Nonstructural Concrete – IBC Code Mandates Entrained Air
Non-structural concrete is defined by the International Building Code (IBC) as any element made of plain or reinforced concrete that is not part of a structural system required to transfer either gravity or lateral loads to the ground. This definition enables the code user to correctly apply the durability requirements of IBC Section 1904 as well as ACI 318 Table 184.108.40.206 (see below):
It is important to realize that the ACI 318 criteria listed in Table 220.127.116.11 (above) is for regular or standard Portland cement concrete and is not applicable to non-structural concrete. ACI 318 does not set forth any acceptance criteria for nonstructural concrete; however, IBC chapter 19, Section 1904.2 does and most of the important chapter 19 criteria is listed in the picture feature box at the bottom of the BLAST page. Not only does chapter 19, Section 1904.2 require entrained air for non-structural concrete but it requires different compressive strength values for the exposure classes (FO, F1, F2 and F3) than those listed in Table 18.104.22.168.
ACI 318 does not have durability requirements for non-structural concrete. Therefore, these limits (in chapter 19) are not exceptions to ACI 318 but rather are a distinct set of requirements. The limits stated in chapter 19 are simply restated versions of the requirements from prior additions of the IBC code.
IBC Chapter 19, Section 1904.2 Non-Structural Concrete shall have a minimum specified compressive strength of 2,500 psi for Class FO, 3,000 psi for Class F1 and 3,500 psi for Classes F2 and F3 concrete. Nonstructural concrete shall be air entrained in accordance with ACI 318. The registered design professional (RDP) shall assign a freeze-thaw exposure class for non-structural concrete as defined in ACI 318 based on the anticipated exposure of the non-structural concrete.
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