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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