Steel Slag Content Research Articles

Destructive and Non Destructive Test Characteristics of Concrete Produced with Iron Slag Aggregate

ABSTRACT The Ground granulated Blast furnace slag (GGBFS) is a waste of industrial materials; it is relatively more recent pozzolanic material that has received considerable attention in both research and application. In the present investigation, Blast Furnace Slag from local industries has been utilized to find its suitability as a coarse aggregate in self-compacting concrete (SCC) making. Replacing all or some portion of natural aggregates with slag would lead to considerable environmental benefits. SCC mixes were designed and coarse aggregates were replaced by 0, 20, 40, 60, 80, and 100% steel slag by weight. Tests were conducted to assess the fresh properties, strength properties and durability behavior (permeability) of SCC. Properties such as slump flow, flow diameter, passing ability, segregation resistance, compressive strength, and both rebound number and ultrasonic pulse velocity were measured. In addition, the relationship between compressive strength and rebound number as well as ultra-sonic pulse velocity (UPV) was discussed. Splitting tensile strength, flexural strength, and permeability were also examined. The results indicate that the mixture of 60% replacement (SCC-SA60) was selected as the optimum mixture in which compressive strength, splitting tensile strength, and flexural strength increased by 5%, 35%, and 10%, respectively. Permeability increased with increasing the steel slag content. The results also illustrated that there is a significant relationship between compressive strength and UPV as well as rebound number for the SCC mixes.

Wetting-Drying Resistance of a Lime Stabilized Soil Amended with Steel Slag and Reinforced with Fibres

The investigation dealt with the stabilization of expansive soil with combinations of lime, steel slag and reinforced with two types of fibres, copper filaments and polypropylene fibres. The investigation began with the characterization of the soil for its geotechnical properties. The initial consumption of lime required for the modification of the soil properties was determined from the Eades and Grim pH test. Cylindrical specimens of soil with dimensions 38 mm x 76 mm were cast using this lime content as a stabilizer along with varying quantities of steel slag for determination of optimum steel slag content. The pure lime stabilized soil as well as lime-steel slag modified soil specimens were reinforced with different proportions of copper filaments for determination of optimum fibre content. One dosage of polypropylene fibres was also adopted as reinforcement in specimen preparation. The optimal combinations identified were then subjected to a maximum of three cycles of wetting and drying followed by determination of unconfined compression strength (UCS). The expansive soil required a minimum of 3% lime for its modification. The optimum dosage of steel slag was identified as 5% and optimum copper filament content as 1%. Polypropylene content of 0.3% was also adopted as one combination. The results of the investigation revealed that lime stabilized fibre-reinforced soil with copper filaments was the most durable combination followed by polypropylene fibres. The introduction of steel slag in the mix could not generate enough beneficial durability to the soil after three cycles of wetting and drying.

Effect of Silica Fume & Steel Slag on Nano-silica based High-Performance Concrete

This study presents strength behaviour of concrete based composites including three different ternary binders namely Nano-Silica (NS), Silica Fume (SF) & Steel Slag (SS). NS as fragmental substitution of cement, SF as the fragmental substitution for the fine aggregates and SS as fragmental substitution of coarse aggregates has been used. The study has been conducted at an optimized content of NS (2%) and by varying the content of SF (10-15%) and SS (10-30%). Cement concrete having M60 grade strength at fixed W/C (0.35) has been explored for the strength behaviour. The studies have revealed that the optimized content of NS, SF and SS can be used as a partial substitute of cement, fine aggregates and coarse aggregates respectively to obtain increased strength. Thus, NS, SF and SS can be used to obtain high performance and eco-friendly concrete structures.

Effect of Elevated Temperatures on Sugarcane Bagasse Ash-Based Alkali-Activated Slag Concrete

The main focus of researchers in construction sector is to check suitability of ecofriendly alternative materials. Sugarcane bagasse ash (BA) and steel slag (SS) is one among such ecofriendly alternative materials. BA and SS has potential to utilize as binder and coarse aggregate, respectively, in concrete production. In the present investigation, BA and SS were utilized in alkali-activated slag/bagasse ash concrete (AASBC) mixture production. Full factorial experimental design was considered with two input variables, i.e., BA (0, 25, and 50%) and SS (0, 50, and 100%) as replacement to ground granulated blast furnace slag and natural coarse aggregate, respectively. Effect of elevated temperatures on BA and SS-based AASBC mixture were examined. Field emission scanning electron microscope study were carried out to check the morphological changes in ambient and elevated temperature condition. In order to rank different BA and SS-based AASBC mixture performance multi-criteria optimization techniques like, grey relational analysis, technique for order preference by similarity to ideal solution, and desirability function approach were utilized. AASBC mixture with 25% BA content and 100% SS content found to be most suitable AASBC mixture based on multi-criteria optimization technique under elevated temperature conditions.

Environmental investigation of bio-modification of steel slag through microbially induced carbonate precipitation

Steel slag (SS) is one of byproduct of steel manufacture industry. The environmental concerns of SS may limit their re-use in different applications. The goal of this study was to investigate the leaching behavior of metals from SS before and after treated by microbially induced carbonate precipitation (MICP). Toxicity characteristic leaching procedure, synthetic precipitation leaching procedure and water leaching tests were performed to evaluate the leaching behavior of major elements (Fe, Mg and Ca) and trace elements (Ba, Cu and Mn) in three scenarios. The concentrations of leaching metals increased with the content of SS. After it reached the peak concentration, the leaching concentration decreased with the content of SS. The leachability of all elements concerned in this study was below 0.5%. The carbonate generated from the MICP process contributed to the low leachability of metals. After bio-modified by MICP process, the leaching concentrations of Ba from TCLP, SPLP and WLT tests were below 2.0 mg/L, which was the limit in drinking water regulated by U.S. EPA. The concentrations of Cu leached out from MICP-treated SS-sand samples were below 1.3 mg/L which is the limit regulated by national secondary drinking water. Compared with the regulations of U.S.EPA and Mississippi Department of Environment Quality (MDEQ), MICP-treated samples were classified as non-hazardous materials with respects to the leaching of metals. Meanwhile, maximum contaminant limits regulated by U.S.EPA states that MICP-treated SS are eco-friendly materials that can be reused as construction materials.

Effect of Dry–Wet and Freeze–Thaw Repeated Cycles on Water Resistance of Steel Slag Asphalt Mixture

As an attractive substitute of natural aggregate for asphalt mixture, steel slag raises many concerns on the water resistance of steel slag asphalt mixture in frozen and wet areas, due to the special interaction between steel slag and asphalt. This study aims to investigate the deterioration process of water resistance for asphalt mixture with different steel slag contents in dry–wet and freeze–thaw cycles environments. The Marshall immersion test and indirect tensile test were conducted, and the residual stability and tensile strength ratio (TSR) were measured to characterize the water resistance of the steel slag asphalt mixture. Furthermore, dry–wet and freeze–thaw repeated cycling conditions were designed to simulate the effect of actual environments on the long-term water resistance of asphalt pavement. Finally, the microstructures of the aggregate–asphalt interface area were observed, and the enhancement mechanism of the steel slag replacement in asphalt mixture was revealed. Results show that steel slag asphalt mixture exhibits significant resistance to water damage. With the increase in dry–wet or freeze–thaw repeated cycles, the water resistance of steel slag asphalt mixture rapidly deteriorates first and then tends to be stable, and there is a limit state of water damage. In dry–wet repeated cycles condition, the asphalt mixture with 50% steel slag content has a better water resistance, while the asphalt mixture with 100% steel slag content has a better water resistance under freeze–thaw repeated cycles condition. The interface phase structure of steel slag asphalt mixture is stable and dense, where the asphalt mortar evenly and tightly wraps the steel slag and forms a certain penetration depth. The enhancement mechanism of steel slag with asphalt mainly includes the physical anchoring effect and the chemical adhesion effect.

Experimental study on the utilization of steel slag for cemented ultra-fine tailings backfill

To improve the properties of cemented ultra-fine tailings backfill (CUTB), the authors intend to outline the framework of the effect of steel slag (SS) on the properties of CUTB. Therefore, flowability, unconfined compressive strength (UCS), hydration products, and pore structure were used to investigate the properties of CUTB samples. The results showed that the incorporation of SS increased the flow spread by increasing the water film thickness (WFT). Unconfined compressive strength (UCS) was observed to be enhanced when the content of SS did not exceed 20 wt%. Hydration phase evolution tested by X-ray diffraction, thermogravimetry, and thermodynamic modeling indicated the additional formation of hydrotalcite-like phases (Ht). This contributed to a denser microstructure. Besides, lower total porosity and critical pore diameter (dcr) obtained by mercury intrusion porosimeter tests were observed in samples with SS addition, which could favor the strength development. On the other hand, toxicity characteristic leaching procedure (TCLP) results indicated that the CUTB exhibited good environmental performance.

Numerical investigation of the behavior of stone ballast mixed by steel slag in ballasted railway track

Recently, implementing steel slag ballast has been proposed as an appropriate material to substitute stone ballast. In this regard, one of the technical concerns is the behavior of steel slag ballast in both time and frequency domains that needs to be assessed, properly. Furthermore, the combination of stone ballast and steel slag is unavoidable in steel slag ballasted tracks during track maintenance concerning the limitation of steel slag resources. Therefore, this paper suggests an optimal stone ballast-steel slag (SB-SS) combination regarding the dynamic behavior of five SB-SS combinations as 0%SS, 25%SS, 50%SS, 75%SS and 100%SS by weight of ballast using a finite element method (FEM) model of a 50-meter test track. Moreover, using elasticity modulus and Moher-coulomb parameters obtained via a series of plate load and shear strength tests for each SB-SS combination turns FEM model to be more close to the real test track results.Experimental results show that adding steel slag particles to stone ballast increases elasticity modulus and friction angle of ballast layer resulting in the improvement of mechanical behavior of railway track. Consequently, the maximum deflections and root mean square (RMS) of accelerations decrease by increasing steel slag content. Analyzing free vibration of ballast layer combinations reveals that damping ratios of 100%SS ballast layer is the maximum value as 0.25 followed by 75%SS, 50%SS, 25%SS and 0%SS combinations. Moreover, the dominant frequencies of each ballast layer combinations determine that 0%SS, 25%SS and 50%SS coincides within the track excitation frequency range made by wheel sets, while 75%SS and 100%SS are out of which. Finally, according to all results, 75%SS ballast layer is proposed as the optimal SB-SS combination.

Durability of a new type of cement-based composite grouting material under effects of chemical corrosion

Corrosion resistance and durability are important performance features for grouting materials in underground engineering. The grouts based on ordinary Portland cement are difficult to solve water inrush disasters. To solve these problems, a new type of sulphoaluminate-cement-based Composite Grouting Material (CGM) has been developed. In this research, the chemical corrosion mechanism was analyzed, and the durability and anti-corrosion performance of CGM were studied under different concentrations of sulfate and chloride ions, steel slag contents and water/CGM (W/CGM) ratios. The flexural strength, compressive strength and corrosion resistance coefficient of CGM were measured in dependence of the days. Scanning electron microscopy (SEM) analysis was carried out to determine the anti-corrosion characteristic of CGM. The results showed that the corrosion resistance coefficients of CGM are generally larger than 1.0 under different sulfate and chloride ion concentrations. Steel slag prevents sulfate ions from penetrating the hardened stone body, and the anticorrosion performance of CGM was relatively low at high W/CGM ratios.

Design and prospect of new pavement materials for smart road

Considering the development of conventional engineering materials, the research on new modern materials and the increasing demand for road infrastructure construction, significant changes regarding both the road fundamental properties and functional positioning have been taking place at an increasing pace. The roads have evolved from early structures meeting basic traffic needs to important assets with well-defined economic and environmental characteristics. Since the beginning of the 21st century, the need for smart and safe travel has steadily created new requirements for road infrastructure. The rapid development of material science and interdisciplinary research has provided viable and technical support for the design and construction of various types of new pavements, thus promoting the continuous expansion within the research field of pavement materials. Therefore, this research introduces and analyzes the technical principles, design, development, and challenges related to new pavement materials characterized by self-capture energy, self-luminescence, self-regulation, and self-healing functions, providing a reference for the future research direction. The main objective of piezoelectric self-powering pavement is to design the structure and optimize the performance of self-powering devices, and apply this technique in road engineering. A series of studies on mechanical modeling, laboratory verification and engineering application of self-powering devices show that the energy harvesting effect of embedded piezoelectric self-powering devices made of block or multilayer piezoelectric materials is considerable, and the piezoelectric self-powering pavement has a broad prospect. Thermoelectric pavement is a new type of pavement, which uses the Seebeck effect of thermoelectric materials to collect excess energy of asphalt pavement and realize green conversion of pavement energy. Meanwhile, it can effectively reduce the temperature of pavement and prolong the service life of road. The composition includes three main parts: Thermoelectric conversion device, hot end and cold end. A new type of thermoelectric asphalt pavement structure is studied in this paper. Results indicate that the power generation 0.564 V of single specimen has good application potential via monitoring the generation voltage of thermoelectric pavement in different seasons. The research of self-luminous pavement mainly focuses on the design and optimization of pavement luminescent materials. The self-luminous paste materials are prepared by adding long afterglow rare earth luminescent powder and glass beads reflective powder into cement materials. The luminescence properties are characterized by afterglow decay time and fluorescence chromatography. The optimum range of particle size of self-luminous pavement materials and reflective powder is determined, which can provide reference for the further research. As for the self-regulation pavement material, the thermogravimetric and differential scanning calorimetry tests are conducted to study the thermal stability and phase transition characteristics of PEG. The results show that PEG has excellent thermal stability; the average molecular weight ranging from 4000 to 10000 of PEG have relatively high phase change heat storage capacity and similar phase change temperature. Based on asphalt properties, the optimum average molecular weight for asphalt pavements can be further decided. Conductive asphalt mixtures are used in this study to investigate the self-healing properties under microwave irradiation. The microstructure and element distribution of steel slag are characterized through scanning electron microscope. The healing level and the optimum content of steel slag are evaluated according to the recovery strength level of steel slag asphalt mixture and the surface temperature distribution of specimen under microwave radiation. Results show that steel slag is an excellent microwave absorbing material, which can effectively improve the healing level of the mixture, meanwhile, there is an optimal addition amount of the steel slag. The significance of innovative material design is not only related to expanding the pavement functions, but also to bolstering the structural technology design concepts of modern road engineering as well as to offering new technologies for the related industry sector.

Behavior of Steel Slag Concrete Subjected to Elevated Temperature

Recycling of materials has become a major interest for engineers. At present, the amount of slag deposited in storage yard adds up to millions of tons/year leading to the occupation of farm land and serious pollution to the environment, as a result of the rapid growth in the steel industry. Steel slag is made at 1500- 1650°C having a honey comp shape with high porosity. Using steel slag as the natural aggregate with a lower waste material cost can be considered as a good alternative for sustainable constructions. The objective of this study is to evaluate the performance of residual mechanical properties of concrete with steel slag as coarse aggregate partial replacement after exposing to high temperatures .This study investigates the behavior of using granulated slag as partial or fully coarse aggregate replacement with different percentages of 0%, 15%, 30%, 50% and 100% in concrete when subjected to elevated temperatures. Six groups of concrete mixes were prepared using various replacement percentages of slag exposed to different temperatures of 400 °C, 600 °C and 800 °C for different durations of 1hr, 1.5hr and 2hr. Evaluation tests were compressive strength, tensile strength, and bond strength. The steel slag concrete mixes showed week workability lower than control mix. A systematic increasing of almost up to 21.7% in compressive strength, and 66.2% in tensile strength with increasing the percentage of steel slag replacement to 50%. And the results showed improvement on concrete residual mechanical properties after subjected to elevated temperatures with the increase of steel slag content. The findings of this study give an overview of the effect of steel slag coarse aggregate replacement on concrete after exposed to high temperatures.

Experimental Research on Steel slag Stabilized Soil and its Application in Subgrade Engineering

An experimental program was carried out to explore the feasibility of steel slag replacing lime used in the pavement of highway subgrade. The compaction test, the bearing ratio test, the unconfined compressive strength test, the splitting tensile strength test and the water stability test were carried out for different mixture ratio. And field test was also carried out to verify the application of steel slag. The test results showed that the immersion bearing ratio of steel slag stabilized soil increased with the increase of compaction degree and content of steel slag. The CBR value of Steel slag stabilized soil with 8–15% slag content was basically equivalent to that of 4% lime soil. The failure strain of 8% or 15% steel slag soil is larger than that of lime soil or cement soil. The strength of lime soil, cement soil and steel slag stabilized increased monotonously with the increase of curing age, but the growth rate of lime soil was significantly higher than that of steel slag stabilized soil. The 7d unconfined compressive strength of 8% steel slag stabilized soil reached 0.41 MPa, which met the requirements of highway subgrade materials. The initial moisture content had a great influence on the steel slag stabilized soil, and it was necessary to strictly control the moisture content for subgrade constructing. The content of steel slag in the steel slag stabilized soil was measured by EDTA method which is effective. The deflection value of 8% steel slag stabilized soil was 130.8 (10−2 mm), which can meet the requirements of the design specification [232.9(10−2 mm)].

Components of steel slag in acid-contaminated porous concrete

The presence of slag as a result of waste from steel production annually increases. Researchers and environmentalists are very concerned to overcome this problem. Currently steel slag has been studied as a substitute for concrete compilers. The focus of this research is to utilize steel slag as a constituent of porous concrete in direct contact with acidic regions, in this case sulfuric acid and chloride. This test was carried out using 243 samples in testing the compressive strength, tensile strength and pore volume of concrete. Content of steel slag used is 0%, 50% and 80%. In the compressive strength test results for normal curing, sulfate curing and chloride curing showed an increase of 6.49%, 5.71%, 8.28% in the 50% slag content and 10.81%, 10.29%, 17.20% in the 80% slag content. Then in the tensile strength test showed an increase of 7% to 11% in the 50% slag content and 16% to 17% in the 80% slag content. As for the pore volume, the value is in range from 17% to 19%. These results indicate that slag can be used as a substitute for aggregate on porous concrete with compressive strength ranging from 10 MPa to 19 MPa.

Preparation and Performance Study of New Type Steel Slag Ceramic

In this paper, steel slag with chemical components of CaO and S1O2 was used as raw materials to prepare new steel slag ceramic by referring to the traditional ceramic production process, and the vickers hardness and flexural strength were studied. The results show that steel slag can be used as raw material in the preparation of ceramic, with the increase of the content of steel slag, the hardness and flexural strength of steel slag ceramic increase to different degrees.

Development of steel slag composite grouts for underground engineering

The grouting materials are new fields where cement clinker (CC) can be replaced by high amounts of steel slag (SS). To develop steel slag composite grouts (SSCG) for constructions and repairs in underground engineering, it is necessary to determine and optimize the performance of SSCG. In this study, the SS and blast furnace slag (BFS) contents in ternary grouts were all 55–75%. The fly ash (FA) contents were 10% and 15% in quaternary grouts, and the SS and BFS contents were all 20–40%. The FA, SS and BFS contents in quinary grouts were 5–10%, 25–40% and 25–30%. The flue gas desulfurization gypsum (FGDG) content was 5%. The water-solid (W/S) range was selected as 0.65–1.2. The properties investigated were: fresh-state properties i.e., mini-slump, effective W/S, stone rate, flowability losing time, setting time; mechanical performance i.e., flexural strength (FS), unconfined compressive strength (UCS), FS/UCS and fracture characteristic; hydration products; microstructure and pore size distribution. The results show that the SS was suggested to combine with BFS to enhance the strengths, the 3-day and 28-day UCSs of the quinary SSCG (19#) increased by 105.3% and 167.7% with 2% B + 6% AA + 0.4% SP. With the approximate activation, the bigger pores (>100 nm) have been transformed into small pores under 30 or 100 nm effectively, and the compactness of gel structure has been improved. The workability, mechanical performance, and microstructures of optimized SSCG with high amount of SS (40%) and industrial residue (80%) are acceptable, it can meet the requirements of grouting practices for underground engineering.

Study on mathematical model of hydration expansion of steel slag-cement composite cementitious material

ABSTRACT This paper studies the expansion laws of steel slag-cement composite cementitious material, and establishes the mathematical model of hydration expansion of steel slag-cement composite cementitious material. Xinyu converter steel slag was mixed into the cement to prepare 25 × 25 × 280 mm steel slag-cement pastes. After boiled and autoclaved tests, the volume changes before and after the steel slag-cement pastes were measured to verify the accuracy of the established mathematical model. The experimental results show that when the content of steel slag is lower than 30%, the hydration expansion of Xinyu converter steel slag conforms to the established mathematical model. When the content of steel slag is 40%, the measured expansion ratio is 10.4% larger than the calculated expansion ratio of the mathematical model; when the content is 50%, due to a large number of internal micro-cracks, the measured expansion ratio is 19.5% larger than the calculated expansion ratio of the mathematical model. When the steel slag content reaches 60%, the steel slag-cement pastes warps seriously, and the mathematical model is no longer applicable to this situation. The mathematical model can accurately predict the expansion ratio when the steel slag content is less than 30%. Therefore, it can be concluded that when the steel slag content is less than 30%, there are only a few cracks in the steel slag-cement pastes, which is of good stability. So the results show that the maximum content of steel slag to prepared the steel slag-cement pastes is 30%.

Microwave Heating Characteristics of Emulsified Asphalt Repair Materials Incorporated with Steel Slag

Emulsified asphalt needs to be cured for a certain age after demulsification to produce strength, which seriously affects the traffic opening time. In this work, microwave heating technology was applied for emulsified asphalt repair materials. Steel slag with high microwave activity was adopted to improve the performance of emulsified asphalt repair materials by microwave heating. Effects of steel slag sizes and contents on the heating rate, temperature distribution, and thermal performance of emulsified asphalt repair materials were analyzed by close microwave heating, open microwave heating, and repair simulation tests. Results show that the temperature of emulsified asphalt repair materials presents three different heating stages under microwave irradiation. The “critical point of phase transition” in the three stages is gradually advanced with the increase in steel slag content. The core temperature and maximum temperature of emulsified asphalt repair materials with different steel slag sizes are basically the same; however, the heat distribution of emulsified asphalt repair materials is significantly different. In contrast to conventional asphalt mixture, there exists a smaller temperature difference. The temperature of repairing materials can reach above 80°C. The interface area can form an embedded interface structure. Incorporation of steel slag and adoption of microwave heating are effective to improve the performance of emulsified asphalt repair materials.

Enhanced mechanical behavior of compacted clayey silts stabilized by reusing steel slag

Finding new uses and applications of byproducts has significant importance due to the present need of minimizing the consumption of natural resources, reducing the amount of the disposal of waste materials and finding novel sustainable applications for these materials. This paper evaluates the behavior of compacted clayey loessical soils stabilized by the addition of steel slag (SS). Used soil is a loessical material made by quarts, feldspar and volcanic glass in different proportions. Different physical, microscopical and mechanical tests were performed in compacted specimens of clayey soil-SS mixtures. The influence of SS content, compaction moisture content and curing time on strength, deformation modulus, particle size, and pore structure were evaluated. The results showed increases in soil resistance and stiffness with the curing time, which can be attributed to the natural cementation that takes place due to interaction between the vitreous fraction of clayey silty particles and SS through pozzolanic reactions. This type of reaction is also confirmed by means of a direct measurement of a pozzolanicity index, evolution of pore sizes with a formation of more homogeneous microstructures and associated reduction in water content.

Study of the long-term water stability of asphalt mixtures containing steel slag aggregate

This article aims to elucidate the long-term water stability of a steel slag asphalt mixture. Both chemical composition and physical morphology of the steel slag were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), the Vickers hardness test and mercury injection testing. Methods of testing wet-dry (W–D) cycles and freeze-thaw (F–T) cycles were designed, and corresponding indices were proposed. The immersion rutting test was conducted to explore the variation in rutting depth, and consequently, the long-term dynamic water coefficient Kl was proposed to analyze the resistance to dynamic water flushing. A regression model was used to analyze the relationship between steel slag content and long-term water stability. Finally, the long-term corrosion characteristics of the steel slag asphalt mixture were analyzed by SEM. The results show that the addition of steel slag can improve the long-term water stability of the asphalt mixture. The water stability of the steel slag asphalt mixture declines with increasing W–D and F–T cycles. The degradation trend becomes gentle after 6 W–D cycles. The attenuation of the water stability of the mixture slows after 15 F–T cycles. The long-term water stability of the steel slag asphalt mixture was evaluated by comparing the residual stability after 6 W–D cycles (MS6) and the tensile strength ratio (TSR) of the steel slag asphalt mixture after 15 F–T cycles (TSR15). The Kl value of the steel slag asphalt mixture first increases and then decreases with increasing steel slag content, and the best effect in terms of long-term dynamic water corrosion resistance is observed for a 30% steel slag asphalt mixture. The SEM results show that, for steel slag asphalt mixture water damage, the steel slag hydrates and produces microcracking on the surface.

Feasibility assessment of the use of basic oxygen furnace slag in open graded asphalt courses

India is the world’s third largest steel producer with a production of 97.8 million tonnes in 2017. Steel slag is obtained as a by-product from steel-making industries during the conversion of iron to steel. Steel slag possesses favorable angularity and strength properties. This study aims to utilize basic oxygen furnace (BOF) steel slag as coarse aggregate for open graded asphalt courses (OGACs). OGAC is a special hot-mix asphalt wearing course that is designed for higher air voids to achieve quick drainage of surface water and better wet weather performance. High air voids in OGAC are created with the use of a higher proportion of uniformly graded coarse aggregates and low amount of fines. In this study, use of BOF slag in OGAC mixes is evaluated through 0% (control mix), 25%, 50%, 75% and 100% replacement of coarse natural aggregate. Further, two types of modified asphalt binders are used: polymer-modified and crumb rubber-modified binder for evaluation of OGAC mixes with and without BOF slag. OGAC mixes are evaluated for volumetric characteristics (bulk density and air voids), stone-on-stone contact, binder draindown, and raveling resistance. Raveling resistance is evaluated through Cantabro abrasion loss test under both unaged and aged conditions. Results of the study indicate that an increase in steel slag content enhances the stone-on-stone contact and improves the resistance to raveling of OGAC mixes. Based on statistical analysis through analysis of variance (ANOVA), binder content and slag replacement percentage are found to have significant influence on the properties of OGAC mixes.