ABSTRACT
Engineers usually regard durability of concrete to mean its long-term satisfactory performance under severe exposure conditions whether these are natural or man-made. It is emphasized in what follows that due consideration should be given to the nature and type of tests being used by different investigators when comparing the results of their investigations. The use of condensed silica fume in concrete causes changes in the microstructure and pore size distribution of the cement-silica fume binder system, and results in more impermeable matrix. The use of nonair-entrained condensed silica fume concrete is not recommended when it is to be subjected to repeated cycles of freezing and thawing. J. Virtanen has compared the frost resistance of condensed silica-fume concrete with other concretes incorporating fly ash and blast furnace slag. The performance of concrete incorporating a silica-fume based admixture in saturated calcium nitrate and ammonium nitrate solutions has been reported from Norway.
