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Hollow Concrete Blocks – All About It
House is a basic need of a person. It is one of the three basic requirements of food and cloth. In the early times, the house is made with stone and mud. Then people use burnt clay brick to construct a structure. Now with the technological advancement and need for a cheaper and fast technique for the construction, the concrete blocks are used.
The concrete blocks are divided into types, solid concrete block, and hollow concrete block. In this article, we will discuss hollow concrete blocks, its advantage and disadvantage, properties, and types.
Start with what is concrete blocks?
The concrete blocks are the rectangular concrete blocks available in solid or hollow. These concrete blocks come in modular sizes and it is different in various countries.
Start with Solid Concrete Blocks
The solid concrete blocks are made from aggregate, Portland cement, and sand. The blocks have solid material not less than 75 percent of total weight calculated from overall dimensions. These blocks are heavy in weight and provide excellent stability to the structure and used for large masonry work. It is used in load-bearing and non-load bearing walls. It is available in various sizes compared to other conventional bricks.
Hollow Concrete Blocks
It is the standard size rectangular hollow blocks made of cast concrete having a high or low density. Portland cement and aggregate, fine gravel, and sand are used as raw material in high density. Industrial waste like fly ash or bottom ash used as a raw material in low-density blocks. It is also known as cinder blocks/breeze blocks in various places.
As per the Indian Standard – IS 2185 (Part-1) 2005 the hollow concrete blocks have one or more large holes or cavities which are a pass-through block or not pass through the block. These blocks have solid material between 50 to 75 percent of the total volume of the block. The holes or cavities reduces the total cross-sectional area of the block.
The hollow blocks are widely used in masonry as it reduces the construction time and require less cement, steel which saves money. The weight of the construction is minimized and enhance the noise and thermal insulation. The electrical conduit, water, and soil pipes are easily accommodated.
Hollow concrete blocks available in which sizes?
The standard hollow concrete blocks are available in full and half size. The full-size blocks are rectangular and have two cores. The half-size blocks are cubical and have one core.
Length: 400, 500 or 600 mm
Height: 200 or 100 mm
Width: 50, 75, 100, 150, 200, 250 or 300 mm
Types of Concrete Blocks
Hollow Concrete Block (Open and Closed Cavity)
The hollow blocks are divided into below categories
Grade A
This type of block is used in a load-bearing unit and has a minimum block density of 1500 kg/m3. These blocks are made with average compressive strengths of 3.5, 4.5, 5.5, 7.0, 8.5, 10, 12.5, and 15 N/mm2 at 28 days.
Grade B
The Grade-B type blocks are also used as load-bearing units and have block density between 1100 kg/m3 and 1500 kg/m3. These types of blocks are made for a minimum average compressive strength of 3.5 and 5 N/mm2 at 28 days.
Solid Concrete Blocks
Grade C
The solid concrete blocks are used as load-bearing units and have a minimum block density of 1800 kg/m3. The grade C blocks are made at a minimum average compressive strength of 4 and 5 N/mm2.
Physical Properties of the Hollow Concrete Blocks
Moisture Movement: Not more than 0.09 %
Water Absorption: Not more than 10 %
Drying Shrinkage: Not more than 0.06 %
Compressive Strength
For Grade A: 3.5 to 15 N/mm2
For Grade B: 3.5 to 5 N/mm2
Density
For Grade A: 1500 kg/m3
For Grade B: 1100 kg/m3 to 1500 kg/m3
Where are the hollow concrete blocks used?
Interior load-bearing walls, Exterior load-bearing walls, curtain walls, fireproofing, partition wall and panel walls, backing from brick, stone, and other facing, piers, column and retaining walls, boundary fences, etc.
What are the advantages of Hollow Concrete Block Masonry?
The hollow concrete block masonry is an easy and fast construction practice compared to others.
These blocks reduce the construction cost as it has a large size which reduces the number of joints
These blocks are durable and have low maintenance
Semi-skill or unskilled labor can work with this masonry practice
The reinforcing of hollow block masonry is possible as it doesn’t require additional formwork or construction machinery
Hollow concrete block masonry is highly durable as it is compacted by high pressure and vibration.
The hollow concrete blocks are lightweight reduces the weight of the structure and requires less percentage of steel of R.C.C.
These blocks have a rough texture which provides excellent bonding between cement mortar and concrete blocks
The voids and cores can fill with steel bars and concrete to achieve seismic resistance
These hollow concrete blocks have excellent insulating properties against sound, heat, and dampness
The blocks have excellent fire resistance
What are the disadvantages of Hollow Concrete Block?
The cost of these blocks is higher than the conventional bricks
The structure built with hollow blocks without any interior reinforcement may damage in earthquake
What are the different types of Hollow Concrete Blocks?
The hollow concrete blocks are divided into various types according to its shape, need, and design
1. Concrete Stretcher Blocks
These hollow blocks are widely used in construction. The blocks are used to join the corner of masonry units. These blocks are placed with their length parallel to the face of the wall.
2. Lintel Blocks
The lintel blocks are called channeled blocks or beam blocks. This is a U-shaped concrete masonry unit. The blocks have a deep groove with a length of the block. After placing the blocks this groove-filled with concrete with reinforcement. These blocks are used at top of the portion of doors and windows as it transfers the load comes from the top.
3. Partition Concrete Blocks
These blocks are ideal for partition wall construction. The hollow part of the blocks is divided into two or three components. The height of the partition block is larger than its breadth.
4. Concrete Pillar Blocks
These blocks are also known as double corner block as both of its corners are plain. The blocks used when two ends of the corner are visible. As of its name, it is widely used in pillars or piers
5. Concrete Corner Blocks
These blocks are used in corners of masonry at the end of the window or at the door opening. One corner of the block is plain and the other is stretcher design. The blocks are arranged that the plane end of the block is at the outside and another end is locked with a stretcher block.
6. Jamb Concrete Blocks
This block is used when the elaborated window opening in the wall. It is connected to the stretcher and corner of the block. These blocks provide space for the casing member of the window.
7. Bullnose Concrete Blocks
These bullnose concrete blocks are similar to corner blocks in structure and function. When the round edges are required these blocks are used.
8. Frogged Brick Blocks
Like the frogged brick these frogged brick blocks have a frog on the top with a header and stretcher. This frog helps the blocks to hold mortar and develop a strong bond with the top lying block.
In conclusion, the concrete blocks are efficient building material than conventional bricks. The blocks increase construction speed and minimize construction costs. The price of the hollow blocks are cheap and it is available in various shape and size.