Owner Canton Ticino Trasportation Department
Design Architetto Bruno Fioretti Marquez, Berlino
Engineering Ingg. Borlini & Zanini, Pambio Noranco
Construction CSC, Lugano
Waterproofing Drytech International
Drytech Tank 1'153 meters sealed, between joints and cracks. 176 sealed formwork holes.
STEELWORKS RESTORATION WORK, BELGIUM / The structure of this Belgium steelworks stands on the banks of the Ancien Canal. The new industrial buildings were constructed in 2010 with an underground storey exposed to 3 metres of groundwater.
Traditional waterstop tapes were used to waterproof the joints. When, however, the pumps were turned off the joints were not waterproof with significant infiltration which flooded the underground levels.
The principle behind the traditional waterstop tape is exclusively the creation of a barrier against water. This barrier can however be circumvented by liquid due to both the pressure of the water and errors in the concrete casting or laying of the tape.
In fact when concrete is not adequately packed down around the tape the danger of infiltration increases because water finds an easy space to go round the waterstop, defeating the barrier function.
In the case of the Belgian construction, the system of tapes chosen by the design engineers did not turn out to be the most suitable one for the specific situation and some installation defects increased the problems.
In the photos above you can see the waterstop tape simply placed against the upper grid of the concrete bed. In this way an asymmetry between the tape and joint was created: the waterstop only passes through the joint for the few centimetres of concrete covering the reinforcement of the foundation bed. The barrier is therefore minimal for the water and the tape can be easily by-passed underneath.
To correctly install the tape, the upper grid of the foundation bed reinforcement must be bent at the joint to create a place in which to house the tape which is at least half of the depth of the tape.
The other problem was a failure to weld the overlaps on the tape. The creation of a physical barrier in fact requires that there are no breaks or gaps.
Drytech intervened by waterproofing the joints with injections of acrylic elastic expanding resin. DRYflex is a two-component acrylic resin which has the same viscosity as water when injected: it therefore fills both the micro pores in the concrete and cavities or gravel pockets caused by the concrete not being adequately compacted during casting.
A short while after the injection, the resin catalyzes transforming into a expanding gel which seals cracks through pressure. Since it does not work through adhesion, the resin is effective whatever the state of the crack and also in the presence of viscous substances such as oil and hydrocarbons.
Since the resin maintains its elasticity over time, it can be injected again, if necessary, also after many years. The restoration work was carried out from inside the structure without any demolition or excavation and, above all, without having to interrupt activities in the facility. Furthermore, with this type of work, effectiveness of the injection can be verified immediately.
Copyright © 2019 Drytech SA. All rights reserved.