Effect of silica fume inclusion on properties of high strength concrete containing high volume of steel slag
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Date
2018-06
Authors
Mohammad Nazeem Mohsin
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Abstract
The use ground granulated blast furnace slag in concrete is advantageous from economic,
environmental and technical points of view. However, the use of slag especially in high
volume may negatively affect the strength and other properties of concrete. Therefore,
this study explores the feasibility of using silica fume as partial replacement of slag in
high strength concrete containing high volume of slag. A control high strength concrete
mix was proportioned to have a 28 days strength of 70 MPa. A similar mix was
proportioned but 60% of the ordinary Portland cement was replaced with slag on massfor-mass basis. Further, another four concrete mixes were proportioned by partially
replacing the slag content with silica fume at 5, 10, 15 and 20%. The effects of the
incorporation of silica fume on workability, density, compressive strength, porosity and
water absorption of the concrete were investigated. The results exhibit that the use of slag
in combination with silica fume tends to reduce the workability of the high strength
concrete. Concrete mixes containing slag as well as combination of slag and silica fume
exhibit higher density than the control concrete. The inclusion of silica fume improves
the strength of the high strength concrete containing high volume of slag, in particular at
higher silica fume content, but the strength obtained does not exceed that of the control
concrete mix. The influence of silica fume inclusion on porosity and water absorption of
the high strength concrete containing high volume of slag is to significantly reduce both
porosity and water absorption in particular at higher silica fume content and longer curing
period. The results show that concrete containing 20% silica fume registers a slump value
of 13 mm, with density of 2544 kg/m3, compressive strength of 76.03 MPa, porosity of
5.29% and water absorption of 3.23% at the age of 56 days.