Sampling and Mechanical Testing of Backfill in Large Mined-Out Area

Table 2

Description of backfill.

Classification	Particle size	Colour	The strength	Cementing effect
No.1	Uniform	Offwhite	Better	Better
No.2	Mainly made of fine particles	Dark grey	Better, light	Better
No.3	Mainly made of coarse particles	Offwhite	Better, heavy	Better
No.4	Mainly made of coarse particles	Dark grey	Worse	Worse