矿渣微粉对细尾砂胶结充填体力学性能及微观结构影响

Effect of slag powder on mechanical properties and microstructure of fine tailings cemented backfill

本文研究了不同矿渣微粉掺量对充填体早期、长龄期强度以及充填料浆流动性、泌水率的影响规律,通过采用X射线衍射(XRD)、扫描电镜(SEM)等技术手段对特定龄期充填体水化产物进行了微观表征并揭示了其强度发展机制。研究结果表明:充填体养护早期(3 d),矿渣微粉的掺入不利于其强度的发展,且掺量越高,充填体强度降低幅度越大;养护龄期超7 d后,矿渣微粉对充填体强度提升作用开始显现,且充填体养护龄期越长,相同掺量下强度提升效果越明显。充填浓度70%,灰砂比1∶6,矿渣微粉掺量80%时,充填体养护28 d、90 d后强度分别为5.02 MPa和6.53 MPa,相较养护7 d充填体强度分别提高211.80%和305.59%。少量矿渣微粉的掺入在一定程度上会降低充填料浆流动性和泌水率,但当矿渣微粉掺量较高时,充填料浆流动性和泌水率均有一定程度的提高。矿渣微粉掺入后充填体内部水化硅酸钙凝胶(C—S—H)、钙矾石(3CaO·Al_(2)O_(3)·3CaSO_(4)·32H_(2)O)等水化产物生成数量的增加,是导致其强度高于纯水泥充填体的重要原因。

The effects of different slag powder content on the early and long-term strength of the backfill and the fluidity and bleeding rate of the filling slurry are studied.The hydration products of the backfill at a specific age are characterized by utilizing X-ray diffraction(XRD)and scanning electron microscope(SEM),and the strength development mechanism is revealed.The results show that at the early stage of backfill curing(3 d),the addition of slag powder is not conducive to the development of backfill strength,and the higher the addition amount is,the greater the reduction backfill strength.After the curing age exceeds 7 d,the effect of slag powder on the strength improvement of backfill begins to appear,and the longer the curing age of backfill is,the more pronounced the compressive strength improvement effect is under the exact dosage.When the filling concentration is 70%,the cement-sand ratio is 1∶6,and the slag powder content is 80%,the compressive strength of the backfill after curing for 28 d and 90 d is 5.02 MPa and 6.53 MPa,respectively,which is 211.80%and 305.59%higher than that of the backfill after curing for 7 d.A small amount of slag powder can reduce the fluidity and bleeding rate of the filling slurry to a certain extent,but when the slag powder content is high,both the fluidity and bleeding rate of the filling slurry are improved to a certain extent.The increased number of hydration products such as C—S—H and ettringite(3CaO·Al_(2)O_(3)·3CaSO_(4)·32H_(2)O)in the backfill caused the strength of the backfill to be higher than that of the pure cement backfill.