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

Abstract

The permeability to gases of cementitious materials is one of the major contenders for becoming a standard parameter for the quantification of the durability of these materials. This coefficient is thought to be closely related to the compressive strength. It is shown systematically here, by conducting permeability studies as a function of the degree of saturation of concrete on two sets of concrete compositions having the same compressive strength (100 MPa and 25 MPa), that entirely different gas permeability values may exist for different mix compositions which have the same compressive strength. These measurements were carried out on 5 cm thick, 15 cm dia. specimens by using a CEMBUREAU permeameter and oxygen as the percolating fluid. The results emphasize the fact that the 28 day compressive strength alone cannot be a criterion of the durability of concrete unless it is coupled with the quantification of the resistance to the entrance of aggressive chemicals.