Schwenk Zement KG

Neu-Ulm, Germany

Schwenk Zement KG

Neu-Ulm, Germany
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Baumgartner B.,University of Augsburg | Moller H.,Schwenk Zement KG | Neumann T.,Schwenk Zement KG | Volkmer D.,University of Augsburg
Beilstein Journal of Nanotechnology | Year: 2017

A facile method to coat carbon fibers with a silica shell is presented in this work. By immobilizing linear polyamines on the carbon fiber surface, the high catalytic activity of polyamines in the sol-gel-processing of silica precursors is used to deposit a silica coating directly on the fiber's surface. The surface localization of the catalyst is achieved either by attaching short-chain polyamines (e.g., tetraethylenepentamine) via covalent bonds to the carbon fiber surface or by depositing long-chain polyamines (e.g., linear poly(ethylenimine)) on the carbon fiber by weak non-covalent bonding. The long-chain polyamine self-assembles onto the carbon fiber substrate in the form of nanoscopic crystallites, which serve as a template for the subsequent silica deposition. The silicification at close to neutral pH is spatially restricted to the localized polyamine and consequently to the fiber surface. In case of the linear poly(ethylenimine), silica shells of several micrometers in thickness can be obtained and their morphology is easily controlled by a considerable number of synthesis parameters. A unique feature is the hierarchical biomimetic structure of the silica coating which surrounds the embedded carbon fiber by fibrillar and interconnected silica fine-structures. The high surface area of the nanostructured composite fiber may be exploited for catalytic applications and adsorption purposes. © 2017 Baumgärtner et al.

Trankle S.,Universitatstrasse 1 | Jahn D.,University of Salzburg | Neumann T.,SCHWENK Zement KG | Nicoleau L.,BASF | And 2 more authors.
Journal of Materials Chemistry A | Year: 2013

The naturally occurring mineral 11 Å tobermorite is an important calcium silicate hydrate phase often used as a model structure for the poorly ordered calcium silicate hydrate phase (C-S-H) present in hydrated cement. In this work we present a hydrothermal synthesis of highly crystalline anomalous 11 Å tobermorite by conventional and microwave treatment. The microwave assisted synthesis provides a faster access to crystalline 11 Å tobermorite material in terms of reaction time, while the conventional method yields samples with a higher crystallinity. For conventional hydrothermal synthesis borosilicate glass was used as a Si precursor, which proves to be an excellent starting material for synthesis of highly crystalline 11 Å tobermorite. Furthermore, to the best of our knowledge, this is the first time the synthesis of unsubstituted 11 Å tobermorite by microwave synthesis is described. IR- and 29Si-NMR spectroscopy reveals Q3 Si-O tetrahedra sites only present in the double "dreierkette" structure typical for 11 Å tobermorite. The water content of the synthesized calcium silicate hydrates was examined by TGA which shows a weight loss (corrected for the loss of CO2 from carbonate) of 8.3-10.7% for tobermorite samples from conventional synthesis and 10.6-12.5% for those from microwave assisted synthesis. While samples from microwave assisted synthesis typically showed a water loss from hydroxyl groups from DTG data at ∼760 °C, this could not be observed for tobermorite from conventional synthesis. By XRD investigations at different temperatures it could further be shown that the samples consist of the anomalous form of 11 Å tobermorite. The morphology of the needle-like tobermorite crystals was examined by AFM and HRTEM. The layered structure of 11 Å tobermorite could be visualized via the HRTEM investigations and the basal spacing of ∼11 Å could be measured directly. © 2013 The Royal Society of Chemistry.

Szabo L.,Duna Drava Cement Ltd. | Csoerge V.T.,Duna Drava Cement Ltd. | Braig T.,Schwenk Zement KG
Cement International | Year: 2010

At the Beremend cement plant of the Hungarian cement producer Duna-Drava Cement Ltd. (affiliated to HeidelbergCement and Schwenk Zement KG), one of the two old 1500 t/dclinker 4-stage preheater kilns was modernised with an extended capacity of 3450 t/dclinker. The results of the project outlined in this article present the equipment selection procedure and first operational experiences during the commissioning phase. During the modernization, the preheater cyclones were replaced by a new 4-stage DOPOL-90 preheater tower in front of the old one. The old tower was used to install the PREPOL AS-MSC calciner and the alternative fuels dosing systems. The kiln system contains in addition the new gas conditioning tower, baghouse filters for kiln, by-pass system and for the POLYTRACK 7/4.0 clinker cooler as well as the process control system. As a result of the efficient cooperation between DDC's project management and the main contractor Polysius AG, who supplied the equipment on semi-turnkey contract basis, the project was successfully completed on time. Duna-Drava Cement took a big step in achieving its long-term production goal for steady and sustainable development.

Hambach M.,University of Augsburg | Moller H.,Schwenk Zement KG | Neumann T.,Schwenk Zement KG | Volkmer D.,University of Augsburg
Cement and Concrete Research | Year: 2016

Here, we introduce a nozzle injection technique for carbon fiber-reinforced cement paste leading to unidirectional alignment of cement-embedded short carbon fibers that follow the movement direction of the guided nozzle. In comparison to non-reinforced cement pastes, this novel material exhibits a tremendous increase of its flexural strength upon admixing and aligning 1 to 3 percent (by volume) of chopped carbon fibers. Cement pastes containing carbon fibers aligned in the stress direction thus acquire high compressive and flexural strength values at the same time. Mechanical tests prove the material to withstand flexural loads larger than 100 MPa in conjunction with a deflection hardening behavior resembling that of high performance fiber-reinforced cementious composites at relatively low fiber volume content. Insights into the preparation, fiber alignment, rheology and the fracture behavior of this material are presented in this study. © 2016

Hambach M.,University of Augsburg | Moller H.,Schwenk Zement KG | Neumann T.,Schwenk Zement KG | Volkmer D.,University of Augsburg
Composites Part B: Engineering | Year: 2016

A systematic development of an electrically heatable cement-based composite, prepared by admixing a few volume percent of chopped carbon fibres without a need of adding further heating elements, is reported. The optimal volume content of carbon fibres is determined to range from 1 to 2 volume percent, if 3 mm long and 7 μm thick carbon fibres are being used. By applying an electrical current to the composite material, a temperature rise suitable for heating rooms and walls can be induced. Mechanical tests show that the flexural strength of carbon fibre reinforced composite is not decreasing during electrical heating at 60°C for 4 weeks. For electrical heating purposes, graphite or silver is found to be the best electrode material. © 2016 Elsevier Ltd. All rights reserved.

Fylak M.,SCHWENK Zement KG | Pollmann H.,Martin Luther University of Halle Wittenberg | Wenda R.,Nurnberg University of Applied Sciences
34th International Conference on Cement Microscopy 2012 | Year: 2012

Advanced Cryo preparation techniques open new ways for SEM investigations on hydrating cementitious systems. Common SEM analyses are not practicable at early hydration times because of the hydrous or liquid state of cement pastes. Preparation and analysis of older specimens often cause a formation of artefacts. The Cryo preparation allows setting liquid, beam and vacuum sensitive specimens into a stable state by shock-freezing. Thus this method enables proper SEM preparations for all kinds of cementitious systems. Fast freezing processes allow sample preparations at very low hydration times and high resolution imaging of cement particles and hydration products. Already after a few seconds of reaction investigations of crystal structures, characterisations of microstructure and EDS analyses are possible. The article shows results of Cryo-SEM investigations combined with in-situ XRD and isothermal Heat Flow Calorimetry. The different methods are combined for early time hydration studies of Portland cements from one minute to three days reaction time. Results are crosslinked to receive detailed information about microstructure, phase development and hydration kinetics. The focus lies on very early hydration products (first minutes), changes in ettringite morphology and C-S-H microstructures. Applications and possibilities of Cryo preparation techniques are discussed.

Heuschkel S.,Marker Zement GmbH | Kuhn A.,Cemex | Lipus K.,VDZ gGmbH | Moller H.,Schwenk Zement KG
Cement International | Year: 2012

Many new and updated ordinances and regulations have been produced in the past f ew years in the field of productrelated occupational safety and health protection, headed by the European REACH, CLP and Construction Products Regulations. This has also required adjustments to national regulations, such as the Chemicals Act and the Hazardous Substances Ordinance. Other important regulations are the Drinking Water and Groundwater Ordinance and TRGS 559.

Konig A.,MFPA Leipzig GmbH | Rasch S.,SCHWENK Zement KG | Neumann T.,SCHWENK Zement KG | Dehn F.,MFPA Leipzig GmbH
Beton- und Stahlbetonbau | Year: 2010

Up to present, surface protective systems are in use for agricultural buildings, for instance: cot plants, tank construction, silo plants or even biogas fermenter. The aim is to avoid infiltration by concrete- and steel corrosion agents. Concrete with high acid resistance are an alternative to dispense using these surface protective systems. The performance of this special-concrete has to be verified in aggressive media through accelerated storagetests, in accordance with the potential of damage of the equivalent application. Based on the young history of development and the absent access to the buildings, none extensive experiences of the processes of damage are noted for the increasing number of biogas plants. Dependant on the used plant-process engineering, a less biogenic acid attack within the liquid state can be expected. Within the gaseous phase under special conditions i.a. sulfuric acid-, carbonic acid attack and carbonation can simultaneously occur. Currently, in the context of the large-scale research project at the MFPA Leipzig GmbH/Leipzig University, the potentials of damage within biogas plants on damaged buildings as well as embedded samples become analyzed. At the same time new acid resistance concretes, i.a. for agricultural buildings will be developed by accelerated storage-tests. © 2010 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin.

Bauer K.,Schwenk Zement KG | Hoenig V.,Verein Deutscher Zementwerke VDZ
Cement International | Year: 2010

Discussions of efficient production processes in the cement industry generally focus on assessments of cement works performance levels measured as fuel energy consumption in a performance test lasting 24 to 48 hours. The fuel energy requirement is also listed in the BAT (Best Available Techniques) Reference Document, abbreviated to BREF, for the cement industry, a document used, for example, by the licensing authorities as a basis for evaluation when formulating approvals. This value cannot, by itself, do justice to the wide scope influencing parameters on the clinker production process and is thus insufficient for assessing normal operations, even over fairly short periods. The objective was therefore formulated of obtaining a description of the performance capability of a cement works that reflects the entire scope of the phenomena occuring in actual practice. With the help of extensive calculations based on a process engineering model developed at the Research Institute of the Cement Industry and using experimental data collected from the cement industry, it is now possible to quantify the essential operational parameters that influence performance. For example, this approach facilitates a clear and reliable description of production lines with widely differing fuel energy requirement levels, due for example to kiln capacities or the properties of both fuel and raw materials. These plants can nevertheless operate on the energy efficiency level. The modelling results have been used as a basis within the revision process of the BREF for the cement industry.

Trenkwalder J.,Schwenk Zement KG
Cement International | Year: 2010

Since 1969 at the cement plant in Karlstadt a rotary kiln with a daily capacity of 3500 t has been in operation for the production of cement clinker. This kiln system from the Polysius corporation is fitted with a 4-stage Dopol preheater, the kiln is 90 m long and has a Claudius Peters grate cooler. This existing plant was expanded by Schwenk to include integrated technology designed for the dehydrating and incineration of sludge, an exemplary concept which today is the only one of its kind in the cement industry. One hundred percent of the thermal energy for the heating of the dryer is obtained from the exhaust air of the clinker cooler. The decoupled waste heat is transported via a thermal oil system to the heat exchangers installed in the dryer. This drying system represents one of the world's largest single-stage belt dryers, with a dehydration capacity of 8 t/h, the annual throughput is roughly 100000 t. With this novel installation concept a highly innovative and environmentally friendly solution was created, and the company has set standards in terms of environmental protection, sustainability and resource conservation.

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