On the compressive strength development of high-performance concrete and paste - effect of silica fume

The compressive strength development of sealed high-performance concrete an d paste specimens, with and without silica fume, have been studied from 1 d ay and up to 4 years. The paste and concrete specimens were prepared in suc h a way that segregation was avoided and the silica fume became well disper sed. Under these conditions silica fume increased the strength of paste jus t as much as it increased the strength of concrete. It appears that the enh ancing effect of silica fume on concrete strength is due to an improved str ength of the paste phase as a whole, and not due to an improved bond streng th between the paste phase and the aggregate particles, as has been suggest ed earlier. The concretes and the pastes with 10% silica fume appeared to l oose strength over a period of time before the strength increased again.