Study on proportion optimization of coal-based solid wastes filling materials

The aim of this study is to prepare a low cost and high strength filling material.Coal gangue is aggregate.Fly ash,desulfurization gypsum and silicium-calcium slag are cementing materials.The uniaxial compressive strength , slump and slump flow of the specimen were measured to investigate the mechanical properties and the influence of each component.The result shows that desulphurization gypsum content and silicium-calcium slag have a strong gelation effect in certain amount range.With the increase of content of fly ash , the initial strength of filling material increases slowly.The content of fly ash should be controlled less than 6.67%.The mixing of fly ash and silicium-calcium slag could activate cementious properties of silicium-calcium slag performance.The optimum mass ratios of coal gangue,fly ash,desulfurization gypsum,silicium-calcium slag and cement are70:6:3:12.5:8.5.The conclusion is verified by response surface method,and the experimental results are consistent with the prediction.