Building Materials

Concrete Blocks

Introduction:

Concrete blocks also known as Concrete Masonry Units are widely used for constructing walls in a building. It is used for all types of buildings, whether it is a small residential building or a high rise building.

Types:

There are different types of concrete blocks depending upon the size and structure.

Based on Size:

  1. 4 inch blocks: The size of these blocks are L=15″, B=4″, H=8″. These blocks are mainly used for partition walls, and boundary walls with heights less than 1.5 m. Partition walls which have height of 10 ft, must be provided with a concrete band at 4 ft height from the bottom. Also, A lintel at a height of 7 ft will provide extra stability. It is better to avoid cut lintel for these type of walls, and it is better to provide through lintels. Also, these partition walls must be plastered at the end to increase lateral resistance from any impacts or blows.
  2. 6 inch blocks: The size of these blocks are L=15″, B=6″, H=8″. Among all the sizes of blocks, these are the ones which are widely used.  These blocks are mainly used for External and Internal Walls in all types of Residential Homes and High Rise Buildings. Unlike the 4″ blocks, these do not need the concrete band nor the restriction to use through lintel. A cut lintel can be used for walls using these type of blocks. When these blocks are used for boundary walls, heights up to 2 m can be reached safely without any lateral instability.
  3. 8 inch blocks: The size of these blocks are L=15″, B=8″, H=8″. These types of blocks are mainly found in Premium Villas, Bungalows and High Rise apartments. These blocks are used in buildings where the column dimension is 8 inch, so as to achieve a smooth wall finish without any protrusions of the columns inside the room or living space. These are also used when  the building is required to have thick external walls in terms of safety against impacts or blows. The disadvantage of these blocks is that they consume more space and are also heavy and time consuming to construct, not to mention they are expensive as well. These types of blocks are avoided in budget homes, and small plot sizes.

Based on Structure:

  1. Solid Concrete Blocks: These are the typical blocks used for construction. Almost all of the standard walls are constructed using these type of solid blocks.
  2. Hollow Concrete Blocks: These blocks have hollow cores in them. The main purpose of these blocks is to reduce the self weight of the wall. These blocks are also used to provide insulation against the exterior heat. These blocks are avoided when constructing a building as they are weak against lateral impacts and this disadvantage overcomes the light weight or insulation advantages.  These blocks are cost same as the Solid Concrete Blocks and hence are avoided by considering their disadvantages.
  3. Interlocking Concrete Blocks: These blocks are similar to hollow concrete blocks, but these are structurally more sound and reliable, also these blocks have notches at the end which interlock with the neighboring block to get the added stability. Also, these blocks have cavities in which reinforced grouting can be poured to increase the strength of the wall.

Composition:

Concrete blocks are made from concrete which consists of Cement, Aggregate (usually M-Sand) to get high density blocks. Low Density Blocks use FlyAsh or bottom Ash which are industrial by-products.

Light Weight Blocks also known as Autoclaved Aerated Blocks are used which are made of FlyAsh.

 

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