Fly ash Bricks | Building Materials and Construction

Fly ash Bricks | An alternative Building Material

Fly ash bricks are masonry units that are used in the construction of buildings. They are considered to be a part of good and affordable building materials. They contain Class C fly ash and water.

Fly ash bricks are made by compressing Class C fly ash and water at 4000psi and then curing is carried on for 24 hours at a temperature of 66 degrees Celsius steam bath. Air entrainment agent is used to toughen the bricks.

Fly ash Bricks

Fly ash Bricks

Since the concentration of calcium oxide is very high in class C fly ash, the brick is described as self cementing.

It is considered to be a good alternative to traditional mud bricks since the method of manufacture of fly ash is energy efficient that is it helps save energy, brings about reduction of mercury pollution and plus it is cost effective.

Raw materials used for the manufacture of Fly ash Bricks:

  • Fly ash – which is the primary ingredient
  • Sand or Stone dust – as fine aggregate
  • Lime – source of calcium carbonate which results in the bricks being called “Self-cementing bricks”.
  • Gypsum – to enhance the fineness of the shape of the bricks
  • Cement – to increase bonding and strength

General Characteristics of Fly ash Bricks

  • The standard size of the brick is 230x110x70
  • The bricks are manufactured and tested as per IS 12894-2002
  • Fly ash bricks are sound, compact and uniform in shape, size and colour. Smooth rectangular faces of the bricks are accompanied with sharp and square corners.
Fly ash Bricks | Available in various colours and shapes.

Fly ash Bricks | Available in various colours and shapes. The above picture shows the bricks in dark peach colour with three holes on it. These holes are used for grouting. The mortar is poured into these holes for proper bonding in between the bricks.

  • They are free from visible cracks, warpage, flaws and organic matter.
  • Compressive strength: 7.5N/mm2 on an average
  • Water absorption: <8%

Advantages of Fly ash Bricks

  • They have high strength which is their primary benefit to be used for construction.
  • Due to uniform size and thickness of joints, plaster consumption is minimized compared to clay bricks, thereby saving cement to the extent of 25% to 30%.
  • Due to lesser water absorption, there is no dampness in walls.
  • Gypsum plaster, Plaster of Paris can be applied directly without the basecoat of plaster.
  • Wastage is very less as compared to clay brick.
  • The bonding between the bricks is excellent since there is high concentration of calcium oxide in it.

Uses of Fly ash Bricks

Fly ash bricks are used for the construction of various types of buildings such as:

  • Factories
  • Warehouses
  • Power plants
  • Homes
  • High rise structures

Basically, they are used in every kind of construction that can be possibly executed with the help of traditional bricks.

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  1. #1 by neeraj on May 5, 2015 - 1:07 pm

    what type of mortar used for construction and plastering of fly ash bricks wall.. is it same as used in conventional clay bricks I.e. cement + river sand mixture mortar

  2. #2 by neeraj thakur on May 4, 2015 - 7:10 pm

    also I want to know about the plant cost with 11520 fly ash bricks manufacturing per day capacity and the prices of raw material

  3. #3 by neeraj thakur on May 4, 2015 - 7:06 pm

    hello sir I am planning to set a fly ash bricks plant.. but I want to know that what type of mortar required for the construction and plastering of these types of bricks wall.. is it the same ( cement+ river sand mixture) as used in the conventional clay bricks walls. also what are the reasons for cracks in this type of bricks wall…

  4. #4 by ER mpsingh on January 22, 2015 - 4:13 pm

    Dear sir, pl letmeknow what are the compostion of material used with percentage in manaufacturing of flyash bricks if arrange to manufacture the bricks

    • #5 by BenzuJK on February 18, 2015 - 12:53 pm

      Fly Ash – 50 to 60%

      River Sand or Stone Dust – 30 to 40%

      Cement – 8 to 12%

  5. #6 by Ajit Kumar Sharma on July 26, 2013 - 2:08 am

    i want ti know that the Proportion of flyash brick ingredient & what is the cost of plant.
    Ajit Kumar Sharma

  6. #7 by shubhakanta barik on July 22, 2013 - 6:57 am

    best idea

  7. #8 by DK on February 10, 2013 - 4:08 pm

    Nice to ready this article.
    I have plan to build my house in Kolkata (near kolkata Dumdum airport)
    Is there any possibility to get Fly ash Bricks. I will be highly obelised if you can share some contacts near by. Thanks, DK.

  8. #9 by Yashwant Kumar on December 15, 2012 - 9:26 am


    I think you should let us know the composition of the mix required for the manufacturer of fly ash brick.

  9. #10 by garima rai on December 6, 2012 - 1:16 am

    is over reinforced beam suitable for building………??????/

    • #11 by BenzuJK on July 26, 2013 - 7:05 pm

      No. Over reinforced or Under reinforced sections are unsuitable for any kind of construction.

  10. #12 by ranjit p john on July 25, 2012 - 3:28 am

    one of my client approached me to do the repair and rehabilitation of a church building constructed during British Era.You have any advise for how to go about it

  11. #13 by Sriram Padhi on June 15, 2012 - 9:36 am

    What is the quantity of raw materials required for 1000 bricks and cost analysis in comparision to AAC blocks

    • #14 by BenzuJK on June 30, 2012 - 4:54 am

      Hello Sriram,
      If you are so curious to find out the quantity of raw materials, then you should contact the manufacturer for details. That would be helpful.


  12. #15 by Gaurav Malhotra on April 20, 2012 - 1:33 am

    Dear mam,

    I am constructing an STP tank at the site its depth is 1.0 m x 7.0 m x 3.0 m…3.0 m being its depth.. Now my question is it necessary to keep this tank away from boundary by 3.0 m..?? As the bounday wall is already constructed i dont want to use the wall of the tank as the foundation for the bounday wall… plz suggest the best posiible way. i consulted a senior and he made a reference to angle of repose..because of which the pressure exerted by water on tank wall should not be transmitted to boundary wall foundation.. but i am not clear with the concept.

  13. #16 by Dhaval on April 19, 2012 - 10:41 pm

    My name is Dhaval and i am study 6th sem. Diploma civil engineering. i can use this brick in all type of structure as wrought in your article. but any minus point of fly ash brick? and what is price differences in Ordinary bricks and Fly ash brick? pls give me ans.

  14. #17 by PARIKSHIT on March 31, 2012 - 10:46 pm

    what ddo wwee ssay that particular brick which has holes?

  15. #18 by mnprasad on March 22, 2012 - 10:01 am

    I have used Fly Ash bricks for house construction. Vertical and Horizontal cracks are appearing on walls. Almost all walls cracks are appearing, day by day cracks are increasing. Red or clay bricks wall this much cracks will not appear. Expert comments are required. Kindly advise me how to construct with fly ash bricks with out cracks.

    • #19 by BenzuJK on December 7, 2013 - 5:13 am

      Flyash bricks are better than regular bricks. If the walls are cracking, then that would mean structure is weak, and is causing beams to sag. Just a case of bad design.

  16. #20 by Narendria Josh on March 9, 2012 - 4:20 am

    can I have some contacts who makes coloured fly ash bricks in india? if any body know please let me know

  17. #21 by raag on March 7, 2012 - 6:18 am

    self cementing mean??

    • #22 by BenzuJK on March 8, 2012 - 11:22 pm

      Hello Raag,
      Self cementing means it has the ability to behave like a bonding agent. It has the ability to make good bonds. The bonding material required to fill the joints reduces to a great extent.

  18. #23 by DIPAK KUMAR M. SHAH on February 6, 2012 - 9:40 am

    flyash, lime, stonedust as aggregate for bricks making and concrete paving blocks technology.

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