Civil Engineering Reference
In-Depth Information
There, an increased carbonation was to be expected along with the drying
of the concrete, and the alkalisation was done as a second preventive action.
Figure 8.11
shows the achieved desalination effect after an application time
of 6 weeks.
Bottom areas of columns and walls in an underground car park
The bottom areas of columns and walls in an underground car park in
Bayreuth, Germany had accumulated large amounts of chloride. On the
other hand, the loss of rebar diameter was still moderate, and no considerable
signs of concrete deterioration were, as yet, to be seen. The chloride ingress
was forced by capillary suction from the extremely wet car park slab into
the dry walls and columns, where up to 11% of free chloride was measured.
To avoid expensive scaffolding support for the conventional repair of
walls and columns and a long period of service disruption, ECE was chosen
as an alternative, non-destructive repair. It was conducted over 8 weeks with
only 2 days of restricted service of the car park (
Figure 8.12).
After its initial
application, a successful treatment could be stated with more than 80% of
the initial chloride content extracted from the concrete also behind the outer
rebar layer, and in the ion exchanger of the electrodes 2.2 kg of chloride were
measured - this equals an amount of 175 g/m² removed from the concrete.
Within 3 months after the treatment the chloride content went up
especially in the outer 4 cm, as seen in
Table 8.1.
This effect could be
related to the ventilation in the car park, which lowered the water content
