New laws are likely which will make putting autoclaved aerated concrete (ACC) into landfills more difficult in the future. Consequently, a project was launched at Xella to reduce the sulphate content in AAC to almost zero. Positive side effects are no risk of thaumasite, agglomeration residue of lime and grey stains. The biggest source of sulphate besides cement is the pure calcium sulphate, which is added either as gypsum or anhydrite to the mixture. Additional calcium sulphate has been used in AAC to improve its material properties for many years. The reduction of calcium sulphate in ordinary cementitious AAC recipes leads to highs shrinkage and less compressive strength of the material. Sulphate free AAC with a low bulk density is not yet being made in mass production. Due to the lag of the hydraulic binder cement, completely sulphate free recipes could not be handled in technologies like Durox, Hebel or Ytong yet. Cement and sulphate free ACC cakes tend to collapse either in the demoulding or autoclaving process, and especially low densities are difficult to process. Technological solutions and recipes were found to produce cement and sulphate free AAC with low bulk densities in moulds with the size of 5,4 m 3 . The material meets the requirements for the German bulk density class PP2/0,35 with λ 0,09 W/(mK). The shrinkage tests show values under 0,20 mm/m according to to DIN EN 680. Finally, it was shown that cement free recipes lead to fewer transportation damages due to less brittle surfaces. Further research is currently in progress.
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This paper gives a short overview on the Ytong Building System and discusses possible seismic verification concepts. Moreover it proposes three-dimensional finite element models for unreinforced and reinforced walls panels in aerated autoclaved concrete on the basis of the concrete damage plasticity constitutive law implemented into the FEM toolkit ABAQUS. The paper focuses on an unreinforced ten panel shear wall and on a reinforced four panel shear wall. For the latter, two different solutions are developed: in the first the reinforcement is directly embedded into the AAC mesh, while in the second grouted cores around the reinforcement bars are taken into account. The quasi-static loading condition was simulated using both static and dynamic implicit analysis, switching from the former to the latter at the occurrence of nonlinearities. The simulation results show that the AAC shear wall models can correctly represent the load-displacement responses as well as the cracking patterns and crack propagations. The concrete damage plasticity constitutive law allows for a proper representation of the cyclic behavior and the damage accumulation of AAC shear walls, which is very important for the performance-based design of structures under seismic loading. Further researches are recommended in order to improve the results and to investigate different combinations of applied axial load, aspect ratios and reinforcement details. The long term goal is the development of a feasible and powerful deformation based seismic verification procedure for the Ytong Building System.
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Płyty dachowe YTONG znajdują zastosowanie w budownictwie mieszkaniowym jednorodzinnym i wielorodzinnym, w dużych obiektach handlowych, budownictwie przemysłowym oraz innych budynkach o przeznaczeniu komercyjnym.
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