Why should lower permeability be important to concrete?
The integrity and disintegration of concrete is usually caused by external agents arising from the environment or by internal agents from within the concrete mass. The permeability factor of concrete is directly responsible for pollutants and or contaminants that are allowed to penetrate concrete. Contaminants and pollutants such as sulphates, acids, seawater and chlorides. Because internal agent attack must come from within the concrete. The attacking agents must be able to penetrate throughout the concrete which therefore has to be permeable. Therefore concretes permeability should be of critical interest. Internal agent attack is aided by internal transport of agents by diffusion due to internal gradients of moisture and temperature and by osmosis. Permeability is sometimes inadvertently increased even further by the use of porous aggregate or by the placing of concrete without the benefit of a proper cure. However, for concrete made with normal weight aggregate permeability is gove
