10.2 Concrete and Masonry Construction (Subpart Q)

10.2 Concrete and Masonry Construction (Subpart Q)

Core Principle: 29 CFR 1926 Subpart Q (1926.700–706) is short by 1926 standards but it governs some of the highest-consequence failures in construction: formwork collapses under wet concrete, lift-slab failures, unbraced masonry walls blown over by a gust, and impalement on unguarded rebar. It is a named elective topic in the 10-hour and 30-hour construction outlines.

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1. General Requirements for Concrete Work (1926.701)

Six rules, all short, all heavily cited.

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. This covers everything from a stack of block landed on a green slab to a scissor lift driven onto a deck that was poured yesterday.

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. Note what the sentence does and does not say: it covers rebar an employee could fall onto and into, and the duty is to eliminate the hazard, not reduce it. Mushroom caps that are not rated to resist impalement, and the common practice of bending the bars over, are the two field solutions inspectors scrutinize; rebar caps designed and tested for impalement protection, troughs, or wooden cap boards are the defensible answers where a fall onto the bars is possible.

Post-Tensioning — 1926.701(c)

• No employee (except those essential to the post-tensioning operation) shall be permitted to be behind the jack during tensioning operations. A tendon that fails releases enormous stored energy along the axis of the jack.
• Signs and barriers shall be erected to limit employee access to the post-tensioning area during tensioning operations.

Concrete Buckets — 1926.701(d) and (e)

• No employee shall be permitted to ride concrete buckets.
• No employee shall be permitted to work under concrete buckets while buckets are being elevated or lowered into position.
• To the extent practical, 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.

PPE for Pneumatic Placement — 1926.701(f)

No employee shall be permitted to apply a cement, sand, and water mixture through a pneumatic hose unless the employee is wearing protective head and face equipment — the shotcrete and gunite rule.

Equipment Lockout — 1926.702(j)

No employee may perform maintenance or repair activity where the inadvertent operation of the equipment could occur and cause injury unless all potentially hazardous energy sources have been locked out and tagged. Note this: Subpart Q contains a genuine lockout requirement, which Subpart K's 1926.417 does not.

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2. Cast-in-Place Concrete: Formwork, Shoring and Reshoring (1926.703)

Formwork Design — 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. Formwork built in conformance with the Appendix to 1926.703 (which incorporates ANSI A10.9) is deemed to meet this requirement.

Drawings or plans, including all revisions, for the jack layout, formwork (including shoring equipment), working decks, and scaffolds, shall be available at the jobsite. A superintendent who cannot produce the shoring drawings on request is in violation independent of whether the shoring is adequate.

The Shoring Inspection Sequence — 1926.703(b)

Memorize this sequence; it is unusually specific:

Supporting rules: sills for shoring must be sound, rigid, and capable of carrying the maximum intended load; all base plates, shore heads, extension devices, and adjustment screws must be in firm contact, and secured when necessary, with the foundation and the form.

Removal of Formwork and Shoring — 1926.703(e)

Forms and shores (except those needed for reshoring) may not be removed until the employer determines the concrete has gained sufficient strength to support its weight and superimposed loads. That determination must be based on compliance with one of the following:

1. The plans and specifications stipulate conditions for removal that have been followed; or
2. The concrete has been properly tested with an appropriate ASTM standard test method designed to indicate the concrete compressive strength, and the test results indicate the concrete has gained sufficient strength.

Reshoring may not be removed until the concrete being supported has attained adequate strength to support its weight and all loads on it.

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3. Precast Concrete (1926.704) and Lift-Slab (1926.705)

Precast concrete (1926.704):

• Precast concrete wall units, structural framing, and tilt-up wall panels shall be adequately supported to prevent overturning and collapse until permanent connections are completed.
• Lifting inserts embedded or otherwise attached to tilt-up precast concrete members must be capable of supporting at least two times the maximum intended load applied or transmitted to them. For other precast members, lifting inserts must support four times the load, and lifting hardware must support five times.
• No employee shall be permitted under precast concrete members being lifted or tilted into position except those essential to the erection.

Lift-slab (1926.705):

• Lift-slab operations must be designed and planned by a registered professional engineer who has experience in lift-slab construction; the plans and designs must include detailed instructions and sketches of the prescribed method of erection and provisions for ensuring lateral stability during construction, and must be implemented by the employer.
• Jacks and lifting units must be marked with their rated capacity and must not be loaded beyond it; jacking equipment must be capable of supporting at least two and one-half times the load being lifted during jacking operations.
• Jacks and lifting units must have a safety device installed which will cause them to support the load in any position in the event any jack or lifting unit malfunctions or loses its lifting ability.
• Jacking operations must be synchronized, and during lifting all points at which the slab is supported must be kept within one-half inch of that needed to maintain the slab in a level position. Where leveling is automatically controlled, a device must stop the operation if that half-inch tolerance is exceeded. Where leveling is maintained by manual controls, those controls must be in a location affording the operator a clear unobstructed view of the slab, and no more than 14 manually controlled jacks or lifting units may be used on one slab.
• No employee, except those essential to the jacking operation, shall be permitted in the building or structure while any jacking operation is taking place, unless the building or structure has been reinforced sufficiently to ensure its integrity during erection — a determination that must be made by a registered professional engineer independent of the engineer who designed and planned the lifting operation.

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4. Masonry Construction (1926.706)

Two paragraphs, both frequently misremembered.

The Limited Access Zone — 1926.706(a)

A limited access zone shall be established whenever a masonry wall is being constructed. There is no minimum wall height for the zone. It must:

1. Be established prior to the start of construction of the wall;
2. Be equal to the height of the wall to be constructed plus four feet, and run the entire length of the wall;
3. Be established on the side of the wall which will be unscaffolded;
4. Be restricted to entry by employees actively engaged in constructing the wall — no other employees may enter; and
5. Remain in place until the wall is adequately supported to prevent overturning and collapse — unless the wall is over eight feet, in which case the zone remains until the bracing requirement in paragraph (b) has been met.

Bracing — 1926.706(b)

All masonry walls over eight feet in height shall be adequately braced to prevent overturning and to prevent collapse, unless the wall is adequately supported so that it will not overturn or collapse. The bracing shall remain in place until the permanent supporting elements of the structure are in place.

Exam Trap: The eight-foot figure is the bracing trigger and the trigger for the longer zone duration. It is not the trigger for the limited access zone itself — that applies to any masonry wall being constructed. Candidates who learn it the other way round get both halves of the question wrong.

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5. Where Concrete and Masonry Meet Other Subparts