What Size is #4 Rebar? A Complete Guide for Construction Professionals
#4 rebar is a staple in reinforced concrete projects, balancing strength, flexibility, and cost efficiency. This guide dives into its technical specifications, industry standards, and practical applications to help engineers and builders optimize structural integrity while adhering to modern codes.
#4 Rebar Size and Technical Specifications
Diameter and Weight
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Diameter: 1/2 inch (12.7 mm) — compliant with ASTM A615 standards.
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Weight: 0.668 lbs per linear foot (0.996 kg/m).
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Cross-Sectional Area: 0.20 square inches (129 mm²), critical for load calculations.
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Grade: ASTM A615 Grade 60 (60,000 psi yield strength) for residential and commercial use.
Surface and Design
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Deformations: Ribbed surface enhances bonding with concrete, reducing slippage risks.
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Material: Carbon steel (standard), epoxy-coated, or galvanized for corrosive environments.
Key Applications in Construction
1. Residential Foundations
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Footings and Slabs: Grid spacing of 12–18 inches prevents cracking from soil shifts and thermal stress.
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Driveways: Handles vehicle loads and freeze-thaw cycles in cold climates.
2. Retaining Walls
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Horizontal Reinforcement: Spaced 6–12 inches apart to counteract soil pressure in walls up to 10 feet tall.
3. Light Commercial Structures
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Beam-Column Joints: Enhances ductility in seismic zones when paired with Grade 60 standards.
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Precast Panels: Compatible with automated rebar-tying systems for factory efficiency.
Installation Guidelines & Best Practices
Spacing and Concrete Cover
| Application | Spacing | Concrete Cover |
|---|---|---|
| Residential Slabs | 12–18 inches | 2 inches (50 mm) |
| Retaining Walls | 6–12 inches | 1.5 inches (38 mm) |
| Industrial Floors | 6–9 inches | 3 inches (75 mm) |
Corrosion Prevention
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Epoxy-Coated Rebar: Mandatory in coastal or high-humidity regions.
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Cathodic Protection: Paired with #4 rebar in bridges or wastewater plants.
BIM Integration
Advanced tools like Revit automate placement in curved walls or complex geometries, minimizing clashes during design.
Industry Trends (2024)
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Sustainable Materials: Recycled #4 rebar (95% post-consumer steel) aligns with LEED v5 certification.
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IoT Sensors: Smart rebar with embedded strain sensors monitors stress in real time for high-risk structures.
FAQs
Q: Can #4 rebar replace welded wire mesh?
A: Yes—it offers superior crack control for heavy loads, while mesh suits lighter applications like sidewalks.
Q: How does #4 compare to #5 rebar?
A: #4 is thinner (1/2″ vs. 5/8″) and cheaper, ideal for moderate loads.
Q: What’s the maximum span for #4 rebar in beams?
A: Up to 12 feet with 9-inch spacing (per ACI 318).