Slag Mix Research Articles

Study on the Cyclic Shear Performance of Waste Steel Slag Mixed Soil

Clay soil has poor engineering properties such as poor permeability and low shear strength. Waste steel slag is an industrial by-product formed in the furnace during the steelmaking process which has high quality, durability, anti-slip properties, gelling, high permeability and good particle interlocking properties. Therefore, in order to improve the engineering properties of clay and increase the utilization rate of waste steel slag, the steel slag was mixed into the clay. Steel slag clay mix was used for the straight shear test, cyclic shear test and post-cyclic straight shear test. To investigate the strength characteristics, damping ratio, shear stiffness variation and mixed soil displacement at the reinforcement-soil interface under different steel slag dosing, vertical stress, moisture content and shear amplitude conditions. The test results show that steel slag can significantly improve the shear strength of the clay tendon-soil interface, and the improvement effect is better than the conventional material sand improved clay. The steel slag mix has a large damping ratio and shear stiffness, suggesting that it has good damping and energy dissipation properties. In this case, the shear strength, damping ratio and shear stiffness of the soil mix at 40% steel slag admixture are better. The shear strength of the steel slag mix is increased after cyclic loading compared to straight shear before cyclic loading. In addition, the water content has a greater effect on the shear strength parameters, shear stiffness and damping ratio of the steel slag clay mix compared to the vertical stress and shear amplitude. The test results can provide a theoretical basis for the replacement of sand by steel slag in improving clay soils.

Improving the Mechanical Properties of Recycled Asphalt Pavement Mixtures Using Steel Slag and Silica Fume as a Filler

Due to its environmental and economic advantages, the use of recycled materials in asphalt mixes is witnessing increased interest, where the properties of those mixes are significantly affected by the properties of the recycled materials in them. This paper discusses the results of an experimental study conducted to evaluate the performance of recycled asphalt mixtures made with reclaimed asphalt pavement aggregate (RAP). These mixtures were also prepared with two filler additives, namely steel slag (SS) and silica fume (SF), at four different percentages by weight of the aggregate. A total number of 234 mixtures were tested. The laboratory results indicated the effectiveness of using such additives as a filler material. The Marshall stability showed improvement for mixes prepared with steel slag ranging from 11.73 to 32.73 kN as the RAP level increased; the highest stability load was recorded for the 75% RAP with a 50% steel slag mix. On the other hand, the silica fume depicted variance in its strength, yet the maximum load value of 31.02 kN was for the 75% RAP with 100% silica fume. The use of steel slag in the presence of water decreased the stability results, while satisfying the ASTM standards.

Feasibility of geopolymer synthesis using soda ash in copper slag blended fly ash-based geopolymer

This study presents the strength development of geopolymer synthesized from class F-type fly ash blended with copper slag in 0–50 % variation using soda ash as the alkaline activator. Physical and chemical characterization of precursors was carried out with particle size analysis, X-ray diffraction, scanning electron microscopy and X-ray fluorescence analysis. The geopolymer paste mixtures were prepared with an activator to binder ratio of 0.32, liquid to solid ratio of 0.3, and cast in 50 mm cubes. The paste cubes were subjected to ambient and heat curing of 80 °C for 3 days and thereafter tested for compressive strength at 3, 7, and 28 days. The results showed varied performance within the sample mix types to curing condition. Ambient curing was most effective in geopolymer pastes with 100 % fly ash composition which developed early strength of 6.79 MPa at 3 days higher than other copper slag blended variations. While geopolymer pastes with 40 % slag mix developed significant strength with heat curing. Overall, the obtained optimum strength at the synthesis parameters with soda ash was 17 MPa.

Performance of Self-Compacted Geopolymer Concrete Containing Fly Ash and Slag as Binders

Geopolymers can replace cement and help reduce the environmental impact of concrete construction, but research is needed to ensure their mechanical properties, durability and practicability. The aim of this investigation is to examine the influence of ground granulated blast furnace slag (slag) content on the performance, at the fresh and hardened states, of fly ash (FA) based self-compacted geopolymer concrete (SCGC). For this purpose, four SCGC mixtures containing 450 kg/m3 of total binder were examined. The alkaline-to-binder ratio was 0.5 for all mixes. FA was substituted with slag at 0%, 30%, 50%, and 100% of the total binder content. The fresh properties in terms of flowability, passing ability, viscosity, and segregation resistance, as well as the mechanical properties in terms of compressive strength and splitting tensile strength, were quantified. The durability behavior of SCGC was also studied to determine sorptivity and long-term free drying shrinkage. The results confirm that slag adversely affects the workability of SCGC mixtures except for the resistance to sieve segregation. Performance of SCGC in hardened states is in general enhanced with slag inclusion but at increased shrinkage strain. Predictions of splitting tensile strength were made using the ACI 318, ACI 363, Eurocode CEB-FIB, and Lee and Lee models. The ACI 363 and Eurocode CEB-FIB models were found to be inaccurate, except for the 30% slag mix. Predicted values obtained from the Lee and Lee model were very close to the actual values of the FA-based SCGC mix. The results of this work could lead to more sustainable concretes using geopolymers instead of OPC.

Geopolymer Concrete with Lightweight Artificial Aggregates.

This article presents the physical and mechanical properties of geopolymer concrete with lightweight artificial aggregate. A research experiment where the influence of fly ash–slag mix (FA-S), as part of a pozzolanic additive, on the properties of geopolymers was carried out and the most favorable molar concentration of sodium hydroxide solution was determined. The values of three variables of the examined properties of the geopolymer lightweight concrete (GLC) were adopted: X1—the content of the pozzolanic additives with fly ash + flay ash–slag (FA + FA-S) mix: 200, 400 and 600 kg/m3; X2—the total amount of FA-S in the pozzolanic additives: 0, 50 and 100%; X3—the molarity of the activator NaOH: (8, 10 and 12 M). In order to increase the adhesion of the lightweight artificial aggregate to the geopolymer matrix, the impregnation of the NaOH solution was used. Based on the obtained results for the GLC’s compressive strength after 28 days, water absorption, dry and saturated density and thermal conductivity index, it was found that the most favorable parameters were obtained with 400 kg/m3 of pozzolanic additives (with 50% FA-S and 50% FA) and 10 NaOH molarity. Changes in the activator’s concentration from 8 to 10 M improved the compressive strength by 54% (for a pozzolana content of 200 kg/m3) and by 26% (for a pozzolana content of 600 kg/m3). The increase in the content of pozzolanic additives from 200 to 400 kg/m3 resulted in a decrease in water absorption from 23% to 18%. The highest conductivity coefficient, equal to 0.463 W/m·K, was determined, where the largest amount of pozzolanic additives and the least lightweight aggregate were added. The structural tests used scanning electron microscopy analysis, and the beneficial effect of impregnating the artificial aggregate with NaOH solution was proved. It resulted in a compact interfacial transition zone (ITZ) between the lightweight aggregate and the geopolymer matrix because of the chemical composition (e.g., silica amount), the silica content and the alkali presoaking process.

Analysis of Welding Start Part Defects According to the Shape of the Electrode Tip during Shield Metal Arc Welding

The main device material used in power generation facilities is high-tension steel, which has a significant impact on weldability and longevity. Therefore, high-base flux and high-base low-hydrogen welding rods are used to reduce hydrogen content.<br/> In this study, welding equipment, polarity, and prior technology were reviewed to implement rapid arc stabilization using AWS E7016 low hydrogen welding rods based on user needs for power generation facilities and global standards, and various shape designs of welding rod fleets were attempted. This increases the arc start current density to induce metal transfer mode using the Hollow Electrode effect and the increase in current value at ignition, thereby implementing initial arc safety and optimal welding atmosphere to solve fatal early welding defects such as pores, slag mix, and fusion.

The Performance of Concrete Made with Secondary Products-Recycled Coarse Aggregates, Recycled Cement Mortar, and Fly Ash-Slag Mix.

The properties of cement concrete using waste materials—namely, recycled cement mortar, fly ash–slag, and recycled concrete aggregate—are presented. A treatment process for waste materials is proposed. Two research experiments were conducted. In the first, concretes were made with fly ash–slag mix (FAS) and recycled cement mortar (RCM) as additions. The most favorable content of the concrete additive in the form of RCM and FAS was determined experimentally, and their influence on the physical and mechanical properties of concrete was established. For this purpose, 10 test series were carried out according to the experimental plan. In the second study, concretes containing FAS–RCM and recycled concrete aggregate (RCA) as a 30% replacement of natural aggregate (NA) were prepared. The compressive strength, frost resistance, water absorption, volume density, thermal conductivity, and microstructure were researched. The test results show that the addition of FAS–RCM and RCA can produce composites with better physical and mechanical properties compared with concrete made only of natural raw materials and cement. The detailed results show that FAS–RCM can be a valuable substitute for cement and RCA as a replacement for natural aggregates. Compared with traditional cement concretes, concretes made of FAS, RCM, and RCA are characterized by a higher compressive strength: 7% higher in the case of 30% replacement of NA by RCA with the additional use of the innovative FAS–RCM additive as 30% of the cement mass.

ПОВЫШЕНИЕ УДАРНОЙ ВЯЗКОСТИ ФИБРОЗОЛОБЕТОНА

The trend in building materials science is to replace the different proportions of Portland cement in the binder. Therefore, the paper proposes the principles of controlling the static and dynamic strength of fiber-reinforced concrete, consisting in the complex effect of the hydro-removed ash and slag mix and basalt fiber on the processes of structure formation of the cement composite. A four-stage purification system for the hydro-removed ash and slag mixture has been developed, including disintegration, flotation and two-stage magnetic separation. It was found that the density of the fresh mix from the dose behaves naturally, and the density of solid samples at low doses slightly decreases. High early strength of the developed composites is noted, in particular, for specimens with ASM, one and a half increase in compressive strength is traced in comparison with non-additive specimens. Combinations of "fiber + ASM" with a quadrupling of strength have a significant effect on bending strength. Successful approximations of the compressive strength and bending strength on the ASM dose for different ages (1, 7, 28 days) are traced with the regular behavior of the coefficients in the power dependences. Revealed a multiple increase in the impact strength of the developed compositions. The use of the results will lead to the possibility of designing high-strength concretes, including for special structures.

Compacted Anthropogenic Materials as Backfill for Buried Pipes.

Buried pipe design requires knowledge about the fill to design the backfill structure. The interaction between the backfill envelope and the pipe impacts the structural performance of the buried pipe. The backfill material and compaction level respond to the backfill’s overall strength and, therefore, for pipe-soil interaction. The strength of backfill material is described in terms of modulus of soil reaction E’ and constrained modulus Eode. As the E’ is an empirical parameter, the Eode can be measured in the laboratory by performing the oedometer tests. In this study, we have performed extensive oedometric tests on five types of anthropogenic materials (AM). Three of them are construction and demolition materials (C–D materials) namely, recycled concrete aggregate (RCA), crushed brick (CB), and recycled asphalt pavement (RAP). Two of them are industrial solid wastes (ISW) namely, fly ash and bottom slag mix (FA + BS) and blast furnace slag (BFS). The results of the tests revealed that AM behaves differently from natural aggregates (NA). In general, the Eode value for AM is lower than for NA with the same gradation. Despite that, some of AM may be used as NA substitute directly (RCA or BFS), some with special treatment like CB and some with extra compaction efforts like RAP or FA + BS.

Technology Production of Ore Coal Pellets from Converter-Coal Slag Mix and Reduction Smelting of Steel

Technology Production of Ore Coal Pellets from Converter-Coal Slag Mix and Reduction Smelting of Steel

Ranking of stabilizers to stabilize/solidify dredged soil as highway construction material

Abstract Contaminated dredged soil generally exhibits poor geotechnical, chemical properties and high organic matter content, As a result, these materials are dumped which lead to long term environmental issues and reduction of the space availability of the landfill site for the future. Similarly, dumping of bottom ash and steel slag wastes is also contributing to environmental harms worldwide. One solution to this problem is the utilization of these wastes into useful products. Thus, the objective of this study was to assess the suitability of contaminated dredged soil stabilized/solidified with cement, cement-bottom ash mix (1:1), cement-steel slag mix (1:1) as a highway subgrade material. Also, thermal treatment of dredged soil has been done to reduce organic matter and ascertain its effect on stabilization/solidification (S/S). Thereafter, specimens which fulfilled the highway subgrade material acceptance norms has been selected and ranked by well established method to select the best optimal specimen. Results revealed that DS-16CS (8% cement + 8% Ground granulated steel slag) was found to be most suitable followed by DS-20CBA (10% cement + 10% Bottom ash) whereas TDS-12CBA (6% cement and 6% bottom ash) was found to the least suitable.

Research on Mechanical and Durability Properties of GGBSand Copper Slag Mix Mortar

Cement is the superb wellspring of ecological impact in cement and mortar making. This is due to parcel of carbon dioxide (CO₂) emanation. This assignment manages supplanting of bond with GGBS and motion sand with copper slag and M-sand along nanoparticles like Titanium dioxide (TiO₂) has been incited to enhance the microstructure and increment the compressive first-rate of the mortar. The mechanical and durability research are finished at 7,28 and 56 days and are been contrasted and the not unusual mortar

Evaluation of a Slag and Portland Cement Mix to Simulate Treatment of Acidic Waste via Solidification/Stabilization in a Deep Soil Mix Application

Site investigations at an oil and gas facility identified a highly acidic waste referred to as residual acid tar that resulted in the transport of dissolved nickel toward the point of compliance at concentrations that exceeded site environmental screening levels. Solidification/stabilization (S/S) via deep soil mixing was selected as the remedial approach and a mixture of ground granulated blast furnace slag cement and Portland cement was subjected to treatability testing to evaluate the reagent mix's ability to achieve treatment objectives. Results from the treatability test showed a cement mix dose of 21 percent was sufficient to raise the pH above the target of 6.0 and reduce dissolved nickel concentrations to below site screening levels in leachate from treated samples of residual acid tar and material impacted by residual acid tar. Cement mix doses of 21 percent or greater were sufficient to achieve target strengths in the unimpacted shallow overburden. However, none of the doses tested were able to achieve target strengths in the residual acid tar or peaty material impacted by the residual acid tar. Results showed soil strengths increased significantly when the pH in leachate from the treated samples approached 12, suggesting the presence of organic acids related to the peaty soils may interfere with the cement set. Recommendations from the study include additional treatability testing to evaluate pre-treatment with hydrated lime to satisfy acid neutralization requirements prior to dosing with the cement mix. ©2016 Wiley Periodicals, Inc.

Механизм и причины образования глубоких поверхностных дефектов на слябах при непрерывной разливке нержавеющих сталей, легированных титаном

The paper considers the structure of metal losses in melting stainless steel with titanium and casting the steel in curved-type continuous casting machine. A hypothesis on the mechanism of surface defect formation on continously cast slabs is described and recommendations to decrease the amount of trimming of defects are given. In other authors’ works it was supposed that this defect is caused by rippled surface like in ingot casting of stainless steel by uphill teeming; by sinking into liquid metal of raw slag-metal shells formed by interaction of dissolved titanium with oxygen and chamotte refractory lining of tundish; that there is relation between surface defects and the quality of slag mix for continuous casting machine mould and the character of distribution of metal streams in the mould. Arguments to criticize the versions that decreasing the amount of dissolved nitrogen is the key factor in obtaining better slab surface quality are also presented. Effect of dissolved nitrogen and titanium on trimming level of continuously cast slabs is shown, the ways to decrease this defect are proposed and the factors affecting its appearance are described.

Production of ‘green’ concrete using red gypsum and waste

The main cost incurred in the production of concrete paving blocks is the cost of the cement-based binders. In addition, there is the environmental cost of quarrying and processing of these primary materials. Gypsum-based industrial by-products have been identified as alternative sources of cement. These materials have little or no production cost and their reuse negates the need for disposal, offering a more sustainable material for the production of paving blocks. Laboratory trials have investigated the properties of red gypsum, derived as a coproduct associated with titanium dioxide manufacture, mixed with pulverised-fuel ash, ground granulated blastfurnace slag, lime and basic steel slag. An assessment of samples was made using unconfined compressive strength after 28 days curing. It was found that a red gypsum ground granulated blastfurnace slag mix achieved the highest unconfined compressive strength (up to 39 MPa) and was selected for further investigation. Two binders, composed primarily of red gypsum and ground granulated blastfurnace slag, were mixed with sand and pea gravel to make 100 mm concrete cubes and compared with Portland cement for uniaxial compressive strength, stiffness and workability. The red gypsum-based binder compared favourably with Portland cement, indicating that there is potential to integrate red gypsum into concrete block mixes.

The effect of Persian Gulf tidal zone exposure on durability of mixes containing silica fume and blast furnace slag

In this research the performance of cement paste and concrete mixes incorporating 7% and 10% of silica fume (SF) as a cement replacement was investigated in three exposure conditions. The results showed that plain type II portland cement performed better than blended SF cement under cyclic wetting and drying conditions. Silica fume specimens under cyclic wetting and drying conditions in simulated seawater exhibited higher strength loss compared to plain type II portland cement where cured under potable water. In addition, the greater the silica fume amount used in the mixes, the more the capillary water absorption under tidal zone exposure or/and under wetting and drying simulation. Further, the ternary blended ground granulated blast furnace slag (GGBS) mix was the worst performing mix in all exposure conditions.

Durability of silica fume and ggbs concrete in a tidal zone

This paper summarises investigations that were conducted to assess the durability of plain and blended type II Portland cement exposed to marine tidal environments. In this research the performance of cement paste and concrete mixes incorporating 7 and 10% silica fume as a cement replacement was investigated in three exposure conditions with seven days’ initial curing in potable water. The performance of plain and blended cements was evaluated by monitoring changes in compressive strength and capillary absorption. The results show that plain type II Portland cement performed better than blended silica fume cement under cyclic wetting and drying conditions. Silica fume specimens under cyclic wetting and drying conditions in simulated seawater exhibited higher strength loss in comparison with plain type II Portland cement when cured under potable water. In addition, the greater the silica fume amount used in the mixes, the more the capillary water absorption under tidal zone exposure and/or under wetting and drying simulation. Further, the ternary-blended ground granulated blast-furnace slag mix was the worst-performing mix in all exposure conditions. An extended initial curing time is recommended for these types of mixes.

Recovery of metal from slag/mixed metal generated in ferroalloy plants—a case study

Most ferroalloy plants lose considerable amounts of metal in their slag and metal–slag mix. A potential source of income for alloy smelters is the massive reserves of metal contained in their slag dumps. Depending on the smelting process and the age of the slag dump, the metal contents vary between 3% and 15%. One important means of reducing costs has been the widespread introduction of metal-from-slag recovery techniques in vogue since mid-1990s. Recovery of metal from mixed metal and slag through mechanized means is widely practiced and assumes immense importance from the metal recovery and environment point of view. A metal-from-slag plant allows producers to cope with fluctuating ferroalloy markets. During times of low prices, a producer can shut down furnaces and rely on the low-cost metal-from-slag product to remain viable. When demand is high, the plant is a low-cost means to boost production. Simple physical (gravity) separation methods like jigging and tabling are in vogue for the recovery of metal. Virtually all charge chrome plants now use the crushing/jigging process to recover chrome alloy from both stockpiled and currently produced slag. Studies were carried out at R&D, Tata Steel to develop a flow sheet for the recovery of metal from metal–slag mix generated in its charge chrome (ferrochrome with 50–60% chromium) plant, Bamnipal. The studies showed that in the case of the charge chrome plant, crushing of mixed metal and slag to below 10 mm followed by jigging of the −10+1 mm material and tabling of the −1 mm material would help recover 10 tpd of metal from the 18 tpd of mixed metal. Based on the studies, a plant is now operational at the Ferro-Alloy Plant (FAP), Bamnipal which recovers ferrochrome metal from mixed metal and slag.

Substitution of Fly Ash, Slag, and Chemical Admixtures in Concrete Mix Designs

The Florida Department of Transportation (FDOT) requires contractors for FDOT’s projects to submit a proposed concrete mix design prior to the production of any concrete. The contractor must use mix designs approved by FDOT. Substitutions of ingredients other than coarse aggregate must be justified through trial mixtures, and authorized in writing by FDOT engineers. The study reported herein investigated whether substitutions of fly ash, slag, air-entraining admixtures, and Types A, D, and G admixtures could be performed and be allowed in FDOT approved concrete mix designs. Substitutions of the ingredients were performed on two typical FDOT hot weather mix designs in this study. The concrete properties considered were slump, air content, and compressive strength. Test data for substitution mix designs were compared with the data for the original mix design. Results show that the substitutions cause variability in concrete properties for both the fly ash and the slag mix designs. Statistically reliable con...

Investigation of the microstructure of alkali-activated cements by neutron scattering

Significant research has been devoted to understanding and modeling the neutron scattering behavior of Portland cement pastes. The present work examines the potential of neutron scattering to noninvasively evaluate the properties of alternative cementitious materials encountered in the field. To interpret the scattering of both alkali-activated and slag-cement systems, alternative models to those typically adopted for Portland cement pastes were considered. Investigation of alkali-activated and slag-cement coupons were conducted for different sample thickness (∼0.5, 1, 2, 4, 6, 8 and 12 mm) over a wide scattering vector ( Q) range (0.0005< Q>0.03 nm −1 and 0.04< Q>4 nm −1) on both ultra (USANS) and conventional small-angle neutron scattering (SANS) spectrometers. This wide Q range allowed determination of the fractal properties of the microstructure as well as the radius of the main scattering particle in the material. An empirical correction for multiple scattering was made based on the Dexter–Beeman equation and demonstrated that for thicker sample widths the theory correlated reasonably well. Alkali-activated fly ash was found to have the largest R value while the OPC and slag mix exhibited the largest Guinier radius. This difference was attributed to variations in the extent of multiple scattering for the samples. Successful application of this model was limited to sample thickness ≥1 mm. A combined power law–Sabine expression was also utilized to successfully model the SANS data over a Q range of 0.04–4 nm −1.