Search Results (15)

This study investigates the impact of steel slag coarse aggregate (SSA) particle size on the macroscopic mechanical properties of concrete. Considering that the macroscopic behavior of concrete is significantly influenced by its mesoscale structural characteristics, and that coarse aggregate particle size is a key factor determining these features, uniaxial compression experiments together with mesoscale simulations were carried out to develop a model linking the mesoscale structure to the mechanical response of steel slag coarse aggregate concrete (SSAC). The results show that SSAC exhibits a failure pattern comparable to that of natural aggregate concrete (NAC), but its stress–strain curve exhibits a steeper ascending branch and higher peak stress. With the increasing SSA replacement ratio, the peak stress continuously increases; within the same particle size range, the elastic modulus shows an initial increase followed by a subsequent decrease, reaching its maximum at a 50% replacement ratio. Expanding the particle size range changes the peak strain response from approximately linear to rapidly increasing; smaller particle sizes result in a gentler post-peak drop, whereas higher replacement ratios produce a steeper decline. The mesoscale model further shows that for SSA particle sizes of 5–20 mm, 5–15 mm, and 5–10 mm, the cohesive strength of the interfacial transition zone (ITZ) increases by 75%, 106%, and 92%, respectively, compared with NAC. Increasing the coarse aggregate volume fraction further enhances the ITZ strength improvement. This study offers valuable insights for improving the mixture design and performance of SSAC. Full article

Pervious concrete is a promising sustainable pavement material for sponge city construction. The incorporation of Steel Slag Aggregate (SSA) as a substitute for natural aggregates has the double role of clean production with significant economic and environmental benefits. While the strength and permeability, known as two critical design parameters of pervious concrete, are closely linked to its porosity, there is limited research on the influence of the porosity on the mechanical properties of pervious concrete. In this paper, both experimental and numerical investigations were performed, focusing on the influence of target porosity on the strength and permeability of pervious concrete with and without SSA. Three different target porosities (15%, 20%, and 25%), five distinct water-to-cement (w/c) ratios (0.25, 0.28, 0.30, 0.33, and 0.35), and five SSA replacement ratios (0, 25%, 50%, 75%, and 100%) were considered in this study. A two-dimensional (2D) finite-element (FE) model was developed, with which the failure mode and the strength variation of pervious concrete under different target porosities were analyzed and verified with the experimental results. The results showed that the porosity had a significant influence on both the strength and permeability of pervious concrete, while the influence of the w/c ratio is marginal. There existed an optimal w/c ratio of 0.3, for which pervious concrete with porosities of 15%, 20%, and 25% achieved 28-day compressive strengths of 27.8, 20.6, and 15.6 MPa and permeability coefficients of 0.32, 0.58, and 1.02 cm/s, respectively. Specifically, at the lowest porosity of 15%, the replacement of 100% SSA resulted in the largest improvement in the compressive strength up to 37.86%. Based on the regression analysis, a series of empirical equations correlating the porosity, strength and permeability of pervious concrete was formulated and validated against the experimental data. The findings presented herein are expected to provide references to the practical evaluation of the optimal mix proportion of previous concrete, considering specific and demanding engineering requirements. Full article

Predicting pavement performance is essential for highway planning and construction, considering traffic, climate, material quality, and maintenance. This study’s main objective is to evaluate Baosteel’s Slag Short Flow (BSSF) steel slag as a sustainable aggregate in pavement engineering by means of durability. The research integrates pavement performance prediction using BSSF and assesses its impact on fatigue resistance and percentage of cracked area (%CA). Using the Brazilian mechanistic-empirical design method (MeDiNa), eight scenarios were analyzed with soil–slag mixtures (0%, 25%, 50%, and 75% slag) in base and subbase layers under two traffic levels over 10 years. An asphalt mixture with 15% steel slag aggregate (SSA) was used in the surface layer and compared to a reference mixture. Higher SSA percentages were applied to the base layer, while lower percentages were used in subbase layers, facilitating field implementation. The resilient modulus (MR) and permanent deformation (PD) were design inputs. The results show that 15% SSA does not affect rutting damage, with %CA values below Brazilian limits for traffic of 1 × 10⁶. The simulations confirm BSSF as an effective and sustainable alternative for highway pavement construction, demonstrating its potential to improve durability and environmental impact while maintaining performance standards. Full article

Steel slag aggregate (SSA), as a high-performance and sustainable material, has demonstrated significant potential in enhancing the mechanical properties of concrete and improving the bond behavior between reinforcement and the concrete matrix, thereby contributing to the seismic resilience of steel slag concrete columns (SSCCs). Nevertheless, the underlying mechanism through which SSA influences the seismic performance of SSCCs remains insufficiently understood, and current analytical models fail to accurately capture the effects of bond strength on structural behavior. In this study, a comprehensive experimental program comprising central pull-out tests and quasi-static cyclic loading tests was conducted to investigate the influence of SSA on bond strength and the seismic response of SSCCs. Key seismic performance indicators, including the hysteresis curve, equivalent viscous damping ratio, and ductility coefficient, were evaluated. The role of bond strength in governing energy dissipation and ductility characteristics was elucidated in detail. The results indicate that bond strength significantly affects the seismic performance of SSCC components. At an SSA replacement ratio of 40%, the specimens show optimal performance: energy dissipation capacity increases by 11.3%, bond–slip deformation in the plastic hinge region decreases by 10%, and flexural deformation capacity improves by 9% compared to the control group. However, when the SSA replacement exceeds 60%, the performance metrics are similar to those of ordinary concrete, showing no significant advantages. Based on the experimental findings, a modified bond–slip constitutive model for the steel slag concrete–reinforcement interface is proposed. Furthermore, a finite element model incorporating bond–slip effects is developed, and its numerical predictions exhibit strong agreement with the experimental results, effectively capturing the lateral load-carrying capacity and stiffness degradation behavior of SSCCs. Full article

In order to explore the influence of steel slag on the road performance of asphalt mastic and its mixtures, steel slag powder (SSP) and steel slag aggregate (SSA) were used to replace limestone mineral powder filler (MF) and natural limestone aggregate (LA) respectively to prepare asphalt mastic and mixture. A series of standardized tests including penetration, softening point, ductility, viscosity, pull-off strength, dynamic shear rheometer (DSR), and bending beam rheometer (BBR) were carried out to evaluate the performance of asphalt mastics with SSP. Meanwhile, high- and low-temperature performance, moisture stability, volumetric stability, and fatigue resistance were evaluated by wheel tracking, uniaxial penetration strength, Hamburg, three-point bending, freeze–thaw splitting, immersed Marshall stability, water immersion expansion, and two-point bending trapezoidal beam fatigue tests. The results show that compared to the asphalt mastic with MF, enhanced high-temperature deformation resistance and reduced low-temperature cracking resistance of asphalt mastic with SSP were observed, as well as superior aging resistance. The improvements in high-temperature stability, moisture resistance, and fatigue performance were confirmed for asphalt mixtures with SSP/SSA. Additionally, compromised volumetric stability and low-temperature crack resistance were found when SSP/SSA was used in mixtures. Although asphalt mixtures with SSA exhibited 257.79%–424.60% higher expansion rate after 21-day immersion than those with LA, the 3-day immersion expansion rates complied with specification limits (<1.5% per JTG F40-2004). Critical volume expansion control measures should be adopted for full-component applications of steel slag powder/aggregates due to the hydration potential of free lime (f-CaO) and magnesium oxide (MgO) in steel slag under moisture exposure. Full article

The environmental risks associated with industrial solid wastes—fly ash (FA), red mud (RM), carbide slag (CS), and steel slag (SS)—are amplified by their massive global accumulation. This study developed a quaternary cementitious system using low-activity industrial wastes—FA, RM, CS, and SS—as alternatives to high-reactivity ground granulated blast furnace slag. The hydration behavior, mechanical properties, and microstructure were investigated, along with the effects of Ca(ClO)₂ and Ca₃(PO₄)₂ as calcium additives. Fresh properties (fluidity, pH, and electrical conductivity), compressive strength, and drying shrinkage were evaluated, while SEM-EDS, XRD, FTIR, and TG-DSC analyzed microstructural evolution. The results show that FA-RM alone failed to solidify, but CS enhanced hydration, reducing fluidity and increasing strength, while SS improved thermal stability as a micro-aggregate. The optimized FA-RM-CS-SS system achieved 16.7 MPa at 90 days. Ca(ClO)₂ accelerated C-S-H gel formation, whereas Ca₃(PO₄)₂ stabilized the matrix via hydroxyapatite precipitation, mitigating shrinkage. This approach enables simultaneous waste utilization, along with Cl- and P-containing pollutant immobilization, offering a sustainable strategy for eco-friendly construction materials. Full article

Conventional concrete causes significant environmental problems, including resource depletion, high CO₂ emissions, and high energy consumption. Steel slag aggregate (SSA), a by-product of the steelmaking industry, offers a sustainable alternative due to its environmental benefits and improved mechanical properties. This study examined the predictive power of four modeling techniques—Gene Expression Programming (GEP), an Artificial Neural Network (ANN), Random Forest Regression (RFR), and Gradient Boosting (GB)—to predict the compressive strength (CS) of SSA concrete. Using 367 datasets from the literature, six input variables (cement, water, granulated furnace slag, superplasticizer, coarse aggregate, fine aggregate, and age) were utilized to predict compressive strength. The models’ performance was evaluated using statistical measures such as the mean absolute error (MAE), root mean squared error (RMSE), mean values, and coefficient of determination (R²). Results indicated that the GB model consistently outperformed RFR, GEP, and the ANN, achieving the highest R² values of 0.99 and 0.96 for the training and testing dataset, respectively, followed by RFR with R² values of 0.97 (training) and 0.93 (testing), GEP with R² values of 0.85 (training) and 0.87 (testing), and ANN with R² values of 0.61 (training) and 0.82 (testing). Additionally, the GB model had the lowest MAE values of 0.79 MPa (training) and 2.61 MPa (testing) and RMSE values of 1.90 MPa (training) and 3.95 MPa (testing). This research aims to advance predictive modeling in sustainable construction through analysis and well-defined conclusions. Full article

Recycling steel slag into asphalt concrete is an important way to save natural resources and protect the environment. The high asphalt absorption and adsorption and the sensitivity of steel slag aggregate (SSA) to the combined damage of temperature and moisture (volume expansion and poor durability under freeze-thaw cycle damage) still pose risks for the use of SSA in asphalt concrete. It is urgent to develop new utilization methods of steel slag. With this in mind, the material properties of steel slag powder (SSP) and performance characteristics of asphalt concrete incorporating SSP filler were evaluated in this research. The SSP was prepared in the laboratory by grinding steel slag with a particle size of 2.36–4.75 mm. Firstly, the material properties of SSP including the specific surface area, particle gradation, apparent density, chemical compositions, and thermal stability were analyzed. Steel slag (2.36–4.75 mm) and common limestone powder (LP) filler were used as control groups. The grindability of steel slag and the advantages of using SSP as a filler in asphalt concrete were preliminarily analyzed based on the test results of material properties. Then, the Superpave method was used to design asphalt concrete incorporating SSP and LP. Considering that steel slag is sensitive to the combined damage of temperature and moisture, the main engineering performance of asphalt concrete after the combined damage of temperature and moisture was evaluated to further reveal the feasibility of using SSP as a filler. Two combined damage modes, namely hot water damage and freeze-thaw cycle damage, were applied. Results suggest that although the steel slag is more difficult to grind compared to limestone particles, grinding steel slag into SSP has improved the uniformity of its material properties. Good uniformity of material properties, high alkalinity, and excellent thermal stability of SSP give it some advantages in its application in asphalt concrete. Although the freeze-thaw cycle damage has a slightly more significant effect on the engineering performance of asphalt concrete than hot water damage, compared to the asphalt concrete with LP filler, even after freeze-thaw cycle damage for three cycles asphalt concrete incorporating SSP still possesses comparable or better volume stability, mechanical performance, high-temperature deformation resistance, low-temperature crack resistance, fatigue crack resistance, and fatigue durability. Full article

Steel slag is a solid waste produced in crude steel smelting, and a typical management option is stockpiling in slag disposal yards. Over the years, the massive production of steel slags and the continuous use of residue yards have led to vast occupation of land resources and caused severe environmental concerns. Steel slag particles can potentially be used as aggregates in concrete production. However, the volume stability of steel slag is poor, and the direct use of untreated steel slag aggregate (SSA) may cause cracking and spalling of concrete. The present research summarizes, analyzes, and compares the chemical, physical, and mechanical properties of steel slags. The mechanism and treatment methods of volume expansion are introduced, and the advantages, disadvantages, and applicable targets of these methods are discussed. Then, the latest research progress of steel slag aggregate concrete (SSAC) is reviewed. Using SSA leads to an increase in the density of concrete and a decrease in workability, but the mechanical properties and durability of SSAC are superior to natural aggregate concrete (NAC). Finally, future research in this field is proposed to motivate further studies and guide decision-making. Full article

Self-healing in asphalt mixtures is a property that can be enhanced by external heating, which causes a thermal expansion that increases the flow of bitumen with reduced viscosity through the cracks. Therefore, this study aims to evaluate the effects of microwave heating on the self-healing performance of three asphalt mixtures: (1) conventional, (2) with steel wool fibers (SWF), and (3) with steel slag aggregates (SSA) and SWF. After evaluating the microwave heating capacity of the three asphalt mixtures with a thermographic camera, their self-healing performance was determined with fracture or fatigue tests and microwave heating recovery cycles. The results demonstrated that the mixtures with SSA and SWF promoted higher heating temperatures and presented the best self-healing capacity during the semicircular bending test and heating cycles, with significant strength recovery after a total fracture. In contrast, the mixtures without SSA presented inferior fracture results. Both the conventional mixture and that containing SSA and SWF presented high healing indexes after the four-point bending fatigue test and heating cycles, with a fatigue life recovery of around 150% after applying two healing cycles. Therefore, the conclusion is that SSA greatly influences the self-healing performance of asphalt mixtures after microwave radiation heating. Full article

The demand for more sustainable transport infrastructure has led to a broader acceptance of waste materials in pavements. An excellent example of this trend is the incorporation of steel slag aggregates (SSA) in asphalt mixtures. This work evaluates the mechanical performance of asphalt mixtures that include SSA in their composition. Asphalt mixtures were evaluated through laboratory tests for affinity between binder and aggregate, Marshall and volumetric properties, stiffness, resistance to fatigue, permanent deformation, and water sensitivity. Two rates of SSA incorporation—20% and 35%—were considered. In general, results indicated that incorporating SSA has not impaired the behavior of the asphalt mixtures. In some cases, the presence of SSA has improved mechanical performance. It was the case of the resistance to permanent deformation, stability, flow, and water sensitivity. This work confirms the suitability of the SSA application in asphalt mixtures beyond the benefit of promoting industrial waste in pavement engineering. Full article

The proper disposal of steel slag has always been a great challenge for the metallurgical industry in China and around the world. In this work, the steel slag aggregate (SSA) was surface pretreated (PSSA) and applied into asphalt mixture. The adhesive behavior between the bitumen and five different types of aggregates (i.e., limestone, diorite, diabase, SSA, PSSA) were evaluated based on the contact angle and binder bond strength tests. The pavement performance of three asphalt mixtures which contain normal aggregate, SSA and PSSA respectively, was analyzed by Marshall stability test, wheel-tracking rutting test, low-temperature bending creep test and water sensitivity test. The results showed that surface modification can improve the surface properties of SSA, reduce its contact angle with bitumen, and eventually lead to the improvement of adhesion between them. In addition to the satisfied low-temperature properties, PSSA was found to significantly improve the anti-rutting property and reduce the water sensitivity of asphalt mixture. This work is expected to promote an alternative application for recycling of SSA in pavement engineering. Full article

Various researchers are developing efforts to integrate waste and by-products as alternative materials in road construction and maintenance, reducing environmental impacts and promoting a circular economy. Among the alternative materials that several authors have studied regarding their use as partial or total substitutes for natural aggregates in the asphalt paving industry, the steel slag aggregate (SSA) and recycled concrete aggregate (RCA) from construction demolition waste (CDW) stand out. This paper reviews and discusses the characteristics and performance of these materials when used as aggregates in asphalt mixtures. Based on the various studies analyzed, it was possible to conclude that incorporating SSA or RCA in asphalt mixtures for road pavements has functional, mechanical, and environmental advantages. However, it is essential to consider some possible drawbacks of these aggregates that are discussed in this paper, to define the acceptable uses of SSA and RCA as sustainable feedstocks for road paving works. Full article

Steel slag is a byproduct generated as waste during the steelmaking process and can be considered a cost-effective and environmentally acceptable alternative to replace natural aggregates. Using steel slag aggregates (SSA) to produce asphalt mixtures promotes sustainability and circular economy principles by using an industrial byproduct as a raw material. Thus, this work mainly aims to design more sustainable asphalt mixtures with high amounts of SSA that fit the circular economy expectations. This work developed two asphalt mixtures with SSA for surface (AC 14 surf) and binder/base (AC 20 bin/base) courses. Initially, the excellent wearing and polishing resistance of SSA and their good affinity with bitumen demonstrated the potential of this byproduct to be used in asphalt mixtures. Then, when analyzing the influence of using two different SSA incorporation rates (50% and a percentage close to 100%) in both asphalt mixtures, it was concluded that the use of SSA should be limited to 75% to avoid excessive air void contents and durability problems. The importance of considering the different particle densities of SSA and natural aggregates was highlighted during the mix design by defining a relationship between an effective and equivalent binder content. Finally, the mechanical performance of AC 14 and AC 20 with 75% SSA incorporation was compared to identical conventional mixtures produced with natural granite aggregates. The results obtained showed that the asphalt mixtures with 75% SSA have some workability problems due to the rough and porous surface of SSA. However, they present an excellent water sensitivity and permanent deformation resistance, surpassing the performance of the conventional asphalt mixtures. Full article

This paper investigates the possibility of utilizing steel slags produced in the steelmaking industry as an alternative to burnt clay brick aggregate (BA) in concrete. Within this context, physical, mechanical (i.e., compressive and splitting tensile strength), length change, and durability (porosity) tests were conducted on concrete made with nine different percentage replacements (0%, 10%, 20%, 30%, 40%, 50%, 60%, 80%, and 100% by volume of BA) of BA by induction of furnace steel slag aggregate (SSA). In addition, the chemical composition of aggregate through X-ray fluorescence (XRF) analysis and microstructural analysis through scanning electron microscopy (SEM) of aggregates and concrete were performed. The experimental results show that the physical and mechanical properties of concrete made with SSA were significantly higher than that of concrete made with BA. The compressive and tensile strength increased by 73% when SSA fully replaced BA. The expansion of concrete made with SSA was a bit higher than the concrete made with BA. Furthermore, a significant lower porosity was observed for concrete made with SSA than BA, which decreased by 40% for 100% SSA concrete than 100% BA concrete. The relation between compressive and tensile strength with the porosity of concrete mixes are in agreement with the relationships presented in the literature. This study demonstrates that SSA can be used as a full replacement of BA, which is economical, conserves the natural aggregate, and is sustainable building material since burning brick produces a lot of CO₂. Full article