Concrete Wedge Anchor (Through-Bolt / Trubolt)
Direct Answer
The Concrete Wedge Anchor (Through-Bolt / Expansion Stud Anchor / Trubolt) is a heavy-duty structural masonry fastener consisting of a solid threaded steel stud with a reverse-tapered conical mandrel and an independent stainless steel expansion clip collar. Driven into solid cured concrete, tightening the upper nut draws the mandrel up into the clip, locking the anchor permanently under thousands of pounds of structural load.
Source: ICC-ES AC193 / ACI 355.2 / ASTM E488
Specs
| Structural Certification | ICC-ES (International Code Council) cracked & uncracked concrete approval / ACI 318 |
| Anchor Diameter Range | 1/4", 3/8", 1/2", 5/8", 3/4", 1" (or M6, M8, M10, M12, M16, M20, M24) |
| Substrate Limitation | Solid uncracked/cracked cured concrete ONLY (Unsuitable for brick, hollow block, or mortar) |
| Installation Style | 'Through-fixture' installation (Drill hole directly through the metal baseplate into concrete) |
| Expansion Mechanism | Tapered conical stud mandrel expands stainless steel clip ring into concrete borehole |
| Ultimate Tension Capacity (1/2" Anchor) | 4,000 to 6,500+ lbs (18 to 29 kN) in 4,000 psi concrete |
| Primary Applications | Automotive 2-post lifts, structural steel column baseplates, seismic heavy machinery hold-downs |
Mechanical Wedging Physics in High-Strength Concrete
When the anchor is hammered into a hole drilled with an ANSI carbide drill bit, the free-floating clip rests against the concrete wall. When a torque wrench applies specified torque to the hex nut, the stud moves upward by a few millimeters. The bottom conical wedge expands the stainless steel clip outward with massive radial pressure, indenting into the solid concrete matrix to create a permanent mechanical interlock.
Solid Concrete Exclusivity Warning
Wedge anchors rely on the immense compressive strength of cured solid concrete (3,000 to 5,000+ psi). They must never be installed in hollow concrete blocks, grout lines, or clay brick, as the extreme outward expansion forces will instantly fracture and blow out brittle masonry.