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Meier A.,Deutscher Beton und Bautechnik Verein
Betonwerk und Fertigteil-Technik/Concrete Plant and Precast Technology | Year: 2014

Structural engineers are often uncertain about how to deal with the concept of restraint stress. A simple case in point is a parking deck exposed to outside air whose pavements tend to expand in summer and shorten in winter. However, this tendency to move may be obstructed by rigid staircases located at both ends of the building that do not allow for these movements. Reinforced-concrete foundation slabs need not always be designed for late restraint stresses. According to common experience, however, the mandatory check if there is any basis at all to design the slab exclusively for early restraint is almost never carried out. The previously applied underground car park design without natural ventilation resulted in relatively uniform temperature conditions, which is why reinforced-concrete foundation slabs were subjected to restraint stresses over time almost exclusively due to shrinkage in horizontal direction, rather than temperature- induced deformation. Source


Conrad W.,Deutscher Beton und Bautechnik Verein
Betonwerk und Fertigteil-Technik/Concrete Plant and Precast Technology | Year: 2010

The Code of Practice on Waterproof Concrete Structures was published in May 2004. According to this code of practice authored by academic, construction and administration experts, the principles and guidelines of this document can be applied to structures in general building and industrial construction but also in a similar manner to other component thicknesses, or they can be transferred to other structural frameworks made of concrete, such as during the construction of waterproof roofs and floors. The Code of Practice on Waterproof includes principles such as the design and storage conditions of roof floors and the ground-plan geometry should enable a clear assessment of the deformation behavior at floor level, strongly articulated floor cross sections should be avoided. This means that, when selecting compact ground-plan geometry, Joints should be inserted where required, and the roof edges (attic) must be concreted in the same work step as the roof floor. To prevent subsequent damage, the layers placed on top of the insulation must be non-vapor retarding. Source


Pisarsky L.,Deutscher Beton und Bautechnik Verein
Betonwerk und Fertigteil-Technik/Concrete Plant and Precast Technology | Year: 2010

The method to be used to seal cracks and voids in waterproof concrete structures is described in the relevant Code of Practice [1], which provides principles and guidelines for this method. This code of practice (1] requires the designer to consider unexpected leakages that are detected after completion already in the course of designing the waterproof concrete structure. Section 7, (5) of the code of practice (1) states that the design must provide for sealing measures in accordance with section 12 for separating cracks that occurred unexpectedly, or separating cracks that are wider than specified in the design. According to the Code of Practice on Waterproof Concrete Structures [1], section 12.3, (1), cracks, leaking joints and concrete textures must be filled with sealants in accordance with the DAfStb Code of Practice on the 'Protection and Repair of Concrete Structures (Repair Code of Practice)' (4], Part 2. The Code of Practice on Waterproof Concrete Structures also permits the application of special methods for subsequent sealing. Source


Schwabach E.,Deutscher Beton und Bautechnik Verein
Betonwerk und Fertigteil-Technik/Concrete Plant and Precast Technology | Year: 2013

The European standard for the execution of concrete structures, DIN EN 13670, comprises the European standard DIN EN 13670 and the corresponding national application rules, DIN 1045-3. For precast concrete components, the curing period of at least half a day specified for execution classes X0 and XCI may be reduced, provided the maturity of the concrete has been certified. Curing compounds may not be used on surfaces subject to visual requirements, unless evidence has been provided that they do not negatively affect the appearance of the concrete surface. Temporary supports, scaffolding and formwork may only be removed after the concrete has attained sufficient strength in order to prevent damage to the surfaces during formwork removal. If retention of the concrete component in the formwork is part of the curing process, the minimum curing times must be taken into consideration in determining the formwork stripping times. The standards do not explicitly specify minimal stripping times. Source


Schwabach E.,Deutscher Beton und Bautechnik Verein
Betonwerk und Fertigteil-Technik/Concrete Plant and Precast Technology | Year: 2013

The actual compressive strength of the concrete is necessary to evaluate when converting structures to other uses following damage. The assessment on the basis of the new compressive strength classes calls for an evaluation in accordance with DIN EN 13791, which specifies the procedure for estimating the compressive strength of concrete in structures and for evaluating the conformity of members according to product standards. The compressive strength for the strength analysis can also be evaluated in accordance with DIN EN 13791. The testing of structural concrete covers both the effects and the material properties as well as the execution. Requisite to a correct evaluation of the compressive strength of a structure is the proper choice of test ranges and locations. A test range comprises in these cases one or several members in the structure where the concrete is known or assumed to originate from the same population. Source

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