Supplementary Cementing Materials

SCMs Help Reduce Emissions

Increasing the use of supplementary cementing materials (SCMs) is a proven method of addressing climate change and clean air. 

Supplementary cementing materials are materials that can be ground with cement clinker to produce blended cement, or can be directly added to concrete as a complementary agent.  SCMs are waste products from other industries that would otherwise require disposal. In Canada, commonly used SCMs include fly ash, blast furnace slag and silica fume. 

Approximately 60% of greenhouse gas emissions associated with cement production are irreducible process emissions that result from heating raw materials to form cement clinker.  For each tonne of supplementary cementing materials used in place of pure Portland cement, approximately one tonne of greenhouse gas emissions is avoided.  This practice also has the added environmental advantages of avoiding air pollutant emissions, reducing energy consumption, making use of materials otherwise destined for landfill, and increasing production capacity without installing new kilns.

Since 2003, the Canadian cement industry has improved its clinker/cement factor, the proportion of pure portland cement used in making cement, from 86.9% to 83.9%.