Alternative Raw Materials

One way sustainable cement is produced is through the use of alternative raw materials instead of the traditional limestone and clay. Materials like fly ash, a byproduct of coal combustion, and slag, a byproduct of steel production, can partially replace the need for virgin raw materials in cement production. This diverts waste from landfills and incinerators and puts them to good use. Around 30-50% substitution of traditional raw materials is possible through the use of these industrial byproducts, thereby lowering the carbon footprint of cement.

Lowering Carbon Emissions

Carbon emissions from Green Cement production arise mainly from the combustion of fossil fuels needed to reach the high temperatures required for chemical reactions and clinker formation. Sustainable cement adopts energy efficiency measures as well as uses alternative fuels to reduce these emissions. Recovering waste heat from clinkering and using it elsewhere in the plant helps improve energy efficiency.

Alternative fuels like refuse-derived fuel consisting of non-recyclable waste help replace the use of fossil fuels. Some cement plants co-process hazardous waste as alternative fuels to eliminate landfill disposal while achieving emissions compliance. Carbon capture and storage technologies are also being implemented to trap some process emissions and lock them away permanently. All these strategies lower the emission intensity of cement.

Intergrinding with Supplements

Intergrinding cement clinker with limestone or other natural or industrial supplements is another green cement technique. This reduces the clinker factor or the percentage of clinker in the final cement. Clinker production requires more energy compared to grinding other supplements. Lowering clinker content through this approach lowers both energy needs and emissions from the process. It results in a composite cement that has comparable or even better performance.

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