LONG-TERM EFFECTS OF NATURAL POSSOLANS AND SILICA FUME AGAINST ALKALI-SILICA REACTIONS IN CONCRETE

摘要

Silica fume has been intermilled with Icelandic cement since 1979. The main reason why silica fume is utilised in this way is to reduce or eliminate alkali-silica reactions in concrete. Now after more than 20 years of service there are no signs of alkali-silica reactions in concrete in Iceland. These findings are supported by standardised alkali silica test methods. However, the homogeneity of silica fume both in cement and hardened concrete is not always as good as expected since small clusters of silica fume can be found in hardened concrete and test results have shown these , lumps to be alkali silica reactive.