Figure 19. Concrete pile damaged by overloading (photo 

 courtesy of Los Angeles Harbor Department) . 



The repair of spalls from reinforcing bar corrosion requires a more 

 detailed study. Simply replacing the deteriorated concrete and restoring 

 the original cover over the steel will not solve the problem. Also, if the 

 structure is salt-contaminated, the electrolytic conditions will be changed 

 by the application of new concrete, and the consequences of these changed 

 conditions must be considered before any repairs are undertaken. 



Basic requirements for achieving a durable repair are: 



(1) The repair material must be thoroughly bonded to the sound 

 concrete of the cavity; 



(2) the shrinkage of the patch should be small enough not to 

 jeopardize this bond; 



(3) the patch and its substrate should be free of cracks; 



(4) the response of the patch and the old concrete to changes in 

 temperature, moisture, and load should be similar enough to avoid 

 gross differences in movement; 



(5) the patch should be low enough in permeability that moisture 

 will not migrate through it to the old concrete underneath; and 



132 



