Experimental Investigation on Rcc by Using Multiple Admixtures

In this article, the effect of replacing cement with silica fume and fine aggregate with copper slag has been investigated. For this research work, concrete of M40 grade is prepared and evaluated for fresh and harden concrete properties such as compressive strength, tensile strength and flexural strength. Further, the cement is replaced with silica fume at 0, 2, 4, 6, 8 and 10 % and fine aggregate replaced with copper slag at 0, 10, 20, 30, 40 and 50 %. Compressive strength, strength and Flexure strength have been tested. It is observed from the results that the use of silica fume and copper slag as partial replacement material improves mechanical properties of the concrete. Concrete with 40 % copper slag and 8 % silica fume shows better performance among all the mixes.


Introduction
Concrete is the most widely used building material which resists predominantly compressive forces. By addition of pozzolanic materials, the properties like workability, durability, strength, resistance to cracks and permeability of concrete can be improved. Modern concrete mixes are modified with addition of admixtures. The subsequent modification of the micro structure of cement composites improves the mechanical properties. Silica fume which is used commonly in cement and contain 85 to 98% silica. Silica fume does not have any cementitious properties but when reacts with calcium hydroxide on hydration of cement produces calcium silicate hydrate gel, which gives good cementitious properties. As for chemical reaction of silica fume, because of high surface area and high content of amorphous silica in silica fume, this highly active pozzolona reacts more quickly than ordinary pozzolonas. The silica fume used in concrete has engineering potential and economic advantage. The use of silica fume , Silica fume will make concrete less permeable and high strength, but it will not change unit weight. This work represents the effect of silica fume on fresh and hardened concrete. Silica Fume is highly effective pozzalonic material. Copper slag is an industrial by-product produced from the process of manufacturing copper. The use of copper slag in production of concrete as replacement for cement can reduce the costs of disposal and helps in protecting the environment.

Cement
Cement confirming to IS: 1489:1991 from Dalmia cement was used and the properties are as shown in Table 1

Fine Aggregate
Fine aggregate used in this study is from the locally available crushing unit and conformed to zone II as per IS: 383-1970.

Coarse Aggregate
The coarse aggregate used in the experimentation were of 20 mm and down size aggregate and conforms to IS: 2386-1963 (Part I, II and III) specifications. The properties of coarse aggregates are as shown in Table3.

Copper Slag
The copper slag used in this study is obtained from Sterlite industries, Tuticorn. This material replaces fine aggregate in mix proportion. The copper slag used in this study confirms to zone II. Table 4 and Table 5 show chemical and physical properties of copper slag respectively.

Silica fume
Silica fume used in this study is procured from BSS private limited, Edapally. Silica fume is fine powder, with particles about 100 times smaller than average cement partial. It confirms to IS: 15388-2003.  The maximum values of mechanical and durability properties are obtained for the mix M-8-40. The percentage increase in flexure strength is 37.92% respectively

Conclusions:
Replacing cement with silica fume and fine aggregate with copper slag effect is examined in this article. The concluding remarks of the paper are listed below.
Workability of the concrete increases with increase in copper slag and decreases with increase in silica fume. Workability is reduced by adding silica fume as it contains copper slag in place of fine aggregate. When replacement level of silica fume increases all the mechanical properties are increased up to 8% and up to 40% replacement level of copper slag all the mechanical properties are increased.
The maximum values of mechanical and durability properties are obtained for the mix M-8-40. The percentage increase in compressive strength, Spilt Tensile strength and flexure strength are 26.53%,31.93% and 37.92%respectively.