The Dosage of Superplasticizer in Cemented Coal Waste Backfill Material Based on Response Surface Methodology

Table 1

Chemical and physical properties of coal gangue, fly ash, and cement [7].

	Coal gangue	Fly ash	Cement
SiO2	28.46	52.42	22.36
Al2O3	16.11	32.48	5.53
Fe2O3	10.86	3.62	3.45
CaO	7.15	3.05	65.08
MgO	3.50	1.01	1.27
TiO2	0.80	1.26	—
Specific gravity (g/cm^3)	2.0	2.2	3.1
Specific surface (m^2/kg)	499	415	349
Fineness (>45 μm) (%)	53.78	42.54	5
Moisture content (%)	8.0	0.56	—
Loss on ignition (%)	—	3.8	2