ABSTRACT
All the durability problems of cement-based materials may be considered to be the consequence of materials and energy exchange between the hardened mas ses and their environments. In the case of a perfectly formed structure, without any crack and differential porosity at different places, the attacking agent or process must progress evenly from the surface inwards. Unless the agent or the process is highly energetic e.g. strong acid etc. its progress will be slow and uniform. If however there are flaws in the structure then the agent or the pro cess may penetrate deep inside the structure selectively through those flaws making extensive damage to the structure. We have studied the flaw making processes for about 20 years and time to time published our results on various aspects (Chatterji and Jeffery, 1971, Wheeler and Chatterji, 1972, Christensen et al 1981). In this report we summarise our present position on interfacial zones only.
