Development of strength with age of mortars containing silica fume

Some experimental investigations on the development of compressive strength with age of mortar incorporated with silica fume with different water/binder (w/b) ratios have been reported. The silica fume content varied from 0% to 30% by weight of cement. Four w/b ratios, 0.35, 0.40, 0.45, and 0.50, were used. At every w/b ratio, the strength developments at 3, 7, 28, and 90 days have been observed. The highest development rate of compressive strength was observed at early ages (3 and 7 days). At w/b ratio 0.35, the highest value has been observed at 3 days with a silica fume content of 22.5%. At w/b ratios 0.35, 0.40, and 0.45, the strength increases up to an optimum content of silica fume, beyond which it decreases as the silica fume content increases. After 7 days, the strength development has been slowed down significantly at these w/b ratios. However, at w/b ratio 0.50, consistent strength development has been observed at the ages of 3, 7, 28, and 90 days. This has been dependent on the continuous availability of water content at all the ages. However, the ratios of strength of mortar at 3 and 7 days to strength at 28 days, and at 3, 7, and 28 days to strength at 90 days have been observed to be higher at w/b ratio 0.35 than those with other w/b ratios