15 Types of Concrete Blocks

Concrete blocks can be divided into two main categories: Solid and Hollow. These two varieties of concrete blocks can be utilized for a variety of tasks in addition to wall construction.

Solid concrete blocks are more solid than hollow concrete blocks, albeit not all of them are totally solid. Below, its described in more detail about the many varieties of concrete blocks, often known as concrete masonry units (CMU).

concrete blocks

Concrete blocks are certainly something we are familiar with. Concrete is made by mixing together the cement, sand and aggregates. 

An alternative to masonry in construction, concrete blocks have both benefits and drawbacks. The mortar joints between concrete blocks require less cement to hold them together since they are larger than bricks. However, concrete blocks are more likely to slide and crack when a foundation shifts than bricks are due to their higher moisture content and greater size.

Concrete blocks come in two varieties: hollow and solid.

The concrete blocks’ nominal dimensions are:

  • 400, 500, or 600 mm in length
  • 200 or 100 mm in height
  • 100, 150, 200, 250 or 300 mm width

Concrete blocks come in hollow and solid types, which are the two most common types used in construction. Fully solid blocks are frequently utilized for paving operations and other tasks requiring stability and endurance. You wouldn’t want to attempt to walk on pavement with holes in it.

When creating boundary walls and other huge buildings, hollow blocks are used, which have holes that occupy more than half of their cross-sectional area. Because of the holes, they are lighter, which can be useful when wiring or running pipes through them. For added stability, you may also thread rebar through the perforations.

Hollow Concrete Blocks

There are three grades of hollow concrete blocks:

  • The minimum density for Grade A is 1,500 kg/m3. The concrete blocks must be produced to have minimum 28-day compressive strengths of 5, 7, 8.5  & 10 N/mm2 each.
  • Density for Grade B varies between 1000-1,500 kg/m3. These must be produced to have minimum compressive strengths of 2.0, 3.0, and 5.0 N/mm2 at 28 days, respectively.
  • The density of grade C is less than 1,000 kg/m3. These must be produced with a minimum 28-day average compressive strength of 1.5 N/mm2.

For load-bearing concrete block walls, grades A and B are used, whilst grade C is used for non-load-bearing walls.

Varieties of Hollow concrete blocks 

Stretcher Block

To join the corners of masonry units, stretcher blocks made of concrete are used in building. Their faces are positioned perpendicular to the wall’s surface.


U-Block are used as an optional support surface under ceiling beams, panels, and masonry bars as well as for casting concrete bands to assure the stiffness of buildings. On construction sites, U-Blocks can also be used to cast monolithic concrete lintels. In that situation, U-Block serve as formwork, and general design guidelines for reinforced concrete structures serve as the basis for the design work.

Jamb/ Sash Block

A shallow groove is used to separate the two holes, and a deeper groove is used at one end. Concrete masonry unit with pre-molded expansion joint material and an end slot for use in openings to receive metal window frames.

Column/Pillar Block

A square or rectangular block with a single or double holes respectively is the standard shape of a column or pillar block. These can be filled with concrete and reinforced with steel rebar inside to form columns.

Corner Block

Corner blocks may be positioned at window and door opening ends or at corners, as would be expected. While the stretcher side is parallel to the wall, the plain side is exposed to the outside.

concrete blocks

Split Blocks

This item is extremely adaptable and suitable for both internal and external use. Split blocks provide several advantages over traditional construction methods, including natural beauty with a contemporary style, affordability, ease of maintenance, and insulating capabilities. Since no plastering or painting is necessary, it reduces construction costs and time. Split blocks can be produced in a variety of colors with smooth or rough surfaces. This block is highly porous, making it susceptible to water damage, but it is also less prone to termite infestation and fire damage.

Bullnose Block

In terms of use and construction, bullnose blocks are identical to corner blocks, with the exception that they have rounded corners. The single rounded edge on this 8″ single bullnose block softens the edges of any building or project. To preserve enduring strength, this block is built of premium concrete. This block is a fantastic option for building or landscaping projects due to its adaptability.


  •       Ideal for foundations and walls
  •       Standard gray color
  •       Single rounded corner

Partition Block

A concrete masonry unit for use in non-load-bearing walls; usually has solid, rectangular end faces and a nominal thickness of 4” & 6”. Used to build interior and exterior walls, partitions, terrace walls and other enclosures. Partition units are gray in color, with a natural finish and uniform shape.

Solid Concrete Blocks

Solid Blocks are manufactured using cutting-edge production technology to meet and exceed all current and future regulations. Sand, cement, and crushed aggregates are combined to make solid blocks, which are frequently used as building foundations.

While often larger, fully solid concrete blocks resemble gray bricks in appearance. They are effective for constructing wind- and weather-resistant walls.

They can also be used to build retaining walls, steps, foundations, garden walls and planters.

Solid concrete blocks are frequently heavier than hollow ones and are less expensive

Solid concrete block varieties.

DescriptionSizeCompressive strengthAverage Weight per Block
4” Solid400x100x200mm7, 8.5, 10 N/mm²16.50 kg
6” Solid400x150x200mm7, 8.5, 10 N/mm²26.00 kg
8” Solid400x200x200mm7, 8.5, 10 N/mm²35.00 kg

Paving Block 

Paving blocks are solid square or rectangular blocks that are used for paving, walkways, and road shoulders (where they should be painted to increase visibility).
They come in a range of sizes and colors, including sandstone, tan, dark brown, charcoal, and light gray, despite the fact that they are frequently brick-shaped.

Typical sizes: 100x100mm, 200x100mm, 200x200mm

Thickness of Paving50mm60mm80mm
Tolerance – Width / Length+/- 2+/- 2+/- 2
Thickness+/- 3+/- 3+/- 3

Fly Ash Block

When combined with water, fly ash, a thin, powdery particle, creates a product like Portland cement. Fly ash is present in more than half of the concrete. In road projects that call for a lot of material, using fly ash for cement concrete can help you save money.

Fly ash is classified into two groups:

  • Class C is a low-carbon variant with a high calcium content of under 2%. It can make up 15% to 40% of the cement’s composition.
  • Class F is a low-calcium material with a carbon concentration of 5% to 10%. It typically comprises 15% to 25% of the cement’s composition.

Utilizing fly ash can lessen permeability and cracking issues, as well as providing resilience against cold temperatures. It can also be used to make a surface that is slick and finely detailed.

Similar to Portland cement, fly ash is a fine powder that has pigment-like properties. Amber, brown, gray, green, olive, red, yellow, or yellow-brown are some of the possible particle colors. Depending on the particle concentration, the resulting color can change, although it is often some variation of gray.

Fly ash bricks typically only exist in tiny sizes because they lose durability as they become larger and are more likely to fracture and split.

Autoclaved Aerated Block (AAC)

AAC block, also known as aerated autoclaved block. AAC lightweight blocks can be used as external wall, internal wall, partition wall to replace traditional concrete blocks and pre-cast concrete. These are lightweight, provide good thermal insulation performance, sound proof performance, good fire proof performance, improve construction efficiency and do not emit harmful gas

The term “aerated” refers to the lightweight concrete blocks’ 80% air content. Nails and screws can be used, and the material can be shaped easily. However, it is not as strong as certain options for denser concrete, making it not the greatest concrete for supporting loads and frequently requiring reinforcement. In order to prevent degradation when exposed to the weather, you need also seal it with a protective finish.

These customizable white to light gray blocks can be used for steel pillars, infill panels, partition walls, sidewalls, and other types of wall construction. They come in panels, blocks, and speciality shapes including U-shaped bond beam blocks and lintel blocks, all of which come in various thicknesses.

Cellular Lightweight Block

Cellular Lightweight Concrete (CLS) is foamed concrete. The CLC is frequently used in construction because it provides a number of benefits over conventional concrete bricks. Portland cement, sand, fly ash, water, and performed foam are mixed in various ratios to create foamed concrete. On construction sites, CLC (Cellular Lightweight Concrete) can be made using the same equipment and molds as regular concrete.

Three ingredients make up cellular lightweight block, a type of construction material: foam, fly ash, and cement. Similar to AAC, it offers effective protection from loud noises and high temperatures. It is affordable, fire-resistant, and environmentally friendly.

They can be produced to order, in a variety of sizes, and used for parapet walls, compound walls, and wall panels.

For load-bearing or dividing walls, high-density cellular lightweight blocks can be used; medium densities can be used for non-load-bearing brickwork.

  • Lower density (400-600 kg/m3): This low-density CLC is perfect for sound and thermal insulation. These dense CLCs are moisture, termite, and fire resistant. Additionally, it serves as a replacement for thermal insulation.
  • Medium Density (800-1000 kg/m3): Pre-cast blocks for non–load bearing brickwork are made from these density bricks. These bricks come in a variety of sizes depending on the design and building requirements.
  • High Density (1200-1800 kg/m3): This structural grade material is used for the construction of low-rise load-bearing walls and ceilings, the formation of partitioning walls, and the production of pre-cast blocks for load-bearing brickwork.

ECA (Expanded Clay Aggregate) Construction Blocks

Expanded Clay Aggregate (ECA) blocks are masonry units manufactured using Expanded Clay Aggregate, Class F fly ash, and Cement. They are used in the construction of non-load-bearing walls.

After the application of a high-performance innovative technology of manufacturing and post-curing process, Expanded Clay Aggregate (ECA) blocks gains superior material properties.

It also offers no reduced shrinkage and a superior fire and chemical resistance adding to several advantages including durability, versatility, speed, and ease-of-use as well as cost benefits and environmental considerations.

ECA Block are available in 2 Sizes

Sizes: 600 x 200 x 225mm (24” X 8” X 9”)
          600 x 200 x 100 mm (24” X 8” X 4”)


Dry Density600-750 Kg/m3 (Average value =700 Kg/m3)
Drying Shrinkage0.005%
Compressive Strength3.5 to 5.0 N/mm2 (MPa)
Flexural Strength1.05 N/mm2
Thermal Conductivity0.14-0.18 W/mk
Sound Insulation IndexUp to 46 dB for 100 mm thick wall and up to 52 dB for 230 mm wall

Read more; Method statement for block work

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