Anchor Bolts: Types, Specifications & Applications in Construction and Industry

Every structure attached to concrete depends on anchor bolts. Steel columns bolted to foundations. Equipment mounted on concrete pads. Guardrails fastened to bridge decks. Pipe supports anchored to equipment plinths. Without the right anchor bolt — correctly sized, correctly installed, and correctly specified for the load — the connection fails, and structures shift, tilt, or collapse.

Anchor bolts are one of the most commonly ordered fastener categories for construction projects across Africa, the Middle East, and developing economies, where new industrial facilities, power plants, bridges, and buildings are being constructed at an accelerating pace. This guide covers every anchor bolt type, material, standard, and application — so you can specify the right anchor for your project.

Two Categories: Cast-in-Place vs Post-Installed

All anchor bolts fall into one of two categories based on when they are installed relative to the concrete:

Cast-in-place anchor bolts are positioned in the formwork before the concrete is poured. When the concrete cures, the bolt is permanently embedded. These are the strongest type of anchor because the bolt becomes an integral part of the concrete mass. They require advance planning — the bolt positions must be set before the pour.

Post-installed anchor bolts are installed into hardened concrete by drilling a hole and either expanding a mechanical anchor or bonding an adhesive anchor. These are used for retrofit work, modifications to existing structures, and situations where the bolt positions were not known during the original concrete pour.

The rule: For new construction where bolt positions are known in advance, cast-in-place anchors are always preferred — they are stronger, simpler, and cheaper. For existing concrete, retrofit, or when positions cannot be determined before the pour, post-installed anchors are the solution.

Cast-in-Place Anchor Bolt Types

Headed Anchor Bolt

A straight bolt with a heavy hex head (or a welded-on square plate) at the embedded end. The head provides mechanical bearing against the concrete, creating the strongest possible pull-out resistance. This is the standard anchor bolt for structural steel column base plates.

Typical sizes: M16 (5/8") to M64 (2-1/2") diameter. Embedment depth typically 12–25 times the bolt diameter.

Material: ASTM F1554 Grade 36, 55, or 105 (see materials section below).

Best for: Structural steel columns, building foundations, crane rails, heavy equipment foundations, and any application where maximum tensile and shear capacity is required.

L-Bolt (L-Shaped Anchor Bolt)

A round bar bent into an L shape at the embedded end. The 90° bend provides pull-out resistance by hooking into the concrete. Simpler to manufacture than headed bolts, but with lower pull-out capacity because the hook can straighten under extreme loads.

Typical sizes: M12 (1/2") to M36 (1-3/8") diameter.

Best for: Light-to-medium structural connections, base plates for light columns, sign poles, fence posts, and equipment with moderate pull-out loads. The most commonly ordered cast-in-place anchor for general construction.

J-Bolt (J-Shaped Anchor Bolt)

Similar to the L-bolt but with a deeper hook (shaped like the letter J). Provides slightly better pull-out resistance than an L-bolt due to the longer hook engagement with the concrete. Sometimes preferred over L-bolts for equipment mounting where uplift forces are moderate.

Typical sizes: M12 (1/2") to M36 (1-3/8") diameter.

Best for: Equipment mounting, pipe supports, handrail base plates, and general-purpose anchoring where hook-type anchors are acceptable.

Headed Stud (Nelson Stud / Shear Connector)

A round steel stud with a forged head, welded to a steel plate or beam using a specialized stud welding gun. Used as shear connectors in composite steel-concrete structures (steel beams with concrete deck slabs). The studs transfer horizontal shear forces between the steel beam and the concrete slab, creating a composite section with much higher load capacity than either material alone.

Standard: AWS D1.1 (structural welding), ISO 13918 (welding studs).

Best for: Composite steel-concrete bridge decks, composite floor systems in buildings, and any structure where steel beams and concrete slabs must act together as a composite unit.

Post-Installed Anchor Bolt Types

Wedge Anchor

The most common post-installed mechanical anchor. A threaded bolt with a tapered wedge at the embedded end and an expansion clip. When the nut is tightened, the bolt is pulled upward, driving the clip against the concrete wall of the drilled hole, creating a friction-based grip.

Strengths: High load capacity in solid concrete, fast installation, immediate load-bearing (no curing time), cost-effective.

Limitations: Only for solid concrete (not hollow block or brick). Cannot be removed and reused. Requires minimum edge distance and spacing to prevent concrete splitting.

Typical sizes: M8 (5/16") to M20 (3/4") diameter.

Best for: Securing heavy equipment, structural steel connections in existing concrete, guard rails, pipe supports, and medium-to-heavy-duty anchoring in solid concrete.

Sleeve Anchor

A bolt surrounded by an expandable metal sleeve. When the bolt is tightened, the sleeve expands against the sides of the drilled hole. The sleeve distributes the expansion force over a larger area than a wedge anchor, making it suitable for weaker substrates.

Strengths: Works in concrete, brick, and hollow block. More forgiving in terms of hole quality. Good for medium-duty loads.

Limitations: Lower ultimate capacity than wedge anchors in solid concrete.

Best for: Brick and masonry applications, handrails, electrical boxes, shelving, signage, and medium-duty anchoring where the substrate may not be solid concrete.

Chemical (Adhesive / Epoxy) Anchor

A threaded rod bonded into a drilled hole using a two-part chemical adhesive (epoxy, polyester, or vinylester resin). The adhesive is injected into the hole, the rod is inserted, and the resin cures to create a bond between the rod, the adhesive, and the concrete.

Strengths: Highest load capacity of all post-installed anchors when properly installed. Works in cracked concrete. No expansion forces — can be placed close to edges and to other anchors. Excellent for seismic applications (when using qualified systems). Can anchor into virtually any substrate including stone, brick, and hollow block (with mesh sleeves).

Limitations: Requires clean, dry holes for proper adhesion. Curing time needed before loading (typically 15 minutes to 24 hours depending on temperature and resin type). Temperature-sensitive installation — cold temperatures slow curing, very hot temperatures accelerate it. Hole must be thoroughly cleaned (blown out and brushed) for the adhesive to bond properly.

Typical sizes: M8 to M30+ (limited only by hole depth and resin volume).

Best for: Heavy structural connections in existing concrete, seismic retrofit, anchoring into cracked concrete, close-to-edge applications, overhead anchoring, and any high-load post-installed application.

Drop-In Anchor

A female-threaded anchor body that is inserted into a drilled hole and set by driving an internal expander plug with a setting tool. After installation, a threaded rod or bolt screws into the anchor body. The anchor sits flush with the concrete surface.

Best for: Overhead anchoring (hanging ductwork, cable trays, pipe supports, sprinkler systems), and applications requiring a flush, female-threaded anchor point.

Undercut Anchor

A specialized mechanical anchor that creates a bell-shaped cavity (undercut) at the bottom of the drilled hole using a special drill bit. The anchor's expansion mechanism locks into this undercut, creating a mechanical interlock similar to a cast-in-place headed bolt — but installed in existing concrete.

Strengths: Highest reliability among mechanical post-installed anchors. Approved for cracked concrete and seismic zones. Performance approaches cast-in-place headed bolts.

Limitations: Requires specialized drilling equipment. Higher cost than wedge or sleeve anchors.

Best for: Safety-critical applications, nuclear facilities, seismic retrofit, heavy dynamic loads, and applications where the highest reliability is required from a post-installed anchor.

Anchor Bolt Materials

For most structural projects in Africa and the Middle East: ASTM F1554 Grade 36 (for general anchoring) or Grade 55 (for heavier loads and weldable anchors) in hot-dip galvanized finish covers the majority of requirements. For equipment mounting in industrial plants, ASTM A193 B7 (same as flange bolting) is commonly specified. For coastal or marine environments, stainless steel 316 is mandatory.

Key Standards

How to Specify Anchor Bolts

1. Type: Cast-in-place (headed, L-bolt, J-bolt) or post-installed (wedge, sleeve, chemical, undercut)

2. Material and grade: ASTM F1554 Grade 36/55/105, A36, A193 B7, stainless 304/316

3. Diameter: Metric (M12, M16, M20, M24, M30, M36, M42, M48) or imperial (1/2" through 2-1/2")

4. Length: Total length for cast-in-place. Embedment depth + projection above concrete + nut engagement for post-installed.

5. Finish: Plain (black), hot-dip galvanized (HDG per ASTM A153/F2329), or stainless steel

6. Thread: Fully threaded or partial thread. Thread length must be sufficient for washer + nut + leveling nut (for base plate applications). Specify UNC or metric per project requirements.

7. Template / bolt plan: For cast-in-place anchors, provide the bolt pattern layout (bolt circle diameter, bolt spacing, orientation) to ensure accurate placement in the formwork.

8. Quantity: Number of bolts + nuts + washers. Each anchor typically requires 1 heavy hex nut + 1 hardened washer. Base plate applications often need 2 nuts per bolt (one leveling nut below the plate, one securing nut above).

Example order:

200 pcs — L-Bolt Anchor, M24 × 600mm, ASTM F1554 Grade 36, hot-dip galvanized per ASTM F2329, with 2 heavy hex nuts A563 Grade A + 2 hardened washers F436 per bolt.

Which Anchor for Which Application?

Supply from Kasko Makine

Kasko Makine supplies the complete range of anchor bolts for structural, industrial, and infrastructure projects:

Cast-in-place anchors: Headed bolts, L-bolts, J-bolts, U-bolts. ASTM F1554 Grade 36, 55, and 105. ASTM A36, A193 B7. Diameters M12 to M64 (1/2" to 2-1/2"). Hot-dip galvanized, plain, or stainless steel.

Post-installed mechanical anchors: Wedge anchors, sleeve anchors, drop-in anchors. Carbon steel, stainless steel 304/316. Zinc plated and HDG finishes.

Chemical anchor systems: Epoxy and vinylester resin cartridges with threaded rods. Qualified per ACI 355.4 for structural and seismic applications.

Headed shear studs (Nelson studs): AWS D1.1 compliant. For composite steel-concrete structures and bridge decks.

We also supply the steel plates, structural steel, and geotextile for your foundation and structural projects — single-source procurement for construction materials.

All anchor bolts supplied with EN 10204 Type 3.1 material test certificates, dimensional verification, and coating certificates (for HDG). Third-party inspection available on request.

FAQ SCHEMA

Q: What are the main types of anchor bolts? A: Anchor bolts are divided into cast-in-place (headed bolts, L-bolts, J-bolts — embedded in wet concrete) and post-installed (wedge anchors, sleeve anchors, chemical/epoxy anchors, drop-in anchors, undercut anchors — installed into hardened concrete). Cast-in-place anchors are stronger and preferred for new construction. Post-installed anchors are used for existing concrete and retrofit work.

Q: What is the strongest type of anchor bolt? A: For new construction, headed cast-in-place anchor bolts provide the highest load capacity because they become an integral part of the concrete. For existing concrete, chemical (epoxy) anchors provide the highest post-installed capacity, especially in cracked concrete. Undercut anchors are the highest-performing mechanical post-installed option.

Q: What material should anchor bolts be made from? A: ASTM F1554 Grade 36 for general structural anchoring, Grade 55 for heavier loads and weldability, and Grade 105 for high-strength and seismic applications. For corrosive or outdoor environments, hot-dip galvanized (ASTM F2329) finish is standard. For marine and coastal structures, stainless steel 316 is required.

Q: What is the difference between an L-bolt and a J-bolt anchor? A: Both are cast-in-place hook-type anchors. An L-bolt has a 90° bend forming an L shape. A J-bolt has a deeper hook forming a J shape, providing slightly better pull-out resistance. L-bolts are more common for general anchoring, while J-bolts are preferred when slightly higher uplift resistance is needed without using a headed bolt.

Q: What standard governs anchor bolt design in concrete? A: ACI 318 Chapter 17 (Anchoring to Concrete) governs the design of both cast-in-place and post-installed anchors in concrete structures. It covers embedment depth, edge distance, spacing, tensile and shear capacity, and interaction equations. ASTM F1554 covers the material specification for structural anchor bolts. Post-installed anchors must be qualified per ACI 355.2 (mechanical) or ACI 355.4 (adhesive).

Q: How deep should anchor bolts be embedded in concrete? A: Embedment depth depends on the bolt diameter, load requirements, and concrete strength. A general guideline for cast-in-place headed bolts is 12–25 times the bolt diameter. For post-installed anchors, follow the manufacturer's embedment depth specification, which is determined by the anchor type and the required load capacity per ACI 318.

Request anchor bolt pricing — send us your bolt schedule, diameters, lengths, material grade, and finish requirements to info@kaskomakine.com or WhatsApp +90 (537) 521 1399. We respond within 24 hours and deliver to construction projects across Africa, the Middle East, Central Asia, and beyond.