TY - JOUR A1 - Schmidt, Wolfram A1 - Brouwers, H.J.H. A1 - Kühne, Hans-Carsten A1 - Meng, Birgit T1 - The working mechanism of starch and diutan gum in cementitious and limestone dispersions in presence of polycarboxylate ether superplasticizers N2 - Polysaccharides provide high potential to be used as rheology modifying admixtures in mineral binder systems for the construction industry such as concrete or mortar. Since superplasticizers have become state of technology, today, concrete is more and more adjusted to flowable consistencies. This often goes along with the risk of segregation, which can be effectively avoided by adding stabilising agents supplementary to superplasticizers. Stabilising agents are typically based on polysaccharides such as cellulose, sphingan gum, or starch. Starch clearly distinguishes in its effect on rheology from other polysaccharides, mainly due to the strong influence of amylopectin on the dispersion and stabilisation of particles. Based on rheometric investigations on cementitious and limestone based dispersions with different volumetric water to solid ratios, the mode of operation of modified potato starch is explained in comparison to a sphingan gum. It is shown that the stabilising effect of starch in a coarsely dispersed system is mainly depending upon the water to solid ratio and that above a certain particle volume threshold starch mainly affects the dynamic yield stress of dispersions, while plastic viscosity is affected only to a minor degree. Sphingans operate more independent of the particle volume in a coarsely dispersed system and show significantly higher effect on the plastic viscosity than on the yield stress. In systems incorporating superplasticizers, influences of both stabilising agents on yield stress retreat into the background, while both observed polysaccharides maintain their effect on the plastic viscosity. KW - Cement KW - Limestone KW - Rheology KW - Stabilising agent KW - Coarsely dispersed systems KW - Diutan gum KW - Starch ether PY - 2013 DO - https://doi.org/10.3933/ApplRheol-23-52903 SN - 1430-6395 SN - 0939-5059 VL - 23 IS - 5 SP - 52903-1 EP - 52903-12 PB - Kerschensteiner CY - Lappersdorf AN - OPUS4-29932 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmidt, Wolfram A1 - Kühne, Hans-Carsten T1 - Kusum-Kontrollkarten mit V-Maske in der Prozesssteuerung N2 - Seit Juli 2014 liegt die EN 206:2014 als neue Betonnorm vor. Neben kleineren Änderungen ergibt sich hierdurch als einschneidende Änderung zur Vorgängerversion EN 206-1:2008 ein ergänzendes Konzept zur Konformitätsbewertung der Druckfestigkeit von Beton. An dieser Stelle werden neben dem bekannten Mittelwertkriterium alternativ sogenannte Kontrollkartenverfahren möglich. Für die Konformitätsbewertung stellt in diesem Zusammenhang insbesondere die Kusum-Methode (kumulierte Summen, aus dem Englischen cusum – cumulative sum) ein Novum dar. Weiterführende Informationen zu Kusum-Methode in der Konformitätsbewertung können der Literatur entnommen werden. Eigentlich ist die Kusum-Methode aber nicht für die Konformitätsbewertung entwickelt worden, sondern vielmehr für die Produktionskontrolle. Der Unterschied zwischen Konformitätsbewertung und Produktionskontrolle ergibt sich daraus, dass die Konformitätskontrolle eine Bedeutung für die öffentliche Sicherheit hat und dass eindeutige technische Grenzwerte vorliegen müssen, die nicht unterschritten werden dürfen, während die Produktionssteuerung ein Werkzeug mit frei wählbaren Grenzwerten für Hersteller ist. Der Handlungsbedarf ist für die Produktionskontrolle optional und ergibt sich in der Regel aus Wirtschaftlichkeitsbetrachtungen. PY - 2015 SN - 1439-7706 IS - 4 SP - 38 EP - 44 PB - ad-media-Verl. CY - Köln AN - OPUS4-33580 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmidt, Wolfram A1 - Uzoegbo, H.C. A1 - Bella, N. A1 - Rongai, G. A1 - Kühne, Hans-Carsten A1 - Diergardt, T. T1 - Cement testing in Africa - Conclusions from the first africa-wide proficiency testing scheme N2 - African cement infrastructure is quite complex. Apart from Northern Africa and South Africa in particular, cement plants are scarce resulting in highly unstable cement pricing. Clinker and cement are imported from overseas, e.g. from Portugal, Turkey, Pakistan, Indonesia, and China. Imports are typically determined by the lowest price, and as a result the countries of origin of products vary regularly yielding large scatter of properties. Quality control and a good quality infrastructure are thus of utmost importance for the safety of the populace, an issue, which is actually often neglected. With funding of the German Metrology Institute (PTB) and support of the SPIN project, a proficiency testing scheme for cement testing according to EN 196 was set up for African laboratories. Proficiency testing schemes, also called round robins, are inter-laboratory performance comparisons allowing participants to evaluate themselves against pre-established criteria. They are a powerful tool to help laboratories improve their performance as well as demonstrate their competences to accreditation bodies or customers. 26 laboratories from 20 nations, 18 of which from Africa, participated. The BAM Federal Institute for Materials Research and Testing acted as coordinator and provider of the scheme. The aim of the round robin was to interpret the submitted data further beyond the pure statistic analyses. The data provided a positive picture of the performance of the participants in general, but it also exhibited a number of technical fields that need improvement. The paper provides the general results of the scheme and analyses identified strengths and weak points based on the submitted and non submitted data as well as on discrepancies from the EN 196 procedures during measurements. The application of EN standards for material testing is critically discussed and since quality infrastructure is also always an issue between industrial and political stakeholders, suggestions for the mitigation of the identified shared problems are given. KW - Round robin KW - Quality control KW - Cement testing KW - Proficiency testing PY - 2013 SN - 2225-0514 SN - 2224-5790 VL - 4 SP - 54 EP - 58 PB - International Institute for Conservation of Historic and Artistic Works CY - New York, NY, USA AN - OPUS4-29933 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmidt, Wolfram A1 - Sonebi, M. A1 - Brouwers, H.J.H. A1 - Kühne, Hans-Carsten A1 - Meng, Birgit T1 - Rheology modifying admixtures: The key to innovation in concrete technology - a general overview and implications for Africa N2 - Innovative admixture technology has significantly widened up the ränge of possibilities of concrete engineers. For many decades the water to cement ratio (w/c) was the major influencing factor for the performance of concrete. Due to the need to adjust a consistency, which still allowed reasonable workability, the w/c was typically significantly higher than technologically reasonable. Rheology modifying admixtures Support adjusting the concrete consistency largely independent of the w/c. It was only after the invention of the first superplasticizers that modern concrete technology significantly evolved in terms of flowability, strength, and durability, and only due to the steady evolution of the technology modern innovations, such as Self-Compacting Concrete, Ultra-High-Performance Concrete, or Engineered Cementitious Composites were made possible. Today’s superplasticizers are extremely versatile and can be adjusted to individual technologicalspecifications. However, the other side of the coin of versatility is that cementitious Systems incorporating superplasticizers have become more sensitive against environmental influences, such as the environmental temperature, which may cause unwanted effects or demand for supplementary admixture use such as stabilizing admixtures. Hence, concrete mixture composition with admixtures demands for a high level of expertise and offen there is lack of awareness about the mode of Operation of rheology modifying admixtures among concrete technologists. The paper gives a comprehensive overview about rheology modifying admixtures such as superplasticizers or stabilizing agents, and how they can be used depending upon the application in the most favourable way. Based on experiences with the sub-Saharan African concreting boundary conditions, which exhibit many challenges in terms of environmental boundary conditions and construction site logistics, conclusions are finally drawn, how admixtures can be used in the most beneficial way to improve the concrete casting Situation. KW - Rheology KW - Admixtures KW - Concrete KW - Superplasticizers KW - Polycarboxylate ether KW - Viscosity modifying agents PY - 2013 SN - 2224-3224 SN - 2225-0956 VL - 5 SP - 115 EP - 120 PB - International Institute for Conservation of Historic and Artistic Works CY - New York, NY, USA AN - OPUS4-30948 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - de Carvello, J. M. F. A1 - Schmidt, Wolfram A1 - Kühne, Hans-Carsten A1 - Fiorotti Peixoto, R. A. T1 - Influence of high-charge and low-charge PCE-based superplasticizers on Portland cement pastes containing particle-size designed recycled mineral admixtures N2 - Design : and use of engineered recycled mineral admixtures obtained from industrial and mineral waste are promising strategies to increase the range of materials suitable for use in cement-based composites. In this work, Portland cement-blended pastes containing mineral admixtures designed for improving particle packing were evaluated in the presence of low- and high-charge polycarboxylate-based superplasticizers. The powders were obtained from basic oxygen furnace slag, iron ore tailings, quartz mining tailings, and quartzite mining tailings. The zeta-potentials of the particles were obtained via electrophoretic mobility. The flow properties were evaluated by rheological tests performed in a Couette type rheometer. The hydration kinetics was evaluated by isothermal calorimetry and an adapted method based on the Vicat needle test. The high-charge PCE and the finer mineral admixtures produced more stable blends. Coarser mineral admixtures led to increased flowability and delayed hydration compared to finer ones. Steel slag powders presented the most significant plasticizer effects, but also the largest setting delays and segregation tendency. Quartz-rich superfines reduced the setting delays caused by the superplasticizers. In summary, both superplasticizers were effective in improving flow properties, but the high-charge PCE was effective in preventing segregation in pastes containing mineral admixtures coarser and heavier than cement. KW - Engineered recycled mineral admixtures KW - Rheology KW - PCE-Based superplasticizer KW - Steel slag KW - Mining tailing PY - 2020 DO - https://doi.org/10.1016/j.jobe.2020.101515 VL - 32 SP - 1 EP - 16 PB - Elsevier AN - OPUS4-58395 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Priebe, Nsesheye Susan A1 - Vogler, Nico A1 - Sturm, Patrick A1 - Neubert, M. A1 - Schröder, H.-J. A1 - Kühne, Hans-Carsten A1 - Hünger, K.-J. A1 - Gluth, Gregor T1 - Calcined brick clays and mixed clays as supplementary cementitious materials: Effects on the performance of blended cement mortars N2 - While calcined clays in general have been credited with a great potential to mitigate CO2 emissions related to cement production and consumption, calcined brick clays are currently understudied in this regard. In the present work, two brick clays, a low-grade kaolinitic clay, and a mixed clay composed of 50% brick clay and 50% low-grade kaolinitic clay were studied regarding transformations on calcination, and strength and durability performance as well as pore structure of mortars made with the blended cements. All calcined clays exhibited pozzolanic reactivity, with the performance of the brick clays inferior to the low-grade kaolinitic clay. However, the mixed clay performed very similar to the low-grade kaolinitic clay, which points to a viable option for optimal use of brick clays in cementitious systems. The carbonation resistance of the blended cement mortars was generally worse than that of the plain Portland cement mortar, as expected, but the former exhibited a significantly improved chloride penetration resistance. The latter improvement was due to pore structure refinement in the blended cement mortars, compared to the Portland cement mortar. KW - Brick clay KW - Illitic clay KW - Calcined clay KW - Blended cement KW - Supplementary cementitous materials PY - 2021 DO - https://doi.org/10.1016/j.conbuildmat.2020.120990 N1 - Geburtsname von Priebe, Nsesheye Susan: Msinjili, N. S. - Birth name of Priebe, Nsesheye Susan: Msinjili, N. S. VL - 266 SP - 120990 PB - Elsevier Ltd. AN - OPUS4-51362 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Vogler, Nico A1 - Lindemann, Mathias A1 - Drabetzki, Philipp A1 - Kühne, Hans-Carsten T1 - Alternative pH-indicators for determination of carbonation depth on cement-based concretes N2 - The most common method for determination of the carbonation depth is the sprayed application of indicator solutions, Phenolphthalein in particular. Since the aerosols of Phenolphthalein are suspected to be carcinogenic, efforts have been intensified to use alternative indicators for the determination of carbonation depth. The subject and aim of this research paper are to examine indicator solutions from Alizarin Yellow R, Thymol Blue and a Mixed Indicator. These indicator solutions are commercially available and are not suspected to be carcinogenic. For the purpose of this research, samples previously stored under accelerated carbonation conditions (1% CO2) were examined by thermogravimetric analysis (TGA) and examination of the pH value. Additionally, the electrolytic back-titration for determination of total CO2 amount was carried out comparatively to TGA. KW - Thermal analysis KW - Accelerated carbonation KW - pH-indicators KW - Concrete PY - 2020 DO - https://doi.org/10.1016/j.cemconcomp.2020.103565 VL - 109 SP - 1 EP - 9 PB - Elsevier Ltd. AN - OPUS4-50458 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Grunewald, Thomas A1 - Grätz, Rainer A1 - Kühne, Hans-Carsten T1 - Werkzeuge zur Verwendung in explosionsgefährdeten Bereichen - Erkenntnisse zur Zündwahrscheinlichkeit von Edelstahl und NE-Metallen gegen Baustahl und Estrichbeton in Wasserstoff und Acetylen N2 - Üblicherweise werden Werkzeuge für den industriellen Einsatz aus hochlegierten Chromstählen hergestellt. Für den Einsatz in explosionsgefährdeten Bereichen werden oft Werkzeuge aus speziellen Nichteisen-Metalllegierungen (NE-Metall) verwendet. Für diese sogenannten funkenarmen Werkstoffe und deren mögliche Schlagpartner gibt es bisher keine umfassenden Untersuchungen mit Aussagen zur Zündwahrscheinlichkeit. Die TRGS 723, Abschn. 5.15, fordert den Nachweis der Funkenfreiheit der verwendeten Werkstoffpaarung. Jedoch sind Werkzeuge keine Geräte oder Schutzsysteme im Sinne der Richtlinie 2014/34/EU. Deshalb ist es nicht möglich, Werkzeuge in Übereinstimmung mit dieser Richtlinie zu zertifizieren. Der Nachweis der Erfüllung dieser Anforderungen ist durch Zertifizierungen im sogenannten "gesetzlich nicht geregelten" Bereich möglich. Die BAM bietet diese Zertifizierung für "Funkenarme Werkzeuge" im Rahmen ihres Zertifizierungsprogrammes an. Die bisherigen Ergebnisse der hier vorgestellten Untersuchung haben gezeigt, dass es keine funkenfreien, metallischen Werkzeuge (non-sparking Tools) gibt. Entscheidend ist im Hinblick auf die TRGS 723, ob zündfähige Funken entstehen oder nicht. Es ist immer die Frage, worauf die Werkzeuge im praktischen Anwendungsfall schlagen oder fallen gelassen werden können, d.h. aus welchem Material der mögliche Schlagpartner besteht. Dies können metallische Schlagpartner, aber auch Betonoberflächen sein. Unterschiedliche Kombinationen von Werkstoffen ergeben bei Schlagbeanspruchung im explosionsgefährdeten Bereich jeweils unterschiedliche Zündwahrscheinlichkeiten. Aber auch die Höhe der beim Einsatz der Werkzeuge möglichen kinetischen Schlagenergie und der Brenngas/Luft-Atmosphäre im betreffenden explosionsgefährdeten Bereich sind wichtige Einflussgrößen. KW - Mechanisch erzeugte Funken KW - Nichtelektrische Funken KW - Schlagfunken KW - Schleiffunken KW - Reibfunken KW - Funkenarmes Werkzeug KW - Funkenfreies Werkzeug KW - Nichtelektrischer Explosionsschutz KW - Non sparking tools PY - 2021 DO - https://doi.org/10.37544/2191-0073-2021-11-12-33 SN - 2191-0073 VL - 11 IS - 11-12 SP - 33 EP - 37 PB - VDI Fachmedien CY - Düsseldorf AN - OPUS4-53936 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kühne, Hans-Carsten T1 - Handlungshilfe zur Betoninstandsetzung N2 - Die TR Instandhaltung des Deutschen Instituts für Bautechnik wird als maßgebliches Bezugswerk der Betoninstandsetzung ür die Fachöffentlichkeit hinsichtlich ihrer Inhalte und Zielrichtung vorgestellt KW - Beton KW - Instandsetzung KW - Technische Regel KW - Planung KW - Ausführung KW - DIBt PY - 2021 UR - https://www.ingenieur.de/fachmedien/bauingenieur/ PB - VDI Fachmedien GmbH & Co. KG Unternehmen für Fachinformationen CY - Düsseldorf AN - OPUS4-52117 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hüsken, Götz A1 - Shamsuddoha, Md A1 - Pirskawetz, Stephan A1 - Hofmann, Detlef A1 - Baeßler, Matthias A1 - Kühne, Hans-Carsten T1 - Potential of a Repair System for Grouted Connections in Offshore Structures: Development and Experimental Verification N2 - Grouted connections are intensively used in offshore rigs, platforms as well as jacket and monopile offshore wind turbine structures. Being located in remote offshore conditions, these connections can experience considerable adverse loading during their lifetimes. Degradation was reported inside similar connections, which were installed in the last three decades. Grouting in the offshore sites may often be proven difficult, which eventually leads to reduced load-bearing capacity of connections in the long run. Thus, repair and rehabilitation of such connections should be planned ahead to minimize operational delays and costs. In this study, scaled grouted connections were manufactured using a novel mould, whose integrity were monitored using digital image correlation (DIC). The connections were loaded under static load to visualize the main failure pattern using distributed fibre optic sensors and acoustic emission (AE) analysis. Grouted connections were then repaired using a cementitious injectable grout. The effectiveness of the grout injection was monitored using dye penetration technique. Finally, specimens are reloaded to identify the potential of such repair for grouted connections. KW - Offshore KW - Grouted connection KW - Fibre optic sensors KW - Acoustic emission analysis KW - Cracks KW - Repair KW - Rehabilitation KW - Static loading PY - 2021 DO - https://doi.org/10.1016/j.marstruc.2021.102934 VL - 77 SP - 102934 PB - Elsevier Ltd. AN - OPUS4-52059 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sturm, Patrick A1 - Moye, J. A1 - Gluth, Gregor A1 - Vogler, Nico A1 - Taffe, A. A1 - Kühne, Hans-Carsten ED - Rossignol, S. ED - Gluth, Gregor T1 - Properties of alkali-activated mortars with salt aggregate for sealing structures in evaporite rock N2 - Concrete structures for sealing of tunnels in the host rock are an essential part of systems for nuclear waste storage. However, concretes based on blended cements or magnesium oxychloride cements, which are commonly considered for this application, can deteriorate severely due to a significant heat of hydration and associated deformation and cracking. Alkali-activated materials (AAMs) offer a potential solution to this problem because of their low heat release during hardening. To explore their suitability for the construction of sealing structures in evaporite rock, various AAMs with salt aggregate were studied regarding fresh properties, heat release, mechanical properties and microstructure. The heat of reaction of the AAMs was up to 55% lower than that of a blended cement designed for sealing structures, indicating significant benefits for the intended application. Other relevant properties such as mechanical strength and permeability depended strongly on the mix-design of the AAMs and curing conditions. KW - Alkali-activated materials KW - Geopolymers KW - Nuclear waste storage KW - Sealing structures KW - Evaporite rock PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-519422 DO - https://doi.org/10.1016/j.oceram.2020.100041 SN - 2666-5395 VL - 5 IS - Special issue: Alkali-activated materials and geopolymers in ceramics and beyond SP - 1 EP - 8 PB - Elsevier CY - Amsterdam AN - OPUS4-51942 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Shamsuddoha, Md A1 - Hüsken, Götz A1 - Schmidt, Wolfram A1 - Kühne, Hans-Carsten A1 - Baeßler, Matthias T1 - Long-term mechanical and shrinkage properties of cementitious grouts for structural repair N2 - Grouts have numerous applications in construction industry such as joint sealing, structural repair, and connections in precast elements. They are particularly favoured in rehabilitation of structures due to penetrability and convenience of application. Grouts for repair applications typically require high-performance properties such as rapid strength development and superior shrinkage characteristics. Sometimes industrial by-products referred as supplementary cementitious materials (SCM) are used with neat cement due to their capabilities to provide binding properties at delayed stage. Micro silica, fly ash and metakaolin are such SCMs, those can modify and improve properties of cement products. This study aims at investigating long-term mass loss and linear shrinkage along with long-term compressive and flexural strength for grouts produced from ultrafine cement and SCMs. A series of mixtures were formulated to observe the effect of SCMs on these grout properties. Properties were determined after 365 days of curing at 23oC and 55% relative humidity. The effect of SCMs on the properties are characterised by statistical models. Response surfaces were constructed to quantify these properties in relation to SCMs replacement. The results suggested that shrinkage was reduced by metakaolin, while micro silica and fly ash had positive effects on compressive and flexural strength, respectively. T2 - International Conference on Sustainable Materials, Systems and Structures (SMSS 2019) CY - Rovinj, Croatia DA - 20.03.2019 KW - Grout KW - Long-term shrinkage KW - Micro silica KW - Fly ash KW - Metakaolin PY - 2019 DO - https://doi.org/10.21809/rilemtechlett.2019.82 SN - 2518-0231 VL - 4 SP - 9 EP - 15 PB - RILEM Publications SARL CY - 4 avenue du Recteur Poincaré, 75016 Paris, France AN - OPUS4-48712 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Priebe, Nsesheye Susan A1 - Gluth, Gregor A1 - Sturm, Patrick A1 - Vogler, Nico A1 - Kühne, Hans-Carsten T1 - Comparison of calcined illitic clays (brick clays) and low-grade kaolinitic clays as supplementary cementitious materials N2 - The use of calcined clays as supplementary cementitious materials (SCMs) has been identified as a viable option to decrease the CO2 emissions related to cement production. However, while extensive data is available about kaolinitic clays in this context, other clays such as illitic clays appear to be under-studied. Therefore, in the present study, two illitic clays were compared to two low-grade kaolinitic clays in terms of transformations in the calcination temperature range 650–900 °C, and performance of the calcined clays in blended cement pastes as measured by strength evolution, heat release, hydrated phase formation and portlandite consumption. The illitic clays required a higher calcination temperature for complete dehydroxylation of their illite than what is necessary for dehydroxylation of kaolinite. These higher calcination temperatures also led to particle sintering, significantly decreasing the specific surface area of the illitic clays, particularly for the clay with the higher Fe2O3 content. Nevertheless, while the kaolinitic clays generally exhibited the best performance as SCM, the illitic clay with lower Fe2O3 content performed similar to the kaolinitic clays when calcined at optimum temperature and applied at a moderate substitution rate. These findings demonstrate that several different clays have the potential to be used as SCM and indicate possible routes to identify suitable deposits for this purpose. KW - Blended cement KW - Calcined clay KW - Brick clay KW - Illite KW - Kaolinite PY - 2019 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-488195 DO - https://doi.org/10.1617/s11527-019-1393-2 SN - 1359-5997 SN - 1871-6873 N1 - Geburtsname von Priebe, Nsesheye Susan: Msinjili, N. S. - Birth name of Priebe, Nsesheye Susan: Msinjili, N. S. VL - 52 IS - 5 SP - Article Number 94 PB - Springer Nature AN - OPUS4-48819 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hlavacek, Petr A1 - Gluth, Gregor A1 - Lüchtenborg, Jörg A1 - Sturm, Patrick A1 - Mühler, T. A1 - Kühne, Hans-Carsten A1 - Günster, Jens T1 - A Novel Approach to Additive Manufacturing of Alkali-activated Materials: Laser-induced Slip Casting (LIS) of Lithium Aluminate/Silica Slurries N2 - Additive manufacturing of alkali-activated materials currently attracts a lot of attention, because of the possibility to produce customized high-performance elements for a range of applications, potentially being more resource-efficient than conventionally produced parts. Here, we describe a new additive manufacturing process for alkali-activated materials that is based on selective laser-heating of lithium aluminate/microsilica slurries. The new process-material combination allows to manufacture elements with complex geometries at high building rates and high accuracy. The process is versatile and transferrable to structures of sizes differing by orders of magnitude. The mechanical strength of the obtained materials was in the range of values reported for conventional metakaolin-based geopolymers, and superior to what has been hitherto reported for alkali-activated materials produced by additive manufacturing. This mechanical performance was obtained despite the fact that the degree of reaction of the lithium aluminate and the microsilica was low, suggesting that significant reactions took place only at the surface of the microsilica particles. KW - Laser-induced slip casting KW - Alkali-activated materials KW - Additive manufacturing PY - 2019 DO - https://doi.org/10.29272/cmt.2018.0011 SN - 2612-4882 VL - 1 IS - 2 SP - 138 EP - 144 PB - Techna Group AN - OPUS4-49142 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -