Cleaning, Homogenizing, Shielding Elements

Immediately prior to the adjustment of the shut-off pipes and the reinforcement, the connecting surfaces must be cleaned (eg with an eccentrically suspended slot wall chisel, fig. 1.9) to the already concreted slot wall elements in order to ensure the best possible tightness of the joints. The sludge deposited on the slit wall sole after the excavation has to be removed.

The supporting liquid is to be homogenized, by which means the stirring of the supporting liquid in the slot (for example, by moving up and down with the slot wall gripper) is used for the purpose of reversing disagreements. In this case, water may be introduced in a controlled manner in order to reduce the flow limit. The service life between the end of homogenization and the start of concreting must not exceed 5 hours.

The concreting section is limited by the jointing or cutting-off pipes (for beginner slats / 2 elements, for rotor slats / 1 element). These are heavy steel pipes (Fig. 1.10), which form half-gaps between the individual slit wall elements (Fig 1.11).

The pipes, which are open at the bottom, are pressed slightly into the slit so that the concrete can not rise in the pipe. They are therefore filled with supporting liquid during concreting.

Abb. 1.10 Abschalrohr (Quelle [4])

For slot thicknesses of more than 1.0 m, flat gland cladding elements are used.

Fig. 1.11 also shows finished parts as a limitation of concreting sections, but they have been less well reinforced, so that today almost exclusively shut-off pipes are used.

Fig. 1.11 Cut-off pipe and precast concrete as a boundary of the concreting section (source [1]).