The effects of sodium salt of naphthalene formaldehyde sulfonic acid and st
earic acid on the hydration of silica fume and Ca(OH)(2) have been investig
ated. The hydration was carried out at 60 degrees C and W/S ratio of 4 for
various time intervals namely, 1, 3, 7 and 28 days and in the presence of 0
, 2% and 5% superplasticizer and stearic acid. The results of the hydration
kinetics show that both admixtures accelerate the hydration reaction of si
lica fume and calcium hydroxide during the first 7 days. Whereas, after 28
days hydration there is no significant effect. Generally, most of free calc
ium hydroxide seems to be consumed after 28 days. In addition, the phase co
mposition as well as the microstructure of the formed hydrates was examined
by using X-ray diffraction analysis (XRD) and scanning electron microscopy
(SEM) respectively.