The Research for Surface Properties of Steel Slag Powder and High-Temperature Rheological Properties of Asphalt Mortar

In order to evaluate the feasibility of steel slag powder as filler,the coating properties of steel slag and limestone aggregate were compared by water boiling test,the micro morphology difierences between steel slag powder and mineral powder(limestone powder)were compared by scanning electron microscope(SEM),and the high-temperature rheological properties of asphalt mortar with difierent ratio of filler quality to asphalt quality(F/A)and difierent substitution rates of mineral powder(S/F)were studied by dynamic shear rheological test.The results show that the surface microstructure of steel slag powder is more abundant than that of mineral powder,and the adhesion of steel slag to asphalt is better than that of limestone.At the same temperature,the lower the ratio of S/F is,the greater the rutting factor and complex modulus will be.In addition,the complex modulus and rutting factor of the asphalt mortar increase with the increase of F/A,and the filler type and F/A have a negligible efiect on the phase angle.

Preparation of High Activity Admixture from Steel Slag,Phosphate Slag and Limestone Powder

The problem of low disposal and utilization rate of bulk industrial solid waste needs to be solved.In this paper,a high-activity admixture composed of steel slag-phosphate slag-limestone powder was proposed for most of the solid waste with low activity and a negative impact on concrete workability,combining the characteristics of each solid waste.The paper demonstrates the feasibility and explains the principle of the composite system in terms of water requirement of standard consistency,setting time,workability,and mechanical properties,combined with the composition of the phases,hydration temperature,and microscopic morphology.The results showed that the steel slag:phosphate slag:limestone=5:2:3 gave the highest activity of the composite system,over 92%.Besides,the composite system had no significant effect on water demand and setting time compared to cement,and it could significantly increase the 7 and 28 d activity of the system.The composite system delayed the exothermic hydration of the cement and reduced the exothermic heat but had no effect on the hydration products.Therefore,the research in this paper dramatically improved the solid waste dissipation in concrete,reduced the amount of cement in concrete and positively responded to the national slogan of carbon neutral and peaking.

Effect of Fine Steel Slag Powder on the Early Hydration Process of Portland Cement

Hydration heat evolution, non-evaporative water, setting time and SEM tests were peorormed to investigate the effect of fine steel slag powder on the hydration process of Portland cement and its mechanism. The results show that the effect of fine steel slag powder on the hydration process of Portland cement is closely related to its chemical composition, mineral phases, fineness, etc. Fine steel slag powder retards the hydration of portland cement at early age. The major reason for this phenomenon is the relative high content of MgO , MnO2, P2O5 in steel slag, and MgO solid solved in C3 S contained in steel slag.

Preparation of Reactive Powder Concrete Using Fly Ash and Steel Slag Powder

To decrease the cement and SF content of RPC by using ultra-fine fly ash （UFFA） and steel slag powder （SS）, the effect of these mineral admixtures on compressive strength of RPC were investigated. The experimental results indicate that the utilization of UFFA and SS in RPC is feasible and has prominent mechanical performance. The microstructure analysis （SEM and TG-DTG-DSC） demonstrated that the excellent mechanical properties of RPC containing SS and UFFA were mainly attributed to the sequential hydration filling effect of the compound system.

Experimental Research of Concrete with Steel Slag Powder and Zeolite Powder

In order to increase use ratio of steel slag solid waste,the concrete containing steel slag powder and zeolite powder as admixtures was prepared by using the orthogonal test method.The effects of water-binder ratio,sand ratio,steel slag powder content and zeolite powder on working properties,mechanical strength and chloride ion permeability of the concrete was studied.It was found that the early strength of the concrete had a decrease with the mixing of steel slag and zeolite powders,but its later strength approached to pure concrete.Moreover,the physical filling and pozzolanic activity of the admixtures increased the density of the concrete,resulting in the improvement of the durability of the concrete by the migration speed of Cl−reducing.The optimum mix ratio of C40 steel slag powder-zeolite powder concrete is obtained,and which had the slump of 220 mm,the 3 d,7 d and 28 d compressive strengths of 27.8 MPa,37.5 MPa and 48.4 MPa,the 6 h electric flux of 950 C and the diffusion coefficient of 1.65×10−12 m2/s.

Effects of Steel Slag Powder on Workability and Durability of Concrete

The workability and durability of a type of sustainable concrete made with steel slag powder were investigated. The hydrated products of cement paste with ground granulated blast furnace slag（GGBFS） alone or with a combined admixture of GGBFS-steel slag powder were investigated by X-ray diffraction（XRD）. Furthermore, the mechanism of chemically activated steel slag powder was also studied. The experimental results showed that when steel slag powder was added to concrete, the slumps through the same time were lower. The initial and fi nal setting times were slightly retarded. The dry shrinkages were lower, and the abrasion resistance was better. The chemically activated steel slag powder could improve compressive strengths, resistance to chloride permeation and water permeation, as well as carbonization resistance. XRD patterns indicated that the activators enhanced the formation of calcium silicate hydrate（C-S-H） gel and ettringite（AFt）. This research contributes to sustainable disposal of wastes and has the potential to provide several important environmental benefi ts.

Study on rapid stabilization of steel slag powder

Dry ball milling and wet ball milling were used to treat converter slag with particle size < 10 mm and the converter slag powder was stabilized by H_2O only and H_2O coupled with CO_2.respectively.Results showed that when CO_2 &H_2O was used,the free-calcium oxide(f-CaO) content in converter slag decreased significantly and after an-hour treatment the f-CaO content was reduced to 3%;however,when only treated by H_2O without CO_2, f-CaO needed 3-hour stabilization to decrease its content to 3%.When f-CaO in converter slag powder was treated by CO_2 &H_2O,its main reaction products were CaCO_3 and then Ca(OH)_2;however,when only H_2O was used, the f-CaO content decreased gently and the main products were Ca(OH)_2.

TiC-Maraging stainless steel composite:microstructure, mechanical and wear properties

Particulate TiC reinforced 17-4PH and 465 maraging stainless steel matrix composites were processed by conventional powder metallurgy （P/M）. TiC-maraging stainless steel composites with theoretical density 〉97% were produced using conventional P/M. The microstructure, and mechanical and wear properties of the composites were evaluated. The microstructure of the composites consisted of （core-rim structure） spherical and semi-spherical TiC particles depending on the wettability of the matrix with TiC particles. In TiC-maraging stainless steel composites, 465 stainless steel binder phase showed good wettability with TiC particles. Some microcracks appeared in the composites, indicating the presence of tensile stresses in the composites produced during sintering. The typical properties, hardness, and bend strength were reported for the composites. After heat treatment and aging, an increase in hardness was observed. The increase in hardness was at- tributed to the aging reaction in maraging stainless steel. The specific wear behavior of the composites strongly depends on the content of TiC particles and their interparticle spacing, and on the heat treatment of the maraging stainless steel.

钢渣复合矿粉对不同养护条件下混凝土性能的影响

为了探讨利用钢渣和矿渣制备复合掺合料的可行性,按质量比3∶7将钢渣与矿渣进行共同粉磨,制备复合矿粉,研究了复合矿粉对不同养护制度下混凝土的工作性和力学性能的影响,并对水化产物进行了表征。结果表明,复合矿粉使混凝土1 h的坍落度损失下降了6.9%,表现出了较好的保坍效果;在20℃标准养护和60℃蒸汽养护下,掺复合矿粉混凝土的立方抗压和轴向抗压强度与对照组相比均有所提高,但掺复合矿粉混凝土的劈裂抗拉强度均略低于对照组。微观分析发现,复合矿粉的掺入,使得生成的水化硅酸钙氧硅比降低,聚合度增加;水泥石总孔隙率由26.34%下降到23.99%;促进生成更多的水化产物。研究表明,在矿粉中掺入适量的钢渣粉制备复合矿粉具有较高的可行性,是同时实现钢渣和矿渣资源化利用的有效途径。

基于ICP-MS研究转炉钢渣微粉吸附镍和铅的动力学机理

随着工业化的发展,水体和土壤中的重金属污染日益严重。其中,重金属镍是一种常见的致敏性金属,会引起人体过敏发炎,甚至会引发癌症;血液中铅浓度的超标会危害人的神经系统、心血管系统和生殖系统,造成终身性的危害。因此,治理镍和铅重金属污染具有十分重要的意义。钢渣是炼钢过程中产生的一种副产物,其存在难以利用与附加值低的问题。同时加之管理制度的不健全,导致大量钢渣露天堆放,对土地资源、地下水源,以及空气质量造成严重影响。钢渣微粉具有比表面积大、多孔、化学活性高等特性,被广泛利用,可以成为吸附材料。本文以转炉钢渣微粉为研究对象,利用激光粒度仪、电感耦合等离子体质谱仪、比表面积与孔隙度吸附仪、X射线荧光光谱仪等测试转炉钢渣微粉的基本性质,重点研究转炉钢渣微粉添加量、重金属初始浓度、溶液pH和吸附时间对转炉钢渣微粉吸附Ni^(2+)、Pb^(2+)的效果,结合吸附动力学与吸附等温线理论揭示转炉钢渣微粉对Ni^(2+)、Pb^(2+)的吸附作用机理,为处理镍、铅重金属污染和工业废水处理提供技术支持与理论依据。结果表明:当转炉钢渣微粉添加量大于12.5 g·L^(-1)、重金属初始浓度小于100 mg·L^(-1)、溶液pH大于3和吸附时间大于120 min时,转炉钢渣微粉对Ni^(2+)、Pb^(2+)的吸附效果良好,即基本达到90%。转炉钢渣微粉对Ni^(2+)、Pb^(2+)的吸附符合准二级动力学模型,吸附速率由边界扩散和颗粒内扩散共同控制,吸附过程以化学吸附为主。转炉钢渣微粉的结构具有多孔性为物理吸附Ni^(2+)、Pb^(2+)提供吸附空间,转炉钢渣微粉的化学成分不仅具有碱性与Ni^(2+)、Pb^(2+)形成络合产物,而且水化过程中CaO与SiO_(2)生成C—S—H凝胶,对Ni^(2+)、Pb^(2+)形成络合吸附与硅酸盐体系包裹。转炉钢渣微粉对Ni^(2+)、Pb^(2+)吸附可能存在多层吸附。吸附Ni^(2+)、Pb^(2+)的过程为优惠吸附,吸附容易进行,其理论最大吸附量分别为18.785和17.002 mg·g^(-1)。

三元矿物掺和料胶砂试件性能研究

为解决煤矸石及钢渣作为单一掺和料强度不足的问题,以煤矸石、钢渣和矿粉为原材料制备复合掺和料水泥砂浆。研究不同配合比下掺和料对水泥砂浆抗压强度的影响,并利用X射线衍射(XRD)、热重-差热分析(TG-DTA)、扫描电镜(SEM)等手段分析不同体系试块的水化机理和微观结构。结果表明,单掺煤矸石、钢渣均表现出较低的活性,而矿粉具有良好的反应活性;三元掺和料中煤矸石-矿粉-钢渣复掺比例为1∶7∶2时,试块的抗压强度最高,28 d抗压强度可以达55.26 MPa。在三元掺和料体系中,煤矸石、矿粉和钢渣可以相互促进水化,增多水化产物,加深水化程度,三者具有一定的耦合作用,具有制备三元矿物掺和料的潜力。

水泥和钢渣粉协同固化高含水率疏浚泥的力学性能研究

研究了钢渣粉的掺入方式(内掺、外掺)和掺量(0、5%、10%、15%)对水泥固化高含水率疏浚泥力学性能的影响。结果表明:当水泥掺量一定时,随着钢渣粉外掺量的增加,固化疏浚泥的3、7、14、28、90 d无侧限抗压强度均先增大后减小,14 d峰值应力和峰值应变也呈先增大后减小的趋势,钢渣粉的最佳外掺量为10%;对于纯水泥固化疏浚泥,其变形系数随着水泥掺量的增加而增大,抵抗变形的能力降低;外掺适量钢渣粉降低了固化疏浚泥的变形系数,提高了固化疏浚泥抵抗变形的能力;钢渣粉内掺取代部分水泥降低了固化疏浚泥的无侧限抗压强度,建议钢渣粉采用外掺方式。

钢-PVA混杂纤维高性能混凝土抗渗性能试验研究

为探究钢纤维掺量、聚乙烯醇(PVA)纤维掺量和矿粉掺量对钢-PVA混杂纤维高性能混凝土(HFHPC)抗渗性能的影响,本文开展了钢-PVA HFHPC抗渗性能试验,并对试验结果进行了极差分析、方差分析和回归分析。结果表明:对HFHPC抗渗性能的影响程度从高到低依次为钢纤维、矿粉和PVA纤维。在试验水平范围内,得出混凝土试件抗渗性能最佳水平组合:钢纤维体积掺量1.0%、PVA纤维体积掺量0.7%、矿粉质量取代率20%。当钢纤维掺量超1.0%时,HFHPC抗渗性能略有下降,但仍高于基准素混凝土。最后采用多元回归分析,建立了HFHPC渗透系数与钢纤维、PVA纤维和矿粉的预测模型。

早强型钢渣基胶凝材料的制备及其水化机理研究

钢渣是炼钢过程中产生的主要废弃物,具有用途单一、产生量大、污染环境等特点。本文使用钢渣微粉、42.5普通硅酸盐水泥分别与增强剂Ⅰ、增强剂Ⅱ混合制备早强型钢渣基胶凝材料,通过测定原料化学成分、矿物组成,测试胶凝材料的力学性能,分析其热稳定性、微观形貌来揭示胶凝材料的水化机理。研究结果表明:胶凝材料的早期抗压强度大幅提高,后期抗压强度良好;这是因为增强剂能促进Ca(OH)2消耗并提高水化反应速率,Ca(OH)2水解出的OH-能促进钢渣微粉中玻璃体溶出硅酸盐,与Ca^(2+)生成C-S-H凝胶;增强剂含有的硫酸盐能与胶凝材料生成钙矾石AFt,并填充于凝胶孔隙中,增强了材料的密实度。早强型钢渣基胶凝材料的最优配比为钢渣微粉125 g、增强剂Ⅱ用量10 g。研究成果为早强型钢渣基胶凝材料的制备提供了新思路,也可为钢渣综合利用研究提供借鉴。

三元固废掺和料耦合机理分析和活化

为实现铁尾矿固废材料的再生利用,提高工业固废利用率,利用陶瓷粉和钢渣组成三元固废掺和料(铁尾矿-陶瓷粉-钢渣)并耦合活化。通过对铁尾矿进行不同时间的机械研磨,加入不同活化剂进行化学活化来提高铁尾矿的活性。采用差热-热重(DTA-TG)分析、扫描电镜(SEM)等方法研究三元掺和料的耦合活化和机械-化学活化机理。结果表明,适当增加铁尾矿研磨时间可以提升掺和料体系的活性指数,Na2SiO3活化剂对掺和料体系活性提升最显著。在三元掺和料体系中,铁尾矿、陶瓷粉主要起填充作用,而钢渣中活性CaO、硅酸二钙(C2S)和硅酸三钙(C3S)成分可以参与水化反应生成较多水化产物,从而提升后期强度,复掺时活性指数均满足普通型Ⅱ级掺和料使用标准,最高活性指数可达88.29%,具备制备三元复合掺和料的潜力。

Enhancing flotation recovery of residual carbon from gasification waste by mixing hydrophobic powder with diesel as collector

Coal gasification fine slag(CGFS)is a solid waste containing residual carbon and ash generated during the coal gasification process,and the separation of the two components is the essential way to realize its environmental pollution reduction and resource value increase.Froth flotation is the preferred method for separating CGFS,but there is a barrier of low carbon recovery in this process due to the extensive adsorption of collector by the well-developed pores on residual carbon.In this study,a sufficiently simple yet innovative collector,a mixture of hydrophobic powder and diesel,was proposed in an attempt to break the bottleneck.Flotation experiments with common diesel and this novel collector were performed respectively,and FTIR,XPS,and SEM-EDX were employed to analyze the collector action mechanism.Flotation results revealed that the novel collector could significantly improve the residual carbon recovery;test results demonstrated that the novel collector could increase the hydrophobic functional group content on the fine slag surface,and the hydrophobic powders in this novel collector mainly appeared at the pore openings of the flotation concentrate.The essence of the mechanism is that the hydrophobic powders play a dual role of blocking pores and providing adsorption sites,thus facilitating the spreading of diesel on the carbon surface and promoting its floatability.The study can provide creative ideas for the efficient disposal of coal gasification waste.

碳化养护制备钢渣粉3D打印材料及其性能研究

本工作提出了一种碳化养护钢渣粉3D打印材料的制备方法。以钢渣粉为主要胶凝材料,利用少量普通硅酸盐水泥的高水化活性保证材料打印成型后的初始强度,增强打印材料的可建造性,材料体系中硅灰颗粒的“滚珠效应”改善了打印材料的可挤出性,使用聚乙烯醇(PVA)、羧甲基纤维素钠(CMC)作为流变调节组分进一步调控打印材料的流变性能,满足材料打印性能需求。研究了拌合水固比与流变调节组分掺量对钢渣粉3D打印材料流变性能、打印性能与力学强度的影响规律,探究了碳化养护过程中钢渣粉3D打印材料成分变化与微观结构演变。结果表明,当浆料拌合水固比为0.16,PVA与CMC掺量分别为0.2%(质量分数,下同)、0.1%时,钢渣粉3D打印材料具有最佳的打印性能与力学强度,打印样品经12 h碳化养护后抗压强度为64 MPa,碳化养护过程中,大量镁方解石碳化反应产物填充基体孔隙,迅速提高打印材料基体的致密程度,是打印材料力学性能快速发展的主要机理。

钢渣基固废掺和料抗压强度与活性分析

为促进固废的资源化利用、解决钢渣活性指数不高等问题,以钢渣、矿渣、陶瓷粉(以下统称为SGC)为掺和料替代部分水泥制备复合胶凝材料。通过力学性能测试、扫描电镜、差热-热重(DTA-TG)和X射线衍射(XRD)分析,探索SGC掺和料体系在不同配比及掺量下对胶砂强度及水化产物的影响,并分析复合胶凝材料的水化机理,确定最佳活化方案。结果表明,单掺钢渣表现出较低的活性;钢渣-矿渣双掺组表现优于钢渣-陶瓷粉。在三掺体系中,水化早期钢渣和矿渣水化生成Ca(OH)_(2)和少量的水化硅酸钙(C-S-H)、水化铝酸钙(C-A-H)胶凝,提供早期强度,活性SiO_(2)和Al_(2)O_(3)与Ca(OH)_(2)发生二次水化反应生成大量C-S-H、C-A-H凝胶等水化产物。且三掺体系部分未发生反应的颗粒相互填充,因此SGC三元掺和料体系中存在耦合协同作用,共同促进体系强度增加,具备制备掺和料潜能。其中,钢渣、矿渣、陶瓷粉质量比为2∶1∶1,并以30%等质量替代水泥时,胶砂抗压强度最高,28 d抗压强度为45.6 MPa,活性指数达到93.08%。

钢渣粉对高强混凝土力学性能和耐久性的影响

超细矿渣是制备高强混凝土的优质矿物掺合料,但是超细矿渣水化放热量较大、凝结较快,不利于高强混凝土的强度和耐久性发展。而钢渣粉具有延缓水泥水化、降低水化放热的作用,可以充当“缓凝剂”。通过在高强混凝土中复掺钢渣粉和超细矿渣,研究了钢渣粉对高强混凝土性能的影响。结果表明复掺15%钢渣粉时初凝时间和终凝时间分别比纯水泥组延长53.0%和35.9%。同时早期强度降低,但与超细矿渣复掺后28 d和90 d强度分别为77.3 MPa和84.6 MPa,比对照组高4.3%和8.6%。此外,钢渣粉有效降低了高强混凝土的绝热温升和自收缩率。单掺15%超细矿渣时7 d自收缩率为1189.63×10^(-6),约为纯水泥组的2.5倍;复掺15%钢渣粉时自收缩率为211.62×10^(-6),比纯水泥组降低了52%。复掺钢渣粉的高强混凝土与纯水泥制备的混凝土的抗氯离子渗透性等级均为“低”。

改性材料及其掺量对超高性能混凝土力学性能的影响

【目的】优选不同掺量的改性材料,并分析改性后的UHPC抗压强度和破坏形态,制备更加经济型的超高性能混凝土(ultra-high performance concrete,UHPC)。【方法】选取钢渣微粉、河砂、粗骨料、钢纤维作为4种改性材料,设计四因素三水平正交试验,根据正交试验结果制备9种试件;通过力学性能实验,对比分析各试件的抗压强度,优选出改性材料最佳配方并分析UHPC的破坏形态。【结果】钢渣微粉、河砂、粗骨料和钢纤维的加入量(掺量)对试件抗压强度平均值影响的极差分别为7.60、7.57、7.77、0.84,粗骨料、钢渣微粉、河砂对UHPC的抗压强度的影响较大,钢纤维对UHPC抗压强度影响较小。由正交试验结果可知,当钢渣微粉、河砂、粗骨料的加入量分别为210、855、640 kg/m^(3),钢纤维的体积分数(掺量)为1.5%,养护龄期为28 d时,经改性的UHPC抗压强度最大,为134.4 MPa。改性后的UHPC受压破坏时不会瞬间炸裂,整体形态完整。【结论】钢渣微粉和粗骨料的添加能降低改性后的UHPC制造成本,经优化4种改性材料的掺量后UHPC的抗压强度降幅较小,但韧性增强,力学性能得到保障。