Coaching Conversations (ICC Structural Masonry)
These are actual coaching conversations from our online ICC Structural Masonry course.
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On this question, where it says # horizontal ties “encase” the vertical bars, and “Reinforced cells are grouted solid” isn’t it talking about that the entire column is going to be grouted solid?
The question is: "A column is 24 inches long and 16 inches wide. It has a vertical #8 bar placed in each corner of the column, 4 total. #3 horizontal ties encase the vertical bars and are placed every 16 inches vertically. Reinforced cells are grouted solid. Which part of the column is out of compliance?"
Answer 1: More vertical bars are required
Answer 2: The entire column must be grouted solid
Answer 3: The tie spacing exceed the allowable maximum
Answer 4: Larger diameter tie bars are required
The correct answer is: Answer 2.
My answer was: Answer 1.
In this question, the dimensions for the column are 24" x 16", which would basically be 3 full blocks placed together. Each block has 2 cells, so that would be 6 cells total. The question says that reinforced cells are grouted, so it implies that the remaining 2 cells are not grouted, which is not permitted in columns.
I'm not seeing anything in ASTM A615 Table 2 that talks about joint reinforcement. Am I missing something?
The question is: "Which of the following has the highest value in pounds per square inch (psi)?"
Answer 1: Grade 40 tensile strength
Answer 2: Joint reinforcement tensile strength
Answer 3: Grade 60 yield strength
Answer 4: Grade 75 yield strength
The correct answer is: Answer 2.
My answer was: Answer 4.
Hi, William. Table 2 in ASTM A615 simply tells us the strengths of rebar so we can compare it to the joint reinforcement strength described in the RCM Handbook.
How do you know that this is spread over two courses?
The question is: "How many longitudinal bars go in the bottom course of the masonry beam at approximately L.2/11 on the 2nd level?"
Answer 1: None
Answer 2: 1
Answer 3: 2
Answer 4: 4
The correct answer is: Answer 3.
In detail C5, right above where it says "Masonry Beam Schedule", it tell us that what to do when we have more than (2) bars to place, like we do in this situation.
I answered 24 to 30 inches, because in the RCM Handbook 2.11.1 General it's written: There is also a self-consolidating grout with a required slump flow of 24 to 30 in. Please explain.
The question is: "Self-consolidating grout must have a slump of:"
Answer 1: Between 4 and 6 inches
Answer 2: Between 8 and 11 inches
Answer 3: Between 24 and 30 inches
Answer 4: No requirement
The correct answer is: Answer 4.
My answer was: Answer 3.
This is a bit of a trick question since it is asking for slump and not slump flow. You would be correct if it were asking for slump flow. 👍
The question is: "Which of the following masonry units should not be wetted before laying?"
Answer 1: ASTM C62
Answer 2: ASTM C216
Answer 3: ASTM C90
Answer 4: ASTM C140
The correct answer is: Answer 3.
My answer was: Answer 2.
ASTM C90 contains no language saying the masonry units shouldn't be wetted. 2.3.5 in the RCM book just says they should be protected from rain.
Hi, Justin. Check out the first paragraph of 2.3.5 that says they should be dry when used. See figure 4.3 also.
Why we need to do 3/8" plus 3/8"?
The question is: "What's the largest allowable head joint thickness for a typical project?"
Answer 1: 3/4-inch
Answer 2: 3/8-inch
Answer 3: 1-1/4-inch
Answer 4: 1/2-inch
The correct answer is: Answer 1.
My answer was: Answer 2.
Good question. See 3.3.B.2 that tells us 3/8" is the typical head joint thickness, then we add the 3/8" tolerance to get 3/4" maximum.
With regards to the spacing of expansion joints the fast facts lists spacing between 150 to 200 feet in CMU masonry, but in the RCM handbook it lists spacing as 15-20 feet in masonry veneer and 60 ft in structural masonry. was wondering if which is correct.
Hi, Eric. I think you may be interchanging control joints and expansion joints. Expansion joints would be about every 150 to 200 feet while control joints would be about every 60 feet.
With this question.. How do I determine that it's 2 cells vs 1 cell or 3 cells?
The question is: "On the north side of the elevator on the second level at approximately F.5, a steel beam bears on the masonry wall. What vertical reinforcement is required to support the beam?"
Answer 1: No additional vertical bars are required
Answer 2: 1 #5 bar
Answer 3: An MC-1 column
Answer 4: 2 grouted cells, each with 1 #5 bar in them
The correct answer is: Answer 4.
Hi, James. If we're talking about the vertical reinforcement supporting the beam, when it says it's grouted 16 inches long we automatically know that means 2 cells since cells are each 8 inches.
the defenition in the book says its a solid unit if the gross cross sectional area makes up 75% or more. the question here asked what type if its gross cross sectional area is 25% so this would be hollow
The question is: "If the cells in a CMU block make up 25% of the block's gross cross-sectional area, then the block is considered:"
Answer 1: Unacceptable for use
Answer 2: Clean and ready for grouting
Answer 3: Solid
Answer 4: Hollow
The correct answer is: Answer 3.
My answer was: Answer 4.
If 25% exactly is cell area (hollow), then 75% exactly is load bearing (solid). Hollow would require the load bearing area to be less than 75%.
Hi there, where do I find if this is a double or a single mat?
The question is: "Along the wall at F/9-10, what is the minimum required lap splice for the horizontal rebar?"
Answer 1: 3 feet and 6 inches
Answer 2: 5 feet and 2 inches
Answer 3: 3 feet and 3 inches
Answer 4: 60 bar diameters
The correct answer is: Answer 2.
Hi, Jesus. Since the schedule on D5/S-002 tells us the horizontal reinforcement comprises (2) #6 bars, that is a double mat. If it was just (1) #6 bar, that would be a single mat.
Sorry, but I cant seem to find "Article 3.3F" in the TMS? It's probably right in front of my face...
I wonder if you are looking at TMS 402 instead of TMS 602? Both are in the same publication but TMS 602-16 has the article 3.3.F. Check out page S-64 in the actual book.
Why does the question ask for "minimum average height" and Table 2.1 says "maximum average height"?
The question is: "What is the minimum average height of a deformation on a #3 rebar?"
Answer 1: 0.015 inches
Answer 2: 3/8-inch
Answer 3: 0.38 inches
Answer 4: 0.143 inches
The correct answer is: Answer 1.
My answer was: Answer 2.
Hi, Benny. This is an error in the RCM Handbook unfortunately. In ASTM A615, it is properly titled "minimum average height".
Snippet on Handbook says: head joints are mortared a minimum distance from each face equal to the face of shell thickness
The question is: "The head joint of a block does not have to be fully mortared if:"
Answer 1: Hollow units are used
Answer 2: Solid units are used
Answer 3: Units are used in a wall with no piers, columns, or pilasters
Answer 4: The unit being mortared is the first course above the foundation
The correct answer is: Answer 1.
My answer was: Answer 4.
Right, so what's that saying is that head joints are fully mortared on hollow blocks. Instead, they are mortared to accommodate the face shell thickness, but not in the middle really.