TY - CONF A1 - Hlavacek, Petr A1 - Rünger, M. A1 - Gluth, Gregor A1 - Kühne, Hans-Carsten T1 - Alkali activated fly ash mortars: Identification of chloride transport coefficient for various mixture compositions N2 - The main objective of this work is to determine chloride migration coefficients for alkali activated fly ash-based mortars. The effect of various mixture composition is studied. The identified values will be used in simulations of chloride transport in the alkali-activated composites, mainly to determine a critical time span of exposition to chlorides causing corrosion of reinforcement. Rapid chloride migration experiments (RCM) are performed on cylindrical specimens, 100 mm diameter, 50 mm height. Low voltage electric field (10–30 V DC) is applied as a driving force for the accelerated chloride penetration. The chloride front in the sample is identified according to NT Build 492 standard after given time of penetration (depending on the electrical current ~ 3 hours) on a fracture surface using silver nitrate solution. Further, accelerated diffusion experiments are performed in order to verify the migration coefficients obtained using RCM. The total chloride content is determined, and chloride profiles obtained on powder ground from separate layers of the specimen. T2 - EuroCoalAsh 2017 CY - Brno, Czech Republic DA - 06.02.2017 KW - Alkali activation KW - Fly ash KW - Chloride transport PY - 2017 SN - 978-80-214-5469-9 SP - 27 EP - 30 AN - OPUS4-39143 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mundra, S. A1 - Bernal, S. A. A1 - Criado, M. A1 - Hlaváček, Petr A1 - Ebell, Gino A1 - Reinemann, Steffi A1 - Gluth, Gregor A1 - Provis, J. L. T1 - Steel corrosion in reinforced alkali‐activated materials N2 - The development of alkali‐activated materials (AAMs) as an alternative to Portland cement (PC) has seen significant progress in the past decades. However, there still remains significant uncertainty regarding their long term performance when used in steel‐reinforced structures. The durability of AAMs in such applications depends strongly on the corrosion behaviour of the embedded steel reinforcement, and the experimental data in the literature are limited and in some cases inconsistent. This letter elucidates the role of the chemistry of AAMs on the mechanisms governing passivation and chloride‐induced corrosion of the steel reinforcement, to bring a better understanding of the durability of AAM structures exposed to chloride. The corrosion of the steel reinforcement in AAMs differs significantly from observations in PC; the onset of pitting (or the chloride ‘threshold’ value) depends strongly on the alkalinity, and the redox environment, of these binders. Classifications or standards used to assess the severity of steel corrosion in PC appear not to be directly applicable to AAMs due to important differences in pore solution chemistry and phase assemblage. KW - Corrosion KW - Alkali-activated PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-435162 DO - https://doi.org/10.21809/rilemtechlett.2017.39 SN - 2518-0231 VL - 2 SP - 33 EP - 39 PB - RILEM Publications SARL CY - Paris, France AN - OPUS4-43516 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hlavacek, Petr A1 - Gluth, Gregor A1 - Reinemann, Steffi A1 - Ebell, Gino A1 - Kühne, Hans-Carsten A1 - Mietz, Jürgen T1 - Corrosion of steel reinforcement in geopolymer mortars - carbonation resistance, chloride migration, and preliminary corrosion potential data N2 - Alkali-activated materials such as geopolymers are currently receiving a lot of attention because of their potential to be used as binders for concrete with advantageous engineering properties and reduced manufacturing CO2 emissions. Knowledge of the durability of steel in these concretes and related properties of alkali-activated materials is a prerequisite for their application as building materials, if they are to be used for steel reinforced elements. However, to date only limited data exists on this topic. The present contribution focuses on durability-related transport properties of geopolymer-based mortars (as model systems for concrete). We report results of accelerated carbonation, rapid chloride migration (RCM) and air permeability measurements as well as porosity data for fly ash-based geopolymer mortars, including mixes containing ground granulated blast furnace slag (GGBFS). In addition, we report polarization resistance data and corrosion potential vs. time curves for carbon steel bars embedded in two of the fly ash-based geopolymer mortars and a CEM I-based mortar (as reference). Despite comparable total porosities, the carbonation depths, the chloride migration coefficients and the air permeabilities of the mortars differed significantly. In general, the addition of GGBFS to the binders improved the performance (decreased transport coefficients); however, this was not found to be true for the air permeability in all cases. This latter effect can be explained by drying damage of the C-(A-)S-H gel in GGBFS-containing binders. On the other hand, low transport coefficients can also be achieved by optimization of the binder formulation without the addition of GGBFS, which is also reflected in the material’s air permeability. Thus, there exists no simple correlation between air permeability (of harshly dried mortars) and durability-related transport coefficients for the studied alkali-activated materials. The corrosion potential vs. time curves in combination with polarization resistance values reveal that the steel reinforcement in geopolymer mortars assumed a passive state. However, this happened considerably later than for steel in CEM I-based mortars. The free corrosion potential of carbon steel reinforcement in the geopolymer mortars had different values than the free corrosion potential values for the CEM I-based mortar for both the active and the passive state; possible reasons for this behavior are discussed. T2 - EUROCORR 2017 CY - Prague, Czech Republic DA - 03.09.2017 KW - Geopolymers KW - Alkali-activated materials KW - Corrosion KW - Steel reinforcement KW - Concrete PY - 2017 SP - Paper 87351, 1 EP - 7 AN - OPUS4-41870 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hlavacek, Petr T1 - Steel reinforcement corrosion in alkali-activated fly ash mortars N2 - Corrosion of steel rebars in concrete presents one of the main deterioration mechanisms limiting service life of the reinforced structures. The corrosion is accompanied by an expansion of the corrosion products causing high pressures, concrete cracking and finally spalling of a cover layer. Critical chloride concentration, loss of alkalinity and modeling of the steel corrosion are in researchers' spotlight for decades, however reinforcement corrosion in alkali activated materials is insufficiently described and understood yet. In this work, the steel reinforcement corrosion in alkali-activated fly ash mortars is investigated in terms of electrochemical behaviour of the reinforced mortars exposed to aggressive environments such as leaching, carbonation and chloride ingress. A selected geopolymer mixture based on hard coal fly ash activated with sodium hydroxide and sodium silicate solutions is used for the steel reinforcement-corrosion experiments. The formation of passive layer on the steel rebars is observed after approx. two weeks of hardening at laboratory temperature. However, alternative heat-treatment at 80°C for several hours leads to immediate formation of the passive layer as well as to a faster strength gain (80 MPa after 24h at 80°C). Chloride-induced corrosion, leaching and carbonation resistance of the alkali activated fly ash-based concrete is studied, where leaching in deionized water or carbonation under natural conditions (~0.04 % CO2) for 300 days did not lead to corrosion of the embedded steel. On the other hand, accelerated carbonation under 100 % CO2 atmosphere lead to depassivation within two weeks. T2 - Alkali Activated Materials and Geopolymers CY - Tomar, Portugal DA - 27.05.2018 KW - Alkali-activation KW - Reinforcement corrosion KW - Carbonation KW - Chloride attack KW - Leaching PY - 2018 AN - OPUS4-47446 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hlavacek, Petr T1 - Additive manufacturing of geopolymers by local laser curing N2 - For the additive manufacturing of large components typically powder-based methods are used. A powder is deposited layer by layer by means of a recoater, then, the component structure is printed into each individual layer. We introduce here the new method of local laser drying, which is a suspension-based method specially developed for the manufacturing of large voluminous ceramic parts. The structure information is directly written into the freshly deposited layer of suspension by laser drying. Initially, the technology was developed for ceramic suspensions, however, first experiments with geopolymers reveal a high potential for this class of materials. Metakaolin, fly ash and lithium aluminate-based one-part geopolymers were used in first experiments. The local annealing of the geopolymer slurry results in a drying and crosslinking reaction and, thus, in a local consolidation of the material. First parts made are introduced and their properties are discussed. T2 - CIMTEC 2018 CY - Perugia, Italy DA - 04.06.2018 KW - Additive manufacturing KW - Laser curing KW - Geopolymers PY - 2018 AN - OPUS4-47447 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hlavacek, Petr A1 - Reinemann, Steffi A1 - Gluth, Gregor A1 - Ebell, Gino A1 - Mietz, Jürgen ED - Serdar, M. ED - Stirmer, N. ED - Provis, J. T1 - Behaviour of reinforced alkali-activated fly ash mortars under leaching conditions N2 - Corrosion of steel reinforcement in concrete is one of the major deterioration mechanisms limiting the service life of reinforced concrete structures. While for conventional (Portland cement-based) concretes a great amount of experience exists in this regard, the factors that determine the onset of reinforcement corrosion in alkali-activated materials are incompletely understood yet. One aspect of corrosion protection is leaching and the accompanying changes of the concrete pore solution. In the present study, alkali-activated fly ash mortars with embedded carbon steel rebars were exposed to de-ionised water for periods up to 330 days, and the electrochemical response of the steel (free corrosion potential, polarisation resistance), the alteration of the mortar (ohmic resistance, mechanical strength, pore size distribution) as well as the pore solution composition were monitored. Although substantial alkali leaching was observed, the pH of the pore solution remained at values sufficient to protect the embedded steel from depassivation. The mortar did not exhibit indications of significant deterioration. Thus, the present results suggest that leaching is not critical for protection of steel reinforcement in alkali-activated fly ash mortars and concretes. T2 - International Conference on Sustainable Materials, Systems and Structures (SMSS 2019) CY - Rovinj, Croatia DA - 20.03.2019 KW - Alkali-activated materials KW - Steel corrosion KW - Leaching PY - 2019 SN - 978-2-35158-223-7 VL - 1 SP - 118 EP - 124 PB - RILEM Publications CY - Paris AN - OPUS4-47585 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hlavacek, Petr T1 - Behaviour of reinforced alkali-activated fly ash mortars under leaching conditions N2 - Corrosion of steel reinforcement in concrete is one of the major deterioration mechanisms limiting the service life of reinforced concrete structures. While for conventional (Portland cement-based) concretes a great amount of experience exists in this regard, the factors that determine the onset of reinforcement corrosion in alkali-activated materials are incompletely understood yet. One aspect of corrosion protection is leaching and the accompanying changes of the concrete pore solution. In the present study, alkali-activated fly ash mortars with embedded carbon steel rebars were exposed to de-ionised water for periods up to 330 days, and the electrochemical response of the steel (free corrosion potential, polarisation resistance), the alteration of the mortar (ohmic resistance, mechanical strength, pore size distribution) as well as the pore solu¬tion composition were monitored. Although substantial alkali leaching was observed, the pH of the pore solution remained at values sufficient to protect the embedded steel from depassivation. The mortar did not exhibit indications of significant deterioration. Thus, the present results suggest that leaching is not critical for pro¬tec¬tion of steel reinforcement in alkali-activated fly ash mortars and concretes. T2 - International Conference on Sustainable Materials, Systems and Structures (SMSS 2019) CY - Rovinj, Croatia DA - 20.03.2019 KW - Alkali-activated materials KW - Leaching KW - Steel corrosion PY - 2019 AN - OPUS4-47621 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hlavacek, Petr T1 - Engineering properties of alkali activated fly ash foams N2 - Alkali-activated fly ash foams – mechanical, chemical and physical properties Alkali-activation of fly ash together with an aluminum powder blowing agent led to the synthesis of inorganic fly ash-based foam. The aluminium powder reacts with the alkalies from the activation solution. Hydrogen is released during this reaction and creates a closed-pore structure. The amount of liquid activation solution and aluminium powder was optimized considering proper pore distribution and feasible bulk density of the resulting foam. The viscosity of the initial mix was found as a crucial factor for the foaming process as well as for the stability of the fresh foam. The fly ash foam is characterized in terms of its compressive and flexural strength, thermal conductivity and capacity, resistance to chemically aggressive environments, fire resistance and 2D morphology. The fire resistance test shows, that almost all mass loss occurres below 500°C and the biggest volume change take place between 800°C and 1100°C. An excellent chemical durability stems mainly from the closed-pore network and absence of leachable Ca in the system. Experiments and micromechanical simulations prove that reasonable bulk densities lie in the range of 400 to 800 kg/m3. T2 - 92. DKG Jahrestagung CY - Berlin, Germany DA - 19.03.2017 KW - Foam KW - Alkali activation KW - Inorganic PY - 2017 AN - OPUS4-39639 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hlavacek, Petr T1 - Corrosion of steel reinforcement in geopolymer Mortars N2 - Study on corrosion of steel reinforcement in geopolymer mortars. Identification of carbonation speed and chloride migration coefficient. Results on preliminary corrosion potential measurements. T2 - EFC-WP 11 Task Group: Steel Corrosion in Alkali-Activated Concrete CY - Berlin, Germany DA - 28.03.2017 KW - Geopolymer KW - Chloride migration KW - Carbonation KW - Steel corrosion PY - 2017 AN - OPUS4-39619 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hlavacek, Petr T1 - Corrosion of steel reinforcement in geopolymer mortars - Carbonation resistance, chloride migration, and preliminary corrosion potential data N2 - Geopolymers present a group of novel building materials exhibiting improved chemical resistance, fire resistance and lower CO2 emissions over traditional OPC-based materials. Corrosion of steel rebars in concrete presents one of the main deterioration mechanisms limiting service life of the reinforced structures. The corrosion is accompanied by an expansion of the corrosion products causing high pressures, concrete cracking and finally spalling of a cover layer. Critical chloride concentration, loss of alkalinity and modeling of the steel corrosion are in researchers' spotlight for decades, however steel corrosion in geopolymer materials is insufficiently described and understood yet. An optimized geopolymer mixture based on German hard coal fly ash activated with sodium hydroxide and sodium silicate solutions was selected for steel reinforcement-corrosion experiments. The formation of passive layer on the steel rebars is observed after approx. two weeks of hardening at laboratory temperature. However, alternative heat-treatment at 80°C for several hours leads to immediate formation of the passive layer as well as to a faster strength gain (80 MPa after 24h at 80°C). Chloride diffusion coefficient, Na+ leaching as well as carbonation rate is identified on unreinforced geopolymer mortar samples. The data are used for simulations and design of the steel rebars-corrosion experiments. The effect of chloride ingress, Na+ leaching and carbonation of the geopolymer mortar on the steel-reinforcement corrosion is studied. T2 - II European Geopolymer Network CY - Madrid, Spain DA - 14.07.2017 KW - Geopolymer KW - Steel corrosion KW - Chloride transport coefficient PY - 2017 AN - OPUS4-41058 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 - TY - RPRT A1 - Hlavacek, Petr A1 - Ebell, Gino A1 - Gluth, Gregor A1 - Reinemann, Stefi A1 - Mietz, Jürgen A1 - Kühne, Hans-Carsten T1 - Betonstahlkorrosion in Geopolymerbetonen bei Angriff von Kohlenstoffdioxid und Chlorid N2 - Der kritische, Korrosion auslösende Chloridgehalt für die Beurteilung der Korrosions-beständigkeit von Betonstahl in Geopolymerbetonen ist von großer Bedeutung für die Dauerhaftigkeitsprognose für bewehrte Elemente aus solchen Materialien. Es sind kaum experimentelle Daten in der Fachliteratur vorhanden und die vorliegenden Werte unterscheiden sich zwischen den Studien erheblich. In diesem Projekt wurde der kritische, Korrosion auslösende Chloridgehalt für Betonstahl (BSt 500) in flugaschebasierten (Ca-armen) Geopolymermörtel für verschiedene Beaufschlagungskombinationen bestimmt: Chloridbeaufschlagung mit 1 M NaCl-Lösung; Auslaugen in entionisiertem Wasser und anschließende Chloridbeaufschlagung im 1 M NaCl-Lösung; Auslaugen in entionisiertem Wasser, Carbonatisierung in Luft bei 20 °C und natürlicher CO2 Konzentration und anschließende Chloridbeaufschlagung mit 1 M NaCl-Lösung. Für Referenz-Zwecke wurde zusätzlich der Korrosion auslösende Chloridgehalt für eine Portland-Zement Mischung bei Auslagerung in 1 M NaCl-Lösung bestimmt. KW - Korrosion KW - Geopolymer PY - 2019 SP - 1 EP - 83 AN - OPUS4-49752 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gluth, Gregor A1 - Ebell, Gino A1 - Hlavacek, Petr A1 - Mietz, Jürgen T1 - Chloride‐induced steel corrosion in alkali‐activated fly ash mortar: Increased propensity for corrosion initiation at defects N2 - Chloride contents at the steel–mortar interface that initiate steel corrosion were determined for carbon steel in alkali‐activated fly ash mortar for three different exposure conditions: exposure to 1 M NaCl solution; leaching in deionized water and then exposure to 1 M NaCl solution; and leaching in deionized water, aging in air at 20°C and natural CO2 concentration, and then exposure to 1 M NaCl solution. For comparison, a Portland cement mortar, exposed to 1 M NaCl solution, was studied. The median values of the corrosion‐initiating chloride contents (average over the full length of the rebar) in the alkali‐activated fly ash mortar varied between 0.35 and 1.05 wt% Cl with respect to binder, consistently lower than what was obtained for the Portland cement mortar, but with no clear trend regarding the exposure conditions. For most of the alkali‐activated fly ash mortar specimens, preferential corrosion at the connection between the working electrode and the external measurement setup was observed, while preferential corrosion did not occur for the Portland cement mortar. Scanning electron microscopy and auxiliary experiments in synthetic solutions indicated that this behavior was caused by inhomogeneities at the steel–mortar interface in the alkali‐activated mortar, likely due to its peculiar rheological properties in the fresh state. KW - Alkali-activated materials KW - Steel corrosion KW - Critical chloride content KW - Steel-concrete interface PY - 2020 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-507268 DO - https://doi.org/10.1002/maco.202011541 VL - 71 IS - 5 SP - 749 EP - 758 PB - Wiley-VCH AN - OPUS4-50726 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gluth, Gregor A1 - Hlavacek, Petr A1 - Reinemann, Steffi A1 - Ebell, Gino A1 - Mietz, Jürgen ED - Alexander, M.G. ED - Beushausen, H. ED - Dehn, F. ED - Moyo, P. T1 - Leaching, carbonation and chloride ingress in reinforced alkali-activated fly ash mortars N2 - Alkali-activated fly ash mortars were studied with regard to durability-relevant transport coefficients and the electrochemical behaviour of embedded carbon steel bars on exposure of the mortars to leaching, carbonation and chloride penetration environments. The transport coefficients differed considerably between different formulations, being lowest for a mortar with BFS addition, but still acceptable for one of the purely fly ash-based mortars. Leaching over a period of ~300 days in de-ionized water did not lead to observable corrosion of the embedded steel, as shown by the electrochemical data and visual inspection of the steel. Exposure to 100 % CO2 atmosphere caused steel depassivation within approx. two weeks; in addition, indications of a deterioration of the mortar were observed. The results are discussed in the context of the different reaction products expected in high- and low-Ca alkali-activated binders, and the alterations caused by leaching and carbonation. T2 - International Conference on Concrete Repair, Rehabilitation and Retrofitting (ICCRRR 2018) CY - Cape Town, South Africa DA - 19.11.2018 KW - Alkali-activated materials KW - Steel corrosion KW - Leaching KW - Carbonation PY - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-464381 DO - https://doi.org/10.1051/matecconf/201819902025 VL - 199 SP - Article Number 02025 PB - EDP Sciences AN - OPUS4-46438 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Salari, Farid A1 - Zocca, Andrea A1 - Bosetti, Paolo A1 - Hlaváček, Petr A1 - Italiano, Antonino A1 - Gobbin, Filippo A1 - Colombo, Paolo A1 - Kühne, Hans-Carsten A1 - Sglavo, Vincenzo M. T1 - Powder-bed 3D printing by selective activation of magnesium phosphate cement: Determining significant processing parameters and their effect on mechanical strength N2 - The present work addresses powder bed binder jetting additive manufacturing by selective magnesium phosphate cement activation. Despite the potential of this technology to aid the digitalization of the construction industry, the effect of processing parameters on the mechanical performance of printed materials has not yet been studied to generate a guideline for the further development of the technology. Statistical methodologies were used to screen the effect of four printing process parameters (printing speed, layer thickness, raster angle, and build direction on flexural and compressive strength). As the exploited technology works with constant fluid pressure, the physical interpretation of the effect of each factor can be considered taking into account the interactions between the binder materials in the powder bed. Analysis of variance (ANOVA) indicated that printing speed and layer thickness significantly affect mechanical performances. Furthermore, the layout of samples for the printing process is preferable to be parallel the printhead movement. An anisotropic behavior was observed, and the samples subjected to compressive forces parallel to the layer plane possessed lower strength values. This effect can be interpreted as a result of a weak area of low density in between layers, leading to a pronounced delamination under compression. Even though the strength of the printed material is not suitable for a structural concrete, it can be marginally improved by design of experiment and optimized for non-structural applications, such as for porous artificial stone. Design of experiment coupled with ANOVA methods can be used in the future to support the development of novel material mixtures, thus expanding the fields of application of this novel additive manufacturing technology. KW - Concrete 3D-printing KW - Particle-bed binder jetting KW - Design of experiment PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-601654 DO - https://doi.org/10.1016/j.oceram.2024.100609 VL - 18 SP - 1 EP - 11 PB - Elsevier B.V. AN - OPUS4-60165 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -