ABSTRACT
Although the development of high-performance concrete is quite recent, there are already high-performance concretes that have gained the qualification of ‘special’. As is the case in usual concrete, these special high-performance concretes depart in some way from the standard composition of more usual high-performance concretes. For example, a special high-performance concrete could have been made with a heavyweight aggregate to increase its unit mass or, alternatively, with a lightweight aggregate to decrease it, or fibres could have been added to increase its toughness, its impact resistance or its ductility. Highperformance concrete can be confined in a thin, highly resistant (in tension) envelope in order to increase further its compressive strength and ductility. The placing method could be different from the usual placing method, as in the case of roller-compacted high-performance concrete or self-levelling high-performance concrete. It is certain that there are and there will be other types of special high-performance concrete with which the author is not familiar, but all these special high-performance concretes have one important thing in common: they have a very low water/binder ratio, a high compacity and consequently a great durability.
