Effect of Silica Fume on Compressive Strength and Water Absorption of the Portland Cement–Silica Fume Blended Mortar

The unique physical and chemical properties of silica fume enhance the compressive strength and water resistance of cement mortar. The study aims to investigate the effect of silica fume in cement mixes in terms of strength-gaining characteristics and water-resistance attributes. The silica fume was added in amounts of 0%, 10%, 20%, and 25% as a partial cement replacement for the production of mortar. A total of 120 mortar cubes were prepared with steel molds of 50 × 50 × 50 mm dimensions. Two water-cement ratios (w/c) of 0.4 and 0.5 were utilized to investigate the water-resistance properties. A water-resistant property was calculated using the compressive strength ratio in the saturated surface dry (SSD) state to the oven-dry condition. The compressive strength ratios in SSD and the oven-dry state were measured after curing in water for 3, 7, 28, 45, and 90 days. After 90 days of curing, the sample with a water-cement ratio of 0.4 exhibited the greatest compressive strength and the highest ratio of SSD to the oven-dry state. The higher SSD to oven-dry strength ratio shows the silica fume possesses superior water resistance. This study concludes that silica fume possesses great pozzolanic activity and excellent resistance to water. The incorporation of silica fume creates a concrete composition that enables the construction of durable concrete structures.