Reference

Initial status

Within the repair of a sewer in Winterthur it was
necessary to construct a new element of approximately
160 m in Rebwiesenstrasse. The new sector was
intended to be built as a rectangular cross-section in
concrete. The aim was to develop a structural design
which would be as simple as possible and highly
durable at the same time. The sulphate resistance was
defined as the main class of exposition of the concrete. The concrete must meet the
demands of class XA2.

Solution and evaluation

To realize a monolithic solution without expansion joints, the low-shrinkage concrete Concretum® D-ZERO was chosen. Cracking can be avoided thanks to its low
shrinkage. A moulding system of 12 m was used.
The complete rectangular cross-section including
footwall, walls and ceiling could thus be built in just
one workstep. The consistency of the concrete was set
up in a way which allowed casting the surface of
the footwall with the necessary transverse slope of
10%, despite the hydrostatic pressure put on the
footwall by the higher situated fresh concrete in the walls.
No further measures of sealing were used in the joints. The reinforcement ratio and the low shrinkage guarantee that the joints remain closed. A ceramic semi-pipe was put
in the middle of the footwall and the remaining concrete was finished with a highly abrasive resistant sand. This increases the surface durability. No further layers were applied. The
sulphate resistance of the concrete was controlled and
observed during the construction process.