Investigations on Microsilica (Silica Fume) As Partial Cement Replacement in Concrete
Now a day, we need to look at a way to reduce the cost of building materials, particularly cement is currently so high that only rich people and governments can afford meaningful construction. Studies have been carried out to investigate the possibility of utilizing a broad range of materials as partial replacement materials for cement in the production of concrete. This study investigated the strength properties of Silica fume concrete. The specific gravity and chemical composition of silica fume and cement were replaced with micro silica from 0 to 25% in steps of 5% by weight, mix proportioning was based on 1:2:4 mix ratio. Cubes (150 x 150 x 150 mm) were produced and cured in a curing tank for 3, 7, 14 and 28 days. The cubes were subjected to compressive strength tests after density determination at 3,7,14 and 28 days respectively. The chemical composition and physical composition of micro silica and cement were determined. Ordinary Portland cement was replaced with silica fume. The total amount of Tricalcium aluminate in the cement was 7.7% and this was above the requirement. (Table 3.1 shows 3.5 max, Specified by BS12/EN196:1996),others chemical compositions for silica fume such as SiO2, moisture content, loss of ignition, carbon, > 45 micron, bulk density. Tables 3.1 were within the specified limit. Also % chemical composition and physical properties for SiO2, Al2O3, Fe2O3,CaO, MgO, SO3, Alkalis ( Na2O + 0.658K2O), loss of ignition (Lo1), insoluble residue (IR), Tricalcium, silicate, Dicalcium silicate, CaO / SiO2, chloride, fineness (Blaine air permeability test) in Cm2/g, soundness (mm) table 3.1 were in compliance with BS Standard. The density of the concrete decreased with increased in percentage of micro silica replacement up to 10%. Increase in the level of micro silica fume replacement between 15% to 25% led to a reduction in the compressive strength of hardened concrete (table 3.3) This study has shown that between 5 to 10% replacement levels, silica f
