United States
Hong KongMasonry
Four of 115 scored questions covering units, mortar and grout, reinforcement and control joints, and cold and hot weather masonry. The limited access zone rule comes from OSHA.
Four questions. Small, and with two things in it that are asked disproportionately often.
The three subtopics
- Units, mortar and grout
- Reinforcement, bonding and control joints
- Cold and hot weather masonry and protection
Mortar types
M, S, N and O, running from highest to lowest compressive strength.
The letters come from the alternate letters of MASON WORK, which is a memory hook worth having because the order is otherwise arbitrary.
Stronger is not automatically better. Mortar should generally be weaker than the units so that cracking occurs in the joint rather than through the block.
Control against expansion joints
Control joints accommodate shrinkage in concrete masonry. Expansion joints accommodate expansion in clay masonry.
Concrete shrinks as it cures. Clay expands as it takes up moisture. The joints do opposite jobs and the exam asks which material needs which.
A wall over 8 feet needs a limited access zone on the unscaffolded side, equal to the wall height plus 4 feet, and bracing until permanent support is in place. That is 29 CFR 1926.706 and the answer is in the OSHA standards rather than a masonry text.
Cold weather
Forty degrees Fahrenheit is the threshold below which cold weather provisions apply, the same figure as for concrete.
One number covering two categories is worth remembering as one number.
Common questions
How many masonry questions are on the exam?
4 of the 115 scored questions.
What are the mortar types?
M, S, N and O, from highest to lowest compressive strength.
Should mortar be stronger than the units?
Generally not. Weaker mortar means cracking occurs in the joint rather than through the block.
What is the difference between control and expansion joints?
Control joints accommodate shrinkage in concrete masonry; expansion joints accommodate expansion in clay masonry.
What is the limited access zone?
A zone on the unscaffolded side of a masonry wall over 8 feet, equal to the wall height plus 4 feet, under 29 CFR 1926.706.