Phæno Science Centre Wolfsburg Germany Zaha Hadid

issue 04 Phæno Science Centre
Forming the cones
The formwork for the cones consisted of planed boards, with the
joint pattern and nail positions of the trapezoidal boards specified
as accurately as the locations of the tie bar holes.
The prefabricated formwork elements were artificially aged with
a cement wash on site.
As the cones open out upwards, the outside formwork panels –
that is the exposed concrete formwork face – had to be erected
first and supported on the underside with heavy duty props.
The reinforcement was placed and tied together on this formwork
before the inner formwork panels were erected. The release
agent, a formwork wax which proved to be particularly weatherresistant
in several tests, was sprayed on to the formwork.
In view of the complicated shape of the reinforcement cage,
the spacer blocks for the starter bars for subsequent pours were
exactly positioned and fixed in place with the aid of templates.
The spacer blocks posed a problem for the exposed concrete
wall surface, whereby the weight of the reinforcement pressing
into the solid wood boards caused defects – spacer block pimples –
in the exposed concrete, which were very noticeable after
stripping. To tackle the problem, a detail was developed on site
that allowed the formwork tie bar cones to also act as spacers.
Excerpt from Exposed Concrete –
Technology and Design (Birkhauser 2005)