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The issue of rainfall-induced slope failure has attracted more attention from geotechnical engineers as a consequence of global warming. Current cumulative waste disposal has generated scientific interest in the utilization of waste materials in geotechnical design for climate change adaptation measures. Taking into consideration the effect of slope height and angle, steel slag—a waste product derived from the production of steel—was investigated as a slope cover against rainfall. To assess the stability of the slope and the infiltration of water into the soil, numerical analyses were conducted using both SEEP/W and SLOPE/W software in conjunction with rainfall conditions. Based on the findings, it can be concluded that increasing the slope's elevation and inclination will have an adverse effect on its safety factor. Steel slag can nevertheless be utilized for minimizing rainwater infiltration into the slope, as indicated by the pore-water pressure variations and graphs of the safety factor versus time. For a 20-m slope height, steel slag slopes have demonstrated a lower factor of safety difference in comparison to the initial slope without remediation. Regardless of slope angle and slope height, the safety factor reduces marginally during rainfall. [ABSTRACT FROM AUTHOR]

In order to study the effect of water erosion on the adhesion characteristics of warm-mix crumb rubber-modified asphalt (WCR)-steel slag interface, hot-mix crumb rubber-modified asphalt (HCR) was used as the control group. The WCR-aggregate interface adhesion model was established based on the surface energy test. According to the surface energy theory, the adhesion work of WCR-aggregate can be used to calculate their contact angle. Then, the permeability work and spreading coefficient of asphalt-aggregate were obtained. Three processes of asphalt wetting aggregate (adhesion wetting, immersion wetting, and extended wetting) and the compatibility of asphalt-aggregate were analyzed. The interfacial pull-out test and freeze-thaw splitting test were also used to further analyze the adhesion characteristics and water stability of asphalt-aggregate under the action of hydrothermal coupling. Finally, the low-temperature beam bending test of warm/hot-mix crumb rubber-modified asphalt mixture was carried out to verify the experimental results of adhesion characteristics of the asphalt-aggregate interface. The results show that with the erosion of water, the adhesion and water stability of the WCR-steel slag interface and the low-temperature crack resistance of warm/hot-mix crumb rubber-modified asphalt mixture gradually weaken. At the same time, the higher the water bath temperature, the faster the asphalt film destruction, the positive effect of the warm agents on asphalt-aggregate adhesion was weakened, and the WCR-steel slag interface adhesion characteristics were better. The experimental results of low-temperature performance also verify the accuracy of the adhesion characteristics of the asphalt mixture. Finally, the correlation analysis revealed that there was a strong correlation between mechanical indexes (the pull-out strength P, the residual strength ratio, the pull-out strength loss rate η) and water stability index (the freeze-thaw splitting strength ratio). All of them could characterize the water stability of the asphalt-aggregate well. Furthermore, the correlation between η and TSR was the highest, so it is more reliable for evaluating the water stability and adhesion of asphalt and aggregate. [ABSTRACT FROM AUTHOR]

The performance of composite binders with high-volume steel slag (SS), granulated blast furnace slag (GBFS) and desulfurization gypsum (DG) were systematically investigated. The results show that the synergistic effects of high volume (40–60%) of SS with GBFS and less than 15% of DG could perform adequate setting time, higher strength, well volume stability and soundness as well as dense microstructure. The higher compressive strengths exceeding 70 MPa at 28 days and up to 80 MPa at 90 days could be obtained for composite pastes with high-volume SS, which exhibit tight relationships with [CaO]·[SO3]/[Al2O3]·[SiO2] and [CaO]·[Al2O3]/[SO3]2 molar ratios. More (15–19%) AFt and less (about 1%) portlandite produced during the hydration of composite binders. C–S–H gels and calcite crystals were formed. The composite binder possesses lower energy consumption, high carbon reduction and low cost compared with Portland cement in favor of the low-carbon cementitious material production and effective utilization of SS. [ABSTRACT FROM AUTHOR]

Amidst the global pursuit of sustainable alternatives in concrete production, this study explores the viability of incorporating by-products or waste materials as aggregates to support the concrete construction industry, with a specific emphasis on steel slag. The objective of this study is to evaluate the effectiveness of steel slag as a partial replacement for fine and coarse aggregates in concrete production. The experiment involved casting 30 cubes and 10 beams, replacing fine aggregate from 0 to 60%. Flexural and compressive strength tests at 7 and 28 days followed the ACI method. Results revealed that a 30% replacement of fine aggregate with steel slag led to higher compressive strength at both 7 and 28 days, while a 45% replacement showed superior flexural strength at 28 days. Further chemical analysis and optimization are recommended for deeper insights. The study concludes with marginal improvements in compressive and flexural strength with steel slag partial replacement, identifying 30% for fine aggregate and 45% for coarse aggregate as optimal replacements. In addition, the mineral composition of steel slag exhibits significant variability, with compounds, including silicon dioxide (SiO2), iron oxide (Fe2O3), manganese oxide (MnO), aluminum oxide (Al2O3), and calcium oxide (CaO). Chemical analysis indicates high silicate content and minimal alkali content, contributing to enhanced strength during concreting. Higher steel slag replacement reduces workability, confirmed by slump tests. However, all mixes maintain a true slump, and unit weight increases with steel slag aggregate replacement. Compressive strength improves incrementally with higher steel slag content, echoing prior research. In addition, flexural strength rises with steel slag replacing both coarse and fine aggregates, suggesting enhanced performance in reinforced concrete structures. These findings highlight steel slag's potential as a sustainable alternative in concrete production, aiming to advance its application in the construction industry, promoting environmental sustainability and economic viability. [ABSTRACT FROM AUTHOR]

This study evaluates the laboratory performance of Warm-Mix Asphalt (WMA) containing locally sourced Steel Slag (SS) and limestone (LS), focusing on stiffness and moisture sensitivity. Four asphalt mixes were tested: Hot mix with limestone (HL), hot mix with steel slag (HS), warm mix with limestone (WL), and warm mix with steel slag (WS). The binder used for all mixes was AC 60/70 penetration grade, and Aspha-min served as the warm mix additive. Testing included Marshall Stability, boiling water, indirect tensile strength, moisture-induced damage (TSR), and dynamic modulus. Image Analysis quantified the aggregate-retained coated area after the boiling test. Despite performance differences, all mixes met Egyptian code requirements for asphalt concrete mixes. Visual inspection and image analysis demonstrated the effectiveness of using steel slag to mitigate asphalt mix stripping. The retained coated area for limestone mixes ranged from 60 % to 75 %, while SS mixes exhibited over 95 %. Dynamic modulus tests indicated no significant stiffness difference with SS, and stability increased by 8 % and 14 % with and without the warm additive. Economic study confirmed the feasibility of utilizing SS. In conclusion, combining Aspha-Min and steel slag improves AC mix production and construction processes, offering a sustainable and advantageous option in Egypt. [ABSTRACT FROM AUTHOR]

In this study, a composite modifier (CMCDL) containing coal gasification residue, dicyandiamide waste slag, and lake sediments was used to modify steel slag at high-temperature. Five kind of raw materials was analyzed in physicochemical properties, mineral composition and microstructure, cementitious properties and soundness, and particle size analysis, the same to steel slag after high-temperature modification (SHTM). The new mineral phases were found that tricalcium aluminate (C 3 A), gehlenite (C 2 AS), magnetite (Fe 3 O 4), spinels (MgFe 2 O 4), quartz (SiO 2), celite (C 6 AF 2) and diopside (CMS 2) formed in the SHTM when the mass fraction increase from 10% to 30% in CMCDL. The HTM with CMCDL increases the glass phase and hydrated mineral (C 3 A, C 3 S, C 2 S) and in raw steel slag, promoting the disassembled of RO phase, turning the phase from FeO into MgFe 2 O 4 and Fe 3 O 4. MgFe 2 O 4 and Fe 3 O 4 have similar crystal structures, and they form mixed spinels. When the content of CMCCL (coal gasification residue: dicyandiamide waste slag: lake sediments =7:9:4) is 20%, the temperature is 1250 °C, result showed that the mass fraction of f-CaO in SHTM using CMCCL decreases from 4.81% to 1.86%, with a decrease of 61.3%, the 28-day activity index of SHTM increases up to 17.6% compared with raw steel slag, reaching 86.2%. Therefore, the CMCDL-blended SHTM can be applied harmlessly in cement and concrete, enabling low-energy fine grinding of steel slag. [ABSTRACT FROM AUTHOR]

Nighttime warming decreased single rice production in southern China, while silicate supply increased the yield and stress resistance. It is still unclear regarding the impacts of silicate application on the growth, yield and quality in rice under nighttime warming. A field experiment was conducted to investigate the impacts of silicate application on the growth, yield and quality during rice growing period under nighttime warming. The warming was set at two levels, that is, ambient temperature (CK) and nighttime warming (NW). The open passive nighttime warming was used in this study, that is, rice canopy was covered with aluminium foil reflective film at night (19:00–6:00). Silicate fertiliser (steel slag) was applied at two levels, that is, Si0 (0 kg SiO2·hm−2) and Si1 (200 kg SiO2·hm−2). The results indicated that, compared with the control, the average nighttime temperature on rice canopy and at 5 cm soil layer increased by 0.51°C–0.59°C and 0.28°C–0.41°C during the rice growing period, respectively. Under nighttime warming, silicate supply increased the dry weight of shoot, total dry weight of the whole plant and yield by 64.1%, 55.3% and 7.1% at the filling‐maturity stage, respectively. Silicate application significantly reduced dry matter translocation rate with 15%–18%, but significantly increased the root‐shoot ratio with 0.39–0.41 in rice. Under nighttime warming, silicate supply significantly increased milled rice rate, head rice rate and total starch content by 2.3%, 2.5% and 41.8%, respectively. Nighttime warming reduced the yield by decreasing the number of effective panicle, seed setting rate and 1000‐grain weight, but increasing empty chaff grain. Silicate supply increased the yield by increasing the number of effective panicle, filled grains per panicle, seed setting rate and 1000‐grain weight, but reducing empty chaff grain. This study suggests that silicate supply can effectively alleviate the suppressive effects of nighttime warming on single rice growth, yield and quality in Southern China. [ABSTRACT FROM AUTHOR]

To investigate the effect of steel slag used as substrate on the rooting of Hydrangea macrophylla cuttings, and to develop a new mixed substrate that can partially replace conventional cutting substrates and realize the high-efficient utilization of solid waste, we examined the physical and chemical properties of different mixed substrates containing 10% (T,), 20% ( T2), 30% (T3), and 40% (T4) volume fractions of steel slag, and investigated the rooting of H. macrophylla ' Red Beauty' cuttings growing on these substrates, with conventional cutting substrates (peat and perlite) as the control (CK). The results showed that pH value, electrical conductivity, and bulk density of the mixed substrates were significantly higher than those of CK. The aeration porosity of T2 was higher than other treatments, while the total porosity and water holding porosity differed little from others. Both fresh weight and dry weight of all the four treatments were higher than those of CK, with stem diameter being higher than that of CK ( except T4), plant height showing no significant difference compared to CK ( except T4), and leaf chlorophyll content being significantly lower than CK. Root length ranked as T2 >CK>T, >T3 >T4, the root surface area and root volume both ranked as T2>T, >CK>T4>T3, the root tip ranked as T2>CK>T, >T4>T3. Both average root diameter and root activity were significantly higher than that of CK, with the highest value being observed in T2. Soluble sugar content in the leaves of T2 was the highest, followed by T4, T3, CK, and T,. The weight ranking of root growth indices was root activity > average root diameter > root volume > root surface area > root tip number > root length. Redundancy analysis indicated that pH value, electrical conductivity, aeration porosity, and water holding porosity of substrates were key factors influencing root growth and development of cuttings. Our results suggested that substrates mixed with 10% to 40% steel slag could be used for H. macrophylla cutting propagation, and 20% ( T2) being the best one because it could significantly improve the survival rate, growth status, and root development of cuttings. Steel slag would be a novel substrate to partially replace conventional unrenewable substrates such as peat and perlite for flower seedling propagation, which could reduce agricultural production cost and provide a high-value utilization way of industry solid waste. [ABSTRACT FROM AUTHOR]

Using steel slag for the preparation of mine backfill materials is vital to utilizing its resources. Therefore,this study reviewed the impact of different processing technologies and sources on the physical and chemical properties of steel slag,analyzed the application modes and hydration mechanisms of six kinds of steel slag backfill cementitious materials,and discussed the advantages,disadvantages,and development trends of steel slag in the field of mine backfill. This study indicates that:(1) Desulfurized gypsum could promote the hydration and dissolution of steel slag,while cement clinker,slag,and fly ash provide an alkaline environment for steel slag hydration,and silica fume offers a large amount of highly reactive silicon;(2) Steel slag could improve the workability of filling slurry and increase the late strength of backfill,extend the setting time of backfill material and reduce the early strength of backfill. (3) The addition of steel slag could enhance the plastic deformation characteristics of the backfill body, therefore offering references for the prevention and control of dynamic impact hazards in coal mines. [ABSTRACT FROM AUTHOR]

In this paper, steel slag powder was used to replace part of the cement in road concrete, and group tests were carried out on coarse aggregates with different water–cement (W/C) ratios, different steel slag parameters, and different particle sizes. A sample of 100 mm × 100 mm × 100 mm was prepared and cured for 3 days, 7 days, and 28 days. In addition, the fluidity and compressive properties of the samples were also tested. The outcomes of this study revealed that, at a constant W/C ratio, increasing the proportion of steel slag improved the concrete's fluidity but reduced its compressive strength; the 3-day (3 d) compressive strength of 40% steel slag was lower because the early activity of steel slag was lower than that of cement; steel slag also decreased the early-hydration rate of concrete. Comparisons across different W/C ratios demonstrated that steel slag made a more significant contribution to lower W/C ratios than higher ones. The water requirement for steel slag was relatively moderate, and the compressive strength of steel slag concrete with a high W/C ratio notably improved in the later stages. Based on the experimental conditions, the optimal content of steel slag was found to be 35%. Reusing steel slag as a replacement for sand in coarse aggregate can effectively lower costs and offer an innovative approach to steel slag treatment. [ABSTRACT FROM AUTHOR]

The cement industry is known for being highly energy-intensive and a significant contributor to global CO2 emissions. To address this environmental challenge, this study explores the potential of using the waste materials of steel slag (SS) and eggshell powder (ESP) as partial replacements for cement in alkali-activated mortars (AAMs) production, activated by NaOH and Na2SiO3. Mortar samples are prepared with 50% of ordinary Portland cement (OPC) as part of the total binder, and the remaining 50% is composed of ESP, incrementally replaced by SS at levels of 10%, 20%, 40%, and 50%. The activation process was performed with an 8% NaOH concentration and a silica modulus of 2. Key findings include that the workability of AAMs decreased with increasing SS content, requiring admixtures like superplasticizers or additional water to maintain workability. At 50% SS replacement, the water consistency and slump flow values were 32.56% and 105.73 mm, respectively, with a setting time reduction of approximately 36%, losing plasticity within 2 h. Both absorption capacity and porosity decreased as SS content increased from 10% to 50% of ESP. Additionally, the bulk density, compressive strength, and uniformity of the hardened mortar samples were enhanced with higher SS content, achieving maximum compressive strength (28.53 MPa) at 50% SS replacement after 56 days of curing. Furthermore, OPC-based AAMs incorporating SS and ESP demonstrate good resistance to sulfate attack and thermal heating. Microstructural analysis reveals the presence of C–S–H, C–A–S–H, and N–A–S–H phases, along with minor amounts of unreacted particles, and the microstructure shows a dense, highly compacted, and homogeneous morphology. These findings suggest that replacing eggshell powder with up to 50% steel slag enhances the hardened properties of AAMs. Further research is recommended to explore cement-free alkali-activated granular ground blast furnace slag (GGBFS) with ESP for more sustainable construction solutions. [ABSTRACT FROM AUTHOR]

Alkali-activated materials (AAMs) are favoured for their low carbon emissions, excellent mechanical properties, and excellent chemical resistance. In this paper, ternary alkali-activated cementitious materials were prepared from slag, steel slag, and lithium slag to investigate their strength and resistance to sulphate attack. A series of experiments were conducted using a variety of material combinations, alkali activator combinations, water–binder ratios, and exposure environments. These experiments employed both macro and micro comparative analyses. The hydration reaction products, physical phase composition, and microstructure of the ground granulated furnace slag, lithium slag, and steel slag (GLS) ternary AAMs were analysed using x-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). It was experimentally demonstrated that the GLS ternary AAMs had excellent compressive strength, good resistance to sodium sulphate erosion, and that resistance to magnesium sulphate erosion decreased with time. This study contributes to the advancement of knowledge regarding the utilisation of lithium slag and steel slag, and offers new insights into the field of alkali-activated cementitious materials and their resistance to sulphate erosion. [ABSTRACT FROM AUTHOR]

Steel slag (SS) is a by-product of the steel industry, and its recycling is of great significance. In this study, the influence of SS fineness and curing regimes on the hydration properties of cement and the effects of SS content on the compressive strength of pastes were investigated. The hydration products and microstructure of pastes were further explored through X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that the compressive strength decreases gradually with the increase of SS, and increases with the increase of the specific surface area of SS. The compressive strength of paste after steam curing is improved, and the compressive strength of the paste mixed with 30% SS can reach more than 50 MPa after 90 days of steam curing. The hydration products of paste mixed with SS are not significantly different from those of cement, which mainly comprise calcium hydroxide (Ca(OH)2) and calcium silicate hydrate (C–S–H) gel, accompanied by a small amount of calcium carbonate (CaCO3). SS has secondary hydration after long-term ageing and can fill and refine the pore structure, according to SEM. Using SS as a supplementary material is beneficial in terms of reducing cement cost and lowering carbon dioxide (CO2) emission. [ABSTRACT FROM AUTHOR]

Phosphogypsum (PG) occupies a large amount of land due to its large annual production and low utilization rate, and at the same time causes serious environmental problems due to toxic impurities. PG is used for mine backfill, and industrial solid waste is a curing agent for PG, which can save the filling cost and reduce environmental pollution. In this paper, PG was used as a raw material, combined with steel slag (SS) and ground granulated blast-furnace slag (GGBS) under the action of an alkali-activated agent (NaOH) to prepare all-solid waste phosphogypsum-based backfill material (PBM). The effect of the GGBS to SS ratio on the compressive strength and toxic leaching of PBM was investigated. The chemical composition of the raw materials was obtained by XRF analysis, and the mineral composition and morphology of PBM and its stabilization/curing mechanism against heavy metals were analyzed using XRD and SEM-EDS. The results showed that the best performance of PBM was achieved when the contents of PG, GGBS, and SS were 80%, 13%, and 7%, the liquid-to-solid ratio was 0.4, and the mass concentration of NaOH was 4%, with a strength of 2.8 MPa at 28 days. The leaching concentration of fluorine at 7 days met the standard of groundwater class IV (2 mg/L), and the leaching concentration of phosphorus was detected to be less than 0.001 mg/L, and the leaching concentration of heavy metals met the environmental standard at 14 d. The hydration concentration in PBM met the environmental standard. The hydration products in PBM are mainly ettringite and C-(A)-S-H gel, which can effectively stabilize the heavy metals in PG through chemical precipitation, physical adsorption, and encapsulation. [ABSTRACT FROM AUTHOR]

The physicochemical properties of steel slag were investigated using SEM and IR, and it was found that free calcium oxide and free magnesium oxide in steel slag produce calcium hydroxide when in contact with water, leading to volume expansion. Thus, the expansion rate of steel slag itself was first investigated, and it was found that the volume expansion of steel slag was more obvious in seven days after water immersion. Then, the cement dosages of 5% and 6% of the steel slag expansion rate and cement-stabilized gravel volume changes between the intrinsic link were further explored after the study found that the cement bonding effect can be partially inhibited due to the volume of expansion caused by the steel slag, so it can be seen that increasing the dosage of cement can reduce the volume expansion of steel slag cement-stabilized gravel with the same dosage of steel slag. Finally, a prediction model of the expansion rate of steel slag cement-stabilized gravel based on the BP (back propagation) neural network was established, which was verified to be a reliable basis for predicting the expansion rate of steel slag cement-stabilized aggregates and improving the accuracy of the proportioning design. [ABSTRACT FROM AUTHOR]

Pb-contaminated soil poses serious hazards to humans and ecosystems and is in urgent need of remediation. However, the extensive use of traditional curing materials such as ordinary Portland cement (OPC) has negatively impacted global ecology and the climate, so there is a need to explore low-carbon and efficient green cementitious materials for the immobilization of Pb-contaminated soils. A red mud/steel slag-based (RM/SS) geopolymer was designed and the potential use of solidifying/stabilizing heavy metal Pb pollution was studied. The Box–Behnken design (BBD) model was used to design the response surface, and the optimal preparation conditions of RM/SS geopolymer (RSGP) were predicted by software of Design-Expert 8.0.6.1. The microstructure and phase composition of RSGP were studied by X-ray diffractometer, Fourier transform infrared spectrometer, scanning electron microscopy and X-ray photoelectron spectroscopy, and the immobilization mechanism of RSGP to Pb was revealed. The results showed that when the liquid–solid ratio is 0.76, the mass fraction of RM is 79.82% and the modulus of alkali activator is 1.21, the maximum unconfined compressive strength (UCS) of the solidified soil sample is 3.42 MPa and the immobilization efficiency of Pb is 71.95%. The main hydration products of RSGP are calcium aluminum silicate hydrate, calcium silicate hydrate and nekoite, which can fill the cracks in the soil, form dense structures and enhance the UCS of the solidified soil. Pb is mainly removed by lattice immobilization, that is, Pb participates in geopolymerization by replacing Na and Ca to form Si-O-Pb or Al-O-Pb. The remaining part of Pb is physically wrapped in geopolymer and forms Pb(OH)2 precipitate in a high-alkali environment. [ABSTRACT FROM AUTHOR]

In order to guide the gradation design of stone mastic asphalt (SMA) using steel slag, mixture design and vibrating compaction experiments of coarse aggregates were conducted to investigate the rules of voids in coarse aggregate (VCA) formed by different combination schemes of steel slag coarse aggregate (SSCA), basalt coarse aggregate (BCA), and hybrid coarse aggregate (HCA) of steel slag & basalt, respectively. Also, three regression models of VCA were established. The results show that there is a multiple nonlinear relationship between the VCA of SSCA and the proportion of each coarse aggregate in mixture, and the VCAs of BCA and HCA also have similar variation rules. For the same of aggregate gradation, the VCA value of SSCA is different from those of BCA and HCA. The size order of VCA and VMA values can be predicted using the regression model, which can provide basis for the determination of aggregate gradation in SMA proportion design. [ABSTRACT FROM AUTHOR]

Copyright of Industrial Water Treatment is the property of CNOOC Tianjin Chemical Research & Design Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Ocean alkalinity enhancement (OAE) via the enhanced weathering of alkaline minerals is a promising carbon dioxide removal (CDR) technology. Theoretically, these includes iron and steel slags, although their dissolution kinetics in seawater are unknown. Here, we conducted lab-scale experiments to assess the alkalinity generation potential and dissolution kinetics of various slags in seawater. We show that the alkalinity generated per mass of iron slag was logarithmic, i.e., higher amounts of iron slag added had diminishing alkalinity returns. In contrast, the relatively quick dissolution of steel slags and their linear generation of alkalinity per mass of feedstock dissolved in seawater makes them better OAE candidates. Furthermore, despite the presence of potentially toxic metals in these feedstocks, their low to non-existent presence as dissolution products suggests that harmful concentrations should not be reached, at least for the slag tested here. Finally, if all steel slag produced annually was used for OAE, between 10 and 22 gigatonnes of CO2 could be captured cumulatively by 2,100, highlighting significant CDR potential by slags. [ABSTRACT FROM AUTHOR]

Copyright of New Building Materials / Xinxing Jianzhu Cailiao is the property of New Building Materials Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract Amidst the global pursuit of sustainable alternatives in concrete production, this study explores the viability of incorporating by-products or waste materials as aggregates to support the concrete construction industry, with a specific emphasis on steel slag. The objective of this study is to evaluate the effectiveness of steel slag as a partial replacement for fine and coarse aggregates in concrete production. The experiment involved casting 30 cubes and 10 beams, replacing fine aggregate from 0 to 60%. Flexural and compressive strength tests at 7 and 28 days followed the ACI method. Results revealed that a 30% replacement of fine aggregate with steel slag led to higher compressive strength at both 7 and 28 days, while a 45% replacement showed superior flexural strength at 28 days. Further chemical analysis and optimization are recommended for deeper insights. The study concludes with marginal improvements in compressive and flexural strength with steel slag partial replacement, identifying 30% for fine aggregate and 45% for coarse aggregate as optimal replacements. In addition, the mineral composition of steel slag exhibits significant variability, with compounds, including silicon dioxide (SiO2), iron oxide (Fe2O3), manganese oxide (MnO), aluminum oxide (Al2O3), and calcium oxide (CaO). Chemical analysis indicates high silicate content and minimal alkali content, contributing to enhanced strength during concreting. Higher steel slag replacement reduces workability, confirmed by slump tests. However, all mixes maintain a true slump, and unit weight increases with steel slag aggregate replacement. Compressive strength improves incrementally with higher steel slag content, echoing prior research. In addition, flexural strength rises with steel slag replacing both coarse and fine aggregates, suggesting enhanced performance in reinforced concrete structures. These findings highlight steel slag’s potential as a sustainable alternative in concrete production, aiming to advance its application in the construction industry, promoting environmental sustainability and economic viability.

To realize the utilization of industrial solid waste resources and solve the shortage problem of pavement materials, this paper uses steel slag, mineral powder, and coal gangue to prepare a mixture. A uniform test with 2 factors and 6 levels was designed. Through regression analysis, response surfaces were established to study the mechanical properties of the coal gangue mixture. The hydrated products at different ages were microscopically analyzed by XRD and SEM. The durability including freeze-thaw cycles, dry and wet cycles, and immersion expansion rate were researched. The results show that the 7d unconfined compressive strength of the mixture reaches 2.14 – 6.46 MPa, with a 180d resilience modulus of 954 – 1098 MPa, and a 180d splitting tensile strength of 0.66 – 0.83 MPa. With the increase of steel slag content, the 7d unconfined compressive strength of the mixture first decreases and then increases. The content of mineral powder is positively correlated with the 7d unconfined compressive strength. The 180d compressive resilience modulus decreases first and then increases with the increase of steel slag and mineral powder content. The 180d splitting tensile strength is positively correlated with the content of steel slag and mineral powder. The mixture is less affected by freeze-thaw cycles, with mass loss rates of only 1.77 % – 2.13 %. The mass loss rate of the admixture is 0.87 % – 0.99 % after 10 dry and wet cycles, and the strength is slightly improved. The maximum expansion rate of the mixtures immersed in water for 10d is only 0.28 %. The hydrated reaction between steel slag, mineral powder and coal gangue promotes the formation of more hydration products such as AFt, C-S-H, CaAl2(SiO4), and Ca(OH)2. The C-S-H and CaAl2(SiO4) are intertwined into a dense network to wrap Ca(OH)2, which improves the compactness of the mixture and effectively resists the freeze-thaw expansion stress. The steel slag-mineral powder-coal gangue mixture meets the requirements of relevant norms and can be well used in pavement bases.

This study evaluates the laboratory performance of Warm-Mix Asphalt (WMA) containing locally sourced Steel Slag (SS) and limestone (LS), focusing on stiffness and moisture sensitivity. Four asphalt mixes were tested: Hot mix with limestone (HL), hot mix with steel slag (HS), warm mix with limestone (WL), and warm mix with steel slag (WS). The binder used for all mixes was AC 60/70 penetration grade, and Aspha-min served as the warm mix additive.Testing included Marshall Stability, boiling water, indirect tensile strength, moisture-induced damage (TSR), and dynamic modulus. Image Analysis quantified the aggregate-retained coated area after the boiling test. Despite performance differences, all mixes met Egyptian code requirements for asphalt concrete mixes.Visual inspection and image analysis demonstrated the effectiveness of using steel slag to mitigate asphalt mix stripping. The retained coated area for limestone mixes ranged from 60 % to 75 %, while SS mixes exhibited over 95 %. Dynamic modulus tests indicated no significant stiffness difference with SS, and stability increased by 8 % and 14 % with and without the warm additive. Economic study confirmed the feasibility of utilizing SS. In conclusion, combining Aspha-Min and steel slag improves AC mix production and construction processes, offering a sustainable and advantageous option in Egypt.

In this study, a composite modifier (CMCDL) containing coal gasification residue, dicyandiamide waste slag, and lake sediments was used to modify steel slag at high-temperature. Five kind of raw materials was analyzed in physicochemical properties, mineral composition and microstructure, cementitious properties and soundness, and particle size analysis, the same to steel slag after high-temperature modification (SHTM). The new mineral phases were found that tricalcium aluminate (C3A), gehlenite (C2AS), magnetite (Fe3O4), spinels (MgFe2O4), quartz (SiO2), celite (C6AF2) and diopside (CMS2) formed in the SHTM when the mass fraction increase from 10% to 30% in CMCDL. The HTM with CMCDL increases the glass phase and hydrated mineral (C3A, C3S, C2S) and in raw steel slag, promoting the disassembled of RO phase, turning the phase from FeO into MgFe2O4 and Fe3O4. MgFe2O4 and Fe3O4 have similar crystal structures, and they form mixed spinels. When the content of CMCCL (coal gasification residue: dicyandiamide waste slag: lake sediments =7:9:4) is 20%, the temperature is 1250 °C, result showed that the mass fraction of f-CaO in SHTM using CMCCL decreases from 4.81% to 1.86%, with a decrease of 61.3%, the 28-day activity index of SHTM increases up to 17.6% compared with raw steel slag, reaching 86.2%. Therefore, the CMCDL-blended SHTM can be applied harmlessly in cement and concrete, enabling low-energy fine grinding of steel slag.

A modified steel slag adsorbent was prepared with composite modifier(NaOH or Al(OH)3+fly ash) at high temperature. The effects of alkali melting temperature, alkali melting time and alkali doping on the adsorption performance of Pb(Ⅱ) was investigated. Chemical composition, mineral composition, microstructure and pore size was analyzed with XRF, XRD, SEM, BET and other methods. The heavy metal leaching toxicity, regeneration ability and selectivity of the modified steel slag prepared under the optimal conditions were investigated. The results showed that the best adsorption of Pb(Ⅱ) was achieved under the conditions of 700 ℃ alkali melting temperature, 4 h alkali melting time and 100∶10∶20 mass ratio of steel slag, fly ash and Al(OH)3. There was not new crystal in the modified steel slag, but the original crystal structure was destroyed, and porous aluminum silicate salt with certain activity was formed. Loose fine molten particles were accumulated on the surface of steel slag, and pore size was concentrated in the range of 5-20 nm. Under the combined effect of pore adsorption, chemical precipitation and ion exchange, the removal rate of Pb(Ⅱ) from wastewater reached 98.15%. The modified steel slag adsorbent had better regeneration and selectivity, which was a green and safe heavy metal ion adsorbent.

Steel slag-based glass ceramic for thermal energy storage was first fabricated by quenching method, and then their high temperature corrosion behavior in the eutectic carbonates and related mechanism have been investigated using X-ray diffraction，Raman spectroscopy and scanning electron microscope techniques. The results show that holding time has a significant influence on the corrosion layer thickness at 800oC. As the holding time was extended, the thickness of the corrosion layer with obvious cracks tended to increase. Further EDS analyses disclosed that the divided corrosive layers along the extended directions of the cracks should be similar in both the compositions and microstructure. Based on these observations, the possible corrosion mechanism was discussed after defining phase structure of nonstoichiometric (Fe 0.35 Al 0.20 Mg 0.44) Ca 0.96 (Fe 0.08 Si 0.70 Al 0.20) 2 O 6.12 as a combined system of CaMgSi 2 O 6 (Di)-CaFe3+AlSiO 6 (Es)-CaAl 2 Si 2 O 8 (An). Oxygen offered by the molten carbonates salt is regarded to play a critical role in the corrosion process. In an atmosphere rich in oxygen, both Na+ and K+ ions diffused into the diopside can replace Ca2+ and Mg2+, etc. resulting in polyhedral structural reorganization for electrical neutrality. On the other hand, the bonding stability of the cation-oxygen bonds in diopside was proved to be weaker than that in single oxides. These two aspects contribute to the continuous dissolution of Ca2+ and Mg2+, etc. in the molten carbonates salt. [ABSTRACT FROM AUTHOR]

• Develop fiber-reinforced steel slag-bentonite mixture to construct hydraulic barrier. • This new material reduces desiccation cracks and ensures a low water permeability. • Fiber content and length affect hydro-mechanical properties and crack behavior. • Optimal use 0.3 % 9 mm-fiber to reinforce steel slag (90 %) mixed with bentonite (10 %) Desiccation-induced cracks in a compacted clay liner significantly deteriorate the hydraulic barrier performance of landfill covers. The present study explores the effects of polypropylene (PP) fiber reinforcement on the hydrological response and crack resistance of compacted steel slag (SS; 90 wt%) – bentonite (10 wt%) mixtures under drying and wetting cycles. Comprehensive tests were conducted to explore the impact of different fiber lengths (6–12 mm) and contents (0–0.4 % wt.%), including hydraulic conductivity tests for measuring the saturated hydraulic conductivity (k s), unconfined-penetration tests for measuring the tensile strength, small-sized plate tests for quantifying crack development, and large-sized bucket tests for studying the hydrological response and crack characteristics. Higher fiber contents and longer fiber lengths increased the k s -value of the specimens. For a 0.3 % fiber content, the tensile strength peaked for the 9-mm fiber. Consistently, the specimen reinforced with the 9-mm fibers exhibited significantly fewer cracks than those reinforced with the 6-mm and 12-mm fibers. It was because the 6-mm fibers had a shorter anchorage length, while the 12-mm fibers tended to agglomerate. The large-sized bucket tests showed that fiber reinforcement limited crack development significantly under wetting and drying cycles, reducing the rainfall infiltration by 40 % and enhancing the soil water retention capacity. Finally, a 0.3 wt% of 9-mm PP was recommended to reinforce the compacted SS-bentonite mixtures. [ABSTRACT FROM AUTHOR]

The magnesium oxysulfate (MOS) cement has problems of short setting time, poor water resistance, and volume instability. This paper investigates the potential of steel slag (SS) to modify the properties and microstructure of the MOS cement prepared by magnesium desulfurization byproducts (MDBs). The results showed that SS delayed the setting time, restrained the volume shrinkage, and improved the water resistance of the MOS cement. The hydration products of the MOS cement were the fibrous 318 phase (3 Mg(OH)2•MgSO4•8H2O), lamellar Mg(OH)2, and MgCO3. The addition of SS increased the pH and decreased the overall hydration reaction rate and the amount of Mg(OH)2 in the MOS cement. SS reacted with Mg(OH)2 at the late stage to form an amorphous M–S–H gel, which increased the gel pore volume and the density of the cement. In conclusion, SS enhanced the application potential of MOS cement, through improving its macroscopic properties.

This is an article in the field of ceramics andcomposites. C30 concrete was prepared with steel slag powder with different particle size as admixture, and the effect of steel slag powder particle size on the durability of concrete was studied. The test results show that the internal pores of concrete are mainly concentrated in 100~1000 nm, and the number of pores decreases with the refinement of steel slag powder, and the pores of about 10~100 nm increase with the refinement of steel slag. The addition of steel slag can improve the workability of concrete; With the continuous refinement of steel slag, the 7, 28 and 56 d compressive strength of concrete decreases first and then increases. The 56 d compressive strength decreases from 50.4 MPa to 37.8 MPa and continues to increase to 40.32, 42.84, 45.36 and 48.4 MPa. With the fineness of steel slag from 23.1 MPa decreases to 16.8、12.2、10.1、4.2 μm. The activity of m steel slag increased from 75% to 96%. After 100 freeze-thaw cycles, the mass loss of concrete without steel slag group is 7.6%. When 30% steel slag is added, the frost resistance of concrete decreases. With the change of steel slag fineness, the frost resistance of concrete increases continuously, when the fineness is 10.1、4.2 μm, the mass loss is reduced to 7.4% and 6.1%. The addition of steel slag can promote the solidification and storage capacity of concrete to CO2 and enhance the pressure strength of concrete. The finer the steel slag is, the stronger the carbonization resistance of concrete is.

In this work, an alternative alkali-activated cement (AAC) made of ladle slag precursor mixed with sodium hydroxide and sodium silicate has been developed to enhance the bearing capacity of estuarine soils in coastal conditions via deep soil mixing (DSM). The AAC was optimized to use a low reactivity precursor (ladle slag) and to deal with a contaminated high-water content natural sediment cured under water. The material performance was analysed by comparison to a mixture made with Portland cement and cured in the same conditions. Flexural and unconfined compressive strength tests as well as seismic waves measurements after 3-, 7-, 14- and 28-d curing were performed to obtain a relationship between elastic stiffness and strength with curing time for both mixtures. Remarkably, the AAC mix demonstrated superior strength results, exhibiting almost double flexural and compressive strengths after 28 d compared to the Portland cement mix. The AAC mix also showed a higher rate of stiffness increase than the Portland cement mix, which has a higher initial stiffness at young ages but lower stiffness evolution. Leachate analysis confirmed that the proposed AAC could effectively immobilise any contaminants from soil or precursors. The effect of curing under stress was analysed in triaxial compression tests and found to be insignificant, indicating that laboratory data obtained without stress curing can represent the material's behaviour in a DSM column, which will cure under the weight of the column.

Abstract The issue of rainfall-induced slope failure has attracted more attention from geotechnical engineers as a consequence of global warming. Current cumulative waste disposal has generated scientific interest in the utilization of waste materials in geotechnical design for climate change adaptation measures. Taking into consideration the effect of slope height and angle, steel slag—a waste product derived from the production of steel—was investigated as a slope cover against rainfall. To assess the stability of the slope and the infiltration of water into the soil, numerical analyses were conducted using both SEEP/W and SLOPE/W software in conjunction with rainfall conditions. Based on the findings, it can be concluded that increasing the slope's elevation and inclination will have an adverse effect on its safety factor. Steel slag can nevertheless be utilized for minimizing rainwater infiltration into the slope, as indicated by the pore-water pressure variations and graphs of the safety factor versus time. For a 20-m slope height, steel slag slopes have demonstrated a lower factor of safety difference in comparison to the initial slope without remediation. Regardless of slope angle and slope height, the safety factor reduces marginally during rainfall.

Steel slag as an alkaline industrial solid waste, possesses the inherent capacity to engage in carbonation reactions with carbon dioxide (CO2). Capitalizing on this property, the current research undertakes a systematic investigation into the fabrication of high-carbonation precast concrete (HCPC). This is achieved by substituting a portion of the cementitious materials with steel slag during the carbonation curing process. The study examines the influence of varying water–binder ratios, silica fume dosages, steel slag dosages, and sand content on the compressive strength of HCPC. Findings indicate that adjusting the water–binder ratio to 0.18, adding 8% silica fume, and a sand volume ratio of 40% can significantly enhance the compressive strength of HCPC, which can reach up to 104.9 MPa. Additionally, the robust frost resistance of HCPC is substantiated by appearance damage analysis, mass loss rate, and compressive strength loss rate, after 50 freeze–thaw cycles the mass loss, and the compressive strength loss rate can meet the specification requirements. The study also corroborates the high-temperature stability of HCPC. This study optimized the preparation of HCPC and provided a feasibility for its application in precast concrete. [ABSTRACT FROM AUTHOR]

Slag and fly ash (FA) are mostly used as precursors for the production of alkali-activated materials (AAMs). FA is the waste discharged by power plants, while slag and steel slag (SS) both belong to the iron and steel industry. The effects of SS and FA on the strength, microstructure, and volume stability of alkali-activated slag (AAS) materials with different water glass modulus (Ms) values were comparatively investigated. The results show that adding SS or FA decreases the compressive strength of AAS mortar, and the reduction effect of SS is more obvious at high Ms. SS or FA reduce the non-evaporable water content (Wn) of AAS paste. However, SS increases the long-term Wn of AAS paste at low Ms. The cumulative pore volume and porosity increase after adding SS or FA, especially after adding FA. The hydration products are mainly reticular C-(A)-S-H gels. Adding SS increases the Ca/Si ratio of C-(A)-S-H gel but decreases the Al/Si ratio. However, by mixing FA, the Ca/Si ratio is reduced and the Al/Si ratio is almost unchanged. The incorporation of SS or FA reduces the drying shrinkage of AAS mortar, especially when SS is added. Increasing Ms increases the compressive strength and improves the pore structure, and it significantly increases the drying shrinkage of all samples. This study provides theoretical guidance for the application of steel slag in the alkali-activated slag material. [ABSTRACT FROM AUTHOR]

Steel slag as a large stock of bulk of industrial solid waste in China, the current domestic of its utilization is only 30% . The main reason limiting the large-scale resource utilization of steel slag is that the unstable substance in steel slag is easy to hydrate in water, resulting in the volume expansion of steel slag. By using linear variable displacement transducer(LVDT) test method, the expansion rate of asphalt trabecular specimen with steel slag was measured, and the influences of steel slag mixing ratio, oil stone ratio and particle size of steel slag on the expansion rate of the mixture were explored. The results show that the expansion rate of the mixture can be controlled more effectively when steel slag is not more than 50% of the mixture, the actual oil stone ratio of the mixture is increased by 1. 5% on the basis of the optimal oil stone ratio, and using large steel slag. In addition, the active substance in the steel slag is constantly hydrated, which will lead to local expansion and aggregate spalling and other damage. [ABSTRACT FROM AUTHOR]

This paper aims to evaluate the performance of steel slag in improving the properties of concrete by using different homogenization models and finite element simulations. The free vibration of functionally graded (FG) concrete beams reinforced with steel slag is investigated by using the Euler–Bernoulli and Timoshenko beam theories. It has been assumed that the modulus of elasticity and the density change in the thickness direction according to the power law. The equations governing the free vibration are resolved in an exact way for Euler–Bernoulli theory and by using ANSYS software for Timoshenko theory. Then, a parametric study is carried out in order to analyze the influence of volume fraction and distribution of steel slag, beam slenderness ratio and shear on the dynamic behavior of FG beams. The results demonstrate the significant effect of the studied parameters on the vibration of concrete beams reinforced with steel slag. [ABSTRACT FROM AUTHOR]

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Copyright of New Building Materials / Xinxing Jianzhu Cailiao is the property of New Building Materials Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The construction industry is looking for sustainable and cost-effective alternatives to conventional building materials. As the world faces increasing environmental challenges, the need for greener construction practices has become more urgent. Cement production is known for its high energy consumption and significant carbon dioxide emissions. Therefore, it is essential to find ways to reduce the environmental impact of cement production and use. One promising area of research is the use of industrial byproducts such as steel slag to partially replace cement in concrete. The use of these by-products not only solves the problem of waste disposal but also provides a sustainable solution to improve the properties of building materials. When mixed with cement, steel slag participates in pozzolanic reactions, in which reactive silica from the slag reacts with calcium hydroxide, produced during the hydration of cement, to form calcium silicate hydrate gel (CSH). This CSH gel is responsible for the strength and durability of concrete. Incorporating steel slag can improve the mechanical properties of concrete, including compressive, flexural, and tensile strength. In addition, steel slag can improve the durability properties of concrete, such as resistance to chemical attack, reduced permeability, and increased resistance to physical and chemical degradation over time. This paper investigates the durability properties of cement when partially replaced by steel slag, focusing on various aspects of durability, including resistance to chemical attack, mechanical strength, and long-term performance under various environmental conditions. The study includes a comprehensive experimental program designed to evaluate the impact of steel slag on the durability of concrete through a series of tests and analyses. [ABSTRACT FROM AUTHOR]