Inspection . A vigorous inspection program will be required in order 

 to detect problems early so that corrective action may be taken. Three 

 zones need inspection for different mechanisms of deterioration; these 

 are the submerged, splash, and atmospheric zones. 



The submerged zone requires underwater inspection to check for cracking 

 of concrete due to fatigue stress, overloading conditions, or corrosion of 

 reinforcing steel. Corrosion of reinforcing steel is unlikely in the 

 submerged zone. Inspection for sulphate attack is warranted and will be 

 revealed by a surface-softening effect which will permit abrasion by 

 currents or water jets used to clean the concrete surface. 15 3 J A rough, 

 exposed aggregate surface may indicate sulphate attack, and hence, a 

 more detailed inspection would be indicated. 



The splash zone will be most susceptible to reinforcing steel cor- 

 rosion. At advanced stages of corrosion, rust marks bleeding from the 

 concrete surface will be observed. More serious corrosion will cause 

 spalling of concrete cover. Less obvious corrosion problems will be harder 

 to detect. Electrical potential difference tests can be conducted to 

 determine the potential between different sections of concrete. When 

 potentials are greater than 0.35 volts the probability is 95% that 

 steel is corroding, t' j Successful field application of the half-cell 

 potentionmeters has occurred on highway bridge-decks and buried concrete 

 pipe. 



The atmospheric zone is also susceptible to reinforcing steel cor- 

 rosion but to a lesser degree than the splash zone. Particular problem 

 locations are inside corners on overhanging or vertical sections. It is 



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