Study On The Compressive Strength And The Early Crack Resistance Of Steel Slag Concrete

The early cracking of concrete is one of the hot spot of current research at home and abroad.This topicused the steel slag powder, the sand shape steel slag, the stone shape steel slag respectively and equallyreplaced the cement, fine aggregate, coarse aggregate in the concrete to compound steel-slag concrete.According to the two indexes of the strength and the early cracking resistance of steel slag concrete, aroundthe influence factors: the water binder ratio, amount of different size steel slag to do experimental research.The research focused on many influence factors such as water-binder ratio, steel slag dosage in differentgrain diameter by set up two experimental indexes: strength test were taken1d,3d,7d,28d,60dcompressive strength of steel slag concrete strength as the evaluation index, and take early cracking testused knife-edge method, the maximum crack width, crack length and per unit area on the total crack area asthe steel slag concrete’s early cracking performance evaluation index. The test results show that:（1）The stability test results show that, the steel slag powder and sand shape steel slag in concretedosage should not be more than70%,85%; the sand(stone) shape steel slag are1.2%and1.37%tested bysaturated vapour pressure method, and it could be found that the slag powder of large particles sieve area ismore than small particles of sieve area, this indicates that the steel slag of larger particles sieve area volumestability is relatively poor.（2）The strength tests show should that the optimal dosage of the steel slag powder and the sandshape steel slag in concrete content are10%,30%. When the water-cement ratio is constant, thecorresponding optimal dosage steel slag concrete strength at28ages are near or higher than ordinaryconcrete.（3）When water-cement ratio are0.30and0.35and0.40, use the same amount of pre-absorbent stoneshape steel slag preparation instead of coarse aggregate mixing concrete.the compressive strength of slagconcrete at28d and60d ages is increases first and decreases afterwards with the increasing of steel slagdosage, the optimal dosage of stone shape steel slag is30%at the same water-cement ratio.（4）Water-cement ratio is one of the most important factors that affect the steel slag concrete crackresistance. In constant water-cement ratio, crack resistance of steel slag concrete are superior to thecorresponding water-binder ratio of normal concrete, and the crack resistence of steel slag concrete isincreased as the water-cement ratio increased. Under the same conditions, mixing pre-absorbent stoneshape steel slag concrete crack resistance is stronger than mixing the pre-absorbent the sand shape steelslag concrete, the crack resistance of the steel slag powder concrete only stronger than ordinary concrete.（5）From the view of internal curing, the pre-absorbent porous steel slag can effectively restrain theearly shrinkage of steel slag concrete by improving the internal relative humidity of concrete, in addition, itis helpful to improve the early cracking resistance of concrete.（6）The test results analysis show that, the compressive strength and the early crack resistance ofsteel slag concrete may meet the needs of the engineering construction. The steel slag concrete can not onlyimprove the structural strength of concrete but also reduce early cracked concrete and effectively solve theproblems of rational use of slag, play energy conservation, the role of protecting the environment andreducing the cost of production of concrete.