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Hamburg, Germany

The article discusses how cementitious floorings were repaired in the Stachus-Passagen mall in Munich. The cracks that had formed after several weeks were to be repaired because their edges broke out as a result of heavy floor use. Also, the cracks showed a considerable degree of soiling and had a strongly disruptive effect on the appearance of the flooring. Cracking was due to temperature- and shrinkage-induced shortening and local bond disruptions, cavities within the screed and toward the base, and crack propagation in the reinforced- concrete base. The concept included the use of a cementitious material to fill the major part of the large cracks from the top and the closure of narrow cracks so as to prevent epoxy resin from penetrating to the surface and causing discolorations during the subsequent epoxy injection. Cracks had to be firmly closed, and the bond to the base was to be restored by removing existing cavities. Source

Flohrer C.,Hochtief Group
Betonwerk und Fertigteil-Technik/Concrete Plant and Precast Technology

Ducon consists of numerous layers of reinforcement in the form of point-welded wire mesh and high- performance fine mortar infiltrated into the wire mesh. To strengthen the columns in a bank building, a Ducon shell approximately 7 cm thick was planned to be installed in the public area to guard against possible bomb attacks. Although the Ducon material can be applied as spray mortar, reinforcement in such cases would have to be installed layer by layer. The use of spray mortar, moreover, is not possible in banks. In the Ruhr region in North Rhine-Westphalia, Germany, as well as elsewhere, sand-lime brick was commonly used around 20 years ago in construction of basements of detached homes and row houses. The composition of these materials was not suitable for permanent exposure to the action of moisture. As expansion took place owing to the action of moisture, caused by defective sealing, deformation and cracking occurred to such basement walls. Source

The plugging effect of open-ended piles and hence the change in the load bearing behavior has been investigated in this research work. The state of knowledge assumed that the plug can close up the pile base completely and for this reason it was treated monolithically. The load bearing behavior was comparable to a closed-ended pile. But the soil-mechanical processes were mostly unknown. The experimental part contains model tests and PIV-(Particle Image Velocimetry) tests. The test piles were arranged with equipment for measuring each part of the pile resistance (inner and outer shaft resistance and resistance of the pile toe). Because of variation the boundary conditions the main influence factors of the plugging effect could be analysed. Furthermore numerical calculations with the FEM were carried out, which show a good agreement between the experimental data and the calculations. The investigations show, that the load transfer in the plug occurs in an inner shaft friction. A fully plugged soil could not be identified and so the classical model representation could be disproved. Based on this results an analytical calculation method is derived, in which each proportion of the pile resistance could be determined. Finally in the statistical part new values of experience for the pile resistance are suggested for the EA-Pfähle. ©Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin. Source

Budach C.,Hochtief Group | Thewes M.,Ruhr University Bochum

Soil conditioning for Earth-Pressure-Balance shield tunnelling with foams, polymers or high density slurries has proven to be an effective measure to extend the application ranges of EPB-Shields towards mixed-grained soils with a low content of fines and coarsegrained soils. By conditioning, the properties of the support medium in the excavation chamber, which mainly consists of the excavated ground, can be changed in order to positively influence i.e. its deformability and permeability. Acknowledging existing results of research on EPB conditioning a new investigation programme was developed, which aimed at a broad and systematic variation of coarse soil types as well as conditioning agents. Based on the results of the laboratory research, a chart for the application ranges for EPB-Shields using various conditioning agents was developed, which shows some significant differences to the existing empirical charts that by large are based on job site experience. Copyright © 2013 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin. Source

In the Polish city of Swinemünde, a new liquefied natural gas (LNG) processing facility is being constructed for completion by 2014. The liquefied gas is transported to the facility by sea. This makes it necessary to provide a new port facility. A key element of this port is a 3 km long breakwater with integrated mooring facilities for gas tankers. This will create an enclosed port basin between the shore and the sea, with a water depth of up to 14.50 m. The construction consists of sheet piling at the centre of a bank, which is constructed to be suitable for vehicular traffic. In addition to the infrastructure for handling the ships, the breakwater includes a complex pipe system which is used to convey the liquid gas. Copyright © 2012 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin. Source

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