Wellbore special concrete admixtures

The invention discloses a special concrete additive for shafts, which comprises 6 to 10 weight parts of water reducer, 60 to 80 weight parts of mineral powder, 10 to 15 weight parts of siliceous dust and 16 to 37 weight part of fly ash. When the additive is used for making concrete, the added amount of the additive is 10 to 20 percent, and under a condition of low sand and stone quality level, concrete with a C60 to C100 strength grade can still be made.