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Hurst Peirce + Malcolm are often instructed to appraise multi-storey car
park structures varying in age from when they became popular in the 1960’s
to car parks which are just a few years old.
When looking at reinforced concrete car parks, chloride attack
and carbonation are common problems encountered.
Chloride attack leads to enhanced corrosion of the reinforcement.
In most cases the chloride originates from road salt brought in
by cars using the car park but on occasions it has been applied by the
owners to the ramps of the car park. It can cause serious damage to the
reinforced concrete including ‘scabbing’ of the upper concrete surface
where large areas of concrete loosen. It is expensive to eradicate. Ingress
can be prevented by the application of protective coatings.
Carbonation occurs to
all exposed concrete surfaces and is a process where carbon dioxide and water form a weak acid, which neutralises the alkalinity of the concrete: the main protection against reinforcement corrosion. The carbonation penetrates the concrete progressively from the surface and as it reaches the reinforcement
corrosion commences leading to spalling.
Carbonation can be effectively prevented with the application of
a good anti-carbonation coating.
It is never too early to start taking preventative measures to stop chloride ingress and carbonation. The sooner it is done the greater the saving in later repair costs.
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