In 20 minutes I would like to talk briefly about some important aspects of my sphe-re of work, "Industrial Floors", in which I have specialised for 25 years now. My talk should be seen in the context of the preceding contributions by W. Mormann (University of Siegen) on the subject of "Chemistry and Characterisation of Reac-tion Polymers" and G. Ruttmann (Bayer Leverkusen) dealing with "Requirements for Reaction Polymers in Construction". As a highly relevant example of the use of polymers in construction, I have selected those polymers which improve concrete or other substrates (incl. mastic asphalt, bitumen emulsion screed and magnesite screed) to such a degree that the surface is able to permanently withstand all the loads imposed on an industrial floor. There are numerous types of strength to take into account.

In practical applications one encounters rutted joints in concrete floors, such as the particularly glaring example shown in Fig. 1. This kind of damage can be repaired with reaction polymers:

In my talk I shall restrict myself to (1) concrete as substrate and (2) polyurethane as polymer. There are many other substrates that are used as industrial floors. And, of course, there are also the epoxides and the polymethylmethacrylates, which are used as coating materials with great success. With regard to the inevi-table omissions in such a short talk, I refer you to the wide-ranging literature on the subject. RILEM, the International Union of Material Testing Institutes, took up a suggestion by Prof. Sasse (RWTH Aachen) and founded the Technical Committee "Industrial Floors" under my direction with the aim of achieving a better un-derstanding of the processes involved in future.

The terminology is explained in the work sheet A 80, "Industrial Floors made from Reaction Polymers", published by the Industrial Construction Working Group (AGI). Furthermore, there is an entry in the Römpp "Dictionary of Chemistry" explaining the terminology. I refer you to these sources.

Before industrial floors can be planned, a check list must be strictly observed.

Independent experts know from long experience that in many cases concrete floors are laid incorrectly, and for this reason do not last. A badly made concrete surface must be repaired. Occasionally the properties of the concrete are inade-quate for the intended use, e.g. chemical resistance or crack bridging. There are many parties involved who must reach agreement about the "industrial floor" as a structural component.

Finally, I shall describe a typical repair, in which seven steps have to be observed:

1. Preparation of the existing floor (substrate)
2. Stabilising the concrete skin by impregnation
3. Levelling out deep depressions with repair mortar (joints, cracks, holes)
4. Creating a flat surface using a self-levelling coating (levelling out unevenness extending over a wider area)
5. Producing a 1 mm to 5 mm thick protective layer
6. Non-skid properties in wet areas
7. Sealant for ease of maintenance and "aesthetics"

These steps involve processes that are carried out in situ under the widely fluctua-ting climatic conditions that prevail on the building site. However, the reactions are very complex in physicochemical terms, without there being an engineer present to supervise, still less a process computer.

The level of foolproofness demanded of the materials used is therefore extremely high. To sum up, one can state that, from the scientist's perspective, industrial floors remain an area of construction that is full of pitfalls. We are still waiting for the building material that is as simple and uncomplicated to use as the aspirin is in the field of medicine. For young, imaginative scientists, there is plenty to be done in this field.