How often do you need a control joint in CMU?
The National Concrete Masonry Association (NCMA TEK 10-2C) recommends that control joints be spaced at 25 feet or 1.5 times the height of the wall, whichever is less.
Do you need expansion joints in a retaining wall?
Solutions: Expansion joints are required in masonry walls. Typically these are at 6 m centres for concrete blockwork and 12 m centres for brickwork. Suitable materials must be used in expansion joints to allow adequate movement of the masonry.
How thick is grout between CMU blocks?
Also, remember that all the mortar joints—beneath the blocks and between the blocks—must be 3/8-inch thick.
What is a control joint in CMU wall?
Control joints in masonry are vertical weak planes intentionally built or cut into masonry to control where cracking occurs. Control joints should be installed in any masonry assembly that expected to experience net shrinkage over time. Usually, we think of control joints in concrete masonry (CMU).
How long should wall be before expansion joint?
An expansion joint should be placed within approximately 10 ft (3 m) of the corner in either wall, but not necessarily both. The sum of the distance from a corner to the adjacent vertical expansion joints should not exceed the spacing of expansion joints in a straight wall, as shown in Figure 3b.
Does CMU expand?
The clay masonry will expand as a result of moisture expansion. This is a permanent expansion that begins from the time the units are removed from the kiln. The concrete masonry, in contrast, will undergo drying shrinkage.
What are control joints used for in masonry?
Control joints are used to relieve stress induced by small amounts of movement caused by shrinkage during curing or small expansion and contraction movements as the result of absorption and expulsion of moisture in concrete or masonry (brick, CMU, etc).
What is a fully grouted CMU wall?
When all cores, with or without reinforcement, are grouted, the wall is considered solidly grouted. If vertical reinforcement is spaced close together and/or there are a significant number of bond beams within the wall, it may be faster and more economical to solidly grout the wall.
How much grout do I need for 8 CMU?
Grout Calculations for Concrete Blocks
| Standard Two Cell Block | Grouted Cells Vertical Steel Spacing | Block per Cubic Yards (8″ high by 16″ long) |
|---|---|---|
| 6″ Thick Wall | 32″ O.C. | 320 |
| 8″ Thick Wall | All cells filled | 100 |
| 16″ O.C. | 171 | |
| 24″ O.C. | 225 |
What’s the difference between a control joint and an expansion joint?
In building materials, a control joint is used to control cracking while an expansion joint is designed to handle structural movement. A control joint can be formed during placement of the building material or cut after the material is placed.
What does CMU mean in a concrete constructed wall?
A concrete block is primarily used as a building material in the construction of walls. It is sometimes called a concrete masonry unit (CMU). A concrete block is one of several precast concrete products used in construction. The term precast refers to the fact that the blocks are formed and hardened before they are brought to the job site.
What is the cheapest material to build a retaining wall?
Retaining wall materials vary in price from relatively inexpensive to very expensive. In order of price, these are some costs for retaining wall materials: Treated pine and is the least expensive material. However, it won’t last as long as other materials.
What is the best concrete to use for a retaining wall?
If you’re building a retaining wall, use a blended mason mix, which includes the heavy-duty mortar type S masonry cement and graded sand. This is high-strength, contractor-grade and pre-blended mortar. This is also ideal for stone columns.
What types of material are best for retaining walls?
Concrete Blocks. Concrete blocks are a very modern and sophisticated material.