Aeolian Sand Paste Filling Material Ratio Based on Repeated Orthogonal Test

In order to provide a high-quality, low-price paste filling material ratio for filling and mining in Shagoucha Coal Mine in northern Shaanxi Province. In this paper, aeolian sand is used as the filling aggregate, and four factors of different (fly ash, cement, aeolian sand) and slurry mass concentration are used as the objects, three levels were taken from each object, and the effect of these levels on the slump, bleeding rate, and compressive strength of the filling material at 7 days and 28 days was studied by means of a repetitive orthogonal experiment. The results showed that: the slurry concentration had the most significant influence on the slump and the bleeding rate, and the other factors had less influence; when the slurry mass concentration of 74% and 76% was selected, the requirements of slump and bleeding rate were met. Through the analysis of range and variance, it is found that the most obvious and most important factor for the compressive strength of the filling body at 7 days and 28 days is the cement content, followed by the amount of fly ash, and then the amount of aeolian sand, but, when the amount of aeolian sand is more than 45%, the compressive strength at different ages is gradually reduced. Finally, the slurry mass concentration has the least influence on the compressive strength. Through comprehensive analysis, the optimal ratio was obtained: the fly ash was 440 kg/m3, the cement was 220 kg/m3, the eoluvial sand was 45%, and the mass concentration was 76%.