EFFECT OF STEEL FIBRES & FLY ASH ON
STRENGTH PROPERTIES OF
SELF-COMPACTING CONCRETE
Nikhil Verma Nitin Thakur
M.Tech Scholar Associate Professor
OITM, Hisar OITM, Hisar
1. INTRODUCTION:
Though concrete itself is very strong and durable , in order to further enhance its properties the study is being carried out which aims to investigate the fresh, strength and durability properties of self-compacting concrete (SCC), with fly ash as partial replacement of cement incorporating steel fibers. SCC consists of same components as the normal vibrated concrete. These components are cement, fine aggregate, coarse aggregate, water, additives and admixtures. These components are so adjusted so that concrete flows under its own weight, passes through narrow openings of reinforcement and finally, completely fills the form work without segregation of coarse aggregates in absence of vibration. SCC have advantages over normal concrete but still in hardened state it behaves same as normal concrete and as time moves on it starts developing cracks. The durability of concrete when reinforced with conventional bars is a major concern in aggressive environments. To address this problem, there have been efforts, in recent years, to develop alternatives to conventional bars. Fiber reinforced concrete have shown better behavior because of their inherent ability to stop or delay crack propagation.Furthur to make the SCC mix economical, some amount of cement is being replaced with fly ash so that the overall cost of mix remains almost same as that of normal concrete.
2. OBJECTIVE OF STUDY:
The study is focused on:-
Ø Improvement of self compacting concrete using fly ash and steel fiber .
Ø Evaluation of durability and strength properties of normal SCC and fiber-reinforced SCC using different mix proportions.
3. METHODOLOGY:
Material to be used in study are:-
Cement: A cement is a binder, a substance used in construction that sets and hardens and can bind other materials together.
Fly Ash: It is a by-product obtained from combustion of coal, composed of fine particles that are driven out of the boiler with the flue gases.
Aggregates: Aggregates constitute bulk of the total volume of concrete.
Aggregates are of two types:-
Ø Fine aggregates: Locally available natural river sand are used as the fine aggregates.
Ø Coarse aggregates: Crushed stones of standard sizes are used as coarse aggregates.
Fibers: The various types of fibers like carbon, glass, synthetic, steel etc. can be used in reinforcing concrete. In this study, steel fibers were incorporated in concrete.
MIX- DESIGN :
‘Japanese method’ was initially used for mix design of SCC.
4. EXPERIMENTAL:
In this study we perform the tests on different mixes of specimens i.e. a specimen without a mixture means in its pure form and another with a mixing of steel fibers and fly ash with different proportions. We prepare the mixes of different quantities and conduct the test on them and compare the result of different specimens of concrete so obtained.
Ø Compressive strength test
Compressive strength test is initial step of testing concrete because the concrete is primarily meant to withstand compressive stresses. Compressive strength tests were carried out on 150 mm × 150 mm × 150mm cubes with compression testing machine of 3000KN capacity. The specimens after removal from the curing tank were cleaned and properly dried. The surface of the testing machine was cleaned. The cube was then placed with the cast faces in the contact with the plates of the testing machine. Cubes were tested at 3, 7, 28 and 56 days of casting and the obtained results are listed in tabular form and strength is determined.
5. CONCLUSION:
From the above study we can conclude the Durability and strength (compressive & tensile) of the standard specimen of cement by comparing different mixes of different proportions. The mixing of fly ash and steel fibers can bring some chemical changes in the concrete specimen and we can check the variation in properties of concrete specimen after addition of fly ash and steel fibers between the virgin SSC and the mixed SSC samples.
6. REFERENCES:
Aggarwal P., “Study of mechanical properties and durability aspects of self-compacting concrete", Ph.D Thesis, Civil Engineering Deptt., National Institute of Technology, Kurukshetra, 2009
Bassuoni M.T. and Nehdi M.L., "Durability of self-consolidating concrete to sulfate attack under combined cyclic environments and flexural loading”, Cement and Concrete, Research vol.39, 2009