We recently completed
repairs of concrete damage on our building so why has the
problem shown up again?
Assuming the repairs
were installed correctly, they probably did not include provisions
for stopping the underlying problem of corrosion and could
have even inadvertently accelerated corrosion.
What is the difference
between repair and rehabilitation?
Repair techniques
are used to restore the structural integrity and shape of
a concrete element. For example, a balcony slab can be repaired
so that it does not have any damaged concrete or unsafe indentations.
Repair techniques generally include removal of damaged concrete
and placement of new concrete in its place. Repair methods,
however, do little to address the cause of deterioration.
Therefore, in the case of reinforcing steel corrosion, simple
repairs typically fail prematurely since nothing is done to
mitigate or stop the primary deterioration mechanism. Rehabilitation
methods, in addition to restoring structural integrity and
shape, mitigate or stop the process responsible for the damage.
Because rehabilitation includes addressing the cause of the
problem itself, the repairs last significantly longer.
Is it ever cheaper
to replace a balcony rather than repair and install a corrosion
protection system?
Yes, when damage
on a balcony exceeds a certain threshold, complete replacement
is more cost effective than repair and installation of a corrosion-protection
system.
Should we conduct
the same repair on all of our balconies?
If the amount
and/or predominant cause of damage is significantly different
in one section or on one side of the building versus another,
different repair and corrosion mitigation systems may be used
on the same structure to control the overall cost.
What types of
corrosion protection systems are presently available for balconies
and parking garages?
There are numerous
types of corrosion protection measures that can be used. These
include cathodic protection systems, electrochemical chloride
extraction, corrosion inhibiting chemicals, sealers, membranes,
overlays, specialty concretes, reinforcement coatings, and
others.
Do different
corrosion problems require different rehabilitation strategies?
Yes, just as different
cancers require different treatments, different corrosion
problems require different corrosion protection solutions.
For example:
- A cathodic
protection system would be needed to stop corrosion if a
balcony slab contained admixed chloride ions and exhibited
a high level of concrete damage.
- An element
with insufficient concrete cover over the steel and carbonation
of the concrete may require increasing the cover by placement
of an overlay and/or coating of the reinforcement.
- If damage is
limited to cracking and corrosion of steel is occurring
in cracked areas only, simple sealing of the cracks may
be the best solution.
Just because
our condominium is located on the ocean front, are we bound
to have a corrosion problem?
Unfortunately,
most reinforced concrete buildings situated on the ocean front
are likely to suffer corrosion induced damage at some point
in time.
Do we have to
immediately repair the damage or can we wait some time prior
to starting construction?
More often than
not, depending on the severity of the damage, repairs can
be delayed or phased over several years.
Do hollow sounding
tiles mean that I have deteriorated concrete under my tiles?
Not necessarily.
Hollow sounds under tile can also be caused by voids in the
grout used to place the tile.
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