The application of power plant ash to mine goaf filling can enrich aggregate source and consume a large amount of solid waste，which has important social benefits.Power plant ash mainly refers to the ash produced by coal-fired power generation，which is a kind of bulk solid waste with the characteristics of large discharge and low utilization rate.The properties of ash produced by different types of power plants are very different，but they generally have certain pozzolanic activity and gelation characteristics，so they are good filling materials.In order to explore the influence of different ash residues on the strength of the filling body，fluidized bed bottom slag，fluidized bed fly ash and fly ash were mixed with different ratios as filling aggregate，ordinary silicate cement was used as cementation material，and add water to prepare paste material，then fluidity test and compressive strength test were carried out.The results show that：（1）The fluidized bed ash contains some cementation components，the fly ash has the water-reduction effect and the pozzolanic activity，both of which are good downhole filling materials.（2）When the moisture content of paste material exceeds its critical moisture content，the fluidity will be greatly improved，which will also lead to segregation and dehydration of the filling material，then reduce the strength of the filling body.（3） When the ratio of fluidized bed bottom slag，fluidized bed fly ash and fly ash is 6∶2∶1，cement content is 10%，the slurry concentration is 73%，the slump is 20 cm，and the 28 d strength of the filling body can reach 3.3 MPa.This ratio not only meets the requirements of slurry fluidity and backfill strength，but also greatly reduces the filling cost.（4）Taking the above ratio as the control group，the grading optimization experiment was carried out.The undisturbed bottom slag was broken，then the fine particles with different particle sizes and proportions were used as fine aggregate to replace the undisturbed bottom slag.When the particle size of the broken bottom slag less than or equal to 5 mm and the replacement rate is 10%~15%，the strength of filling body reaches 2.4 MPa on 7 day and 3.5 MPa on 28 day，and the strength is significantly improved.The experimental study of the paste filling material prepared from the ash residue of power plant with a specific ratio provides data support and theoretical basis for engineering application，which is of economic value and environmental protection significance.

http://www.goldsci.ac.cn/article/2021/1005-2518/1005-2518-2021-29-4-582.shtml