We are getting much closer to full-scale building with the CEB – with September 15 as our starting date. Another collaborator will arrive here around that date, Alex Rollin – which is extremely exciting becuase he is also an information architect, organizer and integral thinker – so we’ll be likely to double the organizational efforts at Factor e Farm. The pen is mightier than the sword, especially when the other hand is in the dirt.
We are currently discussing the issue of stabilizing compressed earth blocks with Class C flyash (cementitious flyash), which is a byproduct of coal-burning power plants and can be obtained for free or near free. As far as I know, its performance is similar to Portland cement, and I have hearsay evidence that it actually performs better than Portland in the long term.
We are looking at building structures with stabilized CEBs below-grade – 3 feet down to the frost line, on a gravel foundation. As such, the CEB blocks are part of the foundation. To do this, we need to stabilize the bricks to make them moisture resistant. Each 4x6x12 inch brick weighs about 15 lb. We are considering 25% weight ratio of fly ash cement to soil. These are the options that we are considering for a 600 square foot addition, with 18″ thick walls with insulation between the two layers of brick:
- Using stabilized bricks down to 3 feet below grade. Disadvantage: requires 6 tons of flyash to stabilize the bricks – and flyash must be transported to our site. Advantage – seems like a sure bet.
- Using unstabilized bricks, with either cement stucco or tar for the water resistance. Advantage – allows us to use local soils for the foundation, with only a thin layer of cement or tar for the required stabilization. Disadvantage – effectiveness of this stabilization method is in question.
- Start the wall at ground-level, with gravel foundation to below the frost line, and insulation extending 3 feet down. Advantage – the goal of retaining warmth is accomplished – and issues of brick stabilization are avoided or minimized. Disadvantage – 18 tons of transported gravel are necessary to fill the foundation.
We need your help on these issues. What are the suggestions from any builders out there? Please post this question to other forums as well.