doi:10.16186/j.cnki.1673-9787.2023080046

Received:2023-08-31

Revised:2023-10-23

Online Date:2023-11-30

Study on properties and hydration mechanism of new fluorine gypsum-basedfilling material（Online）

WANG Chun1,2, ZHANG Yifei1, ZHU Mingli1, REN Yumeng1, ZHAN Shuaifei1

1.School of Energy Science and Engineering，Henan Polytechnic University，Jiaozuo  454000， Henan，China;2.Collaborative Innovation Center of Coal Work Safety and Clean High Efficiency Utilization， Jiaozuo  454000， Henan ，China

Abstract:Aiming at the problem of high cost of cement-based filling materials， fluoropgypsum and fly ash were used instead of cement as cementing materials. The optimal ratio of fluoropgypsum based filling materials was determined by orthogonal experiment method， and its mechanical properties， hydration products， hydration mechanism and microstructure were studied. Combined with the results of regression analysis and orthogonal experiment， the strength of the optimal matching material backfill for 1 d， 7 d and 28 d could reach 1.41 MPa， 4.11 MPa and 6.47 MPa， and the slump， diffusion and bleeding rate of the paste were 22.7 cm， 42.6 cm and 2.58% respectively. The three influencing factors in the material ratio are the content of fluorine gypsum， the content of fly ash and the concentration of slurry. The factor that has the greatest influence on the strength of filling belt is the concentration of slurry on the 1 d， the strength of 7 d and 28 d and the flow rate is the content of fly ash； the factor that has the greatest influence on the slump and diffusion of paste is the content of fluorine gypsum. The uniaxial failure mode of the backfill is shear failure， and the cohesion and internal friction angles are 2.02 MPa and 32.6° respectively. The hydration products include ettringite， calcium sulfate dihydrate and calcium silicate hydrate gel， and the fluorine gypsum consolidated body is transformed from anhydrous phase to diaqueous phase， in which the increase of ettringite and calcium silicate hydrate gel will form a dense structure， which is conducive to the improvement of strength. The experimental results show that the paste prepared with fluorine gypsum hasthe feasibility of filling, and the amount of solid waste accounts for more than 90%, the cost is low, it can bring significant economic benefits, and the application prospect is bright.

Key words:fluorine gypsum-based filling material;mechanical properties;hydration mechanism;hydration products;microstructure

CLC：TD803;TQ177.375