Meikuang Anquan (Jul 2023)
Performance study on filling and treating fly ash-building aggregate slurry in coal mining subsidence area
Abstract
In order to effectively combine the filling governance of coal mining subsidence with utilization of solid waste, in this paper, fly ash and construction solid waste are used as raw materials to make filling slurry, and the physical and mechanical properties of different proportions and types of slurry are studied. The results show that the fluidity of fly ash cement slurry decreases with the decrease of water-solid ratio and the increase of fly ash proportion. The structure and properties of fly ash have a great influence on the performance of slurry. The minimum value of serous stone rate in each group was 93.7%, and the maximum value was 97.3%, the compressive strength of slurry stone at each age increased with the decrease of water-solid ratioand the maximum compressive strength at 28 days and 90 days reached 3.95 MPa and 8.15 MPa respectively. The proportion of cement has an obvious effect on the compressive strength of stone body, when cement∶fly ash increases from 2∶8 to 2.5∶7.5, the average growth rate of slurry stone compressive strength is 81.2% and when cement∶fly ash increases from 2.5∶7.5 to 3∶7, the average growth rate of slurry stone compressive strength is 25.5%. The building aggregate slurry prepared in this study has appropriate fluidity and high stone rate, and the average compressive strength of the slurry stone body at 28 days and 90 days is increased by 61.3% and 27.6% respectively, compared with the basic fly ash cement slurry; it is known that the structure of the stone body has low density and loose distribution in the early stage. In the later stage, with the continuous generation of products such as Ca（ＯＨ）2, AFt and gel, the internal compactness increases. The addition of aggregate further increased the compactness of the system, which caused increase of the compressive strength of stone body.
Keywords
