Table 4 Levels of factors.
From: Uniaxial compressive strength of cemented coal gangue backfill based on response surface methodology
Levels of factors | Mass concentration | Fly ash content | Fine gangue ratio |
|---|---|---|---|
Code | X1 (%) | X2 (kg) | X3 (%) |
− 1.000 | 80.0 | 3.0 | 35.0 |
0.000 | 80.5 | 3.5 | 40.0 |
1.000 | 81.0 | 4.0 | 45.0 |
