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Wiesbaden, Germany

This year Dyckerhoff celebrates the company's one hundred and fiftieth anniversary. It was founded during the period of increased German industrialization in the second half of the 19th century by Wilhelm Gustav Dyckerhoff with his two sons Gustav and Rudolf. The company philosophy according to which priority is given to quality before price has continued to this day. The company's history reflects the advances in process technology in the fields of cement production and cement types over its years in existence. Raw material extraction after the blasting, for example, started with manual loading of horse-and-carts and was progressively replaced by powerful excavators and mechanical means of transport. The burning technology started with the semi-wet process and ring kilns and developed into the present dry process and the use of secondary fuels. The types of cement have grown from the grey Portland cements to white cements and high performance cements using Nanodur technology. In all these development stages Dyckerhoff has made significant contributions to the cement industry and the use of cement. After 150 years the company has merged into the Buzzi Unicem group with its head office in Italy. Source

Palm S.,VDZ gGmbH | Proske T.,TU Darmstadt | Rezvani M.,TU Darmstadt | Hainer S.,Dyckerhoff AG | And 2 more authors.
Construction and Building Materials

This paper deals with the performance of concretes made of cements containing high levels of limestone between 35 and 65 wt.-%. The Article mainly focuses on cements with 50 wt.-% limestone. Several experiments regarding the fresh and hardened concrete properties were carried out. Chloride penetration, freeze-thaw resistance, carbonation resistance and long-term deformation behavior were analyzed. The results show that concretes with cements containing up to 50 wt.-% limestone and a water/cement-ratio of 0.35 may have sufficient properties for practical application if a stringent supervision is ensured. Furthermore, these concretes can exhibit mechanical and durability properties comparable to concretes according to EN 206-1 and the German national application document DIN 1045-2 made of EN 197-1 cements. Besides, the results revealed that these properties depend highly on the limestone characteristics. Life cycle assessment analysis revealed that a cut-off up to 25% in global warming potential of concretes made with such cements is achievable in comparison with German average cement with the same performance. © 2016 Elsevier Ltd. All rights reserved. Source

Ohrdorf K.-H.,Ingenieurburo fur Bentonit Technology Dipl. Ing. Ohrdorf | Kaufhold S.,Bundesanstalt fur Geowissenschaften und Rohstoffe | Russmann F.,Dyckerhoff AG | Ufer K.,TU Bergakademie Freiberg | Flachberger H.,University of Leoben
Applied Clay Science

Bentonites from different deposits worldwide often show unexplainable differences with respect to their performance in different applications. Examples are the water uptake capacity and bleaching ability (Kaufhold, 2001; Kaufhold et al., 2010). The present study focused on the rheological parameters of bentonite-cement slurries used in civil and underground engineering. By measuring the viscosity and yield point of several different Na+-activated calcium bentonites mixed with blast furnace cement, behavior of a Milos bentonite was detected characterized by an unusual increase of the viscosity after addition of the cement. A detailed mineralogical characterization was conducted to identify the reason. The most striking difference of the samples was the content of soluble silica making up 27mass% of the bentonite (soluble in hot sodium carbonate solution). However, the addition of silica gel to bentonites free of soluble silica proved the effect on the rheological parameters viscosity and yield point. © 2011 Elsevier B.V. Source

Israel D.,Dyckerhoff AG | Boos P.,HeidelbergCement AG | Neumann T.,Schwenk Zement KG | Wanzura F.,Cemex
Cement International

During the last decade the German cement industry has taken the objectives of the Kyoto Protocol into account by lowering the clinker factor from 0.81 to 0.75. The CEM II/B cements have made a substantial contribution to this and it has been possible to provide a wider raw material base for CEM II/B cements. For example, the combination of established main constituents, such as granulated blastfurnace slag, siliceous fly ash and burnt oil shale, with the limestone available to the cement plants from their own resources has led to the development of numerous CEM II/B-M cements. By varying the production conditions for the CEM II/B cements it is possible to achieve properties that are comparable with, or even better than, those of Portland cements. The effectiveness of CEM II/B cements is apparent from the increasing use of these cements in practice and the rising number of CEM II/B-M cements with building inspectorate approval. Source

Clemens P.,Mahltechnik und Automation | Espig D.,Technologieberatung | Pohl M.,Dyckerhoff AG | Sievert T.,Dyckerhoff AG | Schnedelbach G.,UVR FIA GmbH
Cement International

Although the tube ball mill was invented 120 years ago its grinding media charge grading is still calculated on subjective guidelines. The technical literature only provides inadequate solutions to more recent requirements, such as the design of the fine grinding chamber of a ball mill for finish grinding cement that has already been preground in a high-pressure roller mill. Assisted by trials and based on systematically acquired knowledge this article not only provides new findings but also suggests how the fine grinding chambers in ball mills should be designed and the grinding media charge should be graded. Starting from the fact that for two ball mills of different size virtually the same specific power consumption is required if the same comminution progress is to be achieved in the two mills the opportunity is taken to transfer the results from a batch-operated pilot plant mill to an industrial ball mill. The article focuses on results obtained by measurements on an industrial ball mill at Dyckerhoff AG's Geseke cement plant. This is used as the second, open-circuit, grinding stage to an upstream KHD roller press operated in circuit with a separator. It grinds cement that has been preground to 4600 cm2/g Blaine to an end fineness of 5300 cm2/g Blaine. When the grinding balls in the second grinding chamber with diameters of 12 to 30 mm had been replaced by virtually the same weight of grinding balls with dimensions of 12 to 16 mm the power consumption of the mill motor fell by 18.9 % from 370 kW to 300 kW and the output rose by 11.7 % from 47.0 t/h to 52.5 t/h. The cement produced after this change in grinding media fulfilled all the quality requirements of a high-grade cement. The results obtained in the operational trials are regarded as an incentive to carry out further investigations into the influence of ball size and charge grading on output, particle size distribution and power consumption in the fine grinding chambers of ball mills and at the same time to consider how these parameters can be taken better into account when designing and calculating the performance of a ball mill. Source

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