Technology Outline (Process Description)

The country produces 40 – 50 million tonnes of construction and demolition waste (CDW). Currently CDW mainly goes into landfills. The technology of producing compressed low-carbon bricks using CDW and non-OPC binders (lime-slag and alkali activated) without firing was developed and demonstrated. The manufacturing process involves (a) crushing CDW to sand size fraction, (b) preparing binder (lime-slag and alkali solution), (c) processing the CDW-binder mix, (d) pressing the brick in a machine and (e) curing. The bricks and the blocks can be manufactured using CDW and the non-OPC based binders. The alkali activated binders can be lime-GGBS based or geopolymer based. 

Compressive strength of low-carbon bricks was in the range of 15 – 30 MPa. The compressive strength of low-carbon bricks can be designed by tweaking the mix proportions. The water absorption for these bricks is well within the limits of IS code and the new bricks possess good durability characteristics. The embodied carbon is low at 0.075 kgCO2eq per kg of brick as against 0.20 – 0.45 for other masonry materials.