Glencoe: 22 Flashcards
Nominal size of standard CMU
7 5/8 wide
7 5/8 wall
15 5/8 long
This allows for 3 /8 mortar joint
Head joint:
Bed Joint:
A vertical mortar joint
Horizontal mortar joint
Which is stronger
3 core or 2 core CMU
3 core
Most common types of CMUs
Stretcher (3core)
Corner
Stretcher (2core)
Specialty CMU blocks:
Split face - one side looks like stone
Insulated blocks - contain polystyrene, reduces heat transfer between blocks
Glazed surface blocks.
Common bond:
Block courses are laid in a common bond. Which is an overlapping arrangement.
Full bedding:
Mortar should be spread fully on all contact surfaces of the block
Joints should be X between CMUs
tooled smooth to seal them against water seepage.
Stack Bond pattern
blocks are placed directly above one another
Story pole (course pole)
Board with markings 8” apart. It can be used to gauge the top of the masonry for each course.
Two common joint tooling types to be used unless otherwise specified
V-joint and Concave joint
V-joint is an indent that looks like the letter V from the side
Concave looks like a half circle impressed into the joint
When is tooling done to mortar joints:
When the mortar has become thumb print hard (when the thumb leaves no thumb print when pressed into mortar)
Tooling:
Process of using shaped metal bars to compact the mortar and force it tightly against the masonry on each side of the joint.
Which order should tooling be done:
head joints first using a small S-Shaped jointer, then the bed joints.
Estimating block wall material:
When estimating materials for block walls you must consider the number of blocks, the amount of mortar, and the cost of labor.
The number of blocks needed for a foundation can be determined by the area of each wall to be built.
Get the total wall area in square feet. Divide by 8 then multiply that by 9. 25' x 40' with 7' high walls. 25*2 + 40 * 2 = 130' 130' * 7 = 910 910 / 8 = 113.75 113.75 * 9 = 1,024 blocks
Alternative way: get the total square feet of wall and divide by (128 / 144). because 1 std. block is 0.88… sq feet
1 sq. ft is X sq. in.
144 sq. in
After the walls are complete, additional steps should be taken to ensure they X
are able to resist moisture. In some cases, block walls can be assembled using surface bonding techniques
Like concrete walls, block walls must either be
dampproofed or water proofed
Parging:
process of spreading mortar or cement plaster over the block to block water infiltration.
How thick should parging be:
3/8”
What do you do when parging is dry?
coating of asphalt is applied to the exterior side of the wall. This along with properly designed footing drain will normally ensure a dry basement
When added protection is needed to block wall, such as when soil is wet:
The entire wall should be waterproofed like a solid concrete foundation
When must a lintel be installed?
Where openings occur in the foundation.
Lintel:
horizontal member that supports the weight of the wall above. A lintel in a masonry wall is like a header in a wood frame wall. It directs loads around the opening.
Ways to create a lintel:
L-shaped steel angles
Reinforced pre-cast concrete placed over an opening as a wood header would be placed.
Lintel blocks, which are temporarily supported over the opening by a wood framework. The open portions of the blocks are filled with concrete and rebar. When concrete has cured, the wood framework can be removed.
