| Summary: | The effect of silica fume (SF) and metakaolin (MK) on properties of high strength
concrete mixes containing 0%, 10% and 15% silica fume and metakaolin as partial
replacement of cement has been investigated. Experimental studies have been conducted
to determine the influence of both mineral admixtures on the workability, strength
development, surface hardness, porosity and permeability of high strength concrete. The
slump, compacting factor, plastic density, compressive strength, Rebound number,
ultrasonic pulse velocity, porosity and permeability tests were performed. The specimens
were cured in water for periods varying from 1, 3, 7, 28 to 56 days before testing. It was
observed that the specimens with 15% silica fume had the highest compressive strength,
ultrasonic pulse velocity, Rebound number, lowest porosity and permeability at the age of
56 days. Whereas, the specimens with metakaolin had the compressive strength,
ultrasonic pulse velocity, Rebound number lower than the specimens with silica fume but
porosity and permeability higher than specimens with silica fume. The inclusion of
mineral admixtures reduced the workability of concrete mixes. Nevertheless, it can be
concluded that the mineral admixtures generally improved the compressive strength,
ultrasonic pulse velocity, surface hardness and durability of high strength concrete.
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