Concentration of CO2 in the Atmosphere

Better Concrete Here and Now

Greg Whitchurch

While it’s heartening to read here about some of the research and development efforts for lower-carbon concrete, in the meantime standard concrete is contributing to irreversible climate damage.

Climate crisis disasters are driving “climate migration.” A few years ago, Vermont created a commission to address the enormous stresses of soaring immigration to our sparsely-populated state. Ironically, as this influx drives bidding wars on Vermont homes and land, turning real estate sales into auctions, the use of climate-damaging concrete skyrockets as the newcomers build and renovate. And as we repair our outdated and climate-damaged infrastructure, even more concrete is employed.

We know that the cement used in concrete is a major contributor to climate change. The problem is cement’s embodied carbon! (See A LOT of carbon is released when making cement. This Girl Scout video is a must-watch:

How, you might ask, can I avoid some of concrete’s CO2 damage right now? You can start by asking your local concrete providers about their lower carbon concrete offerings or by insisting that your contractor specify low-carbon concrete.

I’ve contacted Vermont and New Hampshire suppliers. The two most popular cement replacement additives are fly ash and slag. Both are by-product waste from steel-making. My wife and I are installing a solar PV ground-mounted system at our home and will be using a 20% fly ash concrete mix for the foundation.

Replacing some cement with slag will result in a stronger final set, but current state requirements measure strength too early, when pure cement is stronger but before the slag mix overtakes it later on. This suggests that some engineering specifications could be updated to address these greener alternatives.

Contractors might argue to a homeowner that longer cure times interfere with their “business-as-usual” scheduling. Well, isn’t that just too bad! Here’s where your personal values and interests should be your guide, and perhaps serve as a learning experience for your contractor.

Do what you can, as soon as you can.

Greg Whitchurch powers his EVs with solar in Middlesex, Vermont.

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