This book consists of a series of high level contributions on one of the most rapidly advancing subjects in the field of cement and concrete - that of the interfaces between the various components of cementious materials: cements, aggregates, fibres, reinforcement. The microstructural, chemical and physical processes that govern the behaviour of all cement-based materials are dependent on the way in which these components interact, and the powerful techniques which are commonly used in other fields of materials science are now being applied to cementitious materials. The book contains new data from many of the leading research groups around the world dealing with this topic, and will be valuable for all those involved with research into and development of cement-based materials. It forms the proceedings of the international conference organised by RILEM Technical Committee 108 and the Laboratory for Materials and Durability of Construction at the National Institute for Applied Science, at Toulouse in France, and held in Toulouse in October 1992.