Comparing the performance of metakaoline with silica fume on properties of high performance concrete

Nowadays، the use of high performance concrete is rapidly increasing due to its capability of being a good substitute for poorly constructed structures and also concrete structures in corrosive environments which suffer from short life span and immature failure. However، in the last decades the pozzolans are greatly used in order to produce concretes with improved mechanical properties and durability. One of the most usable pozzolans is silica fume and metakaoline. In present paper، the mechanical properties and durability of high performance concretes containing metakaolin of 5، 10 and 15% of cement replacement is compared to those containing silica fume with 5، 7. 5 and 10 % of cement replacement using compressive strength test، water absorption، void volume، sorptivity، electrical resistance and gas permeability tests. According to the results، metakaoline showed better results compared to silica fume regarding improvement of mechanical properties and durability of high performance concretes and it is found that the optimum content of metakaoline is about 10 to 15% of cement replacement which can make it a good substitute for silica fume.