Introduction of CMU Wall
CMU is a modern building unit that has various benefits as compared to bricks. The CMU blocks are available in various shapes and sizes in the market and are widely used in the construction of walls of the building.
In this article, we will discuss all about the concrete masonry units.
What is CMU Wall?
The CMU wall is constructed with the help of standard sizes concrete masonry units. A concrete masonry unit (CMU)is a versatile and environment-friendly building unit that is available in a variety of shapes and sizes in the market.
The Full form of the CMU is Concrete Masonry units. The CMU walls act as load-bearing walls which are widely used in the construction of residential as well as commercial buildings. The concrete masonry unit has a rectangular shape.
The concrete masonry units have an interlocking system that gets fitted into each other. The concrete blocks are interlocked with the help of interlocking tongues and grooves. The CMU Walls are comprising of steel as a reinforcement and other types of composite materials.
Concrete Masonry Unit (CMU) Specifications
Following are the standards which are given by the American society for testing and materials.
Designation of ASTM
Types of Concrete Masonry Unit
|ASTM C55||Concrete Bricks|
|ASTM C73||Calcium silicate face brick|
|ASTM C90||Load bearing Concrete masonry units|
|ASTM C139||CMUs for construction of Catch Basins and Manholes|
|ASTM C744||Calcium Silicate Masonry Units and prefaced concrete|
|ASTM C936||Solid interlocking concrete paving units|
|ASTM C1372||Segmental Retaining wall units|
Concrete Masonry Units (CMU) Shapes
The CMU concrete units are available in various shapes in the market which are as follows.
- Single corner unit: – The single corner unit has only one end which is squared off. It is generally used at the end of the wall where the end of the block is exposed.
- Stretcher Unit: – The stretcher unit has a flange extension on both of its ends. It is generally used in the middle of the walls where both ends are covered by the adjoining bricks.
- Double corner unit: – The Double corner unit has two ends that are squared off. This type of block is generally used to create vertical pillars.
- Sash units: – Sash units have slots cut in the flat ends. These are used around the windows and door openings to provide the expansion space.
- Cap Units: – The Cap units are the solid and thin concrete blocks that are generally used to open the cavities at the top of the concrete block walls.
- Bullnose blocks: – The bullnose blocks are also available in the market with one end rounded.
These all are the various shapes of the concrete masonry units which are available according to the requirement and the design of the construction projects.
CMU Wall Details (Concrete Masonry Units)
The concrete masonry walls get manufactured from the precast concrete and it is the most versatile building unit which is very easy to construct. The construction done with the concrete masonry unit is very fast. The CMU walls required very less maintenance and they are more durable.
CMU Block Dimensions
Concrete Masonry blocks are available in various sizes in the market. The concrete masonry blocks are also available in the half sizes due to which the end of the corner of the walls can be constructed accurately.
The concrete masonry blocks are identified with their depth and the thickness of the wall. The nominal dimensions of the concrete masonry blocks are given below in the tabular format. CMU or cinder Block Weight. The concrete masonry blocks are made with a mixture of Portland cement, sand, aggregate, and water in the appropriate proportion
Sizes of the CMU Blocks
Nominal Dimensions of the CMU Blocks
|4” Full Blocks||4” x 8” x 16”|
|4” Full Blocks||4” x 8” x 8”|
|6” Full Blocks||6” x 8” x 16”|
|6” Full Blocks||6” x 8” x 8”|
|8” Full Blocks||8” x 8” x 16”|
|8” Full Blocks||8” x 8” x 8”|
|10” Full Blocks||10” x 8” x 16”|
|10” Full Blocks||10” x 8” x 8”|
|12” Full Blocks||12” x 8” x 16”|
|12” Full Blocks||12” x 8” x 8”|
CMU or Cinder Block Weight
The weight of the cinder blocks or Concrete masonry units mainly depends upon the density of the concrete used in the manufacturing of the concrete blocks.
The concrete block units are classified into three categories according to their weight
- Lightweight CMU Blocks: The weight of the lightweight cinder blocks is less than 105 fb/ft3.
- Medium weight CMU blocks: The weight of the medium weight concrete masonry blocks ranges between 105 fb/ft3 to 125 fb/ft3.
- Normal weight CMU blocks: The weight of the normal weight CMU blocks is more than 125 fb/ft3.
CMU Blocks Compressive Strength
The compressive strength is one of the most important criteria which should be tested before using any construction material or building unit. The concrete masonry walls have compressive strength which ranges from 7MPa up to 35 MPA. The compressive strength of the concrete masonry unit mainly depends upon the mix design and the quality of concrete used in the manufacturing of the concrete masonry blocks.
Advantages of CMU Walls
- There are various advantages of CMU walls which are as follows
- The concrete masonry unit walls are more durable as compared to the brick walls. The concrete masonry units are very easy to install and require very little maintenance. The CMU walls have good resistance to fire.
- The construction of the CMU Walls is economical as compared to the brick walls.
- The concrete masonry units are larger than conventional bricks.
- The steel reinforcement is also used in the CMU walls which increases the load-bearing capacity of the CMU walls.
- CMU walls are best suitable for areas with aggressive environmental conditions.
Disadvantages of CMU Walls
There are also some disadvantages of CMU wall construction which are as follows
- The concrete masonry unit does not have good resistance to water penetration.
- The concrete masonry blocks require an additional coat to its surface to make it water-resistant which increases the cost.
- Concrete masonry blocks have less thermal resistance.
Applications of Concrete Masonry Unit
Concrete masonry units have wide applications in construction which are as follows
- The concrete blocks are used in the construction of the foundation walls and the basement walls.
- The concrete masonry blocks are also used for the decorative purpose which will enhance the aesthetical view of the structure.
- CMU is also used in the construction of the exterior walls as well as partition walls.
CMU Wall Construction
The step by step process of the CMU wall construction are as follows
1. Marking of the Layout of the Foundation
The first step before starting the CMU wall construction is marking the layout of the foundation on the ground with lime as per the design plan. The layout of the complete building should be marked on the ground.
The next step after the marking of the foundation is to excavate the earth for the construction of the foundation. The depth of the excavation on the ground depends upon the design of the foundation.
3. Construction of the Foundation
The CMU walls should be rest on the firm foundation. The footing should be constructed at the required depth. The foundation should be constructed and poured with concrete. It is necessary that sufficient curing of the foundation should be done.
4. Construction of CMU Wall
The suitable size and the shape of the concrete masonry blocks should be selected as per the requirement and the design of the CMU walls. CMU walls are constructed with different types of blocks such as stretchers and corner units. Each layer of the joint should be properly connected with each other.
5. Addition of the Reinforcement
The only wall constructed with the concrete masonry units cannot able to resist the tensile stresses which may lead to cracking. The horizontal, as well as the vertical steel reinforcements, should be added to the CMU walls.
6. Finishing of the Joints
The joints of the CMU Walls should be properly finished with the help of mortar.
CMU Block Cost
The cost of the CMU blocks ranges from $3 to $5 per square foot. The labor and the installation cost of the concrete masonry units is around $10 to $12. The concrete masonry units with less weight are less expensive than the high density CMU blocks. Lightweight concrete blocks require less cost for its installation.