Experimental research on mixture proportion and strength of cemented hydraulic fill with waste rock and eolian sand based on RSM-BBD

The selection of cement-tailings ratio directly determines both the strength of the filling body and the run- ning cost of a mine. The optimum ratio of waste rock and aeolian sand is obtained according to the packing density test of two kinds of mixed aggregates. Using Box-Behnken design and response surface methods ( RSM) in Design-Expert software,the influence laws of the slurry concentration,dosage of cement and aggregate ratio on the strength properties of cemented hydraulic fill (CHF) at different ages are studied. Two order polynomial regression model with three fac- tors is established,in which the strengths of 3 days,7 days and 28 days are used as response values. And the suitability of the regression model has been verified. The research shows that the strength of the filling body is not only affected by single factor,and the interaction between the two factors is also significant. According to the response surface,the initial,medium and post strength of backfill body are remarkably affected by the interaction of the slurry mass concen- tration and aggregate ratio,cement content and aggregate ratio and the slurry mass concentration and cement content respectively. By the regression model and the cost function of backfill materials,a set of optimum slurry mixture ratio is obtained,and the field test has proven that it can meet the requirement of production.