Rammed Earth Construction

[StructuralEngGuy]

Hi all,

Does anyone have any experience with Rammed Earth Construction? I'm about to start a highly sustainable commercial-type project in New Mexico and rammed earth is being considered for the envelope. I've been searching google for information, but most things I find are not technical in nature and apply to residential construction. If anyone has any good information about this subject (particularly in regards to structural design) I would be greatly appreciative.

Thanks

 

[ishvaaag]

The Instituto Eduardo Torroja emitted in the seventies model code

p.i.e.t.70 obras de fábrica

that essentially -through its port to mandatory codes- has covered the design of any kind of masonry works since 1970 to 2005 in which was superseded by mandatory code CTE Código Técnico de la Edificación, now standing.

The interesting thing about this code -and what makes it a long lasting contribution- is that it unified the design of any kind of masonry, be it any kind of stone, brick, masonry block AND earthen works in a single structural model, and being from the 70's it already discounts the unknowns of traditional design of these things, mainly made of always on a matter of proportions (something you can stil see in the codes when a maximum slenderness is mandated, and was much still standing in the seventies for the simplified models, say in the corresponding DIN code for masonry). So the material modelization was common and graduation of the behaviour was through the limit strengths.

 

[concretemasonry]

The vast majority of rammed earth construction (1000x more than commercial) is for residential construction in develeloping and semi-developed regions.

Because of this there is a very limited amount of accurate information on structural and other physical properties because the undocumented materials are highly variable as is the production parameters.

Rammed earth is a very good construction method for residential when other types are not available or economical. In most areas, the logical step was to improved masonry materials since masonry is a preferred material for residential construction in these areas. This was the evolution in SW USA, Central America, Africa and portions of SE Asia.

In the area of your project (and Mexico) the logical step was to adobe, which relied the higher strengths and accurate dimensions possible. This would be an option if a local "flavor" to exposed materials was desired.

If you are looking for technical support for the design, there are more advanced units inspired by the adobe stone that are machine produced. They are referred to as concrete Adobe Stone" or "Slump" block that have the same appearance, but are usually required to meet the ASTM C90 requirements for masonry units (performance standards and not proportion-based requirements), so they also fall under the ACI 530 standards and most codes. In the USA, they are available 4" & 6" high, and 4",6",8", 10" and 12" thick)in NM, AZ, CA and many other local markets plus some international markets. - It looks similar, but has documented properties and standards, but may be a more viable alternate.

Engineer and international traveler interested in construction techniques, problems and proper design.

 

[vandede427]

I designed a low-rise multi-story office bldg that had shallow spread footings that beared on rammed aggregate piers. the rammed aggregate piers were designed by a third party geotech firm that has copywrited the product with a name. I'm not sure whether it's ok to post that name or not on the forum.