Overview

This document provides an overview of two primary types of anchor bolts commonly used in concrete: concrete embedded anchor bolts and expansion anchor bolts, with specific attention to their material finishes (zinc-plated and stainless steel) and sizing in imperial units (inches). Concrete embedded anchor bolts are cast into wet concrete, offering robust, permanent connections, while expansion anchor bolts are installed into pre-drilled holes in cured concrete, using an expansion mechanism for grip. Both types are critical for securing structural and non-structural elements to concrete, with material choice driven by environmental conditions and required corrosion resistance.

Concrete Embedded Anchor Bolts

Definition

Concrete embedded anchor bolts (also known as cast-in-place anchor bolts or foundation bolts) are heavy-duty fasteners designed to be precisely positioned and set into wet concrete before it cures. These bolts typically feature a bent end (e.g., L-shaped or J-shaped) or a headed end with a washer and nut, ensuring a strong mechanical interlock with the concrete once it hardens. They provide a foundational anchor point for structural elements like columns, walls, and machinery.

Advantages

• Highest Load Capacity: Offers superior strength and pull-out resistance as they are fully integrated into the concrete structure.
• Permanent and Reliable: Once the concrete cures, the embedded bolt provides an extremely durable and permanent connection.
• Reduced Installation Costs (long-term): While initial placement requires precision, it eliminates the need for post-drilling and complex installation procedures after concrete curing for heavy loads.
• Suitable for Critical Applications: Ideal for securing primary structural members where high integrity and safety are paramount.

Applications

• Foundation Attachments: Anchoring steel columns, precast concrete panels, and support plates to building foundations.
• Machine Base Fixing: Securing heavy industrial machinery and equipment vibrating or exerting significant forces.
• Retaining Wall Connections: Providing robust connections for precast retaining wall sections.
• Bridge Abutments: Anchoring bridge structures to their concrete supports.

Expansion Anchor Bolts

Definition

Expansion anchor bolts are post-installed fasteners that are inserted into pre-drilled holes in cured concrete. They feature an expansion mechanism (such as a wedge, sleeve, or shell) that, upon tightening or setting, presses firmly against the walls of the drilled hole, creating a secure mechanical interlock. These bolts are available in various styles and materials to suit different load requirements and environmental conditions.

Advantages

• Flexibility in Installation: Can be installed after the concrete has cured, allowing for adjustments or additions to structures.
• Versatility: A wide variety of types (wedge, sleeve, drop-in, etc.) caters to different load requirements and base materials (concrete, solid brick, block).
• Ease of Installation: Generally quicker to install than embedded bolts, as they don’t require pre-placement in wet concrete.

Applications

• Non-Structural and Medium-Duty Fixtures: Mounting railings, shelving, light fixtures, electrical conduits, and pipe supports.
• Temporary and Permanent Installations: Suitable for both temporary bracing and permanent fixtures where high-strength, post-installed anchoring is needed.
• Equipment Mounting: Securing machinery, HVAC units, and other equipment to concrete slabs or walls.
• Renovation and Retrofitting: Ideal for projects where existing concrete needs new anchor points without affecting its structural integrity significantly.

Material Finishes and Sizing in Inches

Zinc-plated Anchor Bolts

Zinc-plated anchor bolts (both embedded and expansion types) are coated with a layer of zinc to provide moderate corrosion resistance. This finish is suitable for dry, indoor environments or applications where exposure to moisture is minimal. However, zinc plating offers limited protection against harsh outdoor conditions or corrosive chemicals.

• Common Applications: Interior structural connections, indoor equipment mounting, general purpose fastening in non-corrosive environments.
• Typical Sizes (Diameter x Length in Inches):
  • 1/4 inch x 1-3/4 inches, 1/4 inch x 2-1/4 inches
  • 3/8 inch x 3 inches, 3/8 inch x 4 inches
  • 1/2 inch x 4 inches, 1/2 inch x 5-1/2 inches
  • 5/8 inch x 6 inches, 5/8 inch x 8 inches
  • 3/4 inch x 7 inches, 3/4 inch x 9 inches (also available in longer lengths for embedded applications)

Stainless Steel Anchor Bolts

Stainless steel anchor bolts (both embedded and expansion types) are manufactured from various grades of stainless steel (e.g., 304, 316), offering superior corrosion resistance compared to zinc-plated options. This makes them ideal for outdoor, marine, industrial, or chemically aggressive environments where rust and degradation are concerns.

• Common Applications: Outdoor structural connections, marine environments, food processing plants, chemical facilities, wastewater treatment plants, medical facilities, and coastal areas.
• Typical Sizes (Diameter x Length in Inches):
  • 1/4 inch x 1-3/4 inches, 1/4 inch x 2-1/4 inches
  • 3/8 inch x 3 inches, 3/8 inch x 4 inches
  • 1/2 inch x 4 inches, 1/2 inch x 5-1/2 inches
  • 5/8 inch x 6 inches, 5/8 inch x 8 inches
  • 3/4 inch x 7 inches, 3/4 inch x 9 inches (also available in longer lengths for embedded applications)
  • 1 inch x 10 inches, 1 inch x 12 inches (and larger for heavy-duty embedded applications)