Green Concrete

Cameron Monroe | Feb 24, 2021

I am responding to an article written in your Feb 18th, from Gray Merriam on the topic of Concrete being Green.

In my 40th year working in Concrete Technology, I find this abbreviated article misdirecting, and vague.  

Concrete produced with Portland Cement is the most versatile, durable, and sustainable building material today, although that was not always the case.  When I began in the Concrete Industry in 1981 almost all concrete used in construction in Canada was composed of 100% Portland Cement as the "glue" for fresh Concrete.  For every tonne of Portland Cement manufactured, a tonne of CO2 was released.

Flash forward to the new millennium where concrete of many designs and certainly of the High Performance requirements of new structures, the actual content of Portland Cement has decreased by up to 70%. This is because Supplementary cementitious powders are now common, all of which all are by-products of other industries that would normally be directed to landfill waste sites.  Concrete is engineered for its application and durability, those of us in the industry focus on sustainability of our building materials.

The final paragraph of Mr. Merriam's article references a proprietary technology commercially marketed in North America.  Unfortunately Mr. Merriam does not mention that this technology currently does not sequester  CO2 from CO2 waste emitting industries, rather this company procures its CO2 as manufactured Food Grade CO2 from outside vendors.

Cameron Monroe