What causes concrete decay ...
Even concrete, formerly promoted as being »forever«, is not spared from decay. Various external influ- ences, processing or manufacturing errors, shortcomings in design or combinations of these factors may result in serious concrete decay. The only way to avoid such decay is to recognise the problem and provide protection in good time.
Weathering
Water
Even good quality concrete surfaces suffer attack from no rma l wea t he r over the course of time. The cement
The water absorpti- on characteristics of concrete are deter- mined by its porosity. Hairline cracks and rock pockets may
paste layer is slowly broken down, shuttering board textures disappear and pores are opened up, so increasing the ease with which water and pollutants can penetrate. The surface of the concrete loses aggregate and suffers erosion. Moss and algae start to grow, causing a deterioration in appearance and increasing the effects of decay.
considerably increase water absorp- tion. A high level of water absorption may even result in structural destruc- tion of the concrete on exposure to frost. Water ingress causes rusting on reinforcement parts located in con- crete which has already undergone carbonation. Water accumulating under impervious plastic coatings may result in increased corrosive damage.
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