I liked this post on environmental concrete quite a bit, not least because it reminded me that the best presentation I saw last year came out of the concrete sub-committee of the AB 32 Scoping Plans. I had no expectations for a report on concrete and greenhouse gas emissions, but it was great! Skip slides 1-15, which talk about the Scoping Plan. Go straight to slide 16 and start to learn about cement and climate change! Plenty of pictures of cement mixers, too.
I gather from that presentation that there are two places you can cut your emissions from cement. You can improve your cement factory or you can change the cement mixtures that get used in the world. The second option was more interesting to the water folks in the room. My rough sense of the conversation was that specifications for cement mixtures are something you get from some 1950’s manual and no one has given them much thought since. But, if it is important to make cement with low emissions, it could be done. Even more, you might want to do some thinking about what you need your cement for. You might want a cement mix that hardens overnight, so you can put a first floor on that foundation the next day. But we don’t need that in the water industry. Some of our dams don’t dry for a hundred years*. Quick drying isn’t necessarily a feature we need.
When I talk about adapting to climate change taking thought, this is the sort of thing I mean. Used to be**, you pulled down the ASCE manual on cement, looked up the cement mixture for your strength requirements and ordered it from the factory. Now we should probably figure out what we want specific cement to do and find a mixture that does that while minimizing emissions. With the new exciting cements, perhaps they can also breathe in CO2 as well. This is a lot more thought and finesse than we apply now. Doable for sure, but it adds work.
I’m so tempted to say that this is great new work in an exciting new field. But I bet it isn’t. I bet people have been working on cement for decades and I just never knew about it. They’d roll their eyes if I announced that cement is such an exciting new field just because I didn’t know about it, and they’d be right. One of my big regrets is that I never took the class on cement while I was in school. I suppose I could still do that. Enlightenment and bliss are open so long as one draws breath and I’m pretty sure concrete class is on the path to enlightenment.
*Did you know that? The cement in the middle of a big dam is still wet and will be for decades. This isn’t ‘cause the water from the reservoir is keeping it wet. It is ‘cause the interior dries slowly once the exterior is dry. The cement part of dams gets stronger for decades after it is poured.)
**Probably still is. I’m sure it still is.
3 responses to “It is never too late!”
My grandmother, who was around MIT in the 1940s, used to marvel at the idea that you could get a degree in cement. It’s nice that these subjects are returning to the fore.
Not to be too annoying with corrections, but since the whole post was about cement. It doesn’t “dry”, it “hardens” or “sets”. There’s a chemical reaction that takes place between water and cement. And once water, aggregate, and any additives are added to cement, it is referred to as concrete.
Some of our dams don’t dry for a hundred years*
That the cement in the middle of a big dam won’t be done setting for that long is awesome. Also, doesn’t it liberate incredible amounts of heat?