Theory and Application of Gob-Side Entry Retaining in Thick Three-Soft Coal Seam

Table 2

Road-inside backfill body (RBB) concrete filling material mix proportions.

Item	Cementing material		Water	Aggregate		Additive
Ingredient	Cement	Fly ash	Water	Gravel	Sand	ESA & NSWA
Weight (kg/m^3)	400	80	185	950	700	5