Who does not want to have a
bungalow or flat facing sea. Globally, everyone wants to stay in room in
a hotel that is facing sea-view. The mesmerising nature has its own depth like
ocean which cannot be measured. But not many know that the coastal environment
causes severe damage to the building structure and envelope (i.e., exterior
doors, windows, skylights, exterior wall coverings, soffits, roof systems, and
attic vents). When steel reinforcement corrodes, the corrosion product occupies
more than three times the volume of the original steel, exerting great
disruptive tensile stress on the surrounding concrete, leading to further
cracking, more weather access and further corrosion. In mild cases, rust
staining occurs whereas in more serious cases severe spalling of concrete may
occur and ultimately the concrete members may fail completely.
The corrosive effect of salt-laden, wind-driven moisture in
coastal areas cannot be overstated. Salt-laden, moist air can corrode exposed
metal surfaces and penetrate any opening in the building. Corrosion is most
likely to attack metal connectors that are used to attach the parts of the
structure to one another, such as floor joists to beams and connectors used in
cross-bracing below the finished lowest floor. Galvanized connectors coated with Zinc at the rate of 0.9 ounce per square
foot of surface area (designated G-90) can corrode in coastal environments at a
rate of 0.1 to 0.3 millimetre/year. At this
rate, the Zinc protection will be gone in 7 years. Alternatively, a
G-185 coated connector, which provides twice as much protection as G-90, can
corrode in less than 20 years.
More galvanized protection (more ounces
of Zinc per square foot of surface area to be protected) increases
service life. Corrosion can also affect fasteners for siding and connectors for
attaching exterior-mounted heating, ventilation, and air-conditioning units,
electrical boxes, lighting fixtures, and any other item mounted on the exterior
of the building.
Corrosion of reinforcing steel
is one of the most important causes of deterioration of concrete structures in
coastal environment. High permeability concrete, poor design detailing and
construction defects such as inadequate depth of cover allow the ingress of
salt and moisture into the concrete. High concentration of salt and moisture
result in accelerated corrosion of reinforcing steel thereby significantly
deteriorating the concrete structure.
Corrosion is commonly
associated with deposition of sea salt in presence of moisture on steel and
light metals. Chloride is the most significant corrosive species in the salt
particles. Corrosion is influenced by the amount of salt on the metal surface
and related to speed and direction of wind, distance of structure from the
shore, elevation of the structures, degree of sheltering and frequency and
amount of rain washing. Other factors that influence corrosion include time of
wetness, relative humidity, metal surface temperature etc. Normal steel has
poor resistance in coastal atmosphere and hence requires protection for
durability.
So, moral of the story is… Do
have a SEA facing bungalow or flat, SEE that the steel used is Galvanised…
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