The importance of gas permeability in addition to the compressive strengthof concrete

The permeability to gases of cementitious materials is one of the major con tenders for becoming a standard parameter for the quantification of the dur ability of these materials. This coefficient is thought to be closely relat ed to the compressive strength. It is shown systematically here, by conduct ing permeability studies as a function of the degree of saturation of concr ete on two sets of concrete compositions having the same compressive streng th (100 MPa and 25 MPa), that entirely different gas permeability values ma y exist for different mix compositions which have the same compressive stre ngth. These measurements were carried out on 5 cm thick, 15 cm dia. specime ns by using a CEMBUREAU permeameter and oxygen as the percolating fluid. Th e results emphasize the fact that the 28 day compressive strength alone can not be a criterion of the durability of concrete unless it is coupled with the quantification of the resistance to the entrance of aggressive chemical s.