Abstract:The introduction of filling technology into alpine regions can effectively reduce mining damage to the environment. Aiming at the lack of research on the mechanical properties and consolidation mechanism of the tailings cemented backfill at low temperature, the experiments of uniaxial compression, XRD analysis, thermal analysis and SEM observation were carried out to study the filling body specimens under curing at 5 ℃, the strength evolution law and consolidation mechanism of cemented filling body in low temperature environment were analyzed and discussed from characterization and quantification. The results show that low temperature has a greater impact on the early strength of tailings cemented filling body, among which the main factors are in descending order: cement-tailings ratio, curing age, mass concentration. The main diffraction characteristic peaks of AFt and CSH of cement paste at low temperature are lower than those at room temperature. There is no main diffraction characteristic peak of AFt for cement paste without admixtures at 7 d age, the diffraction characteristic main peak of AFt for cement paste with admixtures at 7 d age appears, which is conducive to the improvement of the early strength of the filling body. At low temperature, the TG-DSC and DTG curves of cement paste with or without admixtures are similar, with 5 endothermic peaks and 4 weight loss peaks. At 7 d age, the TG curve of cement paste with admixtures is below the TG curve of cement paste without admixtures. The weight loss peaks of cement paste with admixtures are also greater than those of the cement paste without admixtures, which is conducive to the early generation of more hydration products in the filling body. In a low temperature environment, the additions of Na₂CO₃ and NaOH can significantly increase the early strength of the filling body, but it is not conducive to the mid-to-late strength growth.

Key words: cemented filling body; alpine regions; consolidation; hydration product; admixture