Zhang Yannian, Dong Mengwei, Zhang Wenjie, Chen Hao, Yang Daokui
School of Civil Engineering, Shenyang Jianzhu University, Shenyang 110168, China.
Materials (Basel). 2022 Jul 25;15(15):5162. doi: 10.3390/ma15155162.
Iron tailing solid waste not only has a high annual output but also has a low comprehensive utilization rate. Low utilization rate of iron tailings seriously restricts the development of comprehensive utilization of solid waste. In order to prepare an iron tailings-based ternary solid waste admixture and to verify its application to concrete, first, the effect of solid waste synergy on the strength of an iron tailings-steel slag-desulfurization ash admixture (ISD) system was investigated. Second, the effect of chemical activator dosing on the strength of an ISD system was studied and the mechanism of chemical activator action on the ISD system was investigated by thermogravimetric analysis (TG-DTA) Then, the effect of this admixture on the strength of concrete was studied. Finally, the mechanism of the effect of this admixture on the strength of concrete was clarified by mercury intrusion porosimetry (MIP) and backscattering electron tests (BSE). The results showed that the 7 d and 28 d compressive strengths of the ISD admixture were significantly higher than those of iron tailings single admixture. The 7 d and 28 d compressive strengths of the ISD system reached 24.9 MPa and 36.1 Mpa, respectively, when the ratio of iron tailings:steel slag:desulfurization ash = 1:1:1. NaSiO is suitable for the early strength agent of the ISD admixture, but the amount of admixture should not exceed 0.6% of the admixture. TG-DTA shows that NaSiO is enhancing the early strength of the ISD system by promoting the consumption of Ca(OH) in the ISD system to produce C-S-H. However, in the late reaction of the ISD system, NaSiO inhibits the late strength development of the ISD system by suppressing Ca(OH) production. Concrete with ISD dosing of 30% or less meets the C40 requirement. MIP and BSE show that ISD provides a filling effect to concrete, but also causes a reduction in the active reactants of concrete and the combined effect of microfilling and active effects affects the strength development of ISD concrete. This study provides a theoretical and scientific basis for the preparation of iron tailings-based ternary solid waste dopants, and, in addition, the study promotes the consumption of iron tailings solid waste and the development of multiple solid waste dopants.
铁尾矿固体废物不仅年产量高，而且综合利用率低。铁尾矿的低利用率严重制约了固体废物综合利用的发展。为了制备一种基于铁尾矿的三元固体废物掺合料并验证其在混凝土中的应用，首先，研究了固体废物协同作用对铁尾矿-钢渣-脱硫灰掺合料（ISD）体系强度的影响。其次，研究了化学激发剂用量对ISD体系强度的影响，并通过热重分析（TG-DTA）研究了化学激发剂对ISD体系的作用机理。然后，研究了这种掺合料对混凝土强度的影响。最后，通过压汞法（MIP）和背散射电子试验（BSE）阐明了这种掺合料对混凝土强度影响的机理。结果表明，ISD掺合料的7天和28天抗压强度显著高于铁尾矿单一掺合料。当铁尾矿:钢渣:脱硫灰的比例为1:1:1时，ISD体系的7天和28天抗压强度分别达到24.9MPa和36.1MPa。硅酸钠适用于ISD掺合料的早强剂，但掺量不应超过掺合料的0.6%。TG-DTA表明，硅酸钠通过促进ISD体系中Ca(OH)的消耗以生成C-S-H来提高ISD体系的早期强度。然而，在ISD体系的后期反应中，硅酸钠通过抑制Ca(OH)的生成来抑制ISD体系后期强度的发展。ISD掺量为30%及以下的混凝土满足C40要求。MIP和BSE表明，ISD对混凝土起到填充作用，但也导致混凝土活性反应物减少，微填充和活性效应的综合作用影响了ISD混凝土的强度发展。本研究为制备基于铁尾矿的三元固体废物掺合料提供了理论和科学依据，此外，该研究促进了铁尾矿固体废物的消耗以及多种固体废物掺合料的发展。
