Technical Specification of Interlocking Blocks

HF 220 Interlocking/ Conduit/ Plain HF150
Use External walls/Fencing/Load bearing constructions Interior/Partition Walls/Framed Constructions
Width 220 mm (9 inch) 150 / 115mm (6/4.5 inch)
Height 115 mm 115 mm
Length 120 mm to 240 mm 120 mm to 240 mm
Weight + – 11 Kg (Full block) for SCEB; + – 8 kg (full block) for fly Ash blocks 5.5-7 kg approx
Application By size, one HF220 is equivalent to three to three & half size of conventional fired bricks. Other sizes are also available.

Raw Material for making blocks

The blocks can be made in Hydraform machine using Fly ash – Lime – Gypsum – Cement- Sand (Fal-G), other fly Ash based combination OR Soil-Cement (Compressed Stabilized Earth Blocks SEB) OR Stone Dust – Cement.

Mix Design

Different mix designs can be made to suit the quality, cost of raw material and compressive strength of blocks required. Eg. the blocks have been successfully made using following combinations :

Fly ash Cement Block

  • Fly ash = 35% – 60%
  • Coarse sand = 35% – 70%
  • Stabilizer = 8% – 15% (including lime, cement, gypsum)

Stabilized Earth Block

  • Soil = 60 – 70%
  • Coarse sand = 20 – 30%
  • Cement = 8 – 10%

Note: The mix ratio will require to be fine tuned based on above factors.We can provide mix design assistance in this respect.

Block Strength

The block strength is determined by nature of Soil / Fly Ash , quantity of Cement and other materials used . The water curing after manufacture of blocks plays a important role in final compressive strength and quality of blocks.

In past we have obtained results as indicated below:

Soil – Cement Blocks Fal-G – C. Sand
Cement Content Strength Cement Content Strength
8% 4 to 5 MPa 8% 7 to 8 MPa
10% 7 to 8 MPa 10% 12 to 13 MPa
1 MPa is equal to 10 Kg / Sq. cm

Thermal Quality

It can be up to 3 times better than conventional brick masonry.

Water Absorption

Good quality blocks can be made from Hydraform machine to give:

  • For Fly Ash- Cement: Up to 15%.
  • For Stabilized Earth Block: Up to 12%.

Block Finish

Block finish is very good and compares even better than face brick finish. It provides option to keep the wall with or without plaster. In case of without plaster, the wall could be given a groove pointing / varnish / sili-coat or tereline coat to protect against weathering effect.


Conduiting can be done using Conduit blocks. Alternatively conventional chase cutting also possible

Block Making

This involves the following steps:

Loading the soil Mixing, soil, cement and water
Loading the soil Mixing, soil, cement and water
Loading the Hydraform machine Carrying the block
Loading the Hydraform machine Carrying the block
Stacking and curing the blocks Laying the blocks
Stacking and curing the blocks Laying the blocks



  • Interlocking Blocks save on Mortar & Plaster cost
  • High Finish Design & Aesthetics
  • Faster Construction
  • Simplicity of Use
  • Cost Efficient
  • High Quality Product
  • Environment Friendly – No Burning of Bricks required
  • Option to Use Waste materials / Fly Ash / Marble Slurry powder / Rice Husk ash / Concrete mix with chips up to 4 mm
  • Minimum mortar required
  • Independence to make at site of construction
  • Training and technical support
  • International proven product used in 45 countries
  • Can be used without plastering
  • Fly ash blocks can be Lighter than conventional masonry
  • Suitable for earthquake resistant construction
  • Local / Unskilled labour can be constructed
  • Conduits / Plumbing possible

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