Shop Drawings for Engineered CMU

[JBBMN]

Does the MSJC/ACI 530 code "require" shop drawings for engineered CMU or is it a standard practice? I have not been able to find a requirement in the MSJC/ACI 530.

 

[JAE]

I don't think there is a requirement - I would probably only ask for rebar shop drawings unless the project was a more minor structure.

 

[cntw1953]

Same as above, maybe include requests on material certificates for major structures.

 

[concretemasonry]

If it an engineered CMU structure, ask for unit test results for the units proposed to be supplied.

Even though the codes are very conservative, you can have some results to hang your "hat" on for professional performance and liability. The producer could make units over twice the required strength, but they would have to be produced and supplied and not just out of existing inventory, since few engineered projects in the U.S. really are few and far between as a test for real performance. Unfortunately, the ASTM standards have not kept pace with the manufacturing abilities or possible applications.

For engineered masonry, the prism test or assumed f'm is the basis for most requirements.

You may just get an "off the shelf" old test result, but it is not difficult to repeat with the manufacturing equipment and processes used. Strength is not a major concern with CMU supplying because high strength units can easily be made uniformly. If the supplier does not have a test submittal, he should be rejected.

Many producers run daily testing in house (for quality and cost control) and monthly have a lab come out and sample a different unit (size or aggregate, etc.). The cheapest way to make CMUs stronger is to add more water to the mix and slow the continuous process down slightly. - The mason is the most critical item in normal supply chain and does not want denser units since the will not have the same appearance and dimensional properties even if they meet the minimal ASTM C90 requirements.

Dick