It is a matter of particular delight to me that Prof. W. Brockmann from the University of Kaiserslautern has consented to present our traditional concluding paper on the subject of "Adhesion over the Centuries". This takes us from the previous lectures on the topic of art history to the history of the natural sciences.

The phenomenon of adhesion is ubiquitous in the industrial flooring sector. Just think of the adhesion between grains of sand and the binder. Depending on the grading curve, the interface may be up to 10 square metres per kg (with a grain diameter of 0.1 mm). Or the adhesion of reaction polymers to the substrate (concrete, mastic asphalt, magnesite screed). Or the intermediate layer adhesion between reaction polymer on reaction polymer after the maximum waiting period. There we also have the problems of osmosis.

This overall problem has resulted in the creation of a technical "Adhesion" committee by RILEM, the international association of materials testing bodies, who will be presenting their conclusions at a symposium to be held in Dresden from 14 to 17 September 1999. The congress is dedicated to H. R. Sasse in acknowledgement of his outstanding services to building chemistry. Prof. Sasse is a very active member of our Programme Planning Committee, as you already know. The Technical Academy is also the organiser of this congress.