STUDY ON THE INFLUENCE OF SOME PARAMETERS OF MIX DESIGN ON THE PERMEABILITY OF HARDENED CONCRETE
The recent statistical studies on the expenditures for the maintenance, repairs and strengthening of road bridges, show the importance , from an economic viewpoint of the problems related to the durability of concrete. The studies that have been carried out by the OECD are very significant in this point. The expenditures origined in this concept during 1.985-1.990, have increased more than 65 per cent. 
Regarding above, a great interest has appeared about all the problems related to the concrete durability. Thus it is necessary to reach an adequate Knowledgement to obtain a
good quality of concrete during its design and making. This is the only way to get a concrete with a good performance concerning durability.