ABSTRACT

Structural concrete and cement-based materials have been extensively used in the building industry for about a century, because they are cheap, strong (in compression) and mainly durable. To improve some of the weak points, such as restricted tensile capacity, or corrosion of reinforcement, waves of developments are appearing with a certain regularity. These developments, sometimes with claimed 'fabulous' characteristics, open up very effective and imaginative improvements or extensions of the range of applications of cement-based materials. They should, however, be treated with a considerable amount of care or even suspicion, especially concerning their long-term behaviour. This will also be applicable to new structural materials presently being developed. A sensible equilibrium between care (suspicion) and imaginative use must be based on a reliable amount of knowledge of durable behaviour, which means interpretation and extrapolation of experimental data, as well as on some engineering judgement. It should be remembered that the effects of improving a weak point (e.g. corrosion) by introducing new materials can be reduced by the introduction of other, unknown, unexpected or less-wanted phenomena (e.g. insufficient stability in alkaline environments).