Steel Slag Content Research Articles

New environmentally friendly substance formulation based on steel slag for the manufacture of stoneware

In this paper, stoneware was prepared using steel slag shale as the main raw material. A typical ceramic sintering procedure was used to evaluate the effects of a sintering temperature of 1050∼1130 °C on the linear shrinkage, water absorption, bulk density, and flexural strength parameters of stoneware samples. The stoneware samples were characterized by XRF, XRD, and SEM. The results showed that the performance of the steel slag content of 40% at sintering temperature of 1110 °C was better than the other samples. The main phases of the sample are composed of the quartz phase, the pyroxene phase, and the anorthite phase. Among them, the water absorption rate is 1.36%, the linear shrinkage rate is 11.36%, the bulk density is 2.46 g cm−3, and the flexural strength is 71.13 Mpa. Anorthite and pyroxene improve the bending strength of stoneware samples, which is realized by the prestress mechanism.

Towards understanding the hydration and hardening properties of the cemented paste backfill with a green steel-slag binder

ABSTRACT Binder is the main cost burden in cemented paste backfill (CPB) and an obstacle towards fully green mining technologies. In this work, an improved, low-cost, efficient, and green binder with steel slag content up to 50 wt% was presented for mine backfill. The binder hydration and CPB hardening properties were experimentally investigated. Results show that the CPB with green SS binder (50 wt% steel slag, 35 wt% blast furnace slag, 15 wt% desulphurisation gypsum) has the highest 28-day strength of 2.21 MPa, which is 2 times higher than the Portland CPB control (0.98MPa). The green binder has less hydration heat and a slower and longer deceleration stage duration. The hydration products of the green binder are mainly ettringite and amorphous gel. The substantial gel-like products obtained from multiple activation processes are the mystery of the outstanding CPB strength. The hardening process of green binder CPB can be divided into fast hydrating stage, compacting stage, and potential refining stage. The findings can help better understand the steel slag CPB properties and improve solid waste valorisation and sustainable development of the mining, mineral processing, and iron and steel making industries.

Thermal and mechanical properties of bio-cemented quartz sand mixed with steel slag

The aim of this study is to disclose the feasibility of improving the thermal conductivity and mechanical strength of quartz sand steel slag mixtures treated by enzyme-induced carbonate precipitation (EICP). In this work, the effects of steel slag content (SSC) and number of treatment cycle (N) on the thermal conductivity and mechanical strength of EICP-treated specimens were investigated. The immersion method was adopted for specimen preparation. The thermal conductivity was measured by transient plane source method (TPS) and the unconfined compressive strength (UCS) was obtained through a uniaxial compression test. Moreover, the SEM test was conducted to obtain the morphology and deposition characteristics of calcium carbonate crystals. The result shows that the thermal conductivity and UCS of EICP-treated sands increase before decreasing as the SSC increases. Consequently, the maximum values of thermal conductivity and UCS are 1.28 W/(m⊡K) and 6.31 MPa, respectively, corresponding to the optimal parameter of 20% SSC at 12 N. The optimal thermal conductivity and UCS increase by 367% and 137%, respectively, compared to that of EICP-treated sand with no addition of steel slag. The SEM analysis indicates that the spherical calcium carbonate exists in the range of 0–20% SSC, whereas there is mainly amorphous calcium carbonate when the SSC varies from 40% to 80%. It also demonstrates that the UCS is more sensitive to the variation of calcium carbonate content than that of thermal conductivity.

Mechanical properties and microstructure of engineered cementitious composites with high volume steel slag and GGBFS

Engineered cementitious composites (ECC) achieve exceptional ductility and durability, but the heavy reliance on cement has notable environmental impacts. In this work, the steel slag (SS) and ground granulated blast furnace slag (GGBFS) are introduced into ECC by largely substituting cement. The impact of SS and GGBFS content on ECC’s mechanical performance is analyzed at macro and micro scales in terms of fiber dispersion, mechanical properties, cracking patterns, cement hydration, and microstructure. The results demonstrate that SS can enhance fiber dispersion due to the low water demand and the strong electronic double layer formed on the surface of SS particles. While ECC with a high volume of SS alone (60 wt% SS) lacks the necessary strength for structural applications, the combination of GGBFS and SS exhibits favorable hydration properties and can effectively refine the pore structure. Thus, ECC with GGBFS and SS attains ideal toughness. ASTM C 1018 based toughness indices reveal that the Imax of ECC with 30 wt% GGBFS and 30 wt% SS is 2.30 times that of OPC based ECC. A sustainability analysis demonstrates that substituting 30 wt% SS and 30 wt% GGBFS for cement leads to a 33% reduction in energy consumption and a 53% decrease in CO2 emissions of ECC.

Direct use of original granular steel slag to prepare multi-phased clinker: Sintering mechanism and properties

Multi-phased sintering technology is an innovative process that directly utilize granular steel slag to calcinate cement clinker. In this study, we synthesized a type of multi-phased clinker with high fractions of original crude granular steel slag and investigated its sintering mechanism and properties. It is found that the diffusion of the molten liquid phase of granular steel slag to the surrounding area influenced the crystallization and growth of the clinker mineral, consequently, a gradient distribution high-ferrite multi-phased clinker was formed. Steel slag changed the clinker mineralogical composition and resulted in the ferrite phase reaching 18.07–28.09%. Laboratory tests showed that the multi-phased clinker with high content of steel slag was technically viable and still obtained exceptional properties. The grindability and soundness of multi-phased clinker were comparable to the ordinary Portland clinker, and the burnability was considerably higher than conventional raw meal. All of which suggested that this process was robust and provided more comprehensive theoretical basis for the industrial application.

Effect mechanism of steel slag on CO2 capture in hydraulic lime

Steel slag (SS) inhibits the early hydration of cement, limiting its application in cement-based materials. In this study, SS was used to prepare hydraulic lime (HL), and the effect of SS on CO2 capture in HL was investigated. SS inhibited the carbonation of HL in the early stages but promoted carbonation in the later stages. Adding more than 10% SS inhibited the formation of hydration products, and the reduction of hydration products inhibited the carbonation product content, increased the porosity of the hydration mortar, promoted the later stage carbonation rate, and reduced the compressive strength. The carbonation area and captured CO2 content of the mortars in SS-HL increased exponentially with an increasing carbonation curing age. With an increasing SS content, the carbonation area and the degree of CO2 capture decreased then increased after 1 day and after 3 days of accelerated carbonation curing, respectively.

Preparation of foamed ceramics from steel slag with high calcium and iron content

AbstractIn this paper, steel slag foamed ceramics were fabricated by using steel slag, kaolin, feldspar, and quartz as main raw materials, and adding SiC as high‐temperature foaming agent. The effects of steel slag content and SiC particle size on porosity and mechanical properties of foamed ceramics were researched. Results indicate that when content of steel slag is 40 wt%, and particle size of SiC is 20 µm, foamed ceramics exhibited optimized properties: water absorption rate of 2.59%, total porosity of 55.91%, bulk density of 1.33 g·cm−3, and compressive strength of 1.21 MPa. The results show that with the increase of steel slag content, the phase composition of foamed ceramics changes, and foam process is hindered. The increase of steel slag content contributes to the formation of diopside. Fe3+, Fe2+ in liquid phase enter into diopside by solid solution, the amount of liquid phase decreases. Liquid phase mass transfer slows down, and content of SiC in liquid phase decreases, so that the porosity decreases. At the same steel slag content, different SiC particle size affects the difference between pressure inside the closed pore and surface pressure, thereby the porosity changes.

Mechanical Properties of Open-Graded Asphalt Friction Course Mixtures with Basic Oxygen Furnace Steel Slag as Coarse Aggregates

Open-graded asphalt friction course (OGAFC) is an asphalt course constructed over a dense-graded and impermeable surface to allow quick drainage of surface water runoff and enable reduction of hydroplaning and splash and spray. OGAFC mixtures demand high-quality aggregates to perform the intended functions while transferring traffic loads to the underlying layer. Steel slag is a byproduct generated during steel production, and large quantities are unutilized in steel-producing countries, including India. This study evaluated the mechanical performance properties of OGAFC mixtures using basic oxygen furnace (BOF) steel slag as replacement for coarse aggregates at percentages of 0%, 25%, 50%, 75%, and 100%. OGAFC mixtures with two types of modified asphalt binders and five percentage replacements of coarse natural aggregates with BOF steel slag were fabricated. The mechanical performance of the OGAFC mixtures was evaluated in terms of rutting resistance (dynamic creep test and Hamburg wheel tracking device test), cracking potential (indirect tensile strength, cracking tolerance index, and semicircular bending test), fatigue life (indirect tensile fatigue test), and modulus properties (indirect tensile stiffness modulus and resilient modulus). The test results indicated that the use of BOF steel slag not only improved the performance of OGAFC mixtures in terms of rutting resistance, cracking potential, and modulus properties, but also increased the fatigue life of the OGAFC mixes. OGAFC mixes up to 100% BOF steel slag content exhibited superior performance compared with the mixtures with natural aggregates.

Compressive strength and piezoresistivity of smart cement paste modified with waste steel slag

This study intends to examine ordinary Portland cement (OPC) with a constant water-to-cement ratio (w/c) of 0.38 and different concentrations of steel slag (SS) from 0 to 30% weight of dry cement behaves in terms of compressive strength, electrical resistivity, and piezoresistivity. Since iron is the main constituent of steel slag, adding steel slag may improve electrical resistivity, which is the main requirement for structural health monitoring of cementitious material. Therefore, using the two-probe (2P) and four-probe (4P) approaches, the resistivity of cement paste was compared and measured from early curing to 28 days. The ideal value of steel slag was chosen for the electrical resistivity and piezoresistivity of cement paste at various curing times based on the compressive strength (CS) findings of smart cement paste modified with various steel slag contents. Since the wire probe is not considered in four-probe, the findings show that 4P is more accurate than 2P for detecting electrical resistivity. According to the findings of the piezoresistivity test, adding 15% of steel slag to cement improves piezoresistivity by 71% compared to cement alone and decreases compressive strength by 16.9% compared to cement without steel slag. At the same time, they were increasing compressive strength and piezoresistivity by 15.85 and 64%, respectively, while substituting 5% of the steel slag with cement weight. The electrical resistivity of cement paste was predicted using a Vipulanandan p-q model during 28 days of curing, as well as the change in electrical resistivity as a function of compressive strength at 3, 7, and 28 days. The Vipulanandan p-q model accurately predicted both the characteristics of electrical resistivity and piezoresistivity.

Effect of Phosphogypsum Based Filler on the Performance of Asphalt Mortar and Mixture.

This study introduced phosphogypsum coupled with steel slag powder to prepare the phosphogypsum based filler (PF) for asphalt mixture. Penetration, penetration index, softening point, ductility, equivalent softening point, moisture stability of asphalt mortars with different steel slag powder content, filler-asphalt ratio, and PF content were studied. Mechanical properties of PF based asphalt mortar (P-AM) were then analyzed to determine the optimum steel slag content in PF. Overall desirability method was used to determine the optimum replacement ratio of PF content in limestone filler. Rheological properties of P-AM were also analyzed through dynamic shear rheometer. Volumetric performance, high-temperature performance, low-temperature performance, and moisture stability tests were carried out on PF based AC-20 asphalt mixture. Results showed that P-AM presented the optimum performance when the content of steel slag powder was 23% by mass of phosphogypsum. Fatigue and rutting factor of asphalt mortar were enhanced by PF. The optimum PF content in replacing limestone filler was 75% through overall desirability evaluation. PF developed the high-temperature performance and moisture stability of asphalt mixture. Additionally, volumetric and low-temperature performance were not significantly affected by PF. It is suggested that using PF which is based on phosphogypsum as a filler of asphalt mixture to partially replace traditional limestone filler was adequate.

Dynamic shear modulus and damping ratio of marine silt improved with wasted steel slag

In this article, steel slag was added into the marine silt to improve its dynamic properties. The characteristics of marine silt that can be studied by XRD, BET surface area, SEM, and FTIR were first described. Then, the influence of the sample density, water content, waste steel slag content, and the confining pressure on the dynamic shear modulus G and damping ratio λ was discussed by conducting resonant column tests. The results illustrated that the dynamic characteristics of the marine silt-steel slag admixtures were considerably improved. Additionally, G increased with the increasing steel slag content and λ increased with the decreasing steel slag content. Moreover, a dynamic model of the admixtures was developed based on the Hardin–Drnevich model. Furthermore, by comparing the dynamic characteristics of the admixtures with Nanjing sand, Fujian sand, Kiyohoro silty clay, and Wenzhou marine clay, it was found that the improved admixtures may be a more suitable geofiller in geotechnical engineering.

Distribution development of pore/crack expansion and particle structure of cemented solid-waste composites based on CT and 3D reconstruction techniques

This work analyzes the effects of Industrial solid waste content and meso-microstructure on the mechanical and fracture behavior of cemented solid-waste composites (CSWC). The mechanical properties of CSWC were investigated using uniaxial compression tests. Quantitative analysis of pore and particle structure and cracks was performed using X-ray computed tomography (CT). In addition, the effects of solid waste content and porosity on the Uniaxial compressive strength (UCS) of CSWC were analyzed, and the effects of pore and steel slag (SS) particle distribution on crack expansion were investigated. The results show that the optimization of solid waste content can improve the pore structure of CSWC and promote the uniform distribution of SS particles within CSWC. SS content is 40 wt%, SS is the main factor affecting the strength of CSWC, SS content is less than 40 wt%, porosity and fly ash (FA) are the main factors affecting the strength of CSWC. Connected pores and microcracks are prone to develop as cracks under the action of external loads. Porosity is less than or equal to 0.10%, pore size is not related to crack development. SS content is greater than 10 wt%, particle structure affects crack development.

Study on the Early Effect of Excitation Method on the Alkaline Steel Slag

The change law of alkaline steel slag cementitious activity was investigated by mechanical excitation, alkaline excitation, and salt excitation methods. The effect of grinding time, chemical activators, and content of steel slag on the properties of cement replaced by steel slag was studied. The hydration products of cement replaced by steel slag were analyzed by XRD and SEM. The results show mechanical excitation can effectively improve the particle size distribution and cementitious activity of steel slag. The best mechanical properties are obtained when grinding for 20 min and adding 10% steel slag. Chemical excitation can further improve the cementitious activity of steel slag based on mechanical stimulation. The optimal mechanical properties are obtained when the dosage of sodium hydroxide is 1.0%, the dosage of early strength agent is 2.0%, and the dosage of steel slag is 25%. The main hydration products of cement replaced by steel slag are calcite (CaCO3), calcium hydroxide (Ca(OH)2), dicalcium silicate (Ca2SiO4), and C-S-H gel. The microstructure presents a fibrous network structure, laying the foundation for improving mechanical properties.

Study on novel steel slag foam concrete pore structure and bp neural network prediction model

In this paper, a new type of steel slag foamed concrete was prepared. Its pore structure was analyzed by MATLAB image processing technique, and the influence of steel slag on the compressive strength of foamed concrete was investigated. In addition, a BP neural network prediction model for the pore structure of foam concrete was established. The research results show that when the content of steel slag is 30%, the pore structure of steel slag foamed concrete is appropriate. The compressive strength of steel slag foamed concrete increases with the decrease of the density and the proportion of irregular pores. With the density remaining unchanged, the compressive strength of foamed concrete increases with the increase of the ratio of round and small pores. The prediction errors of the BP neural network model in the average pore diameter and average pore roundness factor were less than 8.5% and 5%, respectively.This research can provide a theoretical basis for the production of steel slag foam concrete.

Evaluation of Steel Slag Optimal Replacement in Asphalt Mixture under Microwave Heating Based on 3D Polyhedral Aggregate Electromagnetic-Thermal Meso-Model

Replacing conventional aggregate with steel slag waste can boost the microwave absorption properties of asphalt mixtures and reduce pollution to protect the environment. In order to achieve the best healing in steel slag asphalt mixture, the optimum particle size and content of steel slag are essential. For this purpose, a high-efficiency algorithm for the random growth and placement of convex polyhedron aggregate is proposed in this paper. The limestone aggregate is replaced with an equal volume of steel slag, and a three-dimensional mesoscale random model of steel slag asphalt mixture is developed. The process of microwave heating is simulated by FEM. The numerical simulations are compared with the reported experimental data, which proves that the model is reliable (R2 = 99.40%). Both the volume average temperature and the uniformity of temperature distribution indicate that the steel slag replacement rate of 60% at 4.75–9.5 mm and 60% at 9.5–13.2 mm is optimal, among which the heat transfer of 4.75–9.5 mm steel slag is more uniform, and the temperature gradient is lower. Steel slag can dramatically increase the heating rate of an asphalt mixture, and the peak of the temperature gradient is around the boundary of steel slag. The reflection properties of steel slag may be related to the dielectric constant, permeability, and particle size. Excess steel slag will cause overheating in most zones of the specimen and will also depress the absorption efficiency of microwaves. The coefficient of variance for spherical (0.36) and polyhedral (0.32) aggregate specimen temperatures indicates that the aggregate’s shape has a negligible effect on the heat transfer of asphalt mixtures.

Modeling the application of steel slag in stabilizing expansive soil

The objective of this study was to evaluate the suitability of steel slag as an additive to the engineering properties of weak clay soil. Different geotechnical laboratory tests were conducted on both stabilized and natural soils. Steel slag (SS) was added at a rate of 0, 5, 10, 15, 20, and 25% to the soil. Specific gravity, grain size analysis, Atterberg limit test, compaction test, free swell, California bearing ratio (CBR), and unconfined compression strength (UCS) are among the tests that were performed. The Atterberg limit test result shows that the liquid limit decreases from 90.8 to 65.2%, the plastic limit decreases from 60.3 to 42.5%, and the plasticity index decreases from 30.5 to 22.7% as the steel slag of 25% was added to the expansive soil. With 25% steel slag content, the specific gravity increases from 2.67 to 3.05. The free swell value decreased from 104.6 to 58.2%. In the Standard Proctor compaction test, the maximum dry density rises from 1.504 to 1.692 g/cm3, while optimum moisture content falls from 19.77 to 12.09%. From the UCS test, mixing 25% steel slag into the soil increases the unconfined compressive strength from 64.3 to 170.6 kPa. Additionally, the CBR value increases from 3.64 to 6.82% as 25% of steel slag is mixed with the soil. As a result, steel slag has been found to improve expansive soil properties for geotechnical applications.

Determining the Long-Term Skid Resistance of Steel Slag Asphalt Mixture Based on the Mineral Composition of Aggregates

This study intends to predict the long-term skid resistance of steel slag asphalt mixture (SSAM) from the mineral composition of the aggregates. The polished stone value (PSV) and mineral composition of the aggregates were assessed using the accelerated polishing test and X-ray diffraction, respectively. The hardness (H) and surface texture richness (STR) of the aggregates were calculated from the mineral composition of the aggregates, and then a multivariate linear model was established between PSV and H and STR. The British pendulum number (BPN) and three-dimensional morphology of the SSAM were then evaluated using a British pendulum and a pavement laser scanner, respectively. Finally, an exponential relationship was established between BPN, aggregate PSV, and various aggregate amounts of SSAM. The results show that steel slag with H, STR, and PSV was better than natural aggregates and can significantly improve the skid resistance of pavement, but the relationship between steel slag content and long-term skid resistance of SSAM was not linear, and SSAM with 50% steel slag content had the best skid resistance. The mathematical model developed can predict the long-term skid resistance of SSAM from the mineral composition of the aggregates. The model can be used by designers to predict the long-term skid resistance of steel slag asphalt pavements at the design stage and thus better determine the proportion of steel slag to other aggregates.

Experimental analysis of long-term skid resistance of steel slag asphalt mixture based on differential wear

ABSTRACT This study aimed to analyse the attenuation law of skid resistance of steel slag asphalt mixture (SSAM) based on differential wear. In this study, an indoor accelerated wear instrument was used to accelerate the wear of the SSAM surface. A pavement laser scanner and a dynamic friction tester measured the three-dimensional morphology and dynamic friction coefficient (μ) of SSAM. Then, the improvement mechanism of steel slag on the skid resistance of SSAM was expounded by analysing the surface microtexture, mineral composition, and chemical composition of aggregates. The results showed no linear relationship between the amount of steel slag and the improvement of SSAM skid resistance. The SSAM with 50% steel slag maximised the differential wear effect and had the largest μ and the richest surface macrotexture. It was recommended that the steel slag content in the SSAM should not exceed 50%. The more mineral composition and higher average hardness of steel slag were the sources of its excellent skid resistance. In addition, it is suggested that the differential wear between mixed aggregates should be considered in the design of skid resistance pavement, and the proportion of different aggregates should be reasonably distributed.

Exploring the Mechanical Properties, Shrinkage and Compensation Mechanism of Cement Stabilized Macadam-Steel Slag from Multiple Perspectives

Steel slag is characterized by high strength, good wear resistance and micro-expansion. This study aims at exploring the potential of steel slag in cement stabilized aggregates, mainly including mechanical properties, shrinkage and compensation mechanisms. For this purpose, the compressive strength and compressive resilient modulus of cement stabilized aggregates with different steel slag contents (CSMS) were initially investigated. Subsequently, the effects of steel slag and cement on dry shrinkage, temperature shrinkage, and total shrinkage were analyzed through a series of shrinkage test designs. Additionally, in combination with X-ray diffraction (XRD) and Scanning electron microscope (SEM), the characteristic peaks and microscopic images of cement, steel slag and cement-steel slag at different hydration ages were analyzed to identify the chemical substances causing the expansion volume of steel slag and reveal the compensation mechanism of CSMS. The results show that the introduction of 20% steel slag improved the mechanical properties of CSMS by 16.7%, reduced dry shrinkage by 21%, increased temperature shrinkage by 5.8% and reduced its total shrinkage by 19.2%. Compared with the hydration reaction of cement alone, the composite hydration reaction of steel slag with cement does not produce new hydrates. Furthermore, it is noteworthy that the volume expansion of the f-CaO hydration reaction in steel slag can compensate for the volume shrinkage of cement-stabilized macadam. This research can provide a solid theoretical basis for the application and promotion of steel slag in cement-stabilized macadam and reduce the possibility of shrinkage cracking.

Workability and Strength of Ceramsite Self-Compacting Concrete with Steel Slag Sand

This study focuses on the workability and compressive strength of ceramsite self-compacting concrete with fine aggregate partially substituted by steel slag sand (CSLSCC) to prevent the pollution of steel slag in the environment. The SF, J-ring, visual stability index, and sieve analysis tests are primarily employed in this research to investigate the workability of freshly mixed self-compacting concrete containing steel slag at various steel slag sand replacement rates. The experiment results indicate that CSLSCC with the 20% volume percentage of steel slag (VPS) performs better workability, higher strength, and higher specific strength. The 7-day compressive strength of CSLSCC with the 0.4 of the water-binder ratio (W/B), decreases with the increase of steel slag content, while the 28-day compressive strength increases significantly. The ceramsite self-compacting concrete with good comprehensive performance can be obtained when the substitution rate of steel slag sand for fine aggregate is less than 20% (volume percentage).