cocnrete and masonry for april 3 Flashcards
Failure to protect employees from impalement. Rebar not capped or covered.
(1926.701 (b))
Failure to establish limited access zone (LAZ) to limit the number worker in the danger zone where a masonry wall is under construction.
(1926.706(a)(1))
Failure to brace unsupported section of masonry wall over eight feet in height.
(1926.706(b))
Failure to have drawings or plans at the jobsite to indicate jack layout and formwork placement.
(1926.703(a)(2))
What are some effective control measures that can be used to guard rebar so employees cannot fall into or onto the rebar and become impaled?
- Prevent employees from working in an area where they may fall into or onto unprotected rebar.
- If this is not possible, use guardrails or other fall protection measures as outlined in Subpart M to eliminate the fall hazard from elevations.
- Rebar can be capped with special protective rebar covers to keep employees from being impaled. Do not use plastic or paper cups or tape as a rebar cover because they do not protect workers from impalement.
- The rebar can be bent (but only when an engineer has approved this practice) or the rebar can be covered with lumber (e.g., a 2” x 4” board).
What precautions must be taken for post-tensioning work?
- Access should be limited to behind the jack for those who are performing work.
- Signs and barricades are required to limit access
When placing a conrete bucket by a crane what are the two safety rules that must be followed?
- Employees are not allowed to work under concrete buckets being lowered or elevated into position.
- As much as practical, buckets should be routed to minimize the number of employees exposed to over head buckets.
Concrete mixers with capacity greater than ___ must have mechanical device to clear skip of ___.
1 cu. yd.
2. skip of materials
Guardrails should be on each side of ___.
skip
Compressed air hoses on concrete pumping systems must have_____.
fail-safe connectors
Masonry saws must have _______.
semicircular guard enclosure
Concrete buggy handles cannot ____.
Extend past the wheels on either side.
A concrete pump hose must have ____, to prevent separation under load.
connectors
Concrete buckets with hydraulic release must have a device to ______.
prevent accidental dumping
Power concrete trowels must have____.
dead man switch
Bull float handles must be ____ if electrical contact is possible.
non-conductive
What are some of the effective control measures that can be used to eliminate the hazard of being in the danger zone to protect employees from being struck by flying brick and block in the event of a wall collapse?
- Until the wall has gained sufficient strength that overturning (collapse) is no longer a hazard, keep employees out of the area where the wall is being constructed unless they are actually engaged in constructing the wall.
- The most effective control measure is to follow the standard by marking off an area with tape, rope, or chain or any other material that will indicate to employees that they are not to enter the zone (area) that has been marked.
- The zone should be equal to the length of the wall under construction and extend out a distance equal to the height of the wall to be constructed plus 4 feet. So if the wall to be constructed is 10 feet high and 30 feet long, the zone should be 14 feet x 30 feet.
What are some of the ways to brace a wall over 8 feet to provide protection against the hazard of collapse?
a. The project engineer or competent person should determine how best to brace the wall. According to the Magazine of Masonry Construction (November 1988) a typical masonry wall brace includes a vertical member, an inclined strut, stakes, and if necessary a strut-brace.
b. Scaffold planks (2 x 10s) are typically used as the vertical member and the inclined strut, and 2 x 4s for stakes and strut-brace. 2 x 4s and 2 x 6s are considered by most experts to be inadequate for vertical members or inclined struts. All lumber must be in serviceable condition.
c. The American National Standards Institute’s Standard for Concrete and Masonry Work, ANSI A10.9-1983 standard recommends that “The support or bracing shall be designed by or under the supervision of a qualified person to withstand a minimum of 15 pounds per square foot. Local environmental conditions (e.g. strong winds) need to be considered in determining the bracing design. Braces or shores shall be secured in position.”
____ must be secured with wire rope or equivalent.
Tremies
______ required for work on equipment used for concrete & masonry.
lockout/tagout
whenn dealing with cast-in-place concrete, formwork on must be designed, fabricated, erected, supported, braced and maintained so that it will be ____.
capable of supporting without failure on all vertacle and lateral loads.
When dealing with cast in place concrete drawings or plans and any revisions for jack layout, formwork, etc. _____.
must be available on the jobsite.
Drawings and plans dealing with cast-in-place concrete must have what?
- Formwork scaffolding
2. shoring equipment