A commercial building inspector is reviewing the plans for a new single-story convenience store. The masonry walls are constructed with concrete masonry units (CMU). The plans indicate that the grout in the reinforced masonry walls must meet specific requirements. According to the 2021 IBC, which refers to TMS 402/ACI 530/ASCE 5, what is the minimum specified compressive strength (f'm) for masonry grout if the masonry units are 2,000 psi?

Correct answer: D. 2,000 psi

The 2021 IBC references TMS 402/ACI 530/ASCE 5 for masonry design. While the question asks for grout strength, the common practice and code requirements (TMS 402-16, Section 2.1.2.1.1) state that the specified compressive strength of masonry (f'm) shall not be less than 1,500 psi (10.3 MPa). The strength of the grout is typically related to the design requirements of the engineered masonry, but for general reinforced masonry, the grout strength is often specified to be at least 2,000 psi to ensure proper bond and development with reinforcement. However, the direct code requirement for grout compressive strength is that it should be specified and tested, but not necessarily tied to the unit strength in a prescriptive minimum other than ensuring it's adequate for the design f'm. The question is slightly ambiguous by asking for f'm for grout, when f'm is for the masonry assembly. But if the units are 2,000 psi, the grout is usually at least 2,000 psi to ensure composite action and proper bond. Let's re-evaluate based on the typical 'minimum' for grout itself. TMS 602 (Specification for Masonry Structures) states that grout shall have a minimum compressive strength of 2,000 psi (13.8 MPa) at 28 days. This is a general minimum for grout regardless of unit strength, but it implies it should not be less than the units. Thus, 2000 psi is the most appropriate answer as a general minimum for grout.