DRAFT
Please follow this general outline if writing a new topic page for this site. Refer to existing sections for a general idea of what to include.
CSI Number
If you know the CSI number, it can be helpful to designers and spec writers if you supply it here.
Definition
Define your subject matter. Typically 1-3 paragraphs.
Considerations
A general overview of what needs to be included in deciding whether or not to use this material or technique. Not all methods and materials work well in all climates, for instance. Typically 3-4 paragraphs.
Commerical Status
How well developed is the commercial support for this? We typically look at three areas:
Technology
Suppliers
Cost (typically initial cost only, though you’re welcome to include typical payback periods or other lifetime cost analyses)
From one or two words (ie, “limited”, “widely available”) to one sentence or phrase (“5% to 10% higher than conventional installations.”)
Implementation Issues
How easy is it to implement? Three major areas are:
Financing
Public Acceptance
Regulatory
Again, typically one word to one sentence.
Guidelines
Block Materials
(see also adobe in Earthen Materials)
Aerated Concrete Block
Insulating Concrete Forms (ICFs)
1.0 Aerated Concrete
Aerated concrete blocks have been in use since 1924 in Europe, though they didn’t make an appearance in the US until around 1992.
Aerated concrete block is typically made from a combination of sand, cement, lime, water, and gypsum. Small amounts of aluminum oxide or other compounds are added as foaming agents, reacting with the mixture to form hydrogen gas. The gas bubbles act in a similar way to closed-cell foam insulation, forming small bubbles uniformly distributed throughout the mixture.
Many manufacturers autoclave the resulting material to increase its strength and stability. Others instead include microfiber in the mix and are thus able to reduce the energy footprint while maintaining a strong and stable block.
The resulting block is lightweight and insulating, with a typical weight of between 35-40 lbs/sf of 8ft high wall.
Insulation and Fire
Aerated concrete typically achieves a 4-hour fire rating with as little as 4 inches of thickness.
Insulating quality can vary from one manufacturer to the next, but typically range between R-1 and R-1.25 per inch (compared to a typical R-0.125 for conventional masonry). The thermal mass of the concrete portion of the block further contributes to the comfort and energy performance.
- also available as panels from some manufacturers
pros:
lightweight
structural and insulating
fire resistant
can work (nail, saw, screw) with regular tools
cons:
break easily until plastered
iniital cost
Few manufacturers, shipping costs may be a concern (non local, transportation energy raises carbon footprint)
When autoclaved, initial energy footprint is quite high
Can generate a fair bit of waste on the jobsite from broken block, cutting to fit.
2.0 Insulating Concrete Forms (ICFs)
3.0 Earthen and Earth/Composite Block
adobe
stabilized
unstabilized
compressed earth block (CEB)
hand compressed (cinva ram)
machine compressed
mega block
4.0 Papercrete Block
5.0
Resources
We like to pre-load the resources section with a handful of related links on where to find additional information (typically non-sales sites only), and we offer inexpensive listings in the resources to professionals, manufacturers, associations, and the like. We’re happy to recommend good books on the subject, so please let us know of any which are particularly outstanding. If you speak with suppliers or professionals who might benefit from a resource listing while you research your article, please let them know about the availability. While we don’t want you to be overly “sales-y” about it, we will be happy to reward you with a portion of the fee they pay to be listed. If you don’t feel comfortable doing that, we’d appreciate it if you have a list of contacts, associations, etc, that we can contact about being listed as a resource.
