Study Mixing Coal Gangue Concrete With Dynamics And Shrinkage

Coal gangue is a kind of industrial waste residue produced in coal mining and washing process. At present, there is more than 50 billion tons of coal gangue storage in our country, which takes a lot of land. Moreover, harmful gas continuously discharges which serious pollutes the environment. While the use of coal gangue as part replacement of gravel in the concrete products can cut down the use of natural aggregates in the construction industry and makes high economic and social benefits.In this project, gangue was used as coarse aggregates for replacing partial crushed stone in the preparation process of concrete mixed with gangue.The influence of gangue addition,replacement ratio by fly ash, water to binder ratio and the addition of superplasticizer on the fluidity, mechanical properties and contraction properties of concrete mixed with gangue was investigated.The result show that, the fluidity and mechanical properties of concrete decreased as the addition of gangue increased. The value of concrete contraction increased and then decreased. With the increase of fly ash, the fluidity, mechanical properties andcontraction properties were improved. The influence of fly ash on the mechanical properties and contraction properties arose in later age. With the increase of water to binder ratio, the fluidity of concrete increased, the mechanical properties decreased. The lower the water to binder ratio was, the larger the contraction value was. With the increase of addition of superplasticizer, the fluidity and mechanical properties increased. With a large amount of superplasticizer, the early contraction of concrete was inhabited well. However, it is unfavourable for the later contraction. Therefore, the addition of superplasticizer should be controlled in a certain scope. The optimum mix ratio of the mechanical properties of concrete was obtained using orthogonal analysis and linear regression analysis and the ratio was that the addition of fly ash was 20%, water to binder ratio was 0.38 and the addition of gangue was 30%. Meanwhile, the water to binder ratio was the main factor affecting the concrete strength and the addition of gangue was the second then the replacement ratio by fly ash. The regression equation was Y=99.65889+0.01728 X1-124.25X2-0.01897X3. The optimum mix ratio of the contraction performance of concrete was that the addition of fly ash was 35%, water to binder ratio was 0.44, addition of gangue was 55% and addition of the superplasticizer was 1.5%. Meanwhile, the water to binder ratio was the main factor affecting the concrete contraction and the replacement ratio by fly ash was the second then the addition of gangue and the addition of superplasticizer was the least factor. The regression equation was Y=738.20178-0.29528X1-1067.95X2+0.000978X3-0.18912X4.