Ferronickel Slag Research Articles

Understanding the improvement of Mg-rich electrical ferronickel slag on magnesium potassium phosphate cement's performance

Electrical ferronickel slag (EFS), a Mg-rich slag from nickel-iron alloy production, is conventionally recycled by blending it with Portland cement as mineral admixtures. However, the low hydration activity of EFS will lead to severe negative effects on cement. To enhance the reuse value of EFS, this study comprehensively investigated the potential of using EFS in magnesium potassium phosphate cement (MKPC), from properties into hydration mechanisms. A variety of characterization techniques, combined with thermodynamic modelling, were applied. The results demonstrate that incorporating EFS effectively increases compressive strength and refines pore structure at all ages. This improvement is mainly attributed to the additional reaction of Mg2SiO4 and amorphous phases from EFS. Mg2SiO4 reacts at low pH and amorphous fractions are involved at higher pH to generate new products magnesium silicate hydrate M-S-H or magnesium aluminosilicate M-A-S-H gel. The findings will provide insight into the role of Mg-rich pyrometallurgical slags in MKPC systems.

A Study on Mechanical Properties of Modified Soil–Cement Mixed with Ferronickel Slag Powder under Dry–Wet Cycles in Marine Environments

Soft soil foundations in marine environments are under coupling actions of seawater erosion and dry–wet cycles due to tides. Ferronickel slag is a solid waste produced in the smelting of ferronickel alloys. To recycle industrial solid waste and conserve energy, ferronickel slag is partially substituted for cement to solidify the soft soil foundations in marine environments. Unconfined compression tests were conducted for soil–cement mixed with ferronickel slag of various proportions to investigate its apparent erosion characteristics and mechanical characteristics under dry–wet cycles. In the tests, the corresponding numbers of cycles were set to 0, 6, 12, and 18. To further investigate the microscopic action mechanism of ferronickel slag on soil–cement, a nuclear magnetic resonance (NMR) device was utilized to analyze the microstructure of the soil–cement. According to the testing results, the unconfined compressive strength of soil–cement first increased and then decreased when the number of cycles of seawater erosion increased. With other conditions being the same, the addition of ferronickel slag can improve soil–cement strength, and changes in soil–cement strength were more significant than that with no ferronickel slag mixed. Moreover, the optimal amount of admixture was proved to be 45%. As the number of dry–wet cycles increased, the mass of soil–cement first increased and then decreased. With the same number of dry–wet cycles, soil–cement mixed with ferronickel slag had a smaller mass loss rate than that with no ferronickel slag added. After six dry–wet cycles, apparent erosion of soil–cement becomes increasingly serious, including the absence of edges and corners, deformation of surfaces, and even spalling and cracking. The NMR analysis revealed that dry–wet cycles can promote the evolution of small pores into larger ones within the soil–cement, thereby increasing the number of larger pores, leading to an increase in porosity, a decrease in the compactness of the soil–cement, and a reduction in strength.

Study on the synergistic mechanism of sulfuric acid and ammonium sulfate on the extraction of metals from ferronickel slag by roasting

Due to the complex occurrence state of valuable metals in ferronickel slag, the metal extraction rate of the ammonium sulfate roasting process is insufficient. This study proposes a more cost-effective strategy to extract ferronickel slag valuable metals by mixed roasting with sulfuric acid and ammonium sulfate. The effects of the reagent dosage, roasting temperature and roasting time on the metal extraction rate of (NH4)2SO4 roasting, H2SO4 roasting and (NH4)2SO4 and H2SO4 mixed roasting were compared and analyzed. XRD, SEM and TG-DSC were used to reveal the mechanism of mixed roasting to optimize the metal extraction effect from ferronickel slag. The results showed that mixed roasting with a mass ratio of ammonium sulfate to sulfuric acid of 1:1 could reduce the dosage of ammonium sulfate roasting by 2.5 times, and the leaching rates of valuable metals Mg, Fe, Al and Cr increased by 17.46%, 42.8%, 26.06% and 24.89%, respectively. Likewise, comparing to sulfuric acid roasting, the acid consumption of mixed roasting was reduced by two-thirds, and the metal leaching rate was increased by 10.08%, 12.98%, 18.76% and 45.18%, respectively. The “synergistic” mechanism of sulfuric acid and ammonium sulfate on metal extraction by roasting is as follows: ① Before roasting, sulfuric acid partially destroys the surface structure of ferronickel slag particles, forming more pores and channels, creating conditions for the rapid diffusion of ammonium sulfate and sulfuric acid into the slag particles. ② Sulfuric acid reacts with ammonium sulfate to form NH4HSO4, which is more acidic and can accelerate conversion to soluble metal complexes. ③ The addition of sulfuric acid greatly advances the initial temperature of the reaction between ammonium sulfate and metals, widening the temperature range of sulfation roasting and reducing the difficulty of the reaction between ammonium sulfate and metals in ferronickel slag. ④ The liquid–solid reaction increases the reaction interface, improves the mass and heat transfer efficiency and enhances the degree of metal acidification.

SELF-COMPACTING CONCRETE WITH GROUND FERRONICKEL SLAG AS SUPPLEMENTARY CEMENTITIOUS MATERIAL

Ferronickel slag (FNS) is a by-product of the smelting of nickel ore. When ground to powder, it can be used to partially replace ordinary Portland cement (OPC). This study focused on the production of self-compacting concrete (SCC) by replacing OPC with 20%, 35%, and 50% ground ferronickel slag (GFNS). In addition, natural sand was replaced by FNS in all the mixtures. Thus, the significance of this research is the conservation of natural resources by the dual use of FNS and GFNS. The fresh properties of SCC were evaluated as per EFNARC. The results show that the concrete mixtures using FNS and GFNS together met the criteria of SCC. Concrete microstructure was investigated by SEM images, and a detailed phase assemblage was studied by XRD. The highest 28 days compressive strength was found as 68 MPa in the mixture with 35% GFNS. The 50% cement replacement by GFNS showed the lowest compressive strength among all the mixes. The splitting tensile strength results followed a similar development as compressive strength. Hence, it implies that FNS can be a potential eco-friendly material that can be used in the production of SCC

Compressive strength and corrosion behavior of steel bars embedded in concrete produced with ferronickel slag aggregate and fly ash: an experimental study

Compressive strength and corrosion behavior of steel bars embedded in concrete produced with ferronickel slag aggregate and fly ash: an experimental study

Influence of ferronickel slag on the reaction kinetics and microstructure of alkali-activated slag

This study aims to investigate the effects of ferronickel slag (FNS) on the hydration heat, mechanical strength and microstructure of alkali-activated slag (AAS). Sodium hydroxide (SH) and sodium silicate (SS) were used as alkali activators to prepare various alkali-activated slag-FNS cements (AASF). The incorporation of FNS has no significant effect on the reaction process of the SH-activated AASF system while delaying the reaction process of the SS-activated AASF system. The influence mechanism of FNS on the reaction process of AASF is unaffected by variations in alkalinity and modulus of the alkali activators. The delay effect of FNS on the SS-activated AASF system is diminished at 60 °C. The reaction degree of FNS at a later age is significantly higher than that at an early age. Mg in FNS participates in the formation of Mg4Al2(OH)14·3H2O and gel products. The reaction degree of FNS increases with the rise of FNS content in the SH-activated AASF system but has no relationship with the FNS content in the SS-activated AASF system.

Mechanical Properties of Concrete Containing Ferronickel Slag as Fine Aggregate Substitute Using Digital Image Correlation Analysis

This study aimed to analyze the mechanical, displacement, and strain properties of concrete with Ferronickel Slag (FNS) fine aggregate substitute (0%, 50%, and 100%, by mass, later called FNS-0, FNS-50, and FNS-100, respectively) experimentally using the Digital Image Correlation (DIC) method and the Ultrasonic Pulse Velocity (UPV) test. The FNS used in this study is a by-product that came from a Ferronickel smelter in Indonesia coupled with manufactured sand (M-sand) as the fine aggregate control. A D10 × 20 cm3 cylinder and 15 × 15 × 15 cm3 cube specimens were used to analyze the density, compressive strength, and UPV. Additionally, the cube specimens were tested using the DIC method to analyze the displacement and strain properties. The test results show the highest compressive strength was obtained by FNS-50, followed by FNS-100 and FNS-50. The highest pulse velocity was obtained by FNS-100, followed by FNS-50 and FNS-0. The load–displacement response and strain behavior indicate the specimen that had the most load resistance was FNS-50, followed by FNS-100 and FNS-0. Poisson’s ratio obtained using DIC and strain gauges showed consistent results where FNS-0 had the highest values, followed by FNS-50 and FNS-100. Overall, concrete with FNS substitute showed higher density, compressive strength, pulse velocity, and stiffness, as well as lower Poisson’s ratio compared to control concrete (FNS-0).

The interfacial transition zone microstructure of ground ferronickel slag incorporated self-compacting concrete investigated by nanoindentation

The effect of using ground ferronickel slag (GFNS) as a supplementary binder on the interfacial transition zone (ITZ) and strength properties of self-compacting concrete (SCC) were investigated. Cement was replaced by 20–50% GFNS, and mechanical properties of the SCC were assessed. The ITZ was characterized by EDS line scanning. The elastic modulus and hardness properties of ITZ were determined by grid nanoindentation tests. Microstructural changes were followed up by XRD, SEM and EDS analysis, while the macro-level characterization was carried out by compressive and splitting tensile strengths. The strengths showed a decreasing trend with increasing GFNS content. The 28-day compressive strength of the mix with 35% GFNS was 66 MPa as compared to 79 MPa for the control mix. Moreover, up to 35% replacement level, this study finds a compatible ITZ, with a thickness of around 55 μm. The elastic modulus and the hardness values from the nanoindentation test suggest a decrease of the calcium silicate hydrate with the increase of GFNS that decreased strength. XRD data confirmed this finding. The line scanning data from EDS reveals that the presence of Al, Fe and S in ITZ was not significant. Hence, the Ca/Si ratio plays a pivotal role in determining the ITZ characteristic, which increases with the increase of GFNS content in the binder. Strength diminishes gradually with increasing Ca/Si ratio, possibly due to the damaged silicate skeleton and the hydrolytic weakening effect. Therefore, microstructural observations and nanoindentation results well elucidate the strength results, and these experimental outcomes will provide a strong base for utilizing GFNS in SCC.

Rheological behaviour, hydration, and microstructure of self-compacting concrete incorporating ground ferronickel slag as partial cement replacement

Self-compacting concrete (SCC) is a special type of concrete which has some additional requirements beyond those of traditionally vibrated concrete, such as high flowability and consolidation by self-weight without any segregation of the ingredients. In this research, the production of SCC has been investigated by utilizing a metallurgical by-product, namely ferronickel slag (FNS) to enhance the green supply chain in concrete industry. FNS at 40% replacement of natural sand, and ground ferronickel slag (GFNS) at the rates of 0%, 20%, 35%, and 50% replacement of cement was used, and the rheological, hydration, strength, and microstructural development of SCC are presented in this paper. The fresh properties were assessed by rheology, slump flow, T50, V-funnel, J ring, L-box, U-box, and visual stability index tests. The heat of hydration was determined by isothermal calorimetry, and scanning electron microscope, energy dispersive x-ray spectroscopy, and x-ray powder diffraction techniques were used for microstructural analysis. The results were evaluated against the recommendations of the European and Japanese standards for SCC. Increases in fluidity and workability and decreases in yield stress and viscosity were observed with the increase in GFNS content. Delayed hydration heat was observed with the use of GFNS. The low calcium content of GFNS is attributed to this retardation. The 28 days compressive strength decreased from 79 MPa for the control mix by 16% due to 35% cement replacement by GFNS. This is considered reasonable due to the use of low-calcium GFNS as a cement replacement. The heterogeneous and porous morphology of the microstructure of GFNS incorporated SCC is ascribed to this decrement. Considering both fresh and hardened properties, the GFNS incorporated SCC mixtures are found comparable to the control SCC mixture. Therefore, FNS can be used as a promising alternative ingredient for SCC to strengthen the eco-friendly supply chain and sustainable waste management.

Optimal design of ferronickel slag alkali-activated mortar for repair exposed to high thermal load

In this work, the optimal design of a mortar based on alkali-activated material technology is presented. Ferronickel slag, a byproduct of the ferronickel alloy industry, was used both as a binder component (in a finely ground form) and as fine aggregate in alignment with a circular economy approach. The proportions of binder, fine aggregate, and water were optimized using Design of Experiment Design of Mixtures. The performance indicators evaluated were flow, flexural and compressive strength both before and after high-temperature exposure, mass loss, and thermal shrinkage. Life cycle assessment was used to calculate the relative environmental cost of the studied mixes in comparison to a counterpart traditional Ordinary Portland Cement mortar. The optimal mix design exhibited high flexural strength (8.5 and 10.5 MPa, before and after high-temperature exposure, respectively), an unheated compressive strength equal to 69.5 MPa, and a post-heating residual one of 33.9 MPa, 7.7% mass loss and 3.4% thermal shrinkage. Mercury Intrusion Porosimetry along with Scanning Electron Microscopy with Energy Dispersive X-Ray Analysis were also performed on optimal mortar samples in order to link micro-structural heat-induced changes to residual (post-heating) macro-mechanical performances. Finally, when compared to OPC-based products, the optimized mortar mix resulted in 70% lower CO2 emissions indicating great potential for the construction sector where concern about environmental impact keeps growing.

Dual roles of Cr2O3 in preparation of glass-ceramics from ferronickel slag

The dual effects of Cr2O3 in the fabrication of glass-ceramics from ferronickel slag (FNS) with the addition of coal fly ash (CFA) were investigated by varying the content of Cr2O3 from 0 wt % to 2.0 wt %. The crystallization kinetics results showed that as the Cr2O3 content increased from 0 wt % to 1.6 wt %, the crystallization activation energy of the parent glass decreased from 448.23 kJ/mol to 232.65 kJ/mol with the change of crystallization mode from surface crystallization to bulk crystallization. When the content of Cr2O3 reached 1.6 wt %, there existed the highest degree of depolymerization of the glass network and the strongest crystallization tendency. The prepared glass-ceramic was composed of enstatite as the main crystalline phase and spinel as the secondary crystalline phase. The microstructure changed from a loose tabular structure to a dense spherical structure. As the Cr2O3 content further increased to 2.0 wt %, the crystallization activation energy increased to 304.21 kJ/mol and the spherical structure became inhomogeneous due to the coexistence of enstatite particles with different sizes. By controlling the Cr2O3 content of 1.6 wt %, an optimal glass-ceramic with density of 3.17 g/cm3, bending strength of 175 MPa, Vickers microhardness of 9.51 GPa, acid resistance of 99.99% and alkali resistance of 99.97% was obtained. This study provided a novel method for promoting conversion of FNS to glass-ceramics.

Use of various MgO resources for high-purity Mg metal production through molten salt electrolysis and vacuum distillation

A green and effective electrolytic process was developed to produce high-purity Mg metal using primary and secondary resources containing MgO as a feedstock. The electrolysis of various MgO resources was conducted using a Cu cathode in MgF2 – LiF – KCl molten salt at 1043 K by applying an average current of 1.44 A for 12.5 h. The electrolysis of calcined North Korean magnesite and seawater MgO clinker yielded Mg alloys of MgCu2 and (Cu) phases with current efficiencies of 89.6–92.4%. The electrolysis of oxidized MgO-C refractory brick, aged ferronickel slag, and ferronickel slag yielded Mg alloys of MgCu2 and (Cu) phases with current efficiencies of 59.3–92.3%. The vacuum distillation of Mg alloys obtained was conducted at 1300 K for 10 h to produce high-purity Mg metal. After vacuum distillation, Mg metal with a purity of above 99.994% was obtained. Therefore, this study demonstrates the feasibility of the production of high-purity Mg metal from various MgO resources using a novel electrolytic process with a Cu cathode, followed by vacuum distillation.

Effect of replacement ratio of ferronickel slag aggregate on characteristics of cementitious mortars at different curing temperatures

Aggregates significantly affect the quality and durability of concrete, making them vital to the construction industry. Current research is focused on efficiently utilizing various industrial byproducts in the concrete industry to reduce environmental damage and achieve sustainable practices. In this study, we evaluated the mechanical properties of cementitious mortar using blast-furnace-slag powder (BSP) and a mixed aggregate of natural sand, ferronickel slag (FS), and blast-furnace slag (BS) at curing temperatures of 20 and 40 ℃. Microstructural investigations, including scanning electron microscopy (SEM) and energy-dispersive–X-ray spectroscopy (EDS), were performed to evaluate these materials. When cured at 20 °C, the 7-d compressive strength of the samples using only cement as a binder was approximately 16–26.5% higher than that of the control sample, comprising ordinary Portland cement and natural sand. However, the compressive strength of the samples using BSP partial cement replacement was relatively low compared to the control sample. When cured at 40 ℃, the compressive strength of all samples using steel-slag aggregates (including BS and FS fine aggregates) was higher than that of the control sample, regardless of the use of BSP partial cement replacement. In this study, the chloride ion penetrability resistance of the control sample was the lowest among all investigated systems, whereas the use of 40% BSP cement replacement and 50% FS fine aggregate yielded the highest chloride ion penetrability resistance at all curing temperatures. SEM-EDS analysis revealed a denser surface and the presence of numerous hydration products in the sample using slag aggregate compared with the control sample.

Environmental Sustainability of Industrial Waste-Based Cementitious Materials: A Review, Experimental Investigation and Life-Cycle Assessment

Wall plaster production induces significant environmental impacts during its entire life as it consumes a high amount of cement and natural resources. Therefore, in sustainable development, industrial wastes are partially replaced to produce cementitious material to reduce environmental impacts. This study aims to identify the optimal environmental benefits from the waste-based cementitious materials that are used to produce wall plaster. Thus, this study involved conducting a comprehensive review of the mechanical and sustainable performance of industrial waste-based cementitious materials focused on wall construction. Then, an experimental test was conducted to ensure the appropriate mix design to enable the required compressive strength. A comparative analysis of mortar showed that it contained 15% (by weight) of fly ash, blast furnace slag, bottom ash, recycled glass, ferronickel slag, expanded polystyrene and wood ash using life-cycle assessment. The results show that mortar containing fly ash has lower environmental impacts in almost all impact categories (i.e., human health, the ecosystem and natural resources). Endpoint damage assessment of mortar mixtures expresses resource extraction cost as the most affected impact criteria. The replacement of globally consumed cement with 15% fly ash can contribute to monetary savings of up to USD 87.74 billion. The assessment clarifies the advantage of incorporating waste products in cement mortar, which allows policymakers to interpret the analysis for decision making. This study also found that the production of industrial wastes for mortar mixes has a significant impact on the environment.

Pyro-Hydrometallurgy Routes to Recover Silica from Indonesian Ferronickel Slag

Ferronickel slag is a by-product of nickel smelting that provides an abundant silica source. Based on data, every ton of nickel production is equal to eight tons of ferronickel slag production, increasing without any recycling process. It is essential to create an end-to-end process for nickel production and its by-products because this would be a problem in the future and is relevant for many industrialized countries. This study describes a strategy to process ferronickel slag to produce silica. A pyrometallurgy–hydrometallurgy process and ferronickel slag were used to increase the silica content. The process was conducted through alkali fusion; the ferronickel slag was mixed with sodium carbonate at a temperature of 1000 °C for an hour and continued via leaching, precipitation, and cleaning processes. The leaching process was conducted with four concentrations (4 M, 6 M, 8 M, and 10 M) of sodium hydroxide and three different leaching durations (2 h, 4 h, and 6 h). Using hydrochloric acid (HCl) at pH 2 and deionized (DI) water cleaning, the precipitation process was adopted to synthesize a silica powder with the lowest agglomeration and enhance its purity. Characterization was carried out using X-ray Diffraction (XRD), Scanning Electron Microscopy–Energy-Dispersive Emission (SEM-EDS), X-ray Fluorescence (XRF), and Inductively Coupled Plasma–Optical Emission Spectroscopy (ICP-OES). This study highlighted silica characteristics that indicate high recovery by 85% through alkali fusion, HCl leaching, precipitation, and deionized water cleaning.

Influence of Seawater Erosion on The Strength and Pore Structure of Cement Soil with Ferronickel Slag Powder

To promote the recycling of industrial waste residues in the reinforcement of foundation soil, the anti−seawater erosion of cement soil with ferronickel slag powder in the marine environment was studied. Specifically, this paper employed ferronickel slag powder to partially replace the cement. Then, the apparent morphology, unconfined compressive strength, and nuclear magnetic resonance (NMR) tests were performed on specimens of cement soil with ferronickel slag powder soaked in purified water and seawater. The research results reveal that with the rise in the content of ferronickel slag powder, the erosive effect of seawater on cement soil weakens, while the compressive strength of cement soil increases first and then decreases. With an excessive amount of ferronickel slag powder added to the cement soil, its chemically active effect decreases, leading to a decrease in the strength of the cement soil. When the admixture of ferronickel slag powder in cement soil is 45%, it achieves good performance. The addition of ferronickel slag powder improves the plasticity of cement soil. The higher the content of ferronickel slag powder, the greater the failure strain and residual strength of the cement soil. Microscopic studies indicate that with the increase in the content of ferronickel slag powder, the pores in the cement soil become smaller and smaller, the total pore volume decreases, the continuity of the pore size distribution improves, and the structure becomes more compact, thus enhancing the erosion resistance of cement soil.

Facile preparation of thermal insulation materials by microwave sintering of ferronickel slag and fly ash cenosphere

A novel approach for preparing thermal insulation materials by microwave sintering of ferronickel slag (FNS) in the presence of fly ash cenosphere (FAC) was proposed and evaluated. The study showed that during microwave radiation, the contact interface between FNS and FAC would preferentially form magnesium iron chromate spinel and magnesium iron aluminate spinel particles as hot spots by absorbing microwave vigorously, promoting decomposition and transformation of the raw materials into the thermal insulation phases, mainly cordierite and enstatite. After sintering at 900 °C by microwave for only 20 min with the addition of 25 wt% FAC, a thermal insulation material with thermal conductivity of 0.41 W/(m·K), bulk density of 1.46 g/cm3, compressive strength of 30.72 MPa, water absorption of 21.07%, and linear shrinkage of 7.06% was obtained. Compared with the conventional sintering method, the temperature was reduced by 300 °C, with the sintering time shortened by 6 times. This study represents a good example for clean and efficient value-added utilization of FNS, FAC and other relavent solid wastes.

Hydration and compressive strength of supersulfated cement with low-activity high alumina ferronickel slag

This research aims to explore the feasibility of using low-activity high alumina ferronickel slag (FS), carbide slag and hemihydrate phosphogypsum (HG) as main ingredients to fabricate supersulfated cement (SSC). The effect of HG dosage and FS fineness on hydration and compressive strength of SSC-FS was systematically investigated. Experimental results indicated that high mechanical strength can be achieved at ambient temperature by adjusting HG dosage and FS fineness. Increase in HG dosage postpones the initial formation of hydrates to some extent, but the amount of the final hydration products is promoted to generate higher mechanical strength. FS with smaller particle size has higher reaction activity that significantly accelerates the hydration process of SSC, leading to higher compressive strength and smaller volume expansion of SSC, and more ettringite crystals with smallish morphology formed in the pastes. If the particle size of FS is too small, however, ettringite crystals tend to precipitate at the surface of FS particles, which is unfavorable for the development of microstructure and will restrict the generation of C–S–H, thus resulting in a decrease in compressive strength and an increase in volume expansion.

Recycling of ferronickel slag tailing in cementitious materials: Activation and performance

As an industrial by-product containing pozzolanic components, recycled ferronickel slag (FNS) has the potential to be supplementary cementitious materials (SCMs) to reduce the massive carbon footprint of the cement industry, however, the main limitation of ferronickel slag as SCMs is the low hydration rate at an early age. In this study, the pozzolanic activity property results indicate that if the proportion is more than 10 %, FSN can hardly participate in the cement hydration reaction during the early stage, even the mechanical strength of FNS-mortar decreases obviously with the higher proportion of ferronickel slag. Therefore, mechanical grinding and steam curing at an early age are applied to promote the reaction activity of the recycled ferronickel slag tailing in this study. Compared with standard curing, the compressive strength of hardened FNS-cement paste with steam curing at 60 °C or 80 °C increased by 8.2 % or 33.8 %, and the connected porosity decreased by 18.9 % or 17.3 %. And MgO in the ferronickel slag exists as Mg2SiO4 in raw materials and enters the C-S-H gel with the formation of M-S-H gel during the secondary hydration stage. This study provides a theoretical basis for solid waste-based concrete and promotes the recycling, conservation, and resources of solid waste in building materials.

Microstructure and residual properties of raw and ground ferronickel slag incorporated self-compacting concrete exposed to elevated temperatures

Fire safety is a vital parameter for any structure as fire can accidentally occur at any time. This study presents the experimental results on residual strength and deterioration behaviour after high-temperature exposure of high-strength self-compacting concrete (HSSCC) produced using ferronickel slag (FNS). Four HSSCC mixtures were studied using up to 50 % ground FNS (GFNS) as cement replacement and 40 % raw FNS as sand replacement. Cylinder specimens were exposed to 200, 400, and 600 °C for two hours in a furnace. Cracking, change of colour, mass loss, residual compressive strength, thermogravimetric analysis, and ultrasonic behaviour of the specimens were studied. Morphological changes were examined by scanning electron microscopy (SEM), and phase detection was carried out by X-ray diffraction (XRD). The highest mass loss of 8 % was observed in the specimens containing 50 % GFNS, at 600 °C. At 400 °C, compressive strength decreased by about 45 % for the control mixture. In contrast, strength loss for the mixtures containing 20–50 % GFNS was in the range of 17–27 %. However, at 600 °C, compressive strength for all the mixes reduced drastically, by more than 50 %. This is considered to be mainly due to the occurrence of cracks, which was evidenced by the increased travel time of the ultrasonic waves through the specimens. Network of fine cracks were also observed on the surface of all the specimens. The SEM images and XRD results showed the distinct morphological changes at different temperatures for different mixes that correlated with the compressive strength results. Thus, the use of raw and ground FNS offers a wide and viable window of opportunity in production of HSSCC with resistance against high temperature exposure.