In ensuring, for the future, quality of life at a high level for the
people in the Berlin region, the Berlin public transport system is
particularly significant, thanks to the increase in traffic
generally. An important pre-requisite is an attractive range of
transport with a tailored infrastructure. The ongoing development of
that infrastructure requires future expansion of the existing lines
in the Underground network.With the extension of Line U2 from the
Vinetastraße Underground to the North to the new Pankow Urban and
Underground Railway, one year before the 100th anniversary of the
Berlin Underground, a new network link is being formed.
Start of construction of the Pankow Underground was in 1998. The
Pankow Underground was commissioned for use on 16 September 2000. In
the design of the station, the commissioners –
the Berlin Transport Service – and the
appointed
architect practice, Figallo, Birkel & Partner, chose light and
transparency which had to be created, amongst other means, by the
use of glass tiling on the walls and pillars.
Special Features and Base Construction for Glass Tiling
The choice for the wall claddings was fully pigmented, white
glass tiles. In the 50’s and 60’s, glass tiling was often used for
wall claddings because of its resistance to frost and acids and
because it was easy to maintain. It had the advantage that, because
of its homogeneous construction, it eliminated any stresses between
the pot and the glaze. The main problem, however, was the lack of
flexibility of the glass tiles, which cracked due to stresses in the
substrate.
Despite
the stated advantages, glass tiling still has today the problem of a
lack of flexibility – especially where there is vibration as with
passing Underground trains. For this reason, Bernd Burkel,
construction manager for the tiling company Junck from Berlin,
worked in close co-operation with the codex Technical Division. They
decided, for the base construction, to use a render that was not
bonded to the concrete, so as to accommodate the lack of flexibility
– “unique and a one-off” is how Herr Burkel described the special
construction.
Therefore, un-gritted 300 gauge board was nailed to the concrete
walls and pillars to form a barrier. Using dowels, screws and
spacers, the reinforcement mesh was fixed. Reinforcement and
glass-fibre has the job of increasing the structural strength and
eliminating crack formation.
The construction comprised two layers of render, consisting of a
basecoat and a topcoat of cement-lime render with a combined
thickness of 35 millimetres. Overall, the total special construction
was 50 millimetres. The construction, developed by Junck and codex,
ensured that the vibrations from the Underground trains caused no
damage to the glass tiling.
In total, approx. 1,200 m2 of glass tiling was fixed to walls and
concrete pillars. The tiling work was carried out on scaffolding,
often in the narrowest of locations.
The
tiling was white Schudoplack glass tiles from the company Scholl,
Kassel in the Hanover style, 30 x 60 centimetre with fluted backing.
For the wall surfaces that are exposed to heaviest use – for example
on the staircase exits and the waiting areas on the platforms – nine
millimetre ESG safety glass was used and, for other areas, six
millimetre standard glass was selected. The single-pane ESG safety
glass has high resistance to temperature changes, increased
resistance to impact and shock and high tensile bending strength.
The advantage of its use in the Pankow Underground was also based on
the fact that the ESG glass, in the event of breakage, produces a
fine network of broken pieces that are mainly blunt-edged and,
therefore,
present no risk of injury.
In addition to the previously mentioned advantages, glass tiling
is ideally suitable for its appearance, its reflective brightness
and its non-abrasive surface. With glass, brightness effects can be
created that simply cannot be achieved with a glazed ceramic.
The Installation of Glass Tiling
The installation used primer, thin-bed mortar and grout mortar.
The products, from the brand codex, met the pre-requisites for the
bonding of glass, which generally has no absorbency properties, in
guaranteeing long-term functionality and in fully meeting the
criteria and requirements of durability and resistance to cleaning.
Then
the glass tiling was laid on a solid bed of trowelled mortar using the
floating-buttering method. One advantage offered by the thin-bed method is the
rapid installation. This is best achieved when the thin-bed mortar is applied to
the substrate. In trowelling, ridges are formed into which the fluted backing of
the glass tile can be firmly pressed (floating method). In the buttering method,
the thin-bed mortar is applied to the back of the glass tile. Then the tile and
mortar are laid using a light twisting movement and are pressed well down (buttering
method). If, as with the poor absorbency of glass tiling, one has to rely on
especially high adhesion, a
combination
of floating- and buttering- methods are used. Therefore, the thin-bed mortar is
applied to the substrate and the tile backing. Fixing of the tile is achieved by
bringing the two mortar layers together whilst they are still soft and plastic.
The
company Fliesen Junck from Berlin was awarded the work of both producing the
substrate construction as well as installing the glass tiling.
