Normally the thought of ash brings to mind volcano eruptions, funerals, and maybe religious holidays but for us and green builders it’s about flyash and foundations. So, when discussing the topic with one of San Francisco’s up and coming LEED-AP architects (Melanie Jacobson) she mentioned that the CHPS school they are building in the Sacramento area will have a fifteen percent flyash concrete foundation we looked quizzically at her. Why only fifteen percent? She mentioned that that percentage was about as high as their structural engineers deemed to be sound.
We’ve heard other local green buildings contain as high as thirty percent flyash. So, why the discrepancy? It depends on the configuration of the building, the weight on the structure and most importantly what the structural engineer says.
What the heck is flyash? Flyash is a by-product of coal-fired electric generating plants.
Don’t think that this stuff is some newfangled substance. They used flyash concrete to build the Hoover Dam in 1929. Yes, we know that’s out of our area. But consider on your next sojourn to Vegas you can make a side trip to check out the Dam and then impress friends and strangers with your knowledge of flyash.
Raise the green flag for this powdery substance because as an industrial by-product, it would just be waste but now many resource companies recycle it into cement. It gets better because flyash cement requires less water than Portland cement so it is easier to use in cold weather. It can be an inexpensive substitute for Portland cement in many cases. Everyone has their favorite powder but this one happens to be one of ours.
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