Technical Questions

ACI Committees, Membership, and Staff have answered common questions on a variety of concrete related topics.



Placement of welded wire reinforcement (WWR) in a slab-on-ground

Q. I’m looking for clarification regarding placement of welded wire reinforcement (WWR) in a slab-on-ground floor in a warehouse. Does ACI provide recommendations?

 

A. ACI 301-20 provides placement requirements for WWR. It specifies that WWR is to be placed into position prior to concrete placement and is to be supported as indicated in the Contract Documents (Provision 3.3.2.5(a)) and in accordance with CRSI RB4.1 (Section 3.3.2.5). Provision 3.3.2.5(a) of ACI 301-16 limits support spacing to no more than 12 in. (305 mm) for WWR sizes smaller than W4.0 or D4.0.

ACI 302.1R-15, Section 5.2.4, recommends that: “Welded wire reinforcement should not be placed on the ground and pulled up after placement of the concrete, nor should the mats be walked in after placing the concrete.” The same section also states that: “Proper support spacing is necessary to maintain welded wire reinforcement at the proper elevation; supports should be close enough such that welded wire reinforcement cannot be forced out of location by construction foot traffic.”

 

References: ACI 301-20; ACI 302.1R-15

Topics in Concrete: Slab

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