TY - JOUR A1 - Kinne, R. W. A1 - Gunnella, F. A1 - Kunisch, E. A1 - Heinemann, S. A1 - Nies, B. A1 - Maenz, S. A1 - Horbert, V. A1 - Illerhaus, Bernhard A1 - Huber, R. A1 - Firkowska-Boden, I. A1 - Bossert, J. A1 - Jandt, K. D. A1 - Sachse, A. A1 - Bungartz, M. A1 - Brinkmann, O. T1 - Performance of calcium phosphate cements in the augmentation of sheep vertebrae - An ex vivo study N2 - Oil-based calcium phosphate cement (Paste-CPC) shows not only prolonged shelf life and injection times, but also improved cohesion and reproducibility during application, while retaining the advantages of fast setting, mechanical strength, and biocompatibility. In addition, poly(L-lactideco-glycolide) (PLGA) fiber reinforcement may decrease the risk for local extrusion. Bone defects (diameter 5 mm; depth 15 mm) generated ex vivo in lumbar (L) spines of female Merino sheep (2–4 years) were augmented using: (i) water-based CPC with 10% PLGA fiber reinforcement (L3); (ii) Paste-CPC (L4); or (iii) clinically established polymethylmethacrylate (PMMA) bone cement (L5). Untouched (L1) and empty vertebrae (L2) served as controls. Cement performance was analyzed using micro-computed tomography, histology, and biomechanical testing. Extrusion was comparable for Paste-CPC(-PLGA) and PMMA, but significantly lower for CPC + PLGA. Compressive strength and Young’s modulus were similar for Paste-CPC and PMMA, but significantly higher compared to those for empty defects and/or CPC + PLGA. Expectedly, all experimental groups showed significantly or numerically lower compressive strength and Young’s modulus than those of untouched controls. Ready-to-use Paste-CPC demonstrates a performance similar to that of PMMA, but improved biomechanics compared to those of water-based CPC + PLGA, expanding the therapeutic arsenal for bone defects. O, significantly lower extrusion of CPC + PLGA fibers into adjacent lumbar spongiosa may help to reduce the risk of local extrusion in spinal surgery. KW - Sheep KW - PMMA KW - Calcium phosphate bone cement KW - Oil-based KW - Ready-to-use KW - Water-based KW - Micro-CT KW - Compressive strength KW - Young’s modulus PY - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-569072 SN - 1996-1944 VL - 14 IS - 14 SP - 1 EP - 12 PB - MDPI CY - Basel AN - OPUS4-56907 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Brinkmann, M. A1 - Wiehle, Philipp T1 - Correlation between relative humidity and the strength and deformation characteristics of unstabilised earth masonry N2 - The mechanical properties of unstabilised earthen building materials are distinctively influenced by changes in material moisture content. However, this moisture-dependency often remains unconsidered in the calculation of the load-bearing capacity of earth constructions. This paper aims to derive a convenient way to sufficiently consider the impact of different material moisture contents on the mechanical properties of unstabilised earth masonry. Therefore, the influence of relative humidity and temperature on the strength and deformation characteristics of unstabilised earth blocks, earth mortar and earth masonry is evaluated by conducting compression tests under various climate conditions. The results show that the compressive strength and the modulus of elasticity are linearly correlated with the relative humidity, whereas changes in temperature at constant relative humidity have no significant influence. To account the distinct moisture-dependency, a general applicable modification factor for unstabilised earthen materials is provided, which enables the adjustment of the compressive strength and the modulus of elasticity in dependency of arbitrary hygroscopic material moisture contents. KW - Earth masonry KW - Earth blocks KW - Relative humidity KW - Modulus of elasticity KW - Moisture KW - Compressive strength KW - Stress–strain-relation PY - 2023 U6 - https://doi.org/10.1016/j.conbuildmat.2022.130048 SN - 0950-0618 VL - 366 IS - 22 SP - 1 EP - 11 PB - Elsevier BV AN - OPUS4-56732 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wiehle, Philipp A1 - Brinkmann, M. T1 - Material behaviour of unstabilised earth block masonry and its components under compression at varying relative humidity N2 - block and mortar types is analysed with particular regard to the influence of varying relative humidity. The uniaxial compressive strength and deformation characteristics of unstabilised earth blocks and mortars as well as of unstabilised earth block masonry are studied in detail and compared to conventional masonry to evaluate whether the structural design can be made accordingly. An increase of 30 % points in relative humidity leads to a reduction of the masonry´s compressive strength between 33 % and 35 % whereas the Young´s modulus is reduced by 24–29 %. However, the ratio between the Young´s modulus and the characteristic compressive strength of earth block masonry ranges between E33/fk = 283–583 but is largely independent of the relative humidity. The results show that the mechanical properties of the investigated unstabilised earth block masonry are sufficient for load-bearing structures, yielding a masonry compressive strength between 2.3 MPa and 3.7 MPa throughout the range of moisture contents investigated. In general, the design concept of conventional masonry can be adapted for unstabilised earth masonry provided that the rather low Young´s modulus as well as the moisture dependence of both, compressive strength and Young´s modulus, are sufficiently taken into account. KW - Compressive strength KW - Earth block masonry KW - Compression tests KW - Stress-strain relation KW - Relative humidity KW - Moisture content PY - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-562417 SN - 2214-5095 VL - 17 SP - 1 EP - 15 PB - Elsevier B.V. CY - Netherlands AN - OPUS4-56241 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 U6 - 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 - JOUR A1 - von Werder, Julia A1 - Simon, Sebastian A1 - Gardei, André A1 - Fontana, P. A1 - Meng, Birgit T1 - Thermal and hydrothermal treatment of UHPC: influence of the process parameters on the phase composition of ultra-high performance concrete N2 - Several studies show that thermal and hydrothermal treatment can further improve the excellent properties of UHPC in terms of mechanical strength and durability. While for the thermal treatment the increase in strength is attributed to an intensified pozzolanic and hydraulic reaction, for the hydrothermal treatment previous studies accredited it mostly to the formation of tobermorite. In the presented study thermal and hydrothermal treatment of UHPC samples was systematically varied and the phase formation analysed related to the strength development of a reference sample cured for 28 days in water. For the thermal treatment the results show that the strength increase depends on the protection against desiccation and can be ascribed to an improved pozzolanic reaction of the siliceous fillers. To achieve a significant enhancement of strength, a pre-storage time of few days and a long dwell time at elevated temperature/pressure are required. For the hydrothermal treatment already heating the specimens up to 185 °C in saturated steam followed by an immediate cooling leads to a substantial increase in compressive strength. Pre-storage time did not affect the result as far as a minimum of several hours is guaranteed. The improved performance is due to an increase in the pozzolanic and hydraulic reaction. Surprisingly, tobermorite was only found within a very thin layer at the surface of the sample, but not in the bulk. Sulphate and aluminium stemming from the decomposition of the ettringite are bound in the newly formed phases hydroxylellestadite and hydrogarnet. KW - UHPC KW - Thermal treatment KW - Hydrothermal treatment KW - Compressive strength KW - Phase development KW - Durability KW - Tobermorite KW - Hydroxylellestadite KW - Hydrogarnet PY - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-523402 SN - 1871-6873 SN - 1359-5997 VL - 54 IS - 1 SP - Article 44 PB - Springer Nature AN - OPUS4-52340 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 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-489131 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 - JOUR A1 - Kowitz, Astrid A1 - Wu, Cheng-Chieh A1 - Helmerich, Rosemarie A1 - Hille, Falk A1 - Kadoke, Daniel A1 - Gründer, Klaus-Peter A1 - Hauser, S. A1 - Schwarzinger, H. ED - Bland, S. T1 - Impact on a micro-reinforced UHPC: Experimental studies versus numerical modeling N2 - Within the presented research project, experimental and numerical investigations were performed to develop a thin-shelled, modular, mobile element system made of a micro-reinforced ultra-high-performance ductile concrete (DUCON®). Material parameters were experimentally determined to adapt the material model within the numerical analysis applying the Drucker-Prager relationship. Afterwards, for validation of the numerical models, quasi-static and high-velocity impact tests were performed on plate-like structures. Finally, a suitable geometry of transportable barrier elements will be designed, which provides a maximum of resistance against impact by a minimum of weight and a maximum of mobility. KW - UHPC KW - Impact KW - DUCON® KW - Quasi-static and dynamic tests KW - Micro-reinforcement KW - Ductility KW - Mobile elements KW - Numerical modeling KW - Stereo photogrammetry KW - Compressive strength KW - E-modulus PY - 2019 UR - https://www.sciencedirect.com/science/article/pii/S2214785319305115?dgcid=author U6 - https://doi.org/10.1016/j.matpr.2019.03.152 SN - 2214-7853 VL - 12 IS - 2 SP - 474 EP - 483 PB - Elsevier Ltd CY - Amsterdam AN - OPUS4-48181 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hille, Falk A1 - Kowitz, Astrid A1 - Wu, Cheng-Chieh A1 - Helmerich, Rosemarie A1 - Kadoke, Daniel A1 - Gründer, Klaus-Peter A1 - Hauser, S. A1 - Schwarzinger, H. T1 - Impact on a micro-reinforced UHPC: experimental studies vs. numerical modeling N2 - Within the presented research project, experimental and numerical investigations were performed to develop a thin-shelled, modular, mobile element system made of a micro-reinforced ultra-high-performance ductile concrete (DUCON®). Material parameters were experimentally determined to adapt the material model within the numerical analysis applying the Drucker-Prager relationship. Afterwards, for validation of the numerical models, quasi-static and high-velocity impact tests were performed on plate-like structures. Finally, a suitable geometry of transportable barrier elements will be designed, which provides a maximum of resistance against impact by a minimum of weight and a maximum of mobility. T2 - 35th Danubia-Adria Symposium on Advances in Experimental Mechanics CY - Sinaia, Romania DA - 25.09.2018 KW - E-modulus KW - Quasi-static and dynamic tests KW - DUCON® KW - Impact KW - UHPC KW - Ductility KW - Micro-reinforcement KW - Mobile elements KW - Numerical modeling KW - Stereo photogrammetry KW - Compressive strength PY - 2018 AN - OPUS4-47003 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kowitz, Astrid A1 - Wu, Cheng-Chieh A1 - Hille, Falk A1 - Helmerich, Rosemarie A1 - Kadoke, Daniel A1 - Gründer, Klaus-Peter A1 - Hauser, S. A1 - Schwarzinger, H. ED - Pastramă, Ş. D. ED - Constantinescu, D. M. T1 - Impact on a micro-reinforced UHPC: Experimental studies versus numerical modeling N2 - Within the presented research project, experimental and numerical investigations were performed to develop a thin-shelled, modular, mobile element system made of a micro-reinforced ultra-high-performance ductile concrete (DUCON®). Material parameters were experimentally determined to adapt the material model within the numerical analysis applying the Drucker-Prager relationship. Afterwards, for validation of the numerical models, quasi-static and high-velocity impact tests were performed on plate-like structures. Finally, a suitable geometry of transportable barrier elements will be designed, which provides a maximum of resistance against impact by a minimum of weight and a maximum of mobility. T2 - 35th Danubia-Adria Symposium on Advances in Experimental Mechanics CY - Sinaia, Romania DA - 25.09.2018 KW - E-modulus KW - Impact KW - UHPC KW - DUCON® KW - Quasi-static and dynamic tests KW - Micro-reinforcement KW - Ductility KW - Mobile elements KW - Numerical modeling KW - Stereo photogrammetry KW - Compressive strength PY - 2018 UR - https://www.das2018.ro/ SN - 978-606-23-0874-2 SP - 11 EP - 12 PB - Editura Printech CY - Bucarest, Romania AN - OPUS4-47001 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, P. A1 - Miccoli, Lorenzo A1 - Fontana, Patrick A1 - Ziegert, Ch. T1 - Partial safety factors for earth block masonry N2 - In the beginning of the 1980s earth building has undergone a renaissance, which nowadays leads to an increasing use of load-bearing earth constructions and in particular, earth block masonry. At present, there are no common structural standards according to the semi-probabilistic design concept, which is the state-of-the-art in European standards. A solid database is needed for the determination of the partial safety factor on the resistance side. Therefore, compressive strength tests were carried out with two types of earth blocks and two types of prefabricated earth mortar. The evaluation showed that the variation of the compressive strength was remarkably less than expected, which seems to indicate high quality standards of the components earth block and mortar with regard to industrial production. On the basis of these results and together with the reliability method, a partial safety factor for earth block masonry subjected to compression was determined. The main aim of the research was the development of a first valid database for material parameters of earth block masonry with particular regard to statistical characteristics. The results showed that a common calculation method for earth block masonry based on partial safety factors following the valid masonry construction standard is feasible. T2 - Terra Lyon 2016 - XIIth World Congress on Earthen Architecture CY - Lyon, France DA - 11.07.2016 KW - Safety factors KW - Earth block masonry KW - Compressive strength PY - 2016 SN - 979-10-96446-12-4 SP - 1 EP - 8 PB - Editions CRAterre CY - Villefontaine AN - OPUS4-45151 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -