13.1 Cast-in-Place Concrete, Formwork, Shoring & Rebar Impalement (Subpart Q)
Key Takeaways
- 29 CFR 1926.701(b) requires all protruding reinforcing steel onto and into which employees could fall to be guarded to eliminate the hazard of impalement.
- Under 29 CFR 1926.701(a), no construction loads may be placed on a concrete structure until the employer determines, from a person qualified in structural design, that it can support the loads.
- Formwork must be designed, fabricated, erected, supported, braced, and maintained so it supports all vertical and lateral loads, and the drawings or plans must be available at the jobsite (29 CFR 1926.703(a) and (b)).
- Employees are prohibited from riding concrete buckets (29 CFR 1926.701(d)) and from working under concrete buckets while they are being elevated or lowered into position (29 CFR 1926.701(e)).
- Manually guided powered concrete troweling machines must have a control switch that automatically shuts off power when the operator releases it (29 CFR 1926.702(i)).
13.1 Cast-in-Place Concrete, Formwork, Shoring & Rebar Impalement
Concrete and Masonry Construction is one of the fifteen Elective topics in the OSHA 30-Hour Construction Outreach curriculum. It is governed by 29 CFR 1926 Subpart Q (1926.700 – 1926.706).
Concrete work concentrates several hazard families at once: impalement, formwork collapse, chemical burns, crushing, and struck-by. It also produces some of the largest single-event casualty counts in construction history, because a formwork failure during a pour drops tons of wet concrete and steel onto everyone working beneath it.
1. Scope and General Requirements — 1926.700 and 1926.701
Construction loads — 1926.701(a)
"No construction loads shall be placed on a concrete structure or portion of a concrete structure unless the employer determines, based on information received from a person who is qualified in structural design, that the structure or portion of the structure is capable of supporting the loads."
The operative phrase is "a person who is qualified in structural design." Not a competent person, not the superintendent — the determination traces to structural engineering. This is the provision that governs when a freshly poured deck may be loaded with pallets of block, a scissor lift, or the shoring for the deck above.
Reinforcing steel — 1926.701(b)
"All protruding reinforcing steel, onto and into which employees could fall, shall be guarded to eliminate the hazard of impalement."
Read the standard precisely, because the exam does:
- The trigger is "onto and into which employees could fall" — vertical dowels projecting from a footing or a wall pour, rebar cages, and starter bars in a slab edge.
- The requirement is to eliminate the hazard of impalement, not merely to mark it.
[!CAUTION] The mushroom cap trap. Small plastic "mushroom" caps are ubiquitous and are impalement protection only if they are rated for it. An unrated plastic cap will split under the energy of a falling body and the bar passes straight through. Compliant protection is either a rebar cap with a steel insert rated to resist penetration, or troughs / wood 2x4 channel capping over a row of bars, or bending the bars over. Height matters too — a cap protects a worker who falls onto the bar; it does nothing for a worker who falls past it onto an unguarded section.
Post-tensioning — 1926.701(c)
No employee (other than those essential to the operation) is permitted behind the jack during tensioning. Signs and barriers must be erected to limit access. A tendon failure during stressing releases stored energy along the jack axis, and the space directly behind the jack is the discharge path.
Riding and working under loads — 1926.701(d) and (e)
| Rule | Text |
|---|---|
| 1926.701(d) | "No employee shall be permitted to ride concrete buckets." |
| 1926.701(e)(1) | No employee shall be permitted to work under concrete buckets while buckets are being elevated or lowered into position. |
| 1926.701(e)(2) | To the extent practicable, elevated concrete buckets shall be routed so that no employee, or the fewest number of employees, are exposed to the hazards associated with falling concrete buckets. |
Personal protective equipment — 1926.701(b) and Subpart E
Wet concrete is strongly alkaline and produces progressive chemical burns through prolonged skin contact (Section 11.3). Waterproof boots, chemical-resistant gloves, and eye protection are not optional comfort items on a placement crew.
2. Formwork — 1926.703(a)
"Formwork shall be designed, fabricated, erected, supported, braced and maintained so that it will be capable of supporting without failure all vertical and lateral loads that may reasonably be anticipated to be applied to the formwork."
And critically:
"Drawings or plans, including all revisions, for the jack layout, formwork (including shoring equipment), working decks, and scaffolds, shall be available at the jobsite."
Available at the jobsite is a documentary requirement a compliance officer will test on the spot.
The loads formwork must carry
| Load | Source |
|---|---|
| Dead load | Weight of the forms, reinforcing steel, and the concrete itself (~150 lb/ft³ for normal-weight concrete) |
| Live load | Workers, buggies, screeds, vibrators, hoses, stored material |
| Lateral pressure | Fluid pressure of wet concrete against vertical forms — increases with pour rate and decreases with temperature and set time |
| Impact | Dumping concrete from a bucket or pump boom |
| Wind | Especially on tall wall forms and shoring towers |
[!CAUTION] Pour rate is the number crews get wrong. Wall form design assumes a maximum rate of rise. Pouring faster than the design rate raises the lateral pressure above what the ties and walers were sized for, and the form blows out. "We were ahead of schedule" is a recorded cause of form failure.
3. Shoring and Reshoring — 1926.703(b)
| Requirement | Provision |
|---|---|
| All shoring equipment must be inspected before erection and damaged equipment shall not be used | 1926.703(b)(1) |
| Shoring erected must be inspected immediately prior to, during, and immediately after concrete placement | 1926.703(b)(2) |
| Shoring found to be damaged or weakened during placement must be immediately reinforced | 1926.703(b)(2) |
| Reshoring shall be erected, as the original forms and shores are removed, whenever the concrete is required to support loads in excess of its capacity | 1926.703(b)(3) |
| Single post shores must be vertically aligned, spliced to prevent misalignment, and adequately braced in two mutually perpendicular directions at the splice level | 1926.703(b)(5)–(7) |
"During placement" is the phrase that matters. A shoring inspection performed at 6:00 a.m. and never repeated does not satisfy 1926.703(b)(2). Someone must be watching the shoring while the concrete is going in, because that is when a leg kicks out.
4. Vertical Slip Forms and Removal — 1926.703(c) and (e)
Vertical slip forms (1926.703(c)): steel rods or pipes on which jacks climb must be specifically designed for that purpose and adequately braced where not encased in concrete; forms must be designed to prevent excessive distortion; the jacks and vertical supports must be positioned so the loads do not exceed rated capacity; the jacking operation must have a limit stop or similar device to prevent it from exceeding the bracing capability; and the form structure must be maintained within all design tolerances for vertical alignment.
Removal of formwork (1926.703(e)): forms and shores (except those needed to support cantilevered sections) shall not be removed until the employer determines that the concrete has gained sufficient strength to support its weight and superimposed loads. That determination is based on compliance with one of two paths:
- The plans and specifications stipulate conditions for removal, and those conditions have been followed; or
- The concrete has been properly tested with an appropriate ASTM standard test method designed to indicate compressive strength, and the test results indicate sufficient strength.
[!NOTE] Cylinder breaks, not the calendar. "It has been seven days" is not the standard. Either the spec's stated removal conditions were met, or field-cured cylinders were broken and the results support removal.
5. Equipment and Tool Requirements — 1926.702
These short provisions are easy points on an exam because each names a specific device.
| Equipment | Requirement | Citation |
|---|---|---|
| Bulk cement storage bins/silos with discharge openings larger than 2 inches by 2 inches | Must have a bottom guard/grate to prevent an employee from being drawn in | 1926.702(a)(2) |
| Concrete mixers with 1 cubic yard or larger loading skips | Must have a mechanical device to clear the skip of material, and guardrails installed on each side of the skip | 1926.702(b) |
| Powered and rotating-type concrete troweling machines that are manually guided | Must be equipped with a control switch that will automatically shut off the power whenever the operator removes their hands from the equipment handles (a deadman control) | 1926.702(i) |
| Concrete buggy handles | Shall not extend beyond the wheels on either side of the buggy | 1926.702(c) |
| Concrete pumping systems using discharge pipes | Sections must be secured by pipe clamps or equivalent; hose sections must have a positive fastening device; systems must be provided with air-release valves at the pump's reduced-diameter point | 1926.702(e) |
| Bull float handles used where they could contact energized conductors | Must be constructed of nonconductive material or insulated with a nonconductive sheath with electrical resistance sufficient to prevent electrocution | 1926.702(f) |
| Masonry saws | The blade must be guarded with a semicircular enclosure over the blade | 1926.702(j) |
| Compressed air hoses used to apply concrete (shotcrete/gunite) | Must have a positive locking device or equivalent to prevent whipping if a connection fails | 1926.702(h) |
[!NOTE] The powered trowel deadman is a caught-in/between control. Without it, a machine whose operator stumbles keeps walking and pins them against a wall or a form — the exact mechanism described in Section 12.2.
A concrete crew has stripped forms from a foundation wall, leaving a grid of vertical #5 dowels projecting 30 inches above the slab where the next pour will tie in. A carpenter working on scaffold planks four feet above the dowels could fall onto them. Which control satisfies 29 CFR 1926.701(b)?
A superintendent orders shoring stripped from a two-day-old elevated slab because the schedule calls for the deck above to start. Under 29 CFR 1926.703(e), what determines whether formwork and shores may be removed?
Which piece of concrete equipment must be fitted with a control switch that automatically shuts off power when the operator removes their hands from the handles, and what hazard does that device address?