Study On The Effect Of Coal Gangue Mineral Admixture On The Performance Of High-strength Concrete

With the highly efficient aliphatic water reducer and the high active mineral admixture, high-strength concrete in low water binder ratio can be prepared. Due to the shortage of high quality admixtures in our country has been a prominent phenomena, the development of new admixture is imminent. Coal gangue is rich in silicon, aluminum components, after the activation treatment has a certain activity and effect of the micro-aggregate. So the preparation of high quality mineral admixture by coal gangue is possible. Study on making use of coal gangue to prepare mineral admixture is not mature, especially coal gangue. This paper is the National Natural Science fund committee and Shen Hua group co. LTD. jointly funded projects "Research on key scientific problem of Coal gangue in cement and concrete utilization"(U1261122).All the research results are funded by this foundation. The research results as follows:(1)Cement Glue Sand strength evaluation shows:The particle size is less than or equal to 2.5mm coal gangue after calcination treatment and attrition treatment,30% calcined coal gangue-cement glue sand strength is 42.91MPa, the activity index is 0.89. Better than I fly ash, and slightly inferior to S95 slag.(2)The orthogonal test result of compound mineral admixtures show that:fly ash is the best in improvement of properties of concrete mixture workability; With polycarboxylic acid type water-reducer, the effects of coal gangue and silica fume mixed with fly ash. The influence size order of different mineral admixtures on the strength of high strength concrete contribution is calcined coal gangue> spontaneous combustion gangue> fly ash. Several kinds of admixtures increase the long-term strength of concrete with different degree, calcined coal gangue blended with silica fume is the best in improvement of properties of concrete long-term strength.(3) The result of a single factor contrastive experiment of C70 calcined coal gangue mineral admixture shows:The mixing amount of calcined coal gangue has little influence on the slump of fresh concrete mixture. The gradual loss increases with the mixing amount. The concrete 7d strength of 10%mixing amount of calcined coal gangue is the highest. With increasing mixing amount of strength decreased. The concrete 28d strength increased at first and then decreased with the increasing mixing amount, The concrete 28d strength reached peak at 20%. Less than 20%, the concrete strength at 56d still have improved. Incorporation of calcined coal gangue can significantly improve the chloride-penetration resistance of concrete, Incorporation is within 30%, Electric flux at 28d and 56d dramatically reduce with increased incorporation. Coal gangue mineral admixture concrete has excellent frost-resisting property. Calcined coal gangue can improve the frost-resisting property of concrete. The surface still have no significantly abscission, after 1500 times freeze-thaw circle. Quality and loss rate of dynamic elasticity can meet standard requirements. The results of the study show that, preparation of high strength concrete adding single calcined coal gangue is feasible.