Hollow Concrete Block

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Process for making hollow concrete blocks.


In building industries

Salient Features of Process/Technology

Hollow concrete block with nearly one-third hollow area, is a low cost item with adequate strength for construction. It eliminates plastering as well as rendering and reduces dead load of the structure. For manufacture, industrial wastes such as rice husk ash and/or flyash replace 25 to 30% of the cement. Ordinary portland or pozzolana cement is used along with fine sand and crushed coarse aggregates. The blocks are hydraulically bonded using vibration casting method. A hollow concrete block of 22.5 cm x 20 cm x 10 cm size weighs 6 kg, has 14.7% apparent porosity and 2.2 g/cm3 bulk density.




Minimum Economic Unit Size

2 lakh blocks/annum.

Indicative investment

Rs. 35 lakh.

Equipment and Machinery

Mixer, kiln, concrete block making machine (available from CSIR licensee).


Raw materials

Stone chips, sand, cement, flyash/rice husk ash.



For further information please contact

The Director.
Central Building Research Institute, New Delhi