: acroteria and balconies, in any atmosphere, vertical elements
and terraces, in industrial and marine environments are indeed the
most sensitive elements in buildings, due to either their thinness,
or the difficulty to obtain a cover, which is thick enough.
buildings : pillars and slabs are indeed often exposed to
chemical agents. Beams in industrial structures are also elements,
which are particularly sensitive, as they support some floor slabs.
Some of them are sometimes in somewhat surprising conditions.
beams and slabs, in marine or mountain sites. The reason
in both cases is the presence of chlorides (coming respectively
from sea water and de-icing salts). It should be known that many
slabs are of prestressed concrete, this increases the risk of corrosion.
of prefabricated structures : it does seem that no significant
problems are observed, likely because concrete has then a better
making and a better placing. However, some pillars of electrical
lines for example seem to be a subject of concern. It should be
known that in France the set of reinforced concrete pillars is large
(approximately 1 per 2 inhabitant), the oldest of them are more
than 60 years old.
A significant pathology also exists concerning various structural
components, due to the use, in the 1960s-1980s, of concrete accelerators
containing calcium chlorides. This concerns exterior wall panels,
acroteria, flowers stand, etc.
and structures : in these structures, the most significant
zones are decks, supports of superstructures, and deck equipment
(where de-icing salts have a significant influences).
(buried, on ground, in air). The principal problem for these
structures is water leakage, which are due to cracks (of various
origins: thermal, mechanical, etc.) or defects of reinforcement
cover, mainly if the environment contains aggressive salts (chlorides,
On existing structures deteriorated by cracks, or diffuse leakage,
repairs consist in clogging defects or in sealing.
: for storing granular or powdery materials (cereals, cements,
etc.) are subjected to strong strains, in particular during loading
and of unloading. These strains induce cracks (horizontal or verticals).
These cracks can induce water penetration, which initiates reinforcement
Industrial air coolers are subjected to
a severe environment (water fog including vapour and droplets inside,
and sun, rain or freezing outside) generating constraints starting
of the cracks. In addition the strong moisture gradient induces
of water vapour transfer, which can be the origin of concrete deterioration.
(particularly, industrial ones) are subjected to a very severe,
acid environment (sulphuric and hydrochloric acids). Their barrels
are facing phenomena due to the neutralization of concrete alkalinity,
on the one hand, and to sulphate attack, on the other hand (by gypsum
formation). This attack is sometimes very deep, and often depends
irregular on the height.
structures on sea shore are under an attack due to chlorides.
The corrosion intensity depends on the aggressiveness of the environment
(tide, splash, spray zones). Defects in cover failures and concrete
quality are then immediately highlighted.
and prestressed concrete pipes : most of them are buried,
and ruptures occur when the protection due to concrete is no more
sufficient (carbonation, presence of chlorides).
It is also necessary to include historical
monuments (churches or other works designed by architects
like Perret or Le Corbusier), made of reinforced concrete, with
an increasing number, which have their own constraints, in particular
concerning their repair.
At last, the internal concrete
diseases due to its own components (alkali aggregate
reaction, differed ettringite formation, etc.) are particular cases,
which induce various damages (cracking, deformation).