Structural Eng., Semnan University, Semnan, Iran
Faculty of Civil Engineering, Semnan University, Semnan, Iran
Silica fume as new supplementary cements have several effects on initial mechanical characteristics and long term improvement. In this paper, the impact resistance and mechanical properties of concrete mixed with silica fume are statistically investigated with selecting 288 specimens in three mix designs. Zero,7% and 14% of Portland cement by weight was replaced by silica fume in silica-fume mixtures. Twenty 100×100×100mm cubic specimens, twenty100×200mm cylindrical specimens, twenty 60×80×320mm specimens and thirty-six 150×64-mm discs were cast from each batch to prepare specimens for different test purposes. Cubic and cylindrical specimens were used to determine the compressive strength and prismatic specimens were tested to obtain rupturing tensile. Also, cylindrical cutting specimens were subjected to the drop-weight test following the ACI committee 544 to determine impact strength of mixed concretes. Experimental data on the mechanical properties of the different mixes indicated that silica fume improves mechanical properties and impact resistance while statistical analysis done based on these experimental tests showed the reduction the coefficient of variation values. In other words, adding silica fume improves statistical dispersion of data.