9.3 Embedded Items: Anchor Bolts, Conduits, Sleeves & Weld Plates (ACI 318 Section 26.8)
Key Takeaways
ACI 318-19 Section 26.8 uses the approved details and licensed design professional review for unshown embedments. Verify the location and clearance before placement.
Aluminum embedments need coating or covering to prevent reaction with concrete and electrolytic action between aluminum and steel.
Check the approved cast-in anchor location, orientation and embedment before concealment. Record top elevation and projection as separate measurements.
Under model IBC Table 1705.3, cast-in anchors are inspected periodically. Adhesive anchors placed horizontally or upwardly inclined to resist sustained tension require continuous inspection.
For ordinary headed studs under AWS D1.1/D1.1M:2020, distinguish the initial two-stud test from production inspection and follow Clause 9 for both.
Embedded Items: Anchor Bolts, Conduits, Sleeves & Weld Plates
Before concrete placement, compare the installed items with the current approved plans and associated schedules. Record the member, grid or elevation, the specified detail and the measured condition. Address a conflict while the steel cage, sleeves, anchors and attachment points are visible.
1. Verify conduits, pipes and sleeves
ACI 318-19 Section 26.8.1 identifies embedment information to be shown in the design documents, including type, size, details and location for items the licensed design professional designed, specified pipe cover and reinforcement required perpendicular to pipe embedments. Section 26.8.2(a) requires the corresponding information for unshown embedments to be submitted to the licensed design professional for review. This review also matters when a proposed move puts an otherwise shown sleeve in an unshown location.
In solid slabs with top and bottom reinforcement, Section 26.8.2(e) places piping between those layers, with exceptions for radiant heating and snow melting. Section 26.8.2(f) requires fabrication and installation that avoid cutting, bending or displacing reinforcement from its specified position. Use the project’s approved dimensional limits, cover and clearances. An opening that conflicts with the reinforcement or falls near a support requires resolution through the applicable design and approval process. Check any specified opening reinforcement after the disposition is issued.
For example, a slab detail specifies a minimum clear gap of 2 inches between parallel sleeves. Two sleeves with 3-inch outside diameters are installed 4-1/2 inches apart on center. For this geometry the clear gap is 4-1/2 − 3 = 1-1/2 inches, a 1/2-inch shortfall. Record the center spacing, outside diameters and clear gap. Review the planned layers and nearby bars before any proposed relocation. The 2-inch criterion belongs to the approved example detail.
2. Check protection on aluminum embedments
Under Section 26.8.2(b), coat or cover aluminum embedments to prevent both reaction with concrete and electrolytic action between aluminum and steel. Verify the approved protective system at the installed item, including areas where a cut, fastener or tie might interrupt it. When a bare aluminum sleeve is found against a reinforcing bar, identify the sleeve location, material and exposed contact in the report. Bring the discrepancy to the contractor for correction and, if uncorrected, to the building official and the registered design professional in responsible charge before completion of that phase, consistent with model IBC Section 1704.2.4. Where a proposed resolution changes approved construction documents, follow the applicable amendment process under Section 107.4.
3. Inspect cast-in and post-installed anchors
Check the approved anchor diameter, grade, arrangement and effective embedment before placement. Inspect the bearing geometry of a headed rod or the dimensions and orientation of a specified hook. ACI 318-19 Chapter 17 treats different anchor types through the applicable design provisions. Changing a headed rod to a hooked rod or to an adhesive system requires design review.
| Item | Inspection evidence |
|---|---|
| Position and orientation | Use the project grid and benchmark to verify the individual rod centerline and top elevation. Check the axis against the approved detail and apply its tolerance standard. |
| Projection and thread fit | Measure from actual concrete top to rod top. Verify nut engagement and any specified threads beyond the nut against the plate and washer assembly. |
| Effective embedment | Use the approved geometry. For a headed cast-in rod, check depth to the bearing face of the head. |
| Positioning and placement | Verify secure supports, template where detailed, anchor reinforcement, cover and clearance for consolidation. Check exposed measurements again if placement disturbs the assembly. |
Model IBC Table 1705.3 lists periodic special inspection for cast-in anchors. For post-installed anchors in hardened concrete, it lists continuous inspection for adhesive anchors installed horizontally or upwardly inclined to resist sustained tension and periodic inspection for other mechanical and adhesive anchors. Follow applicable requirements in the product research report and the project’s approved statement of special inspections. ACI 318-19 Section 26.7.2 requires installation in accordance with manufacturer instructions, qualified installers for post-installed anchors, and certified installers for the specified horizontal or upwardly inclined sustained-tension adhesive application. For a post-installed system, the approved product and installation instructions provide the drill hole, cleaning, embedment and installation details. Verify the actual procedure and document any deviations from those instructions.
4. Verify embed plates and welded studs
Match the plate mark, face and orientation to the detail. Compare the actual welded stud layout to the approved drawing and check clearances before closing forms. Verify shop documentation or specified field inspection of the welded assembly. Where the project specifies AWS D1.1/D1.1M:2020, use Clause 9 for stud welding. For ordinary unthreaded headed studs, Sections 9.7.1.1–9.7.1.4 require testing the first two studs at the start of each day’s or shift’s production for the setup in use. The initial checks include visual examination for flash around the entire stud base without undercut into the base, and a bend of approximately 30 degrees after cooling. They can be made on the production member or a suitable representative piece under the standard. Sections 9.7.1.5 and 9.7.2 cover retesting and setup changes. Production weld inspection and acceptance follow the applicable provisions of Sections 9.7.3 and 9.8. An incomplete flash in production must be evaluated under those provisions.
Check that the plate will remain on its approved line and elevation during placement. A plate receiving steel on its exposed face must be oriented to fit the approved connection. Check that the concrete can flow around the plate anchors without interference and that the supports keep the embed from moving under placement and consolidation. Record any missing or displaced studs, damage to the coating, or unexpected voids at the plate. Obtain the documented disposition for repair or other corrective work.
A contractor proposes a new conduit through a solid structural slab. Its route crosses a top bar and the conduit is absent from the approved documents. What is the proper next step under ACI 318-19 Section 26.8?
Bend the top bar around the conduit if the cover remains unchanged.
Install the conduit if its diameter is below one-third of the slab thickness.
Move the bar and submit the as-built location after placement.
Submit the proposed type, size, details and location for licensed design professional review before installing it.
What must the protective coating or covering on an aluminum embedment prevent under ACI 318-19 Section 26.8.2(b)?
Aluminum-concrete reaction and electrolytic action between aluminum and steel
Evaporation of moisture from the top of the slab during curing
The formation of bleed water under the reinforcement
Surface corrosion on the concrete form ties during stripping
A shop starts a production period using ordinary unthreaded headed studs under AWS D1.1/D1.1M:2020. What initial testing applies?
Visually inspect one completed weld and use it to qualify the entire production lot.
Bend a stud on a sample plate 90 degrees and omit the visual check.
Check the first two studs for full weld flash and bend them approximately 30 degrees.
Check the first two studs with a torque wrench to verify the anchor nut thread engagement.
Sections you finish are checked off in the contents.