Marine exposure
Durability of concrete exposed to
sea-water again stresses that of all chemical and physical properties,
permeability of concrete is the most important factor influencing performance.
Concrete are achieved by using mixes having high cement contents and low water:
cement ratios, through consolidation and control of thermal and shrinkage
cracking, and limiting cracks due to mechanical loading.
1Physic-chemical effects of sea water on hydrated
cement as follows:
ü Chemical
attack by sea water on cement only occurs in the case of permeable concrete
ü C4AF, in
contrast to C3A has no deleterious effects
ü Portland
cements with C3A contents lower than 10% resist chemical attack in sea-water
ü Cements
containing more than 65% slag are most resistant to sea-water attack
ü The
effects of pozzolan depend on their mineralogical composition and reactivity
ü Compressive
or flexural strengths are not a good basis for assessing durability once
reactions commence; a much b etter basis is the measurement of expansions as
they continue
2Application of materials
ü Mortar
placement
ü Injection
into cracks
ü Large-scale
Repair
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