Effect of red mud on the filling performance of phosphogypsum bio-cement
To solve the problem that the strong acidity of the filling aggregate phosphogypsum degrades the material properties of bio-cemented backfill,the method of introducing alkaline solid waste red mud was put forward.We studied the effects of different mass fractions of red mud on phosphogypsum bio-cemented filling slurry and the mechanical properties of filling.The results show as follows:(1)Due to the properties of low water absorption,small particle size,and difficult settlement of red mud,when the mass fraction of red mud in filling aggregate increased from 0 to 80％under the action of MICP,the bleeding rate of filling slurry increased from 17％to 44％,the apparent viscosity decreased from 585 mPa·s to 121 mPa·s,and the initial and final setting time increased by 139％ and 135％,respectively.(2)The content of red mud affects the Uniaxial Compressive Strength(UCS)of backfill.When the red mud accounted for 20％of the total aggregate,the high alkalinity of the red mud could create a suitable alkaline environment for bacteria,inducing more cementation products and increasing the strength of the backfill up to 2 070 kPa.However,when the additional mass fraction of red mud in the filling aggregate is too high,UCS of the filling body will decrease.On the one hand,due to the relative reduction of calcium source in the aggregate,calcium carbonate production will decrease;on the other hand,the drying shrinkage of red mud itself will lead to the deformation of the filling body,damage the formed colloidal structure of calcium carbonate,and result in the reduction of compressive strength of filling body.This study provides a theoretical basis and technical support for the application of alkaline solid waste red mud in phosphogypsum bio-cemented backfill and realizes the resource utilization of solid waste.
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万方数据
维普
