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ÖFFENTLICHE BAUTEN • PUBLIC BUILDINGS BUILDINGS TECHNISCHER AUSBAU • TECHNICAL SOLUTIONS

W ith more than 70,000 visitors a day, the Bahnhofspassagen in Potsdam are a
highly frequented location. They were opened in December 1999 and were one
of the first projects in Germany where a station and a shopping mall were combined.
The commission for the redesign of the arcades went to the KSP Jürgen Engel
Architekten office in Frankfurt am Main. In 2016, among other measures, the whole floo-
ring in the arcades measuring approximately 6,500 square metres was to be renovated.
The special task was to complete the renovation during active operation since the
Verlegeplan: Platten in Längsrichtung mit deutlichen Fugen • Installation plan: lengthwise panels with clear joints Bahnhofspassagen are continuously being used and the station has no closing times. To
keep the construction work minimal, the first plan was to glue light almost, jointless
flooring on top of the existing one. There was, however, not enough installation height
for this technique. Even for the low material thickness of six millimetres of the new floo-
1. Arbeitsschritt: Abfräsen des Bestandbodens • 1st work step: Milling of the existing flooring
ring, it would have been impossible to afterwards open the doors of the shops in the
shopping arcades as well as the fire- doors. Neither would the thresholds of the lifts or
the escalators still have fitted. Removing the existing flooring of artificial stone comple-
tely was also not an option: time-consuming and expensive. Removing the floor would
furthermore have resulted in considerable disturbances of the ongoing operation and
the time windows when the floor could not be walked on were too large.

Each millimetre means time, dust and money

With the architects and the Laminam consultants joining forces, an innovative solution
was found which was completely new in its extent: It consisted in milling off of the exis-
ting floor – but only as little as was necessary since each millimetre means time, dust
and money. On the abraded floor, Laminam was to be installed – an extremely robust
kind of ceramics with a low material thickness of only 5.6 millimetres – so that the exis-
ting floor only had to be ground down ten millimetres. To keep the inconvenience for
the travellers and the passers-by as small as possible, the work hours were furthermore
postponed until the night hours. In a first step, the existing artificial stone was milled
off. This was not milling in the conventional sense but rather a cutting of the flooring.
2. Arbeitsschritt: selbstnivellierende Universalspachtelmasse • 2nd work step: self-levelling all-purpose putty
The advantage of this method consists in lesser vibrations since these could otherwise
damage the substrate. The resulting surface was to serve as the substrate for the
Laminam large ceramic panels which need a completely level surface. To achieve this,
self-levelling, rapidly hardening all-purpose putty was used. The next step was the
installation and the grouting of the large panels in the format of 3,000 by 1,000 milli-
metres. The panels were installed by hand as well as with an installation robot. For this,
single-component, highly flexible thin-bed mortar as well as two-component, rapidly
hardening, cementitious, highly flexible pourable-bed mortar was used. The installation
was done in the buttering-floating method. What was particularly important was to
ensure the flatness of the edges from one panel to the next across a joint; to achieve
this, a specific levelling system was used. The joints were planned to measure two mil-
limetres, the expansion joints were maintained and movement profiles were used. The
grouting was done with a kind of jointing mortar guaranteeing high mechanical load-
bearing capacity. The panels were installed lengthwise with continuous longitudinal-
and transverse joints so that an unobtrusive installation pattern could be achieved. The
longitudinal direction emphasizes the walking direction and thus guides the stream of
visitors through the arcades. The large ceramic panels by Laminam are absolutely
scratch-resistant, have high abrasion resistance, are resistant to stains as well as easy
3. Arbeitsschritt: Verlegen der Platten mit Verlegerobotern • 3rd work step: Installing the panels with robots
to clean. Even when it is intensely used and frequently cleaned, the surface stays the
same. As regards the slip-resistance, a surface with R10B was chosen so that the pas-
sers-by can safely stroll through the mall even on rainy days. In addition, installing
Laminam produces dust or noise since the material can be cut with the glass cutter.

Recipe for success: communication and cooperation

The result is convincing: Due to its small ratio of joints, the large-format panels make
the mall look generous, light and modern. Because of the unobtrusive appearance of
the floor, the window displays are more in the focus of the passers-by. The bright colour
of the panels has significantly improved the reflection and the effect of the light. Last
but not least: Among other factors, the success of implementing the project is owed to
the excellent cooperation and communication of the various trades. The workers not
only did their job in a highly precise and professional manner but they also cooperated
extremely well. The industry and the suppliers punctually delivered products of perfect
quality. The client and the architects promoted the construction work with quick deci-
sions such as allowing necessary supplements, for instance. We are pleased that an
idea which initially appeared to be unrealistic could be implemented successfully.

148 • AIT 5.2017