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Alkaline activated binders and their use in concrete An increasing number of publications are currently dedicated to the topic of alkaline activated concretes or geopolymers (AAB). The development of appropriate binders is often motivated by the partially controversial discussed idea of reducing CO2 emissions. The present article emphasized that AABs with tailored composition can achieve concrete properties that could not be achieved with conventional concretes so far. Wherein the focus is on the special durability aspect of chemical resistance to acids and alkalis. This makes the described AAB particularly attractive for the production of pipes, shafts and agricultural buildings. Furthermore, a high resistance to high temperatures and thermal shock can be determined. Thus, the binder is also suitable for the production of optimized thermal energy storage systems and construction elements for high temperature applications. The production of such concretes is possible in almost any concrete mixing plant at low investment costs. 相似文献
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Dr.-Ing. Carl Richter Prof. Dr.-Ing. Daniel Pak Prof. Carlos Rebelo Mohammad Reza Shah Mohammadi 《Stahlbau》2020,89(6):531-541
Integrated lifting process for hybrid lattice-tubular-towers for wind energy Higher exploitation of wind energy calls for higher wind towers. As part of the project “Steel Hybrid Onshore Wind Towers Installed with Minimal Effort” (SHOWTIME), funded by the Research Fund for Coal and Steel (RFCS), the question was addressed of how very high hub heights (> 180 m) can be realized competitively in steel construction. The preferred solution is a steel hybrid tower with a lower part constructed as a lattice tower and an upper part as a steel tubular tower. Since mobile cranes to reach such hub heights are very expensive and in some cases not available at all, the consortium was looking for alternative possibilities to erect the tower. Therefore, an integrated lifting concept has been developed, whereby the upper tubular section is lifted upwards at the transition piece by means of a strand lift system. The temporary connection of the two tower sections in the transition piece during the lifting process is also important in this context, as the tubular tower must be prevented from tilting during the lift. In this article the innovative lifting process and different steps for the design of the lifting process and the transition piece are presented as well as the demonstration experiment carried out. 相似文献
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Univ.-Prof. Dr.-Ing. Markus Kuhnhenne Marius Vontein Dipl.-Ing. Gesa Pauli Dr.-Ing. Simon Schaffrath 《Stahlbau》2020,89(11):912-922
Thermally improved steel substructures for metal facades Substructures of facades penetrate the thermal insulation and thus form a thermal bridge, which can be compensated by higher insulation thicknesses or by material selection. This redesign is often done at a late stage and is associated with considerable additional costs. If the construction tolerances allow, the change from a classic two-part substructure consisting of a bracket and mounting rail to a one-part substructure as a Z-profile can be useful and lead to a quicker, and thus more cost-effective, installation. As linear components, one-piece substructures initially exhibit a greater thermal bridge effect than the two-part design with brackets and mounting rail, but can be upgraded by the insertion of slots in such a way that the building law requirements for thermal protection can be achieved without increasing the insulation thickness. The Z-profiles are attached straight to the load-bearing anchoring base and directly form the support profile for the facade elements. Static investigations of the Z-profiles weakened by the slots show that a sufficient load-bearing capacity can be achieved. 相似文献
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Research activities with regard to membrane construction at HFT Stuttgart In the presented article we give an overview to some of the recent and ongoing research projects at Hochschule für Technik Stuttgart (HFT) in the context of membrane buildings. One of the major challenges in the context of membrane building is the regulation of the radiative heat flux entering the building as well as thermal losses across the building envelope while still providing comfortable room temperature and daylight use for the inhabitants. The accomplishment of this task, investigated by means of measurements and numerical simulation was the scope of several research projects at HFT Stuttgart. Within the research project “SoFt” the compatibility of insulation and translucency was investigated and realized within the roof construction of a sports center in Germany. One of the objects of the research project “FMESG” was the realization and numerical simulation of an angle-selective static solution for partial shading, analogous to a miniature saw tooth roof configuration, up to the point of a working prototype. The project “Follow-e2” tackled the influence of low emissivity surface coatings on the energy balance of membrane constructions by means of numerical simulation. Within the project “FLEX-G” the potential for reduction of energy demand by dynamic shading with electrochromic elements was investigated by means of dynamic building simulation and heuristic optimization. 相似文献
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Dr.-Ing. Matthias Lieboldt 《Beton- und Stahlbetonbau》2023,118(Z2):7-10
Short introduction to carbon reinforced concrete In the last two decades, carbon reinforced concrete has become an integral part of research with increasing tendency and has already arrived in construction practice. Due to the increasing number of general building approvals (abZ) and approvals in individual cases (ZiE), the range of applications for carbon concrete is becoming wider and wider, from reinforcement and repair to new construction. Based on this, work on the first technical regulations is being intensively pursued. This article provides a short overview of the development, the material and the current status of its use. 相似文献
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Jan P. Höffgen Dr.-Ing. Michael Vogel Prof. Dr. rer. nat. Oliver Blask Prof. Dr.-Ing. Frank Dehn 《Beton- und Stahlbetonbau》2023,118(4):239-246
Development of thermally and mechanically activated concrete fines as supplementary cementitious material – project presentation and first results In the light of resource demands for construction and limited availability, an efficient recirculation of building materials is essential. For concrete production, this means the use of recycled aggregates as partial replacement of gravel and sand, with the latter being severely restricted. Since crushing yields a concentration of porous hydrated cement in the fine particles, the application of crushed concrete fines as aggregates or milled supplementary cementitious material (SCM) results in limited concrete performance. Present results show that hydrated cement can be reactivated through an additional thermal processing, yielding improved mechanical and durability properties like carbonation or chloride penetration when used as SCM in concrete. The promising results initiated a funded research project, which investigates influencing factors of the thermal-mechanical processing of crushed concrete sands with varying compositions on the performance as SCM. 相似文献