Mixing Slag Research Articles

Analysis of the mechanical properties and prediction of damage life for GBFS-HPMC/fibre pervious concrete after seawater erosion

Pervious concrete has been used in coastal structures to erosion seawater. Based on the orthogonal test method, the effects of granulated blast furnace slag (GBFS), hydroxypropyl methylcellulose (HPMC), and polypropylene plastisol textile fibre (PPTF) on the performance of permeable concrete after seawater erosion were investigated ; the results showed the following: After 30, 60, and 90 d of seawater erosion, the optimal additions of GBFS, HPMC, and PPTF were (15%, 0.15%, 0.5%), (20%, 0.15%, 0.5%), and (20%, 0.15%, 0.5%) respectively. Compared with C-0, the mass loss rate and strength loss rate were reduced by up to 61.60% and 63.93%, respectively, and the relative kinetic–elastic modulus was increased by up to 11.14%. Micromorphology revealed that the proper mixing of slag, cellulose, and plastic fibre significantly improves the structure's stability. Finally, using the relative kinetic–elastic modulus for Weibull and NSGM(1,N) models predictions provides more accurate results.

The Use of PCB Scrap in the Reduction in Metallurgical Copper Slags.

The article presents the results of a study on metallurgical sludge reduction using electronic waste such as Printed Circuit Boards (PCBs). Two aspects were taken into account when selecting such a reducer, namely the environmental aspect and the technological aspect. The research was an attempt to use waste metal-bearing material of which the effective management causes many problems from an environmental point of view. In the technological aspect, the specific chemical composition of this waste was taken into account. Its gasification yields significant amounts of hydrocarbons, which are excellent reducing agents in such process. The separation of these compounds may additionally cause the mixing of the molten slag, which should result in faster separation of the formed metal droplets and the molten slag. In the case of the fragmented PCB (Printed Circuit Board) reducer used in this study, a significant degree of copper removal was achieved, as much as 92%. As the reduction-process time increased, the degree of copper removal also increased. For the 1 h process, the average value of copper removal was 60%, and for the 4.5 h process it was over 70%. The case was the same with the addition of reductant: as the amount of reductant added to the process increased, an increase in copper removal was observed. With the addition of 30 g of the reducing agent (per 65 g of slag), the degree of copper removal was over 90%.

Geochemical tests to study the effects of cement ratio on potassium and TBT leaching and the pH of the marine sediments from the Kattegat Strait, Port of Gothenburg, Sweden

Cement is a key construction material in civil and geotechnical engineering. However, its application for stabilization of marine sediments needs further investigation. This paper tests the effects of varied amounts of Portland cement added to soil samples on the leaching of tributyltin (TBT) from the contaminated marine sediments and evaluates the pH level. Identifying the best combinations of Portland cement / slag / Cement Kiln Dust (CKD) for effective treatment of soil samples is a central challenge in marine geotechnical investigations with major implications for stabilization of dragged coastal sediments. The paper aims to test the TBT leaching as well as pH level and potassium (K) content in soil samples. Materials included marine sediments collected from the seabed of the Port of Gothenburg, Kattegat Strait, southwest Sweden. The methodology applied the existing specifications of the Swedish Institute for Standards (SIS) for geochemical tests of soil stabilized by Portland cement/slag/CKD. Leaching in soil samples was examined for 2.25, 9 and 36 days. Variations in the speed of decline of TBT leaching were noted depending on the ratio of Portland cement. The methodology follows the SIS instructions regarding the procedure of leaching tests: SS-EN 15863. Mixtures with pure Portland cement and cement / CKD gave pH values between 11.5–12 in the surface leaching experiments. Mixing of slag / CKD or slag lowered the pH range to 11–11.5 and 10–10.5, respectively. The leaching of TBT was affected by the changed amounts of seawater in the surface leaching experiments. The study shows that leaching reduces over time when the mobile fraction is being washed away and replaced by other leaching mechanisms and processes. Furthermore, in models in which leaching of TBT and potassium were assessed, there were, on average, changes in behaviour on the 9th day during the experiment time treatment and stabilization afterwards.

The Key Application Technology of Desulfurized Gypsum in Dry-Mixed Mortar

In this paper, in view of the problem of low early and late strength of dry-mixed mortar prepared by cement-fly ash-slag powder composite cementing system, the ratio of mixing fly ash and slag powder to replace cement is 70%. To study the effect of desulfurization gypsum (FGD) on improving the activity of the system. The results show that adding desulfurized gypsum, which accounts for 6% to 8% of the total mass of the cementitious material, has no adverse effect on the workability and can significantly improve the compressive resistance of the slurry. Strength and tensile bonding strength, shrinkage rate is reduced by more than 10%, and the ability to resist carbonization is improved to make the mortar volume more stable.

Investigation of the Effect of Mixing Time on the Mechanical Properties of Alkali-Activated Cement Mixed with Fly Ash and Slag.

This is an experiment on the effect of mixing time for alkali-activated cement (AAC) using a binder mixed with ground granulated blast furnace slag (slag) and fly ash (FA) in a ratio of 1:1 on the mechanical properties. The mixing method of ASTM C305 was used as the basic mixing method, and the following mixing method was changed. Simply adding the same mixing time and procedure, the difference in the order of mixing slag and FA, and controlling the amount of activator and mixed water were considered. As a result of the experiment, the addition of the same mixing time and procedure, pre-injection of slag, and high-alkali mixed water in which half of the activator and mixing water were mixed showed the highest mechanical properties and a dense pore structure. As a result, the design of a blending method that can promote the activation action of slag rather than FA at room temperature was effective in improving the mechanical properties of AAC. In addition, these blending factors showed a clearer effect as the concentration of the activator increased. Through the results of this experiment, it was shown that high-temperature curing, high fineness of the binder, or even changing the setting of the mixing method without the use of excessive activators can lead to an improvement of mechanical properties.

Influence of Chemical Admixtures on Geotechnical Properties of Expansive Soil

The present study is to elucidate and efficacy of Ultra-fine slag and Calcium Chloride in improving the Engineering characteristics of expansive soil. An experimental program has evaluated the effects of Ultra-fine slag 3%, 6%, 9% and CaCl2 0.25%, 0.5%, 1.0%, Free swell index, swelling potential, swell pressure, plasticity, compaction, strength, hydraulic conductivity, Cation Exchange Capacity and microstructural XRD, SEM tests of expansive soil and also a statistical tool was used to predict the experimental values of unconfined compressive strength of the soil. Both admixtures were added independently and blended to the expansive soil. Mixing of Ultra-fine slag, CaCl2 and expansive soil results have shown that plasticity index, hydraulic conductivity, swelling properties of blends decreased and dry unit weight and unconfined compressive strength is increased in combination of soil +6% of Ultra-fine slag + 1% CaCl2. The unconfined compressive strength (UCS) of the samples is again found to decrease slightly beyond 6% Ultra-fine slag and 1% CaCl2. It was found that the optimum quantity of material for a favorable combination of soil +6% of Ultra-fine slag + 1% CaCl2 was taken for further study in view of its economy due to lower CaCl2 content.

Strength and durability properties of waste steel slag mixed concrete

The exploration of natural aggregates for construction leads to the degradation of the environment; thus, the development of environment-friendly construction materials, such as steel slag, is being promoted. Disposal of steel slag without affecting ecology is the central issue of concern, as steel industries produce a million tonnes of steel slags as a by-product every year. To address this issue, we studied the potential of a waste steel slag to use as a replacement of coarse aggregate in the cement concrete. We observed that the mixing of waste steel slag with concrete improves the mechanical and durability properties of the concrete. The abrasion properties of steel slag concrete are comparable with a coarse aggregate concrete. The study concludes that the use of steel slag in concrete improves the physical properties of the cement concrete, and thus, steel slag concrete can be used for building floorings, pavements, or concrete surfaces, which expose to the external forces and severe weather conditions.

The Mechanical Properties of Alkali-Activated Slag-Silica Fume Cement Pastes by Mixing Method

The mixing method is the investigation of the characteristics of alkali-activated cement paste (AACP) with slag and silica fume (SF) of 1: 1. The basic mixing method is ASTM C305, which is defined as 1st-cycle. There are three factors considered in this experiment; (i) the addition of mixing time (2nd-cycle), (ii) the concentration of activator depending on the amount of mixing water, and (iii) the mixing sequence of slag and SF. It was found that the second cycle, the additional mixing time, had the effect of improving the mechanical properties. In addition, accelerated activation through the mixing of slag with a high concentration of alkali solution in the 1st-cycle increases the hydration products and decreases the porosity and increases the mechanical properties. Therefore, it was found that the change of the mixing method in the AACP composed of slag and SF 1: 1 has a great influence on the mechanical properties. As a result, the method of first mixing slag in aqueous solution of high alkali concentration in AASC mixed with slag and SF improves the mechanical properties.

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.

Study of CO2injection on the desulfurization of low-titanium slag

A new idea that the low-titanium slag (LTS) used in the steelmaking process after CO2injection desulfurization is proposed in this paper. The CO2injection process mainly involves the grinding of low-titanium slag, mixing of slag and water, CO2injection, filtration, and then obtains the low sulfur and low titanium slag. The effects of cooling rates (water cooling, air cooling, crucible cooling, and furnace cooling) and CO2injection on the desulfurization of LTS were studied by both experimental and thermodynamic calculations. The results showed that sulfite and sulfate ions couldn’t be removed from LTS using this method, and the main removal substance in slag was sulfide ion S2−. The desulfurization mechanism with CO2injection was that the CO2injection reacted with H2O to form H2CO3, and then the H+disrupted from H2CO3reacted with the S2−in the slag to achieve desulfurization. During the desulfurization process, the desulfurization reaction was mainly determined by S2− + CO2(aq) + H2O (l) = CO32− + H2S(g) within the first 5 min, and then the main desulfurization reaction was S2− + 2CO2(aq) + 2H2O(l) = 2HCO3− + H2S(g). As the cooling rate decreasing, the desulfurization rate of LTS increased. The desulfurization effect of furnace-cooled slag is the highest in four kinds of slag. The desulfurization rate of furnace-cooled slag reaches 72.28%, which is 4.34, 1.75 and 1.15 times than that of water-cooled slag, air-cooled slag and crucible-cooled slag, respectively. The optimal rate of desulfurization is 80.0%.

Measurement of metallic iron in steel making slags

An integrated steel plant generates 200–250 kg of steel making slag for every tonne of steel produced. These slags contain non-uniformly distributed iron in metallic form, inevitably carried into the slag pot during de-slagging. The steel slag is subjected to crushing/magnetic separation to generate different sizes of slag products with varying metallic values. Based on size and metallic content, these products are recycled in sinter base mix, iron making units and as scrap in steel making process. Hence accurate analysis of Fe-metallic in these samples is imperative for better process control. Due to non-uniform mixing and solidification of steel & slag in de-slagging and dumping practice, precise quantification of the metallic portion in these samples is extremely difficult. Existing methods followed by slag processing agencies has always been doubtful. Moreover, uniformity of constituents in a small sample size cannot be ensured even by best of the sampling techniques. In the present work, all the slag products have been subjected to different measurement techniques to develop a method to determine the metallic iron content accurately in the steel-making slags. Separate methods have been formulated for low metallic and high metallic content slag samples based on the dominant characteristics. Specific density balance and grinding-sieving methods are proposed for more practical and accurate measurement. Best sampling technique and optimum sample size have also been suggested for each method. In addition to increase in the efficiency of the process, where it is recycled, accurate analysis of Fe-metallic in slag helps in improving the magnetic separation technique and the process of its application.

Free CaO stabilisation by mixing of BF slag and BOF slag in molten state

ABSTRACTReducing free CaO (f-CaO) in basic oxygen furnace (BOF) slag effectively and efficiently is the prerequisite to achieve the goal of BOF slag's volume stability. In this work, Taguchi experimental design method was used to explore the influencing factors effect on stabilising f-CaO by mixing BOF slag with blast furnace (BF) slag and probe into the relevant mechanism. The results show that, in the setting conditions of this work, the most influential factor on the stabilisation ratio of f-CaO is mass ratio between BF slag and BOF slag, and then mixing temperature and duration time as a queue. The reasonable conditions are obtained as follows: mass ratio of BF slag to BOF slag is 6:1, temperature of mixing is 1783 K and duration time for mixing is 20 min. The f-CaO stabilised mechanism on BF slag and BOF slag molten mixing was regarded as mutual coupling effects of stabilisation reactions and dilution.

CO2 capture performance of cement-modified carbide slag

A novel and low-cost synthetic CO2 sorbent for calcium looping process, cement-modified carbide slag (CMCS), was synthesized from carbide slag, aluminate cement and by-product of biodiesel by combustion. The effects of synthesis conditions such as combustion temperature, combustion duration, hydration, by-product of biodiesel and cement addition and regeneration temperature on CO2 capture performance of CMCS were investigated. The comprehensively optimum preparation conditions of CMCS were obtained. The highest CO2 capture capacity is 0.62 g/g after 10 cycles, which is 2.18 times as high as that of carbide slag. The addition of aluminate cement improves the CO2 capture performance of CMCS, while excessive aluminate cement is adverse for CO2 capture due to the reduced CaO content in CMCS. The addition of by-product of biodiesel contributes to a uniform sol mixing of carbide slag and cement. The CMCS exhibits higher carbonation and calcination rates than CS. The porous and stable pore structure leads to the better CO2 capture performance and cyclic stability of CMCS.

Stabilization of Black Cotton Soil Using Micro-fine Slag

This work presents the results of laboratory tests conducted on black cotton soil mixed with micro-fine slag. Different proportions of micro-fine slag, i.e., 3, 6, 9, 12 and 15 % were mixed with the black cotton soil to improve soil characteristics. The improvement in the characteristics of stabilized soil was assessed by evaluating the changes in the physical and strength parameters of the soil, namely, the Atterberg limits, free swell, the California Bearing Ratio (CBR), compaction parameters and Unconfined Compressive Strength (UCS). The mixing of micro-fine slag decreases the liquid limit, plasticity index and Optimum Moisture Contents (OMC) of the soil. Micro-fine slag significantly increases the plastic limit, UCS and CBR of the soil up to 6–7 % mixing, but mixing of more slag led to decrease in the UCS and CBR of the soil. The unsoaked CBR increased by a substantial amount unlike soaked CBR value. The swell potential of the soil is reduced from medium to very low. The optimum amount of micro-fine slag is found to be approximately 6–7 % by the weight of the soil.

Preparation and characterization of one-part non-Portland cement

This work aims at enhancing the mass production and commercial viability of non-Portland cement (NPC) by preparing one-part-NPC (just add water). NPC is an eco-efficient material compared to Portland cement (PC). It was prepared by mixing of blast-furnace slag (BFS) with 2, 4, 6, 8 and 10% sodium hydroxide (SH) by total weight of BFS, and then mixing it with water. The homogeneous slurry is immediately dried in an oven at 80°C for 24h, followed by pulverization to a fixed particle size. Two main compositional factors were examined: first is the increase of SH wt%, while the amount of water to slag (W/BFS) ratio is kept maintaining constant, and the second includes increasing of W/BFS ratio at constant SH dosage. One-part NPC was mixed with water at W/NPC ratio of 0.25, and then cured. A conventional two-part NPC, containing SH solution (liquid part) and BFS (solid part), was prepared for comparison. The results showed that, the amount of NPC hydration products increase with SH wt% and W/BFS ratio. The compressive strength values of hardened cements proved that, the activation of slag continues after the addition of water to NPC. After 90 days of curing, the compressive strength of one-part NPC mixture decreased by 10% compared to that of the two-part-NPC containing the same activator content. Some selected hardened pastes were analyzed using FTIR, TGA/DTG and SEM techniques. The results of the different analyses are in a good harmony with those of mechanical properties and prove that; one-part NPC can be beneficially used as an alternative to PC.

Fresh and hardened properties of alkali-activated fly ash/slag pastes with superplasticizers

This paper presents results of an experimental study carried out to investigate fresh and hardened properties of alkali-activated fly ash/slag pastes with superplasticizers. The binders were prepared by dry mixing of slag and fly ash with 5 slag-to-binder ratios, 0, 0.3, 0.5, 0.7, and 1. An alkali activator was prepared from NaOH solution and sodium silicate solution. The polycarboxylate-based and naphthalene-based superplasticizers were added to the mixes at the levels of 0%, 1%, 2%, 3%, and 4% by the mass of binder. All specimens were prepared under room-temperature curing conditions. The results showed that the higher contents of slag increased the compressive strength of alkali-activated fly ash/slag pastes, but caused rapid setting and crack due to autogeneous shrinkage in the cases of 70% and 100% of slag to binder ratios. The polycarboxylate-based superplasticizer showed retarding effect on alkali-activated fly ash/slag pastes with negligible effect on the heat of hydration, and improved the workability more significantly than naphthalene-based superplasticizer. From the results of the SEM/EDS tests, it was observed that a higher content of slag led to the formation of denser matrix of hydration products. However, formation of hydration products was not noticeably affected by the addition of superplasticizers.

Numerical Simulation of Depleted EAF Jet Flow

In view of the serious problems that low-rate reduction and excessive oil consumption of reducing oil guns which are used in the depleted EAF, analyzing the jet mixing process through the CFD simulation with the method of liquid level tracking, we find that the purpose of mixing slag layer, guaranteeing matte layer precipitation and saving oil can be achieved by changing combination of gas rate of mixture injected by the oil gun, jet speed and insertion depth. The results of this paper provide a theoretical foundation for optimizing reducing technical process of the slag cleaning furnace operation in a copper industry Company.

Effect of silicate structure on thermodynamic properties of calcium silicate melts: Quantitative analysis of Raman spectra

The distribution of silicate anionic species (Qn units, n=0, 1, 2, 3) and the chemical speciation of oxygen in CaO-SiO2-MO (M=Mn and Mg) slags were investigated by micro-Raman spectroscopic analysis. Furthermore, the thermochemical properties were evaluated using a concentration of free oxygen and a degree of polymerization. A good linear relationship was obtained between sulfide capacity and concentration of free oxygen in the CaO-SiO2 (-MnO) melts at 1500 to 1600 °C. However, even though there was more abundant free oxygen in the CaO-SiO2-MgO system than in the CaO-SiO2 system, the sulfide capacity of the former was lower than the latter, indicating that the sulfur dissolution behavior in the silicate melts cannot be simply explained by the content of free oxygen, because the composition dependency of the stability ratio of oxygen and sulfide ions should be taken into account. The excess free energy of CaO, MgO and MnO linearly decreased as the ln (Q3/Q2) increased. The effect of the degree of polymerization on the excess free energy of mixing of MgO-containing slag was larger than that of MnO-containing slag, which was explained by the difference of the ionization potential between Mn2+ and Mg2+ ions.

The Inhibition Studying of Many-Doped Mineral Admixture for Concrete Alkali Silicate Reaction

In the theoretical basic of only mixing the pulverized fuel ash, the slag or the silicon ash experiments, carrying on concrete alkali-aggregate reaction experiment separately that double-doped the pulverized fuel ash and the silicon ash, double-doped the pulverized fuel ash and the slag, double-doped the slag and the silicon ash, three-mixed the pulverized fuel ash, the slag and the silicon ash. The result indicated the effect of mixing pulverized fuel ash and the silicon ash is better than the mixing silicon ash and slag or pulverized fuel ash and slag. Besides three-mixed the pulverized fuel ash, the slag and the silicon ash can effectively suppress the reaction of concrete alkali-silica acid response（ASR）

Experimental Research on Wind Sand Concrete

This paper propose a new proportion of lining fiber concrete, which can overcome the drawbacks of traditional concrete such as fragile and cracks. Result showed that the concrete strength rise with cement and slag powder increasing. And drop with the increased of fly ash. Double mixing fly ash and slag powder can increase strength more obviously.