Rationale

Since the term “equivalent thickness” is used in ASTM standards, this ballot item proposes the addition of a definition to Terminology C1232. A definition for “equivalent thickness” was not found in TMS 402, TMS 602, ACI 116, ACI CT-21.or ACI/TMS 216.1-14. NCMA TEK 1-4 does have a definition. NCMA TEK 1-4 (2004) - The solid thickness to which a hollow unit would be reduced if the material in the unit were recast into a unit with the same face dimensions (height and length) but without voids. The equivalent thickness of a 100% solid unit is equal to the actual thickness. Used primarily to determine masonry fire resistance ratings. It is recognized that while the term “equivalent thickness” is used in the brick industry, I could not find the term in “ASTM brick standards”. So, the term "equivalent thickness” is being limited to CMUs and related units. If desired, “equivalent thickness” for brick can be addressed as new business.