274-278The present
work aims to study the effect of various amounts of silica fume on the
physico-mechanical properties of slag cement with 5% raw cement dust. Slag
cement is substituted by 4, 8 and 12% silica fume. The results reveal that the increase
of silica fume tends to increase the water of consistency. On the other side,
4% silica fume decreases the setting time (initial and final) . 8 and 12%
silica fume tend to lengthen the setting time due to the increase of mixing
water. The free lime content increases up to 7 days then decreases for all
mixes. As the amount of silica fume increases the free lime content decreases.
Also, the combined water content increases with the amount of silica fume. The
compressive strength of cement paste decreases with silica fume due to the
increase of mixing water