TY - JOUR A1 - Vogler, Nico A1 - Lehmann, Jens A1 - Bohlmann, Tatjana A1 - Kronemann, Jens T1 - Gel-bound Colourants as a Substitute for the Sprayed Application of pH-Indicator Solution N2 - In general, pH-sensitive colorants such as phenolphthalein are applied on freshly split surfaces of building structures to determine the state of carbonation. For years, it has been known that the aerosols of phenolphthalein are suspected of being carcinogenic. Hence, more work has currently being done on alternative indicators for the use in research and the use on construction sites. Over the past years, mainly pH indicators from other research areas and natural dyes were investigated for their usability to cementitious systems. This paper presents the experimental results of using phenolphthalein solution bound in agar-agar gel. This gel-bound indicator allows the future use of the already known phenolphthalein dye without the health hazards for the user. To demonstrate the flexibility of the gel-bound colorant, different application forms of the indicator were carried out and assessed. In addition, the results obtained by the different methods were statistically evaluated to ensure validity. The accuracy of the results was confirmed by thermogravimetric analysis and IR spectroscopic studies as reference methods. It has also succeeded to demonstrate the comparability of the results achieved by the gel-bound colorant with the results of the common sprayed application method. As an additional gain in knowledge, comparative results of indicator tests, TGA analysis, and FTIR investigation are shown. KW - Concrete Carbonation KW - Gel-bound Colorants KW - pH Indicator KW - Thermal Gravimetric Analysis KW - FTIR-ATR Measurements PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-551493 UR - http://www.sciencepublishinggroup.com/j/ajce DO - https://doi.org/10.11648/j.ajce.20221003.16 SN - 2330-8729 SN - 2330-8737 VL - 10 IS - 3 SP - 135 EP - 144 PB - Science Publishing Group CY - New York, NY AN - OPUS4-55149 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rübner, Katrin A1 - Schumann, G. A1 - Hahn, A. A1 - Vöge, M. A1 - Bruch, I. A1 - Schnell, A. T1 - HYTEGRA - Hydrothermalgranulate - Rohstoffliches Recycling von Mauerwerkbruch N2 - Ziel des Projekts HYTEGRA ist die Herstellung leichter Gesteinskörnungen durch hydrothermale Behandlung quarz- und kalkreicher Reststoffe. Als Ausgangsstoffe dienen heterogener Mauerwerkbruch aus Bau- und Abbruchabfällen als SiO2-Träger und Papierasche aus dem Altpapierrecycling als CaO-Träger. Für beide Reststoffe besteht derzeit ein Verwertungsdefizit. Das Verfahren beruht auf der Idee des rohstofflichen Recyclings, d. h. die chemisch-mineralogischen Stoffeigenschaften werden für die hydrothermale Stoffumwandlung genutzt. Bei der Härtung der Hydrothermalgranulate bilden sich Calciumsilicathydrat-Phasen (CSH) aus der Reaktion zwischen Quarzpartikeln und Kalk im Autoklav bei 200 °C und 16 bar Sattdampf. T2 - Innovationstag Mittelstand des BMWK am 22. Juni 2022 CY - Berlin, Germany DA - 23.06.2022 KW - Mauerwerkbruch KW - Papierasche KW - Rohstoffliches Recycling KW - Leichte Gesteinskörnung KW - Bodenfilter PY - 2022 AN - OPUS4-55552 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - THES A1 - Priebe, Nsesheye Susan T1 - Influence of calcination conditions and varying compositions on the reactivity and performance of brick clays as supplementary cementitious materials T1 - Der Einfluss von Kalzinierungsbedingungen und verschiedenen Zusammensetzungen auf die Reaktivität und Eigenschaften von Ziegeltonen verwendet als Zusatzstoffe in Beton N2 - Calcined clays as supplementary cementitious materials (SCMs) have been identified and credited to be a viable solution in mitigating the CO2 emissions related to cement production and consumption. Calcined clays range from a variety of different clay types based on an assortment of varying minerals and compositions. While extensive data is available on kaolinitic clays (based on the 1:1 clay type), other clays such as brick clays (based on the 2:1 clay type) are currently understudied, although such clays are largely more available than the kaolinitic clays. The aim of this thesis is to draw attention to the varying compositions present in two selected brick clays in Germany and elaborate on how such compositions affect their suitability to be used as SCMs in blended cement systems. The novelty of this thesis explains the relationship between the reactivity of the bricks to their varying compositions and their suitability for their employment as SCMs. This was based on their chemical and physical transformations in the calcination temperature range 650–900 or 950 °C, and the performance of the calcined brick clays in blended cement systems measured by their heat evolution, strength development and durability-related properties. The results of their performance were compared to two kaolinitic clays with varying compositions. While the kaolinitic clays generally exhibited the best performance as SCMs, the brick clay with a lower Fe2O3 content showed promising results similar to the kaolinitic clays when an optimum calcination temperature is applied and when substituted at a moderate cement substitution rate. Thus, this finding promoted further efforts made to improve the reactivity of the brick clay by producing a mixed clay composed of 50 % brick clay (with lower Fe2O3 content) and 50 % kaolinitic clay. The mixed clay was compared to the two individual brick clays and one kaolinitic clay, whereby optimum calcination conditions were performed in large-scale simulating an industrial-scale production of SCMs. All calcined clays exhibited pozzolanic reactivity, with the performance of the brick clays inferior to the kaolinitic clay, however, the mixed clay performed very similar to the kaolinitic clay. At a similar degree of hydration compared to plain Portland cement, the good performance of the mixed clays was especially evident in the strength development and improved chloride penetration resistance, which was caused by a refinement in the pore structure in the cementitious systems. Moreover, it was deduced that not only the high surface area, but also, the solubility of Si and Al ions in the resulting calcinate of the mixed clays plays a significant role when calcined at ~600–700 °C, which points to viable options for optimal employment of brick clays in cementitious systems. N2 - Die bei der Zementproduktion freigesetzte CO2-Menge und die daraus resultierenden Folgen für das Klima machen die Entwicklung von Zementersatzstoffen mit geringerem CO2-Fußabdruck erforderlich. Als besonders vielversprechend haben sich dabei die kalzinierten Tone erwiesen. Bei diesen handelt es sich um komplexe Systeme, bestehend aus einer Vielzahl verschiedener Tonminerale in variierender Konzentration und Zusammensetzung. Während für kaolinitische Tone (basierend auf 1:1 Tonmineralarten) bereits umfangreiche Daten gesammelt werden konnten, ist der Kenntnisstand zu anderen Tonarten z.B. Ziegeltonen (basierend auf 2:1 Tonmineralarten) derzeit noch unzureichend. Besonders vor dem Hintergrund der erheblich größeren Verfügbarkeit dieser Tonarten stellt dies einen erheblichen Nachteil dar. Ziel dieser Arbeit ist es, anhand zweier Ziegeltone aus Deutschland, aufzuzeigen welche Auswirkung die unterschiedliche Zusammensetzung der Tone sowohl auf die Reaktivität als auch auf den Einsatz als Zementersatzstoffen in Mischzementsystemen hat. Entsprechende Änderungen in der Zusammensetzung der kalzinierten Tone wurden durch die Variation der Kalzinierungstemperatur im Temperaturbereich zwischen 650 °C und 900 °C bzw. 950 °C und den folglich unterschiedlich ablaufenden chemischen und physikalischen Umwandlungsprozessen der Tonminerale erreicht. Die Leistungsfähigkeit dieser Systeme wurde anhand der Wärme- und Festigkeitsentwicklung sowie den Dauerhaftigkeitseigenschaften bewertet. Als Referenzsysteme dienten zwei 1:1 Tone mit unterschiedlicher Zusammensetzung. Die bei den 1:1 Tonen erzielten Reaktivitäten waren im Vergleich zu den Ziegeltonen zwar höher, aber bei entsprechender Kalzinierungstemperatur und moderater Zementersatzrate konnten auch bei den Ziegeltonen vielversprechende Ergebnisse erzielt werden. Basierend auf diesen Ergebnissen wurden in einem weiteren Schritt Mischtone, bestehend aus kaolinitischem Ton und Ziegelton mit geringerem Fe2O3 Gehalt (50:50), untersucht. Zur Bewertung wurden die zuvor untersuchten Ziegeltone und ein 1:1 Ton herangezogen. Bei allen kalzinierten Tonen konnte die pozzolanische Reaktion nachgewiesen werden, wobei der Ziegelton die geringsten und die 1:1 Tone die höchsten Werte lieferte. Das Mischtonsysteme sind leistungstechnisch bei den 1:1 Tonen einzuordnen. Die strukturverfeinernde Wirkung des Mischtons beim Einsatz als Zementersatz in Portlandzementsystemen führte sowohl bei der Festigkeitsentwicklung als auch beim Chlorideindringwiderstand zu einer Leistungssteigerung. Zudem konnte gezeigt werden, dass nicht nur die große spezifische Oberfläche, sondern auch die hohe Löslichkeit der Si- und Al-Ionen in den Kalzinaten der bei ~600-700 °C kalzinierten Mischtone einen großen Einfluss hat und den Einsatz der Ziegeltone in zementären Systemen begünstigt. Die Möglichkeit zur Herstellung von Zementersatzstoffen im industriellen Maßstab konnte durch Versuche im Großmaßstab ebenfalls nachgewiesen werden. KW - Blended cement KW - Brick clay KW - Calcined clay KW - Hydration KW - Illite KW - Kalzinierte Tone KW - Ziegelton PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:co1-opus4-58816 DO - https://doi.org/10.26127/BTUOpen-5881 SP - i EP - 153 PB - Brandenburgische Technische Universität Cottbus-Senftenberg CY - Cottbus AN - OPUS4-55048 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wiehle, Philipp A1 - Simon, Sebastian A1 - Baier, J. A1 - Dennin, L. ED - Forde, M. T1 - Influence of relative humidity on the strength and stiffness of unstabilised earth blocks and earth masonry mortar N2 - Aim of this study is to provide information about moisture dependent material behaviour of unstabilised loadbearing earth blocks and mortars. Compressive strength and Young’s modulus were investigated after conditioning in varying relative humidity reaching from 40 % up to 95 %. The material composition and physical properties were investigated to understand the influence of relative humidity onto the mechanical properties. A normalisation of strength and stiffness by the values obtained at 23 ◦C and 50 % relative humidity reveals a linear dependence of compressive strength and Young’s modulus that is regardless of the material composition. Thus, it is possible to describe the influence of relative humidity onto the load-bearing behaviour of unstabilised earth masonry materials in a generally valid formulation. KW - Earth block masonry KW - Load-bearing behaviour KW - Compressive strength KW - Moisture content KW - Sorption isotherm PY - 2022 DO - https://doi.org/10.1016/j.conbuildmat.2022.128026 SN - 0950-0618 VL - 342 IS - Part A SP - 1 EP - 15 PB - Elsevier Ltd. AN - OPUS4-54949 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Zhang, K. A1 - Schmidt, Wolfram A1 - Mezhov, Alexander T1 - Influence of the hydroxypropylation of starch on its performance as viscosity modifying agent N2 - Synopsis: Starch is a commonly used viscosity modifying agent (VMA). The performance of starch as VMA depends on its origin (e.g. potato, corn, cassava, etc.) and corresponding molecular properties, such as molecular weight, ratio between amylose and amylopectin etc. Depending upon the application, the efficiency of starch can be enhanced by hydroxypropylation. The maximum degree of substitution (DoS) cannot be greater than 3.0, which is the number of hydroxy groups per glucose monomer in the polymer. In the current research three potato starches exhibiting the DoS of 0.4, 0.6 and 0.8 were utilised. The influence of the modified starch on the rheological properties and hydration of cement paste, as well as the viscosity of the pore solution were investigated. Our findings show that the starch with the highest DoS increases the dynamic yield stress the most, while the plastic viscosity is less dependent on the DoS. Additionally, starch with the highest DoS retards hydration to lower degree than other starches. T2 - 13th International Conference on Superplasticizers and Other Chemical Admixtures in Concrete CY - Milan, Italy DA - 10.07.2022 KW - Potato starch KW - Rheological KW - Cement hydration KW - Pore solutions PY - 2022 DO - https://doi.org/10.14359/51736074 VL - 354 SP - 209 EP - 218 PB - ACI Special Publications AN - OPUS4-58320 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mezhov, Alexander A1 - Zhang, K. A1 - Schmidt, Wolfram T1 - Interactions of Biobased Rheology Modifying Agents with Superplasticizer in Cement Paste N2 - Organic admixtures are an indispensable component of modern concrete. Thus, their purposeful application is not only technically and economically viable but in addition an inevitable tool to make concrete more environmentally friendly. In this context, the use of polysaccharides has increasingly gained interest in the built environment as sustainable resource for performance enhancement. However, due to its origin, biopolymers possess a vast variety of molecular structures which can result in incompatibilities with other polymers present in concrete, such as superplasticizers. The present study highlights effects of the joint application of different types of starches and polycarboxylates with respect to their influence on cement hydration and structural build-up of cement pastes. KW - Polysaccharides KW - Superplasticizers KW - Hydration KW - Cement PY - 2022 DO - https://doi.org/10.4028/www.scientific.net/CTA.1.563 SN - 2674-1237 SP - 563 EP - 568 PB - Trans Tech Publications Ltd, Switzerland CY - Basel, Switzerland. AN - OPUS4-58325 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Strangfeld, Christoph A1 - Schönsee, Eric A1 - Jeyifous, Olubunni Anthony A1 - Mezhov, Alexander A1 - Hüsken, Götz T1 - Introduction of a monitoring system for Bingham fluids in additive manufacturing with concrete N2 - Freeform additive manufacturing of concrete structures is a rising technology in civil engineering with several fascinating advantages. Nonetheless, to ensure reliability and structural integrity, standards and quality control are required in the future to bring this technology into the market. As the concrete is manufactured continuously, continuous quality control of the printing process is also required, i.e. comprehensive process monitoring. At BAM, a test rig will be installed, enabling the printing of concrete structures with a maximum size of 2 m x 1 m x 1 m (l x w x h). Here, process monitoring is the focus of the test rig. In this study, we show the results of the first pump tests, including the measurement of several parameters such as temperature and pressure along the supply system, i.e. from the concrete pump to the printer head. T2 - NDT-CE 2022 CY - Zurich, Switzerland DA - 16.08.2022 KW - Additive manufacturing of concrete KW - Process monitoring KW - Non-destructive testing KW - Bingham fluid PY - 2022 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-556367 SP - 1 EP - 12 AN - OPUS4-55636 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Strangfeld, Christoph A1 - Schönsee, Eric A1 - Jeyifous, Olubunmi Anthony A1 - Mezhov, Alexander A1 - Hüsken, Götz T1 - Introduction of a monitoring system for Bingham fluids in additive manufacturing with concrete N2 - Freeform additive manufacturing of concrete structures is a rising technology in civil engineering with several fascinating advantages. Nonetheless, to ensure reliability and structural integrity, standards and quality control are required in the future to bring this technology into the market. As the concrete is manufactured continuously, continuous quality control of the printing process is also required, i.e. comprehensive process monitoring. At BAM, a test rig will be installed, enabling the printing of concrete structures with a maximum size of 2 m x 1 m x 1 m (l x w x h). Here, process monitoring is the focus of the test rig. In this study, we show the results of the first pump tests, including the measurement of several parameters such as temperature and pressure along the supply system, i.e. from the concrete pump to the printer head. T2 - NDT-CE 2022 CY - Zurich, Switzerland DA - 16.08.2022 KW - Additive manufacturing of concrete KW - Process monitoring KW - Non-destructive testing KW - Bingham fluid PY - 2022 AN - OPUS4-55637 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mundra, S. A1 - Furcas, F. E. A1 - Huthwelker, T. A1 - Simon, Sebastian A1 - Borca, C. N. A1 - Provis, J. L. A1 - Gluth, Gregor T1 - Kinetics of Sulfide Oxidation in alkaline solutions studied by X-ray absorption near-edge structure spectroscopy N2 - The oxidation of sulfur in aqueous solutions is an important process in several geochemical and industrial contexts. In concrete technology, it is particularly relevant for the protection of steel reinforcement in slag cement-based concretes, as the presence of sulfides affects the passivation of the steel and corrosion initiation in the presence of chlorides. However, the knowledge about the kinetics of sulfide oxidation in alkaline solutions, such as concrete pore solutions, is incomplete. To address this issue, we prepared solutions with 0.80 M NaOH, and nominally 10, 100 and 350 mM HS−, respectively, and followed the evolution of the sulfur species during bubbling with oxygen-containing gas (concentration 100% or 22%) using X-ray absorption near-edge structure (XANES) spectroscopy at the sulfur K-edge. Polysulfide, thiosulfate, sulfite and sulfate were identified and quantified via linear combination fitting of the spectra, using previously measured standards. A preliminary analysis of the results shows that the initial rate constant of sulfide oxidation depends strongly on the HS− concentration, while it less strongly depending on the oxygen concentration, in line with previous results for lower pH values. Approaches to fit the data to obtain the rate constants of all relevant reactions will be discussed. T2 - 41st Cement & Concrete Science Conference CY - Leeds, Great Britain DA - 12.09.2022 KW - XANES KW - Sulfide oxidation KW - Kinetics PY - 2022 SP - 1 EP - 3 PB - Institute of Materials, Minerals & Mining (IOM3) AN - OPUS4-55650 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Winkler, Juliette A1 - Beck, M. A1 - Gluth, Gregor ED - Schneider, F. ED - Hehl, K. ED - Heyde, S. T1 - Kurz- und mittelfristige Verbundfestigkeit von alkaliaktivierten Mörteln auf Beton N2 - Ein zentrales Fundament moderner Gesellschaften ist eine intakte Abwasserinfrastruktur. Schäden infolge biogener Schwefelsäurekorrosion von konventionellen Betonen haben jedoch zu einem erheblichen Sanierungsbedarf geführt. Alkaliaktivierte Mörtel besitzen aufgrund eines hohen Säurewiderstands das Potential, einen Beitrag zur langfristigen Lösung dieses Problems zu leisten. Dazu müssen jedoch zunächst die Faktoren, die den Haftverbund zwischen diesen Mörteln und dem Betonsubstrat bestimmen, besser verstanden werden, um die Eigenschaften der Beschichtungssysteme gezielt anpassen und verbessern zu können. Die vorliegende Arbeit liefert hierzu einen Beitrag und zeigt dadurch Wege zu einer technisch machbaren und nachhaltigen Sanierung von Abwasserbauwerken auf. KW - Alkalisch aktivierte Bindemittel KW - Abwassersysteme KW - Reparatursysteme KW - Verbund KW - Dauerhaftigkeit PY - 2022 SN - 978-3-8440-8818-2 SP - 89 EP - 100 CY - Berlin AN - OPUS4-57701 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -