19 Top Concrete Masonry Unit Advantages and Disadvantages
Concrete Masonry Units
A CMU, or concrete masonry unit, is a building material primarily used in the construction of walls and porch slabs. These are made by pouring wet concrete into blocks made of a mixture of cement, sand, and gravel. The wet mixture hardens at room temperature, resulting in a solid material.
CMU blocks come in a variety of sizes and shapes including blocks of various lengths with a square or rectangular cross-section. They are used to create the structure of a building and may also be used as parts of a wall’s outer surface.
Concrete masonry units are a basic construction material that is used in masonry for load-bearing and non-load bearing purposes.
It is usually rectangular or square in shape and is typically made of a mineral such as cement, clay, shale, or slate. It is also made of any combination of these materials.
Cement-based concrete masonry units are considered to be load bearing while clay-based units are considered to be non-load bearing.
There are a few other types of concrete masonry units as well: autoclaved aerated concrete masonry units, clay/linseed oil bricks, concrete masonry panels, and concrete tiles. There can also be variations of concrete masonry units
CMUs are an essential construction material because they are inexpensive and easy to transport. They are also popular because they offer builders several options for their design.
Concrete Masonry Units Manufacturing
Manufacture of concrete masonry units is divided into two main categories:
Automated CMUs are manufactured on a fully automated manufacturing line where the entire process of mixing, forming, and curing can be done without any human interference.
Man-handled CMUs are seen as more traditional because they are individually made by workers using a variety of tools and machines to create each block.
Concrete masonry units can be manufactured in a variety of different shapes and sizes. The most common are rectangular blocks, such as brick, with a square or rectangular cross-section.
Other common shapes include long blocks for floor slabs, short blocks for wall foundations, and round blocks for chimneys and fireplaces.
Concrete masonry unit designs may also include distinctive patterns or textures to create visual appeal.
Concrete Masonry Units Applications & Uses
CMUs are typically used for load-bearing and non-load bearing purposes. Because they are inexpensive, CMUs are most often used in interior applications, such as:
They can also be used for load-bearing exterior walls and foundation. CMU wall panels are often used in place of traditional wood frame construction.
CMUs that have been designed for exterior use can be given a surface to protect them from the weather. They may also be designed to imitate wood or stone so that they “mimic” more costly materials.
CMUs are used in areas where they are less likely to be affected by weathering, fire, and water. Although fire-resistance is not part of the typical CMU design, CMUs can be used to increase fire-resistance when it is necessary.
When used in a load-bearing capacity, masonry walls use steel or concrete reinforcement within the masonry units. This is usually accomplished by having slots cut into the sides of blocks that receive steel or concrete bars or mesh.
CMUs are typically used in interior applications for partition walls, such as the walls between rooms or between a building and an attached garage. They are also used in columns and foundations.
Concrete blocks are used in applications requiring a sudden load and tensile resistance. They can be used in both interior and exterior settings. In addition to being used as load-bearing walls, CMUs may be used as non-load bearing partition walls.
When erected with integral steel reinforcing, concrete block is a fairly common building material for load-bearing walls in what is known as concrete block structure (CBS) construction.
The “crawl space foundation” is a typical foundation style for American suburban houses, consisting of a concrete block wall around the perimeter that supports dimensional timber floor joists.
Retaining walls, which can also be made of concrete blocks, can be built either with blocks designed to be set back each course and used with a sand base and no mortar or reinforcing (gravity wall) or with blocks (typically an architectural style of block or clad with a veneer such as brick) with a concrete base, steel reinforcing, and mortar (piling wall).
Other non-structural applications for concrete block walls include interior fire-rated and exceptionally durable partition walls, as well as exterior backup curtain walls for attachment of building envelope systems (rigid foam insulation and an air/vapor barrier) and veneers (stucco, steel, brick, or split-face concrete block).
Concrete Masonry Unit Advantages and Disadvantages
Advantages of Concrete Masonry Unit
- Blocks are light and easy to install. Any person who has masonry experience can install a concrete block foundation.
- CMU is a sustainable green product because it does not require any energy intensive materials in its production.
- It’s fire resistant (when used with steel).
- Another advantage of CMU wall is that it’s termite resistant.
- It has greater sound insulating value than wood or other materials.
- CMU wall system is less costly than a conventional concrete structure with steel framing.
- Concrete block walls resist moisture penetration, and so help prevent mold and mildew problems inside homes even during extremely humid months.
- The CMU wall is considered to be a good structure for disaster resistance as it can withstand earthquake, hurricane and tornado effects.
- It is also a good choice for fire safety as it doesn’t radiate heat around the structure.
- Concrete masonry unit is more adaptable for both internal and external partitions than any conventional concrete walls or structures.
- CMU walls are an excellent choice for load bearing applications, such as bearing partitions, floors and roofs etc., since it has exceptional load bearing capacity.
- Concrete masonry unit is fire resistant and can withstand the fire for a considerable amount of time as specified by various building codes.
- CMU walls are more attractive than concrete block walls and therefore can be preferred where appearance is important, such as in banks, schools, hospitals churches etc. CMUs which are now available have a wide variety of infill materials like stone, brick, glass blocks or ceramics which can be used to give a better appearance to the wall structure. Its cost is comparatively less and its weight too can be easily handled by any common people. CMUs are easily available in the market.
Disadvantages of Concrete Masonry Unit
- It is limited to indoor applications because of the corrosive nature of concrete and because of its weight.
- It doesn’t ‘breathe’. Therefore, it is not suitable for walls that are in contact with the ground (such as walls of a basement).
- It is limited in its architectural possibilities. It can be used to create only simple arches and flat surfaces.
- It is limited in its shape variety – a wide range of concrete blocks is available, but they share the same structural characteristics and building properties, so that aesthetic individuality is compromised.
- It is a relatively expensive material (the cost of concrete masonry unit is several times more expensive than the cost of bricks).
- The color face on the raw concrete sometimes turns black owing to its fast chemical reaction with moisture and carbon dioxide in the air.
- Concrete masonry units are difficult to pack and install; they need a special crane to hold their weight, which makes it difficult to use them in a narrow construction.
- Concrete block Masonry units are usually not recyclable, which makes it difficult to decrease the usage of these materials.
- The main disadvantage of concrete masonry units is that they have no particular aesthetic character and don’t make it possible to see the specialty in various buildings.
- Concrete blocks remain a permanent characteristic of any building; therefore, they can be seen while driving by and in photographs, and this may lead to an unpleasant impression with visitors.
- A disadvantage of concrete masonry units is that they are heavy materials, which may cause damage to a building.
- Concrete masonry units are not the best choice for areas with high humidity because they can get soft and have problems with moisture absorption.
- Concrete masonry units are often difficult to handle and install by hand.
- Large concrete blocks are heavy and can be hard to move, handle, and install.
- It is not good for interior walls which require a lot of maintenance, because the mortar joints get easily damaged and must be constantly maintained to give the wall a smooth finish that is resistant to water penetration.
- Exposure to moisture can cause rust on some types of reinforcement bars embedded in masonry unit wall construction which may lead to premature deterioration of CMU wall structure.
Concrete Masonry Unit Sizes
Structures can be created in the conventional masonry manner using layers (or courses) of staggered blocks when using blockwork.
Concrete blocks with hollow centers (cores) can be manufactured to save weight, enhance insulation, and provide an interconnected gap into which concrete may be poured to firm the entire wall after it is constructed.
Blocks are available in a variety of modular sizes, with the most common being “4-inch,” “6-inch,” “8-inch,” and “12-inch.” CMU blocks are nominally 16 in (410 mm) long and 8 in (200 mm) wide in the United States.
Their actual dimensions are 38 inch (9.5 mm) smaller than the nominal measurements (to accommodate 38-inch mortar joints between blocks in any orientation).
Blocks in Ireland and the United Kingdom are typically 440 mm 215 mm 100 mm (17.3 in 8.5 in 3.9 in) in size, excluding mortar joints.
Blocks are typically 390 mm 190 mm 190 mm (15.4 in 7.5 in 7.5 in) in Australia, New Zealand, and Canada, excluding mortar joints.