IRC Code:SP:121-2018 – Guidelines for Use of Iron, Steel, and Copper Slag in Rural Roads

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With increasing environmental concerns and the need for sustainable infrastructure, the Indian Roads Congress (IRC) introduced IRC:SP:121-2018, providing guidelines for the use of iron, steel, and copper slag in rural road construction. This standard aims to promote the utilization of industrial by-products, ensuring cost-effectiveness, sustainability, and durability in rural road projects.

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Why Use Slag in Road Construction?

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Slag is a by-product generated during metal production. The major types include:

• Blast Furnace Slag (BFS) – Derived from iron-making.
• Steel Slag – A by-product of steel-making processes like Basic Oxygen Furnace Slag (BOFS) and Electric Arc Furnace Slag (EAFS).
• Copper Slag – Generated from the smelting of copper ore.

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Using slag in road construction offers:

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✅ Reduced environmental impact – Utilization of waste materials prevents landfills.
✅ Cost-effectiveness – Slag is more economical than natural aggregates.
✅ Enhanced performance – Slag exhibits high strength, skid resistance, and durability.

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‍Guidelines for Using Slag in Rural Road Construction

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1. Iron and Steel Slag in Road Layersa) Slag as a Sub-base Material

• Air-cooled blast furnace slag (ACBFS) and weathered steel slag are suitable for sub-base layers.
• Processed steel slag (BOFS) can replace conventional aggregates in rural road projects.
• Granulated Blast Furnace Slag (GBFS) can be used as a fine aggregate or stabilizer when mixed with lime​.

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b) Slag as a Base Material

• Steel slag aggregates (BOFS and EAFS) offer better strength and durability.
• A blend of 80% crushed ACBFS and 20% GBFS is recommended for granular base course construction.
• Steel slag-based layers provide higher density, mechanical interlock, and skid resistance​.

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c) Slag in Asphalt Layers

• Both steel slag and BFS are suitable for bituminous road surfaces.
• Steel slag provides better skid resistance, lower stripping, and high impact resistance.
• Additional bitumen content (0.5% more than conventional mixes) is recommended for optimal adhesion​.

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2. Copper Slag in Road Constructiona) Copper Slag in Embankments and Subgrade

• Coarse copper slag is ideal for embankments and subgrades when blended with soil or fly ash​.
• Mechanical stabilization using soil/fly ash improves structural integrity.
• A protective soil cover (30-50 cm) is required to prevent erosion during monsoons​.

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b) Copper Slag in Base and Sub-base Layers

• Cement-stabilized copper slag mixtures (3-6% cement) can replace traditional base materials.
• Water Bound Macadam (WBM) and Wet Mix Macadam (WMM) layers can incorporate 20-30% copper slag.
• Fine copper slag should be mixed with natural stone dust for gradation compliance​.

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c) Copper Slag in Bituminous Mixes

• Up to 70% copper slag can replace fine aggregates in bituminous mixes.
• Suitable for premix carpet, seal coat, and bituminous macadam applications.
• Higher skid resistance and better drainage properties are observed in copper slag-based roads​.

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Environmental Aspects & Quality Control

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‍The Toxicity Characteristic Leaching Procedure (TCLP) confirms that slag usage in roads is environmentally safe. Regular quality control tests ensure compliance with IRC and MoRD specifications​.

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‍Conclusion

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‍The IRC:SP:121-2018 guidelines advocate for the responsible use of iron, steel, and copper slag in rural road construction, offering sustainable, cost-effective, and high-performance solutions. With proper implementation, slag-based roads can significantly enhance infrastructure durability while promoting circular economy principles.

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