QUALITY REQUIREMENTS FOR BURNT CLAY FLY ASH BUILDING BRICKS

Quality Requirement of Fly Ash Bricks

Quality of Fly ash bricks
Quality of Fly ash bricks

1. General Quality

  • Bricks shall be free from cracks and flaws and nodules of free lime.
  • Bricks shall have smooth rectangular faces with sharp corners
  • Bricks shall be uniform in colour
  • The proportion of soil and fly ash shall be as per IS-2117-1991.
  • Fly ash used to manufacture of bricks shall conform to grade 1 or grade 2 as per IS-3812-1981.
  • Frog size of a hand moulded brick having height of 90 mm or 70 mm shall be as per the figure shown below.
Frog Size for Burnt Clay Fly Ash Building Bricks
Frog Size for Burnt Clay Fly Ash Building Bricks

2. Dimensional Requirements

Dimension for Modular Bricks
Length (L), mm Width (W), mm Height (H), mm
190 90 90
190 90 40
Dimension for Non-Modular Bricks
Length (L), mm Width (W), mm Height (H), mm
230 110 70
230 110 30

3. Physical Requirements

Compressive Strength Minimum average compressive strength shall be as per various class of group (See table below) Compressive strength of any individual brick shall not be less than the minimum compressive strength for the corresponding class of brick. (See table below)
Water Absorption Shall not be more than 20% by weight up to class 12.5 and 15% by weight for higher classes.
Efflorescence Shall not be more than ‘moderate’ up to class 12.5 and ‘slight’ for higher class.

 4. Classes of Burnt Clay Fly Ash Bricks

Class Designation Average Compressive Strength
N/mm2 Kgf/cm2, (approx)
30 30 300
25 25 250
20 20 200
17.5 17.5 175
15 15 150
12.5 12.5 125
10 10 100
7.5 7.5 75
5 5 50
3.5 3.5 35

Reference

IS-13757-1993 – Specification for fly ash building bricks

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