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 - Weise, Frank A1 - von Werder, Julia A1 - Manninger, Tanja A1 - Maier, Bärbel A1 - Fladt, Matthias A1 - Simon, Sebastian A1 - Gardei, Andre A1 - Höhnel, Desirée A1 - Pirskawetz, Stephan A1 - Meng, Birgit T1 - A multiscale and multimethod approach to assess and mitigate concrete damage due to alkali-silica reaction N2 - Alkali-silica reaction (ASR) is a chemical reaction within concrete which can lead over time to cracking and spalling. Due to the complexity of the problem, it still causes damage to concrete constructions worldwide. The publication aims to illustrate the interdisciplinary research of the German Federal Institute for Materials Research and Testing (BAM) within the last 20 years, considering all aspects of ASR topics from the macro to the micro level. First, methods for characterization and assessment of ASR risks and reaction products used at BAM are explained and classified in the international context. Subsequently the added value of the research approach by combining different, preferably nondestructive, methods across all scales is explained using specific examples from a variety of research projects. Aspects covered range from the development of new test-setups to assess aggregate reactivity, to analysis of microstructure and reaction products using microscopical, spectroscopical and X-ray methods, to the development of a testing methodology for existing concrete pavements including in-depth analysis of the visual damage indicator and the de-icing salt input using innovative testing techniques. Finally, research regarding a novel avoidance strategy that makes use of internal hydrophobization of the concrete mix is presented. KW - Mitigation strategies KW - Concrete KW - Damage analysis KW - Alkali silica reaction KW - Road pavement KW - Accelerated testing KW - Non-destructive testing KW - Microstructure PY - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:101:1-2022052515100075090235 SN - 1527-2648 VL - 24 IS - 6 SP - 1 EP - 36 PB - Wiley-VCH CY - Weinheim AN - OPUS4-54951 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - von Werder, Julia A1 - Simon, Sebastian A1 - Meng, Birgit T1 - Internal sulfate resistance of concrete N2 - If the amount of sulfate within the mix design for concrete is not balanced, ettringite formation which first controls solidification continues while the concrete is hardening. Ettringite forms by reaction of sulfate contained in the cement or in some admixture with calcium aluminate (C3A) as cement component. The “late primary ettringite formation” promotes an increase in volume within the hardened concrete leading to cracks. To analyze the effect of substituting part of ordinary Portland cement (OPC) by a treated brown coal fly ash mortar bars were tested according to ASTM C452. This test method was originally developed to extrapolate from the internal to external sulfate attack and is based on the idea that by testing a concrete mixture containing sulfate the process of deterioration is accelerated because it does not have to diffuse into the concrete before reaction first. In addition to the samples prescribed in ASTM C452 further samples in the size of the German SVA procedure were tested also designed for accessing the external sulfate resistance. The results show that while the replacement of 25 % of cement by brown coal fly ash leads to length changes around the limit defined by ASTM, the substitution of 50 % cement exceeded the limit by a multiple. The progress of expansion is the very similar for the two geometries tested. In-situ XRD measurements confirmed that while for pastes made of OPC the formation of ettringite is completed after 20 hours, this is not true for the mixtures containing the brown coal fly ash. In a different study the effect of hydrothermal treatment on the phase composition of ultra-high-performance concrete was analyzed. The results show that the sulfate and aluminate resulting from the decomposition of ettringite are bound into new phases. If this binding is permanent this might allow the larger use of sulfate bearing raw materials. T2 - EuroCoalAsh 2021 Conference CY - Online meeting DA - 02.11.2021 KW - Brown coal fly ash KW - Ettringite KW - Internal sulfate resistance KW - Test methods KW - In-situ XRD KW - Hydrothermal treatment PY - 2021 SP - 131 EP - 137 CY - Thessaloniki AN - OPUS4-54133 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schraut, Katharina A1 - Adamczyk, Burkart A1 - Adam, Christian A1 - Stephan, D. A1 - Meng, Birgit A1 - Simon, Sebastian A1 - von Werder, Julia T1 - Synthesis and characterisation of alites from reduced basic oxygen furnace slags N2 - Basic oxygen furnace slags (BOFS) are by-products of the steelmaking process. Several researchers have studied the production of Portland cement clinker and metallic iron from BOFS via a reductive treatment. In this study, we applied a carbothermal reduction of BOFS in a technical-scale electric arc furnace and characterised the clinker-like products. Those clinker-like non-metallic products (NMPs) had a chemical and mineralogical composition comparable to clinker for ordinary Portland cement (OPC) and contained large elongated alite crystals as major component. The pure NMPs reacted more slowly and achieved a lower degree of hydration compared with commercial OPC. If the reactivity of the products can be further increased by employing specific adaptations, it can be used as a full clinker substitute for OPC. Nevertheless, it is also an option to use the material without further modifications as a cement component or concrete addition, which contributes to the strength development in both cases. KW - BOFS KW - Hydration products KW - Thermal analysis KW - X-ray diffraction PY - 2021 U6 - https://doi.org/10.1016/j.cemconres.2021.106518 SN - 0008-8846 VL - 147 SP - 6518 PB - Elsevier Ltd. AN - OPUS4-52939 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Simon, Sebastian A1 - Bertmer, M. A1 - Gluth, Gregor T1 - Sol–gel synthesis and characterization of lithium aluminate (L–A–H) and lithium aluminosilicate (L–A–S–H) gels N2 - Hydrous lithium aluminosilicate (L–A–S–H) and lithium aluminate (L–A–H) gels are candidate precursors for glass-ceramics and ceramics with potential advantages over conventional processing routes. However, their structure before calcination remained largely unknown, despite the importance of precursor structure on the properties of the resulting materials. In the present study, it is demonstrated that L–A–S–H and L–A–H gels with Li/Al ≤ 1 can be produced via an organic steric entrapment route, while higher Li/Al ratios lead to crystallization of gibbsite or nordstrandite. The composition and the structure of the gels was studied by thermogravimetric analysis, X-ray diffraction, 27Al and 29Si magic-angle spinning nuclear magnetic resonance, and Raman spectroscopy. Aluminium was found to be almost exclusively in six-fold coordination in both the L–A–H and the L–A–S–H gels. Silicon in the L–A–S–H gels was mainly in Q4 sites and to a lesser extent in Q3 sites (four-fold coordination with no Si–O–Al bonds). The results thus indicate that silica-rich and aluminium-rich domains formed in these gels. KW - Lithium aluminosilicates KW - Raman spectroscopy KW - Sol-gel PY - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-558756 SN - 1546-542X VL - 19 IS - 6 SP - 3179 EP - 3190 PB - Wiley AN - OPUS4-55875 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 - CONF A1 - Simon, Sebastian A1 - Meng, Birgit A1 - Selleng, Christian T1 - A new sample holder for fast xrd investigation on UHPC N2 - A new sample holder is described in this poster. It was developed in BAM for fast XRD investigation on UHPC (ultra high performance concrete). Results measuring solid, i.e. not pulverized, samples are shown. T2 - GeoBerlin 2015 CY - Berlin, Germany DA - 04.10.2015 KW - Building Materials KW - UHPC KW - X-ray diffractometry PY - 2015 AN - OPUS4-36949 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Werner, Daniel A1 - Gardei, André A1 - Simon, Sebastian A1 - Meng, Birgit T1 - Microscopic investigation of building materials affected by alkali-silica reaction N2 - Concrete is the most applied building material in modern times. It is present in all kinds of structures and no other material secms to rcplace concrete as the most selected building material in the near future. The prime advantages are the high performance, the easy production and a facile processability. The sustainability and durability are important requirements to concrete. Even if concrete is significantly less susceptible against factors promoting a damage, compared to other materials, there are still mechanisms affecting it. In particular, high-ways and hydraulic structures made of concrete worldwide show cases of alkali-silica reaction (ASR) damages. This article refers to experience at BAM Federal InstituteforMaterials Research and Testing for several decades to ASR research and darnage assessment. ASR is a severe darnage mechanism that can occur in concrete, when certain conditions related to composition and cxposition arise in a critical combination. The chemical reaction is based on the alkalis and the silica in the concrete and was first identified by Stanton in highway structures in California (Stanton, 1940). Actually three components are needed to initiate ASR: alkali-sensitive siliceous aggregates, alkalis coming from internal (cement or other components) or external sources (de-icing salt or sea water) and water. If all of these components are sufficiently present an alkali-silica gel could be formed (Hobbs, 1988). This gel itself needs additional space when it is formed. Furthermore it is able to swell in the presence of humidity, both processes generating an expansion pressure inside the concrete. As a consequence of intensive expansion, cracks can occur, which significantly lowers thc strength of the material. Parameters like amount and chemical composition of the gel as weil as the pattern and width of cracks can help to classify the ASR darnage (Swamy, 1992). The objective of this article is to demoostrate the microscopic work on ASR affected concrete samples, carried out to assess the damaging process or to evaluate various alkali-sensitive aggregates. It will explain the approach of ASR investigation from the macroscale to microscale, starting briefly with the condition assessment, over treatment and investigations of samples in the laboratory, to the use of different microscopical and analytical techniques. In the main part the characteristic features for identifying ASR in concrete are presented by using microscopic images. Especially the emphasis lies on the role of the aggregate. T2 - 15th Euroseminar on microscopy applied to building materials CY - Delft, The Netherlands DA - 17.06.2015 KW - Alkali-silica reaction KW - Concrete KW - Damage analysis KW - Materials characterisation KW - Preparation of thin sections PY - 2015 SN - 978-94-6186-480-2 SP - 1 EP - 11 AN - OPUS4-33791 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sturm, Patrick A1 - Gluth, Gregor A1 - Simon, Sebastian A1 - Brouwers, H.J.H. A1 - Kühne, Hans-Carsten T1 - The effect of heat treatment on the mechanical and structuralproperties of one-part geopolymer-zeolite composites N2 - This contribution presents the results of structural and compressive strength investigations on cured andhigh-temperature treated silica-based one-part geopolymer-zeolite composites. The specimens weresynthesized from two different silica sources, sodium aluminate and water. The phase content as well asthe compressive strength of the cured composites varied depending on the starting mix-design and thesilica feedstock. Besides geopolymeric gel, A-type zeolites and hydrosodalites were the major reactionproducts. One of the silica feedstocks yielded significantly higher compressive strength (19 MPa), whilethe other one appears to cause less variation in phase content. Strength testing indicated an improvementon heating up to 200–400 °C (28 MPa) followed by a moderate decrease up to 700 °C. Above 700 °C the sys-tems underwent new phase formation and shrinkage (volume decrease) deformations. After exposureat 1000 °C the different mixes consisted of a mix of several stuffed silica phases, almost pure hexago-nal nepheline or amorphous phase. Depending on the mix-design, the onset temperature of the hightemperature phase transformations varied. KW - Geopolymers KW - Zeolites KW - Alkali-activation KW - High-temperature treatment KW - Thermal behavior KW - Nepheline PY - 2016 UR - http://www.sciencedirect.com/science/article/pii/S0040603116300855 U6 - https://doi.org/10.1016/j.tca.2016.04.015 SN - 0040-6031 VL - 635 SP - 41 EP - 58 PB - Elsevier Science CY - Amsterdam, Netherlands AN - OPUS4-35967 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Simon, Sebastian A1 - Selleng, C. A1 - Meng, Birgit T1 - Prompt phase analyses of ultrahigh-performance concrete N2 - Powder X-ray diffraction is a time-consuming and challenging task, especially for preparation of sensitive phases like ettringite and calcium-silicate-hydrate (C-S-H) phases. Fine-grained ultrahigh-performance concrete (UHPC) with an average grain size <100 μm could be investigated directly without time-consuming milling. As a proof of concept, small UHPC cylinders with plain surfaces were investigated with a newly designed sample holder. The comparison with conventionally prepared powder shows the feasibility of fast qualitative phase analysis using this approach. As a great benefit, a depth-dependent analysis, as well as a comparison of surface layers and core material, was carried out. KW - Ultrahigh-performance concrete (UHPC) KW - X-ray diffraction (XRD) KW - Sample holder KW - Fast measurement KW - Spatial analyses PY - 2018 U6 - https://doi.org/10.1061/(ASCE)MT.1943-5533.0002163 SN - 1943-5533 SN - 0899-1561 VL - 30 IS - 3 SP - 06018001, 1 EP - 06018001, 5 PB - American Society of Civil Engineers CY - Reston, VA, USA AN - OPUS4-43879 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -