Wedge Anchors for Concrete: Insider Notes from the Jobsite and the Factory Floor

If you’ve ever hung a steel stair or bolted down an HVAC skid, you already know the quiet hero of concrete fixing. I’m talking about through bolt anchors—also known globally as wedge anchors. In essence, it’s an advanced mechanical bolt that expands at the clip to lock into concrete. Simple idea. Brutally reliable when specified right.

What’s changing in the market

Three big trends: (1) more cracked-concrete and seismic C1/C2 approvals; (2) corrosion resistance moving from standard zinc to hot-dip galvanizing or full stainless (A2/A4); (3) traceability—contractors want mill certs, batch test data, the works. In fact, many customers say they’ll pay a little more for consistent torque behavior and cleaner breakout cones.

Technical snapshot (typical values)

Size	Drill Ø	Min Embedment	Rec. Torque	Tension NRd ≈	Shear VRd ≈
M8	8 mm	40 mm	15 Nm	5–7 kN	6–8 kN
M10	10 mm	50 mm	35 Nm	8–11 kN	10–12 kN
M12	12 mm	60 mm	50 Nm	10–14 kN	12–18 kN
M16	16 mm	70–80 mm	100 Nm	18–24 kN	20–30 kN

Data indicative for C25/30–C30/37 concrete; real-world use may vary with edge distance, spacing, embedment, and installation quality.

Process and quality (how they’re made)

Materials: carbon steel grades 5.8/8.8/10.9; stainless A2-70 (304) and A4-70 (316). Methods: cold forging, thread rolling, precision clip assembly, heat treatment, then zinc plating or hot-dip galvanizing. Testing: pull-out and torque per ACI 355.2/ICC-ES AC193, base-material checks, and hardness per ISO 898-1. Service life: ≈25–50 years depending on coating and corrosion category (ISO 9223). To be honest, installation practice makes or breaks performance—hole cleaning and torque matter.

Where they shine

Handrails, racking, pipe supports, curtain wall brackets, solar mounts, machinery bases, and—surprisingly often—temporary safety barriers. Contractors like through bolt anchors for one-pass drilling and immediate loading (within spec).

Vendor snapshot (quick compare)

Vendor	Approvals	Material options	Lead time	Notes
Fastenboen (China)	Options with ETA/ICC on request	Carbon steel, HDG, A2/A4	2–5 weeks	OEM, private label, custom lengths
Hilti	Broad ETA/ICC portfolio	Carbon, SS	Stock/fast	Premium pricing, robust tech support
fischer	ETA/CE, seismic options	Carbon, SS	Stock	Strong European spec presence

Customization and compliance

Length L, thread length, chamfer, clip alloy, and coatings can be tailored. Ask for mill certs, torque-tension curves, and batch traceability. Look for EN 1992-4 design data, ETA with EAD 330232, or ICC-ES ESR per AC193 for through bolt anchors. ISO 9001 at the plant helps, obviously.

Mini case: hospital retrofit

A mid-rise hospital added new air-handling units. M12 through bolt anchors, embedment 70 mm, edge distances checked per EN 1992-4. Field tests showed average tension ≈ 13.6 kN in C30/37 (cracked) and shear ≈ 16.8 kN; torque audit passed at 48–52 Nm. The facility team’s feedback: “No spin-outs, clean seating. Faster than adhesive in our schedule.”

Quick how-to (because site time is money)

• Drill to proper depth; blow–brush–blow the hole. Yes, it matters.
• Insert anchor, seat the washer/nut, torque to spec in one smooth pass.
• Mind edge distance and spacing; avoid hammering on thin slabs.
• For outdoors, pick HDG or A4 stainless; for seismic, check the approval class.

Final thought: through bolt anchors are workhorses. Get the spec right, and they just disappear into the job—exactly what we want.

Authoritative sources

1. ICC-ES AC193: Mechanical Anchors in Concrete Elements
2. ACI 355.2 and ACI 318 (Anchoring to Concrete)
3. EAD 330232 and ETA (Post-Installed Mechanical Anchors)
4. EN 1992-4: Design of Fastenings for Use in Concrete
5. ISO 3506-1: Stainless Steel Mechanical Properties; ISO 9223: Corrosion Categories