29-10-2014, 03:58 PM
Study on Behaviour of Concrete by using Waste Material like Steel Slag as a Partial Replacement of Coarse Aggregate
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INTRODUCTION
Steel slag is a by-product of the iron and steel making process. Steel cannot be prepared in the Basic Oxygen Furnace (BOF) or in an Electric Arc Furnace (EAF) without making its by-product, steel slag [1]. The use of steel slag aggregate in concrete
By replacing natural aggregate is a most promising concept [2].The steel slag present in concrete Satisfy physical properties which slow down the hydration of blended cement due to morphology and low calcium silicate content [3]. Thus steel slag can be used in conventional concrete to improve its mechanical, chemical and physical properties. The only potential problem with steel slag aggregate is its expansive characteristics and undesirable reactions between slag and components of concrete. The only potential problem with steel slag aggregate is its expansive characteristics and undesirable reactions between slag and components of concrete. Studies and tests are being conducted on ways to use this steel slag as an aggregate in concrete.
MATERIAL CHARACTERISATION
Cement: The cement used for this work is OPC of 43 grades. The specific gravity of cement was tested as per IS :8112 and was found to be 3.15.In this research cement used OPC 43 grade confirming to IS:8112. The physical properties of the cement obtained on conducting appropriate are IS: 10262-2009. A cementations material is one that has the adhesive and cohesive properties necessary to proper bond inert aggregates into a solid mass adequate strength and durability.
Water: Clean potable water is used for Mixing and Curing operation for the work. The Water supplied in the campus is of the potable standard of PH value 7 is used. Pure water is not good use with ordinary Portland cement. This can be used with high alumina cement. If impurities in the water may affect the setting time of cement, strength of concrete, and may cause corrosion of the reinforcement.
Super plasticizer: To improve the workability of fresh concrete sulphonated naphthalene based super plasticizer i.e., Conplast SP 430 was used supplied by FOSROC chemicals, 1.4% dosages was used to increase the workability of concrete. Use of Super plasticizer permits the reduction of water to the extent up to 30% without reducing workability. Super plasticizer is a high range water reducer. The super plasticizer produces a homogeneous, cohesive concrete generally without tendency for segregation and bleeding. Super plasticizers are used to produce high- strength concrete with a very low W/C ratio and they are also used to produce flow able concrete at conventional W/C ratios. Chemical admixture like super plasticizer conforming to IS: 9103.
Coarse aggregates: The coarse aggregate used is crushed (angular) aggregate conforming to code IS 383:1970. The maximum size of aggregate considered is 20mm IS sieve passing and minimum size of aggregate considered is 12.5mm IS sieve passing. The results of sieve analysis conducted as per the specification of IS: 383-1970.The fineness modulus of coarse aggregate is 5.82. Soundness is also an important property of coarse aggregates.
Fine aggregates: Locally available clean river sand passing through the IS-480 sieves have been used. The results of sieve analysis conducted as per the specification of code IS: 383 -1970.The fineness modulus of fine aggregate is 3.276.Fine aggregates like river sand , Moran are used in mix proportion of concrete.
Steel Slag: Steel slag is an industrial waste material. It is a by-product of the iron and steel making process. Steel slag is obtained from conversion of iron to steel in a Basic Oxygen Furnace (BOF) or by the melting of scrap to make steel in the Electric Arc Furnace (EAF). Steel slag is defined by the American Society for Testing and Materials (ASTM) as iron-metallic product, consisting essentially of calcium silicates and ferrites combined with fused oxides of iron, aluminium, manganese, calcium and magnesium that are developed simultaneously with steel in basic oxygen, electric arc, or open hearth furnaces. Steel slag is used for manufacture Portland cement. Steel slag aggregates are used for soil stabilization or soil improvement material. In this research the steel slag is used as a partial replacement of coarse aggregate. With the help of slump test to know more about the workability and fresh concrete.
SELECTION OF SUITABLE MIX PROPORTION
Concrete mix design of M40 grade was designed conforming to code IS: 10262-2009. Cubes of standard size 150x150x150mm, Prisms of size150x150x700mm were casted at room temperature and were tested at 7, 14 and 28 days of curing.
FLEXURAL STRENGTH
To determined the Flexural strength of each specimen of standard size 700x150x150mm was supported over a entire span of 600mm and a two point load was applied at the centre of span .The deflection of beam and prisms under the load condition was recorded up to the first crack.All the
The Flexural strength is calculated by the formula
〖 f〗_(b )= (p×l)/(b×d^2 )
〖 f〗_(b )= Flexural strength, Mpa or N/mm
Beams were loaded up to failure. After complete the 7, 14 and 28days to determine the strength of all samples. Flexural Strength results are show in table:
TEST RESULTS AND DISCUSSION
Compressive strength:
Results of compressive strength that , at 28days,with a replacing percentages of steel slag as 30% and we found that increase in compressive strength as compared to 0% replacement. We conclude that the compressive strength at 30% is more than that of 0% replacement.
Flexural Strength:
The average flexural strength of steel slag concrete at the different age of 7days , 14days and 24 days is show in Table 4 results show that at 28 days, with replacing percentage of steel slag as 10% and we found that the increasing strength that of 0% replacement. The maximum flexural strength at 28 days is 7.125 N/mm2 of 10% replacement of steel slag. We conclude that the flexural strength at 10% is more than that of 0% replacement of steel slag.
Workability:
The workability of concrete in M40 grade of concrete it improved upto 30to 50% replacement level and later dropped at 100% replacement by about 8% in case of replacing coarse aggregate with slag.The workability improved in higher grade concrete (M40) due to potential availability of finer materials.
CONCLUSION
Following are the conclusions draw from the above research work.
1. We can conclude that at 30% replacement of coarse aggregate with steel slag gives desirable compressive strength.
2. At 10% replacement of concrete coarse aggregate with steel slag gives desirable Flexural strength which can be accounted for the construction practices.
Hence, it could be recommended that the steel slag aggregate could be effectively utilized as coarse as coarse and fine aggregate in all concrete applications either as partial or full replacements of normal coarse and natural fine aggregate.