Concrete Blocks | Construction Materials | By Ashutosh Nautiyal

Introduction Of Concrete Blocks:- Concrete block is also called a Concrete Masonry Unit(CMU). A Concrete block is primarily used as a building material in the construction of walls. A concrete masonry unit(CMU) is a standard size rectangular block used in building construction.

Concrete Blocks

Concrete Blocks | Construction Materials | By Ashutosh Nautiyal
Concrete Blocks

Introduction Of Concrete Blocks:-

  • Concrete block is also called a Concrete Masonry Unit (CMU).

  • A Concrete block is primarily used as a building material in the construction of walls.

  • A concrete masonry unit (CMU) is a standard size rectangular block used in building construction.

  • A Concrete block is one of the precast concrete products used in construction.

  • CMUs are some of the most versatile building products available because of the wide variety of appearances that can be achieved using them.

  • Concrete blocks are produced in a large variety of shapes and sizes.

  • The first hollow concrete block was designed in 1890 by Harmon S. Palmer in the United States.

  • The concrete commonly used to make concrete blocks is a mixture of powdered portland cement, water, sand and gravel. 

  • Concrete block construction has gained importance and has become a valid alternative to fire clay bricks.

  • They can be produced manually or with the help of machines.

  • Concrete blocks may be produced with hollow centres to reduce weight or improve insulation.

  • The common size of concrete blocks is 39 cm * 19 cm * (30 cm or 20 cm or 10 cm) or 2 inch, 4 inch, 6 inch, 8 inch, 10 inch and 12-inch unit confirmation. 

  • Most concrete blocks have one or more hollow cavities, and their sides may be cast smooth or with a design.

  • In use, concrete blocks are stacked one at a time and held together with fresh concrete mortar to form the desired length and height of the wall.

  • Today, concrete block manufacturing is a highly automated process that can produce up to 2000 blocks per hour.

  • Most commonly used concrete blocks are sized:-

  • Length- 40 cm (half blocks: 20 cm)

  • Height- 20 cm 

  • Width - 8/10/15/20 cm 

Concrete Blocks | Construction Materials | By Ashutosh Nautiyal
Concrete Blocks

  • Solid concrete blocks have no cavities or according to the US standards have no voids amounting to not more than 25% of the gross cross-sectional area.

  • Hollow concrete blocks are the most common type of concrete blocks which are having one or more holes that are open at both sides.

  • The total void area for hollow blocks can amount to 50% of the gross cross-sectional area.

Advantages Of Concrete Blocks:-

Technical Advantages:-

Solid Blocks:-

  • They have high compressive strength, resistance to weathering, impact and abrasion.

  • They have the capability of being moulded into components of any shape and size.

  • They have good fire resistance up to about 400°C.

  • They facilitate rapid construction. 

  • They are having very good stability.

Hollow Blocks:- 

  • They can be made larger than the solid blocks.

  • They are lighter in weight.

  • They facilitate easy and quick construction of walls.

  • Their voids can be filled with steel bars and concrete because of which they acquire high earthquake resistance.

  • The air space in them provides good thermal insulation.

  • The cavities in them can be used for electrical installation for pumping.

Economic Advantages:-

  • The production of concrete blocks can be started with little capital.

  • With concrete blocks, less working time is required for bricklaying work.

  • There is less mortar consumption with concrete blocks.

  • Generally, the production cost of concrete blocks is slightly lower than that of fire bricks.

Limits Of Applications Of Concrete Blocks:-

  • Raw materials of good quality and economically feasible must be locally available.

  • A relatively large amount of cement is needed, which can be expensive and difficult to obtain.

  • Special knowledge and experience of the production process are needed.

Raw Materials For Concrete Blocks:- 


  • Ordinary Portland Cement 

  • Special cements


  • Sand or gravel

  • The maximum particle size of the coarser aggregate is 10 mm.

  • Suitable aggregates are usually obtained from natural sources(river bed, gravel pits, volcanic deposits) or from industrial by-processes(granulated blast furnace slag, sintered fly ash).

Cement-Aggregate Ratio:-

  • A suitable proportion of aggregate to cement must be found by testing.

  • Common ratios are 1:6 and 1:8.

  • Test the quality of blocks produced.

Water-Cement Ratio:-

  • Only drinking quality water should be used to mix the concrete.

  • Recommended water-cement ratio is 0.5.

Equipment Used For Production Process Of Concrete Blocks:-

  • Masonry tools

  • Mixers: Pan mixers; Trough mixers

  • Blockmaking machine: Hand-operated; "Egg-laying" mobile machines; fully mechanised stationary machines.

Production Process Of Concrete Blocks:-

Batching And Mixing:-

  • Batch aggregates and cement by weight.

  • Mix cement and aggregates using mattock, shovel or mixer until it reaches homogeneous condition.

  • Add some water.

  • In hot climates, the fresh mix must be shaded from the sun.


  • Put the mixture into wooden or steel mould boxes or moulding machine.

  • Demould blocks immediately after compaction.


  • Cover the demoulded bricks with plastic sheets for 24 hours.

  • Keep the concrete blocks moist by keeping underwater in tanks or by regularly spraying with water for 7 days.


  • Don't expose to direct sunlight; keep the blocks in a dry and covered area.

  • Store for 2 weeks before using.

Skills Required For Production Process:-

  • Concrete making and masonry skills. 

Lightweight Concrete Blocks

  • Lightweight concrete block is a concrete masonry unit(CMU) made of expanded aggregate to reduce the density and weight compared to standard concrete blocks.

  • Lightweight concrete blocks are made by replacing the sand and gravel with expanded clay, shale, or slate. 

  • The light weight concrete blocks can help reduce heavy lifting and carrying by minimizing the weight of the concrete blocks that must be lifted and carried during brick-laying tasks.

  • Using lightweight concrete block reduces strain and loading on mason's backs.

*Self Typed
*Source- Internet, Books, Self-Analysis

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About the Author

Mr. Ashutosh Nautiyal is a student who is pursuing his post-graduation (MBA in Infrastructure Development and Management) from SCMHRD, Pune. He has done his B.Tech in Civil Engineering from BTKIT, Dwarahat and his schooling from Omkarananda Saraswat…


  1. Thanks Mr. Happy
  2. Helpful content. Thank you for sharing information about Readymade Compound Wall. Keep posting!!
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