钢渣-钒钛矿渣基坑回填料的制备及机理

为了推动钢铁冶金废弃物的综合利用，以钢渣、钒钛矿渣为原料替代水泥制备了全固废预拌固化剂，再与黏土制成基坑回填料，采用力学性能测试法、X射线衍射(X-ray diffraction, XRD)、扫描电镜(scanning electronic microscopy, SEM)和能谱分析(energy dispersive spectrometry, EDS)等测试手段，研究了钢渣细度、钢渣掺量及固化剂掺入比对基坑回填料性能的影响，并测试预拌固化剂的稳定性及水化机理。结果表明：当钢渣比表面积为457 m²/kg,料浆浓度(质量分数)为80%,固化剂掺入比(质量分数)为20%,固化剂配比(质量比)为钢渣∶脱硫石膏∶钒钛矿渣=44∶10∶46时，用其制备的基坑回填料力学性能较好，此时固化剂净浆流动度为136 mm且安定性合格，稳定性优于P·O 42.5普通硅酸盐水泥；在固化剂掺入比为7%～25%,掺入占胶结剂总量0.4%PC型聚羧酸型高效减水剂(polycarboxylic acid, PC),基坑回填料28 d抗压强度均大于0.4MPa,最大为4.7 MPa,回填料坍落...

Preparation and Mechanism of Foundation Pit Backfilling Materials containing Steel slag and Vanadium-Titanium Slag

In order to promote the comprehensive utilization of iron and steel metallurgical wastes, steel slag (SS) and vanadium-titanium slag (VTS) were used as raw materials to replace cement to prepare the full solid waste premixed solidified agent (PSA), then PSA, clay and water were mixed foundation pit backfilling materials (FPBM). The effects of SS fineness, SS content and PSA ratio on the properties of FPBM were investigated via mechanical property test, X-ray diffraction (XRD), scanning electronic microscopy (SEM), and energy dispersive spectrometry (EDS), the soundness of the PSA is tested and the hydration mechanism of the PSA is analyzed. The results show that when the specific surface area of SS is 457 m²/kg, the slurry concentration is 80%, the mixing ratio of PSA is 20%, and the ratio of PSA is SS: desulfurization gypsum: VTS = 44:10:46, the mechanical properties of FPBM prepared with it are better. At this time, the fluidity of curing agent slurry is 136 mm, the stability is qualified, and the stability is better than P . O 42.5 ordinary Portland cement; When the mixing ratio of curing agent is within 7% ~25%, PC water reducer accounting for 1.6% of the total amount of PSA is added. The 28-day compressive strength of FPBM is greater than 0.4 MPa, the maximum value is 4.7 MPa, and the slump of FPBM is greater than 150 mm, which meets the index requirements of T/CECS 1037-2022 Technical standard for backfilling projece by using premixed fluidzed solidified soil. According to the mechanism study, the mineral phases of the PSA after hydration are: C2S, C3S, Ca (OH)2, ettringite (AFT) , C-S-H gel and RO phase. C2S, C3S, CaSO4 and other substances gradually disappeared with the hydration, the crystal content of AFt and C-S-H gel increased.