Study On The Properties Of Self-compacting Steel Fiber Reinforced Concrete With Compound Mineral Admixtures

This paper states that the admixtures of the fly ash, ground granulated blast slag andground steel slag powder and the replacement of partial cement with the method of unitary andmulti-component were used to design the self-compacting steel fiber reinforced concrete. Thisstudy mainly focused on influences that multi-component of steel fiber and admixtures have onthe workability, strength and durability of the self-compacting concrete. It included theorthogonal test of slump divergence and compressive strength, the electric flux test ofanti-chloride ions penetration, the carbonizing test of anti-carbonization and micro structuredmercury intrusion porosimetry test and so on. We have drawn the following conclusions:(1) The orthogonal test studied the effects that water-binder ratio, sand ratio and thereplacement dosage and water reducing dosage of admixtures have on slump divergence andcompressive strength.The workability test states that the impact of water-binder is the strongest, water reducingdosage is weaker and sand ratio is the weakest. Also the admixture dosage has more or lesseffect. Because the multi-component admixtures improve the grain composition, they alsoimprove the workability.The strength test indicates that the influence of water-binder is the most outstanding,admixture dosage is middle, sand ratio is less and water reducing is the lowest. For themaintenance period of multi-component admixtures is28days, it has little impact on theconcrete strength. But if the maintenance period is increasing, it will finally influence thecompressive strength.(2) The electric flux test shows that the multi-component of admixtures can better improvethe anti-chloride ions penetration of concrete. With maintenance period of56days, the electricflux of unitary admixtures is about70%than that of normal concrete, binary concrete is around60%to70%and ternary concrete is50%.(3) The carbonizing test demonstrates that with the additive of admixtures, it decresed theconcrete anti-carbonization. And with the amount increasing, the degree of carbonization isfurther. If we add the multi-component admixtures, they can greatly improve such situation.Under the same conditions, ternary compound carbonization is1mm less than the binary’s and3mm less than the unitary’s. With no doubt that increasing the maintenance period is effectiveto decrease the degree of carbonization.(4) The mercury injection test makes it clear that admixtures can better improve the pore structures of concrete. And because the micro aggregations and superimposed effects ofmulti-component admixtures, the improvement of pore-size distribution is outstanding.(5) The addition of steel fiber can slow down the flowability of new concrete but also canimprove the compressive strength of hardened concrete. The maintenance period of28days canimprove the compressive strength increasing by around3%to5%and56days can be11%. Interms of the durability, steel fiber has side effect on the anti-chloride ions penetration. But therestraint of concrete self-constriction boosted the ability of anti-carbonization. The mercuryinjection test shows that the addition of steel fiber has little effect on the cement pore diameterstructures.