete KW - Bridge PY - 2020 DO - https://doi.org/10.1002/maco.202070064 SN - 1521-4176 SN - 0947-5117 VL - 71 IS - 6 SP - 1036 PB - WILEY‐VCH Verlag GmbH & Co. KGaA CY - Weinheim AN - OPUS4-50838 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Goebbels, Jürgen A1 - Beck, Matthias A1 - Isecke, Bernd A1 - Burkert, Andreas A1 - Bäßler, Ralph ED - Castro-Borges, P. ED - Moreno, E.I. ED - Sakai, K. ED - Gjorv, O.E. ED - Banthia, N. T1 - Self-corrosion of steel in concrete by electrochemical measurements and X-ray tomography T2 - CONSEC`10 - 6th International conference on concrete under severe conditions CY - Mérida, Yucatán, Mexico DA - 2010-06-07 KW - Self-corrosion KW - Steel KW - Concrete KW - X-ray tomography PY - 2010 SN - 978-0-415-59316-8 VL - 2 SP - 1221 EP - 1228 PB - Taylor & Francis CY - London, UK AN - OPUS4-22299 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram A1 - Mota Gassó, Berta A1 - Sturm, Heinz A1 - Pauli, Jutta ED - Greim, M. ED - Kusterle, W. ED - Teubert, O. T1 - Influence of effects on nano and micro scale on the rheological performance of cement paste, mortar and concrete N2 - Chemical admixtures like superplasticisers or stabilising agents are of ever increasing importance for modern concrete technology. They liberate the workability of concrete from its dependency on water content, and thus, open the gate towards innovative and future oriented concrete technologies such as self-compacting concrete. Today, admixture addition has become common practice in concrete technology, but the understanding of their highly complex mode of operation is extremely difficult and demands for understanding of processes within the range between nanometres and centimetres. Due to its complex time-dependent, multi-phase and multi-scale behaviour, flowable concrete systems are highly complicated and cannot be described comprehensively by simple models. It is therefore extremely challenging to identify the relevant parameters that predominantly control flow phenomena on different size scales, since these may occur on any scale between the nano scale (e.g. superplasticizer adsorption) and macro scale (e.g. grading of the aggregates). The present study discusses fundamental mechanisms at the interface between particle or hydrate surfaces and the fluid phase at a very early stage of concrete formation, and links these effects to macroscopic flow phenomena. Methods are discussed that appear promising interdisciplinary tools for enhancement of the understanding of the relevant interactions that are responsible for the macroscopic flow of flowable concrete. T2 - 25. Workshop und Kolloquium Rheologische Messsungen an Baustoffen CY - Regensburg, Germany DA - 02.03.2016 KW - Rheology KW - Cement KW - Concrete KW - Superplasticizer KW - Nano scale PY - 2016 SN - 978-3-7345-1313-8 SP - 294 EP - 307 PB - tredition CY - Hamburg AN - OPUS4-36862 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Meftah, F. A1 - Pesavento, F. A1 - Davie, C. A1 - Dal Pont, S. A1 - Zeiml, M. A1 - Korzen, Manfred A1 - Millard, A. ED - Millard, A. ED - Pimienta, P. T1 - Advanced Modelling N2 - In this chapter, advanced models based on a General thermo-Hydro-Mechanical (THCM) Framework are considered. In These approaches, the concrete is considered as a porous medium, the pores of which are partly filled by gas (a mixture of air and vapour) and water. KW - Concrete KW - High temperature KW - Stress-strain-relation PY - 2019 SN - 978-3-030-11994-2 SN - 978-3-030-11995-9 DO - https://doi.org/10.1007/978-3-030-11995-9 SN - 2213-204X SN - 2213-2031 SP - 27 EP - 65 PB - Springer CY - Cham, Switzerland AN - OPUS4-50174 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schumacher, T. A1 - Murtuz, A. K. M. G. A1 - Hafiz, A. A1 - Dusicka, P. A1 - Niederleithinger, Ernst ED - Gabrijel, I. ED - Grosse, C. ED - Skazlić, M. T1 - Post-earthquake damage evaluation of concrete structures using ultrasonic monitoring: A proof-of concept laboratory study N2 - In earthquake-prone regions such as the Pacific Northwest, damage assessment tools are needed to enable safety evaluations to support recovery. Currently, damage assessment is performed primarily by visual inspection and is often impossible for structural members that are inaccessible, such as deep foundations or interior members hidden by cladding. This study explores the possibility of using embedded ultrasonic transducers to monitor reinforced concrete members for damage progression under earthquake loading. A novel methodology is proposed where changes in the member condition due to an increase in the earthquake-type loading of a full-scale column-foundation specimen are correlated with changes in the recorded ultrasonic waveforms. The discussed preliminary analysis of the ultrasonic signals is based on wave propagation velocity, changes in the coda wave portion, and maximum amplitude of the signals. Three embedded transducers were used to continuously monitor the laboratory specimen during destructive testing. This paper provides an overview of the proposed methodology, outlines the laboratory experiment, and discusses some preliminary observations. T2 - International Conference on Sustainable Materials, Systems and Structures (SMSS 2019) CY - Rovinj, Croatia DA - 20.3.2019 KW - Concrete KW - Monitoring KW - Ultrasound KW - earthquake PY - 2019 SN - 978-2-35158-227-5 DO - https://doi.org/10.1007/978-3-031-07258-1_84 SP - 112 EP - 119 PB - RILEM Publications S.A.R.L. CY - Paris, France AN - OPUS4-47679 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst ED - Gabrijel, Ivan ED - Grosse, Christian ED - Skazlić, Marijan T1 - Ultrasonic monitoring of structural concrete elements N2 - Ultrasonic transmission measurements are used to monitor concrete elements mostly on a laboratory scale since decades. Recently, coda wave interferometry, a technique adapted from seismology, has been introduced to civil engineering experiments. It can be used to reveal subtle changes in concrete samples and even large construction elements without having a transducer directly at the location where the change is taking place. The methodology works best with embedded transducers to avoid coupling issues or excessive environmental influence. These transducers can be used for newly built and existing structures. Recently, large concrete beams have been equipped with a network of transducers and loaded until failure. Using code wave interferometry, it was possible to visualize stress fields and damaged areas. This paper gives an overview of the state of the art, recent results achieved at BAM and a task list for further results and development. T2 - International Conference on Sustainable Materials, Systems and Structures (SMSS 2019) CY - Rovinj, Croatia DA - 20.3.2019 KW - Concrete KW - Ultrasound KW - Monitoring KW - coda wave interferometry PY - 2019 SN - 978-2-35158-227-5 SP - 1 EP - 11 PB - RILEM Publications S.A.R.L. CY - Paris, France AN - OPUS4-47677 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Provis, J. L. A1 - Arbi, K. A1 - Bernal, S. A. A1 - Bondar, D. A1 - Buchwald, A. A1 - Castel, A. A1 - Chithiraputhiran, S. A1 - Cyr, M. A1 - Dehghan, A. A1 - Dombrowski-Daube, K. A1 - Dubey, A. A1 - Ducman, V. A1 - Gluth, Gregor A1 - Nanukuttan, S. A1 - Peterson, K. A1 - Puertas, F. A1 - van Riessen, A. A1 - Torres-Carrasco, M. A1 - Ye, G. A1 - Zuo, Y. T1 - RILEM TC 247-DTA round robin test: mix design and reproducibility of compressive strength of alkali-activated concretes N2 - The aim of RILEM TC 247-DTA ‘Durability Testing of Alkali-Activated Materials’ is to identify and validate methodologies for testing the durability of alkali-activated concretes. To underpin the durability testing work of this committee, five alkali-activated concrete mixes were developed based on blast furnace slag, fly ash, and flash-calcined metakaolin. The concretes were designed with different intended performance levels, aiming to assess the capability of test methods to discriminate between concretes on this basis. A total of fifteen laboratories worldwide participated in this round robin test programme, where all concretes were produced with the same mix designs, from single-source aluminosilicate precursors and locally available aggregates. This paper reports the mix designs tested, and the compressive strength results obtained, including critical insight into reasons for the observed variability in strength within and between laboratories. KW - Alkali-activated materials KW - Alkali-activated slag KW - Compressive strength KW - Concrete KW - Mix-design PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-489131 DO - https://doi.org/10.1617/s11527-019-1396-z SN - 1359-5997 SN - 1871-6873 VL - 52 IS - 5 SP - Article Number 99 PB - Springer Nature AN - OPUS4-48913 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Huismann, Sven A1 - Zeiml, M. A1 - Korzen, Manfred A1 - Millard, A. ED - Millard, A. ED - Pimienta, P. T1 - Engineering Modelling N2 - This chapter presents the most commonly used approach to analyse the thermo-mechanical behaviour of concrete structures subjected to high temperatures as in the case of fire loading. Prescriptions of the Eurocode are detailed for the thermal as well as the mechanical analysis. Finally, recommendations from two national (Austrian and German) guidelines give some improvements for Underground infrastructure. KW - Concrete KW - High temperature KW - Stress-strain-relation PY - 2019 SN - 978-3-030-11995-9 DO - https://doi.org/10.1007/978-3-030-11995-9 SN - 2213-204X SN - 2213-2031 SP - 15 EP - 25 PB - Springer CY - Cham, Switzerland AN - OPUS4-51186 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Oesch, Tyler A1 - Stenzel, Ludwig A1 - Weise, Frank T1 - Non-destructive Evaluation of the Contribution of Polymer-Fibre Orientation and Distribution Characteristics to Concrete Performance during Fire N2 - Although concrete itself is not a combustible material, concrete mixtures with high density, such has high-performance concretes (HPCs), are susceptible to significant damage during fires due to explosive spalling. Past research has shown that the inclusion ofpolymer fibres in high density concrete can significantly mitigate this fire damage. The exact mechanisms causing this increased spalling resistance are not yet fully understood, but it is thought that the fibres facilitate moisture transport during fire exposure, which in turn contributes to relief of internal stresses in the spalling-susceptible region. In this study, X-ray Computed Tomography (CT) was applied to observe the interaction between polymer fibres and cracking during thermal exposure. For this purpose, two concrete samples containing different polymer fibre types were subjected to incremental application of a defined thermal exposure. CT images were acquired before and after each thermal exposure and powerful image processing tools were used to segment the various material components. This enabled a detailed analysis of crack formation and propagation as well as the visualization and quantification of polymer fibre characteristics within the concrete. The results demonstrated that the orientation of both fibres and cracks in polymerfibre reinforced concrete tend to be anisotropic. The results also indicated that crack geometry characteristics may be correlated with fibre orientation, with cracks tending to run parallel to fibre beds. Clear quantitative relationships were also observed between heating and increasing cracking levels, expressed in terms of both crack surface area and crack volume. KW - Concrete KW - Fire resistance KW - Polymer fibre PY - 2019 SN - 978-3-030-00867-3 DO - https://doi.org/10.1007/978-3-030-00868-0_4 VL - 95 SP - 51 EP - 73 PB - Springer Nature Switzerland AG CY - Zürich AN - OPUS4-51077 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Oesch, Tyler A1 - Weise, Frank A1 - Meinel, Dietmar A1 - Gollwitzer, Christian T1 - Quantitative in-situ analysis of water transport in concrete completed using X-ray computed tomography N2 - This paper describes a novel methodology for quantitative in-situ moisture measurement without tracking agents using X-ray computed tomography (XCT). The high levels of grey-scale precision required for the measurement of moisture without tracking agents resulted in the need for an additional image calibration procedure to correct for water-related X-ray scattering and for equipment-variability related artefacts arising during in-situ testing. This calibration procedure was developed on the basis of existing principles of XCT image cor-rection. Resulting images of moisture distribution exhibit a high level of agreement with expected material behaviour. This research demonstrated that XCT can be successfully used to measure both moisture-front movement over time and changes in 3D moisture distribution within samples. This approach to moisture measurement lays the groundwork for the planned future investigation of the interaction between cracking induced by varying chemical and mechanical processes and water transport in concrete. KW - X-ray computed tomography (XCT) KW - In-situ testing KW - Water transport KW - Quantitative moisture measurement KW - Concrete PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-474395 DO - https://doi.org/10.1007/s11242-018-1197-9 SN - 1573-1634 VL - 127 IS - 2 SP - 371 EP - 389 PB - Springer Netherlands AN - OPUS4-47439 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bruno, Giovanni T1 - Brittle Materials in Mechanical Extremes N2 - The goal of the Special Issue “Brittle Materials in Mechanical Extremes” was to spark a discussion of the analogies and the differences between different brittle materials, such as, for instance, ceramics and concrete. Indeed, the contributions to the Issue spanned from construction materials (asphalt and concrete) to structural ceramics, reaching as far as ice. The data shown in the issue were obtained by advanced microstructural techniques (microscopy, 3D imaging, etc.) and linked to mechanical properties (and their changes as a function of aging, composition, etc.). The description of the mechanical behavior of brittle materials under operational loads, for instance, concrete and ceramics under very high temperatures, offered an unconventional viewpoint on the behavior of brittle materials. This is not at all exhaustive, but a way to pave the road for intriguing and enriching comparisons. KW - Microcracking KW - Ceramics KW - Concrete KW - Asphalt KW - Mechanicalproperties KW - Microstructure KW - Strength PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-514558 DO - https://doi.org/10.3390/ma13204610 VL - 13 IS - 20 SP - 4610 PB - MDPI CY - Basel AN - OPUS4-51455 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bruno, Giovanni A1 - Staude, Andreas A1 - Meinel, Dietmar A1 - Hentschel, Manfred P. A1 - Müller, Bernd R. ED - Grellmann, W. ED - Frenz, H. T1 - Moderne bildgebende hochauflösende Röntgenverfahren für die Materialcharakterisierung N2 - Die Computertomographie (CT) ist in der Medizin als Standardtechnik etabliert, in der zerstörungsfreien Prüfung wird sie zunehmend angewendet, in einzelnen Fällen sogar als Referenzverfahren eingesetzt. Gegenwärtig ist eine starke Zunahme von Anwendungen der CT in der Materialcharakterisierung zu verzeichnen. Zudem werden weitere moderne 3D-Techniken für werkstoffwissenschaftliche Fragestellungen genutzt, um die Mikrostruktur - auch in situ (z.B. Druck, Temperatur) - aufzuklären. Hier werden neben der konventionellen Absorptions-CT auch die Potenziale der Refraktions-CT zur Beantwortung prozesstechnischer sowie werkstofflicher Fragestellungen aufgezeigt, die ein „ganzheitliches Bild“ des jeweiligen Werkstoffs zum Ziel haben. T2 - Tagung Werkstoffprüfung 2014 - Fortschritte in der Werkstoffprüfung für Forschung und Praxis - Werkstoffeinsatz, Qualitätssicherung und Schadensanalyse CY - Berlin, Germany DA - 04.12.2014 KW - Computer tomography KW - X-ray refraction KW - Ceramics KW - Concrete KW - Inhomogeneous materials KW - Computertomographie KW - Röntgenrefraktion KW - Keramik KW - Beton KW - Mehrphasige Materialien PY - 2014 SN - 978-3-9814516-8-9 SN - 1861-8154 SP - 1 EP - 12 AN - OPUS4-32565 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Fischer, G. A1 - Bohse, Jürgen T1 - Observation and analysis of fracture processes in concrete with acoustic emission (AE) and digital image correlation (DIC) N2 - Fracture processes in concrete can be characterized by the formation of a Fracture Process Zone (FPZ), which is a region of the crack extending between the elastic region ahead of the crack tip over the crack bridging zone to the region where the crack opening is sufficiently large to prevent transfer of load across the crack faces. The formation of cracks and the development of the FPZ have typically been documented by Acoustic Emission (AE) methods and important conclusions regarding the nature of the FPZ and the propagation mechanisms of concrete have been drawn to form the basis of current fracture models for concrete. The study presented in this paper focuses on Mode I cracking of concrete using compact tension specimens and is comparing the results of AE measurements to those obtained from documenting the cracking process by Digital Image Correlation (DIC). The findings from this comparison show that distinctly different AE events occur ahead of the crack tip, in the cementitious matrix at the crack tip and in the wake of the crack due to the increasing separation of the crack flanks and further opening of the crack. The DIC measurements indicate that crack initiation occurs with locally corresponding AE signals and furthermore suggest a continuous path of the crack from initiation to eventual transition to the stress-free zone. Based on these comparative measurements the study suggests that crack formation in unreinforced concrete is initiated by an individual, sharp microcrack rather than by a region of diffuse microcracking ahead of the eventual crack tip. Later on sharp crack branches originate from the main macrocrack path. Furthermore, the measurements with AE and DIC result in information on the nature of the deformation mechanisms occurring in distinct regions of the entire cracking process. AE signals detected using wideband sensors show quite different characteristics in time (waveform) and frequency (bandwidth) domain. T2 - 31st Conference of the European working group on acoustic emission (EWGAE) CY - Dresden, Germany DA - 03.09.2014 KW - Concrete KW - Acoustic emission KW - Digital image correlation KW - Signal analysis KW - Fracture process KW - Source mechanisms PY - 2014 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-313471 SN - 978-3-940283-63-4 IS - DGZfP-BB 149 SP - Th.3.A.4, 1 EP - 8 PB - BAM / DGZfP AN - OPUS4-31347 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gluth, Gregor A1 - Ke, X. A1 - Vollpracht, A. A1 - Bernal, S. A. A1 - Cizer, Ö. A1 - Cyr, M. A1 - Dombrowski-Daube, K. A1 - Geddes, D. A1 - Grengg, C. A1 - Le Galliard, C. A1 - Nedeljkovic, M. A1 - Provis, J. L. A1 - Shi, Z. A1 - Valentini, L. A1 - Walkley, B. ED - Escalante-Garcia, J. I. ED - Castro Borges, P. ED - Duran-Herrera, A. T1 - RILEM TC 281-CCC Working Group 6: Carbonation of alkali activated concrete—preliminary results of a literature survey and data analysis N2 - The current understanding of the carbonation of alkali-activated concretes is ham-pered inter alia by the wide range of binder chemistries used. To overcome some of the limitations of individual studies and to identify general correlations between their mix design parameters and carbonation resistance, the RILEM TC 281-CCC working group 6 compiled carbonation data for alkali-activated concretes and mortars from the literature. For comparison purposes, data for blended Portland cement-based concretes with a high percentage of SCMs (≥ 66 % of the binder) were also included in the database. A preliminary analysis of the database indicates that w/CaO ratio and w/b ratio exert an influence on the carbonation resistance of alkali-activated concretes but, contrary to what has been reported for concretes based on (blended) Portland cements, these are not good indicators of their carbonation resistance when considered individually. A better indicator of the carbonation resistance of alkali-activated concretes under conditions approxi-mating natural carbonation appears to be their w/(CaO + Na2O + K2O) ratio. Furthermore, the analysis points to significant shortcomings of tests at elevated CO2 concentrations for low-Ca alkali-activated concretes, indicating that even at a concentration of 1 % CO2, the outcomes may lead to inaccurate predictions of the carbonation coefficient under natural exposure conditions. T2 - 75th RILEM Annual Week CY - Mérida, Yucatán, Mexico DA - 30.08.2021 KW - Alkali-activated materials KW - Durability KW - Carbonation KW - Testing KW - Concrete PY - 2023 SN - 978-3-031-21734-0 SN - 978-3-031-21735-7 DO - https://doi.org/10.1007/978-3-031-21735-7_72 SN - 2211-0852 SN - 2211-0844 VL - 40 SP - 667 EP - 676 PB - Springer CY - Cham AN - OPUS4-57157 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gluth, Gregor A1 - Bernal, S. A. T1 - RILEM TC CUC: Carbon dioxide uptake by concrete during and after service life – Opening Letter N2 - The ability of cement to chemically bind CO2 in a carbonation reaction enables the material to act as a carbon sink, which could partly account for offsetting the CO2 emissions associated with cement production. In response to the many open questions in this context, the RILEM Technical Committee CUC was created in May 2024. The focus of the TC will be to facilitate discussions regarding the current approaches to estimate the CO2 uptake by cementitious materials (concrete and other construction products) during and after service life. This Opening Letter presents aspects of the motivation to establish the TC, a brief overview of the state of the art in the field, the scheduled work programme, and the anticipated impact of the TC outputs. Though it is not intended to be an exhaustive discussion of the challenges to be addressed, from what is summarized in this letter, it is clear that work is required to base estimates of CO2 uptake by cementitious materials on a data set that is as extensive, accurate and forward-looking as possible. It is anticipated that the inclusion of interdisciplinary perspectives and data from academia and industry will enable progress in the field. KW - Cement KW - Concrete KW - Recarbonation KW - Carbon dioxide uptake KW - Carbonation rate PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-623724 DO - https://doi.org/10.21809/rilemtechlett.2024.208 SN - 2518-0231 VL - 9 SP - 61 EP - 67 PB - RILEM AN - OPUS4-62372 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gluth, Gregor A1 - Rickard, W.D.A. A1 - Werner, Steve A1 - Pirskawetz, Stephan T1 - Acoustic emission and microstructural changes in fly ash geopolymer concretes exposed to simulated fire N2 - Two fly ash-based geopolymer concretes with quartz aggregates or with expanded clay (lightweight) aggregates were exposed to the ISO 834-1 standard fire curve in a small-scale fire test set-up. Acoustic emission measurements during fire exposure and subsequent cooling were employed to study spalling events and cracking during the tests. Optical microscopy and additional acoustic measurements were conducted after the testing to better understand the crack propagation in the samples. The testing revealed that neither of the concretes were susceptible to spalling, which is particularly notable for the concrete with quartz aggregates, as it is a high-strength concrete. This behavior is attributed to the relatively high permeability of the concretes and their low amount of chemically bound water. Significant crack formation was detected only around the temperature of the alpha–beta quartz transition (573 °C) and on cooling. Because of aggregate deformations at the quartz transition temperature, deterioration after heating was more significant in the geopolymer concrete with quartz aggregates. Crack formation also occurred in the concrete with expanded clay aggregates, caused by shrinkage of the geopolymer paste on cooling. Acoustic emission measurements proved to be a valuable tool to investigate processes during high temperature exposure. KW - Geopolymers KW - Spalling KW - Concrete KW - Acoustic emission KW - Heat exposure PY - 2016 DO - https://doi.org/10.1617/s11527-016-0857-x SN - 1359-5997 SN - 1871-6873 VL - 49 IS - 12 SP - 5243 EP - 5254 PB - Springer AN - OPUS4-36907 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stohl, Leonie A1 - Manninger, Tanja A1 - Dehn, Frank A1 - von Werder, Julia T1 - Understanding bioreceptivity of concrete: material design and characterization N2 - The climate crisis is driving an increasing demand for ecologically oriented concepts. In the building sector, this demand includes not only the use of environmentally friendly materials but also the greening of urban areas. One promising approach is the development of bioreceptive concrete façades, which support the growth of green biofilms directly on their surfaces. These innovative façades are anticipated to deliver benefits comparable to those of macroscopically greened façades, such as enhanced biodiversity and improved air quality, while offering the advantages of being more self-sustaining and stable systems once fully established. However, the development of bioreceptive concrete presents substantial challenges. Due to the interdisciplinarity and novelty of this field, standardized methods for material characterization and bioreceptivity assessment are currently lacking. This study proposes an approach for evaluating surface properties crucial for bioreceptivity, developed on differently structured samples of ultra-high-performance concrete (UHPC). Existing methods and standards from concrete technology are critically reviewed and, where necessary, modified to meet the unique requirements of measuring bioreceptive material properties. Special attention is given to the surface pH value and water retention characteristics, as these are essential for promoting microbial growth and ensuring the long-term stability of green biofilms. The observed surface characteristics vary according to the imprinted surface structures, offering a spectrum of material properties and enabling the evaluation of their impact on bioreceptivity. The findings presented form the foundation for subsequent laboratory weathering experiments, which will be discussed in a complementary publication. KW - Bioreceptivity KW - Concrete KW - Biofilm PY - 2025 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-648180 DO - https://doi.org/10.1617/s11527-025-02863-y SN - 1359-5997 VL - 58 IS - 10 SP - 1 EP - 12 PB - Springer Science and Business Media LLC AN - OPUS4-64818 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Feller, Viktor A1 - Mielentz, Frank A1 - Klewe, T. A1 - Krause, Martin A1 - Orglmeister, R. A1 - Pflugradt, M. T1 - Ultrasonic phased array for investigations of concrete components N2 - This paper describes an innovation of a phased array using dry contact probes to test concrete components. Based on preceding work on pressure waves, a low-frequency ultrasonic phased array consisting of shear wave probes is used in the experiments. This configuration allows the variation and control of the sound field directivity during the measurement. The measurements are carried out on a concrete test block using a scanning laservibrometer and a scanner system in transmission mode. The laboratory measurements are compared to theoretical calculations to investigate the influence of the probes shape and dimension on the resulting sound field patterns. The comparison of the modelling and the measurements demonstrates the suitability of the point source synthesis as a tool for the optimization of probe array designs. Methods of coded are used to improve the signal to noise ratio. T2 - NDT-CE 2015 - International symposium non-destructive testing in civil engineering CY - Berlin, Germany DA - 15.09.2015 KW - Ultrasonic KW - Phased array KW - Concrete KW - Point source synthesis PY - 2015 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-350417 UR - http://www.ndt.net/article/ndtce2015/papers/059_feller_viktor.pdf SN - 1435-4934 SP - 1 EP - 5 PB - Technische Universität Berlin / Bundesanstalt für Materialforschung und -prüfung AN - OPUS4-35041 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Shokouhi, Parisa A1 - Zoëga, Andreas A1 - Wiggenhauser, Herbert T1 - Nondestructive investigation of stress-induced damage in concrete N2 - The changes in the sonic surface wave velocity of concrete under stress were investigated in this paper. Surface wave velocities at sonic frequency range were measured on a prismatic concrete specimen undergoing several cycles of uniaxial compression. The loading was applied (or removed) gradually in predefined small steps (stress-controlled). The surface wave velocity was measured at every load step during both loading and unloading phases. Acoustic Emission (AE) test was conducted simultaneously to monitor the microcracking activities at different levels of loading. It was found that the sonic surface wave velocity is highly stress dependent and the velocity-stress relationship follows a particular trend. The observed trend could be explained by a combination of acoustoelasticity and microcracking theories, each valid over a certain range of applied stresses. Having measured the velocities while unloading, when the material suffers no further damage, the effect of stress and damage could be differentiated. The slope of the velocity-stress curves over the elastic region was calculated for different load cycles. This quantity was normalized to yield a dimensionless nonlinear parameter. This parameter generally increases with the level of induced damage in concrete. KW - Nondestructive testing (NDT) KW - Surface wave velocity KW - Concrete KW - Acoustoelasticity KW - Microcracking PY - 2010 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-215943 UR - http://downloads.hindawi.com/journals/ace/2010/740189.pdf DO - https://doi.org/10.1155/2010/740189 SN - 1687-8094 SN - 1687-8086 VL - 2010 IS - Article ID 740189 SP - 1 EP - 9 PB - Hindawi Publ. Corp. CY - New York, NY, USA AN - OPUS4-21594 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Grohmann, Maria A1 - Müller, Sabine A1 - Niederleithinger, Ernst T1 - Reverse time migration: Introduction of a new imaging technique for ultrasonic measurements in civil engineering N2 - Ultrasonic echo testing is widely used in non-destructive testing in civil engineering to investigate concrete structures, to measure thickness, and to locate and characterise built-in components or inhomogeneities. Currently, synthetic aperture focusing techniques are mostly used for imaging. These algorithms are highly developed but have some limitations. For example, it is not possible to image the lower boundary of built-in components like tendon ducts or vertical reflectors. We adopted reverse time migration for non-destructive testing in civil engineering in order to improve the imaging of complicated structures in concrete. By using the entire wavefield, including waves reflected more than once, there are fewer limitations compared to synthetic aperture focusing technique algorithms. As a drawback, the required computation is significantly higher than that for the techniques currently used. Simulations for polyamide and concrete structures showed the potential for non-destructive testing. The simulations were followed by experiments at a polyamide specimen. Here, having acquired almost noise-free measurement data to test the algorithm, we were able to determine the shape and size of boreholes with sufficient accuracy. After these successful tests, we performed experiments at a reinforced concrete foundation slab. We obtained information from the data by reverse time migration, which was not accessible by traditional imaging. The imaging of the location and structure of the lower boundary of the concrete foundation slab was improved. Furthermore, vertical reflectors inside the slab were imaged clearly, and more flaws were found. It has been shown that reverse time migration is a step forward in ultrasonic testing in civil engineering. T2 - NDT-CE 2015 - International symposium non-destructive testing in civil engineering CY - Berlin, Germany DA - 15.09.2015 KW - Ultrasound KW - Imaging KW - Reverse time migration KW - Reflection seismics KW - Concrete PY - 2015 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-345406 SN - 1435-4934 SP - 1 EP - 10 PB - Technische Universität Berlin / Bundesanstalt für Materialforschung und -prüfung AN - OPUS4-34540 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Niederleithinger, Ernst A1 - Wolf, Julia A1 - Mielentz, Frank A1 - Wiggenhauser, Herbert A1 - Pirskawetz, Stephan T1 - Embedded ultrasonic transducers for active and passive concrete monitoring N2 - Recently developed new transducers for ultrasonic transmission, which can be embedded right into concrete, are now used for non-destructive permanent monitoring of concrete. They can be installed during construction or thereafter. Large volumes of concrete can be monitored for changes of material properties by a limited number of transducers. The transducer design, the main properties as well as installation procedures are presented. It is shown that compressional waves with a central frequency of 62 kHz are mainly generated around the transducer's axis. The transducer can be used as a transmitter or receiver. Application examples demonstrate that the transducers can be used to monitor concrete conditions parameters (stress, temperature, …) as well as damages in an early state or the detection of acoustic events (e.g., crack opening). Besides application in civil engineering our setups can also be used for model studies in geosciences. KW - Ultrasound KW - Transmission KW - Concrete KW - Damages KW - Cracks KW - Stress KW - Monitoring KW - Acoustic emission KW - Transducers KW - Coda wave interferometry PY - 2015 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-345632 DO - https://doi.org/10.3390/s150509756 SN - 1424-8220 VL - 15 IS - 5 SP - 9756 EP - 9772 PB - MDPI CY - Basel AN - OPUS4-34563 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bernal, S. A. A1 - Dhandapani, Y. A1 - Elakneswaran, Y. A1 - Gluth, Gregor A1 - Gruyaert, E. A1 - Juenger, M. C. G. A1 - Lothenbach, B. A1 - Olonade, K. A. A1 - Sakoparnig, M. A1 - Shi, Z. A1 - Thiel, C. A1 - Van den Heede, P. A1 - Vanoutrive, H. A1 - von Greve-Dierfeld, S. A1 - De Belie, N. A1 - Provis, J. L. T1 - Report of RILEM TC 281-CCC: A critical review of the standardised testing methods to determine carbonation resistance of concrete N2 - 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). KW - Concrete KW - Cement KW - Carbonation KW - Testing KW - Standards PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-609364 DO - https://doi.org/10.1617/s11527-024-02424-9 VL - 57 SP - 1 EP - 31 PB - Springer Nature AN - OPUS4-60936 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Henning, Ricky A1 - Sturm, Patrick A1 - Keßler, S. A1 - Gluth, Gregor ED - Lothenbach, B. ED - Wieland, E. ED - Altmaier, M. T1 - Influence of salt aggregate on the degradation of hybrid alkaline cement (HAC) concretes in magnesium chloride-rich saline solution simulating evaporite rock N2 - Concretes produced from salt aggregate and hybrid alkaline cements, an alkali-activated slag/fly ash blend, or a Portland cement were exposed to a magnesium chloride-rich saline solution ([Mg2+] = 3.6 m, [Cl−] = 8.3 m), representing a solution formed after contact of surface water with evaporite rock (rock salt) in a nuclear waste repository. The hydration and deterioration of the concretes were studied with X-ray diffraction, thermogravimetric analysis, pH mapping and permeability measurements. The results show that calcium silicate hydrate (C-S-H) or sodium-substituted calcium aluminium silicate hydrate (C-N-A-S-H) and Friedel's salt were the major reaction products in the concretes prior to exposure to the saline solution. During exposure to the saline solution, increasing amounts of C-S-H/C-N-A-S-H dissolved, and gypsum and a secondary AFm phase formed. The durability of the concretes improved with increasing amounts of Portland clinker in the cements, due to the associated differences in permeability and chemical resistance. Nevertheless, a massive increase of permeability occurred for all concretes, likely caused by crack formation due to the formation of gypsum from anhydrite in the salt aggregate. Thus, the behavior of the concretes differed from, and was more complex than, the behavior of plain cement pastes. T2 - Joint 6th International Workshop on Mechanisms and Modelling of Waste/Cement Interactions (JCCW 2023) CY - Prague, Czech Republic DA - 20.11.2023 KW - Nuclear waste repository KW - Evaporite rock KW - Magnesium chloride brine KW - Concrete KW - Hybrid alkaline cement PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-599928 DO - https://doi.org/10.1016/j.apgeochem.2024.106027 SN - 0883-2927 SN - 1872-9134 VL - 168 SP - 1 EP - 14 PB - Elsevier AN - OPUS4-59992 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tambara, R. F. A1 - Durlo Tambara, Luís Urbano A1 - Venquiaruto, S. D. A1 - Pereira da Costa, F. B. T1 - Evaluation of the mechanical performance and capillary absorption of concretes with incorporation of crystallizing admixtures and subjected to damage at early ages T1 - Avaliação do desempenho mecânico e absorção capilar de concretos com incorporação de aditivos cristalizante submetidos a danos nas primeiras idades N2 - This study assessed the self-healing phenomenon in the mechanical properties and capillary absorption of structural concretes. Two crystalline powder additives were evaluated, dosed according to the manufacturers’ recommendations. Crystalline additives increase the density of the C-S-H gel and form insoluble crystals, effectively blocking fissures. Three concrete mixes were produced: a reference mix, additive-X with 0.8%, and additive-Y with 2.0%, relative to the mass of cement. 75% of the rupture load was applied at 3- and 14-days to induce microfissures for comparison with the reference mix. Subsequently, self-healing was assessed at 28- and 76-days. The property of axial compressive strength was determined at 28-days, revealing that crystalline additives contributed to an average increase of 12% in this property. While the age of loading did not significantly impact axial compressive strength, there were significant variations among the types of additives studied, as indicated by ANOVA. Water absorption properties through capillarity were evaluated at 28- and 76-days, showing an average reduction of 42% in water absorption due to the use of crystalline additives. In conclusion, the inclusion of crystalline additives positively contributed to the self-healing of the studied concretes, suggesting a partial recovery of microfissures. N2 - Esta pesquisa avaliou o fenômeno de autocicatrização nas propriedades mecânicas e absorção capilar de concretos estruturais. Foram avaliados dois aditivos cristalizantes em pó, dosados de acordo com o teor recomendado pelos fabricantes. Aditivos cristalizantes aumentam a densidade do gel C-S-H e formam cristais insolúveis, bloqueando fissuras. Três traços de concreto foram produzidos: referência, aditivo-X com 0,8% e aditivo-Y com 2,0% em relação a massa do cimento. Aplicou-se 75% da carga de ruptura aos 3- e 14-dias para gerar microfissuras e comparar com a referência. Posteriormente, a autocicatrização foi avaliada aos 28- e 76-dias. A propriedade de resistência à compressão axial foi determinada aos 28-dias, revelando que os aditivos cristalizantes contribuíram para um aumento médio de 12% desta propriedade. A idade do carregamento dos concretos não apresentou um impacto significativo na resistência à compressão axial, mas apontou resultados significativos entre os tipos de aditivos estudados, conforme ANOVA. As propriedades de absorção de água por capilaridade foram avaliadas aos 28- e 76-dias, indicando uma redução de absorção de água média de 42% devido ao uso dos aditivos cristalizantes. Em conclusão, a incorporação dos aditivos cristalizantes contribuiu de maneira positiva para a autocicatrização dos concretos estudados, indicando uma recuperação parcial das microfissuras. KW - Self-healing KW - Crystalline admixture KW - Concrete KW - Cracks PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-599140 DO - https://doi.org/10.1590/1517-7076-RMAT-2023-0355 SN - 1517-7076 VL - 29 IS - 1 SP - 1 EP - 20 CY - Rio de Janeiro AN - OPUS4-59914 LA - por AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Mittermayr, F. A1 - Gluth, Gregor A1 - Grengg, C. A1 - Garbe, U. A1 - Jiang, G. ED - Jiang, G. T1 - Concrete corrosion characterization using advanced microscopic and spectroscopic techniques N2 - The aim of this chapter is to give an overview of basic and advanced state-of-the-art microstructural and spectroscopic analytics to investigate inorganic material corrosion in the context of biochemically aggressive sewers. The chapter covers optical methods, electron beam, X-ray and neutron techniques (SEM, MLA, XRF, XRD, CT, Neutron radiography and tomography), and spectroscopic methods (MAS-NMR, FT-IR, and Raman). For each technique, a short section on the fundamental scientific background of the method precedes and examples of data output from the latter in respect to the corrosion of cementitious materials including reinforced concrete is presented. KW - Cement KW - Concrete KW - Deterioration KW - Spectroscopy KW - Microscopy PY - 2023 SN - 978-3-031-29940-7 SN - 978-3-031-29941-4 DO - https://doi.org/10.1007/978-3-031-29941-4_4 SP - 59 EP - 97 PB - Springer CY - Cham AN - OPUS4-57423 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gluth, Gregor A1 - Arbi, K. A1 - Bernal, S. A. A1 - Bondar, D. A1 - Castel, A. A1 - Chithiraputhiran, S. A1 - Dehghan, A. A1 - Dombrowski-Daube, K. A1 - Dubey, A. A1 - Ducman, V. A1 - Peterson, K. A1 - Pipilikaki, P. A1 - Valcke, S. L. A. A1 - Ye, G. A1 - Zuo, Y. A1 - Provis, J. L. T1 - RILEM TC 247-DTA round robin test: carbonation and chloride penetration testing of alkali-activated concretes N2 - Many standardised durability testing methods have been developed for Portland cement-based concretes, but require validation to determine whether they are also applicable to alkali-activated materials. To address this question, RILEM TC 247-DTA ‘Durability Testing of Alkali-Activated Materials’ carried out round robin testing of carbonation and chloride penetration test methods, applied to five different alkali-activated concretes based on fly ash, blast furnace slag or metakaolin. The methods appeared overall to demonstrate an intrinsic precision comparable to their precision when applied to conventional concretes. The ranking of test outcomes for pairs of concretes of similar binder chemistry was satisfactory, but rankings were not always reliable when comparing alkali-activated concretes based on different precursors. Accelerated carbonation testing gave similar results for fly ash-based and blast furnace slag-based alkali-activated concretes, whereas natural carbonation testing did not. Carbonation of concrete specimens was observed to have occurred already during curing, which has implications for extrapolation of carbonation testing results to longer service life periods. Accelerated chloride penetration testing according to NT BUILD 443 ranked the tested concretes consistently, while this was not the case for the rapid chloride migration test. Both of these chloride penetration testing methods exhibited comparatively low precision when applied to blast furnace slag-based concretes which are more resistant to chloride ingress than the other materials tested. KW - Alkali-activated materials KW - Durability KW - Carbonation KW - Chloride penetration KW - Concrete PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-504045 DO - https://doi.org/10.1617/s11527-020-1449-3 SN - 1359-5997 SN - 1871-6873 VL - 53 IS - 1 SP - 21 PB - Springer Nature AN - OPUS4-50404 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mundra, S. A1 - Samson, G. A1 - Masi, G. A1 - Achenbach, R. A1 - Bastidas, D. M. A1 - Bernal, S. A. A1 - Bignozzi, M. C. A1 - Criado, M. A1 - Cyr, M. A1 - Gartner, N. A1 - von Greve-Dierfeld, S. A1 - Legat, A. A1 - Nikoonasab, Ali A1 - Provis, J. L. A1 - Raupach, M. A1 - Gluth, Gregor T1 - Application of electrochemical methods for studying steel corrosion in alkali-activated materials N2 - Alkali-activated materials (AAMs) are binders that can complement and partially substitute the current use of conventional cement. However, the present knowledge about how AAMs protect steel reinforcement in concrete elements is incomplete, and uncertainties exist regarding the application of electrochemical methods to investigate this issue. The present review by EFC WP11-Task Force ‘Corrosion of steel in alkali-activated materials’ demonstrates that important differences exist between AAMs and Portland cement, and between different classes of AAMs, which are mainly caused by differing pore solution compositions, and which affect the outcomes of electrochemical measurements. The high sulfide concentrations in blast furnace slag-based AAMs lead to distinct anodic polarisation curves, unusually low open circuit potentials, and low polarisation resistances, which might be incorrectly interpreted as indicating active corrosion of steel reinforcement. No systematic study of the influence of the steel–concrete interface on the susceptibility of steel to corrosion in AAMs is available. Less common electrochemical methods present an opportunity for future progress in the field. KW - Alkali-activated materials KW - Reinforcement corrosion KW - Steel corrrosion KW - Electrochemical methods KW - Concrete PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-572241 DO - https://doi.org/10.1002/maco.202313743 SN - 1521-4176 VL - 74 IS - 7 SP - 988 EP - 1008 PB - Wiley-VCH CY - Weinheim AN - OPUS4-57224 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -