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 -