SCEBs - University of Colorado Boulder

3.3. Initial Soil Observations
New soil samples undergo an initial visual inspection when received in the
laboratory. The amount of organic material in the sample is observed and noted. The
shape and angularity of the soil particles in the sample is observed and noted. The
sample‟s in-situ moisture content is determined. Any irregularities or inconsistencies in
the sample are also noted.
Presence of organic material should be of high concern when detected. Section
14.7.4.23 of the 2009 New Mexico Earthen Building Code addresses SCEB production
directly (NMAC, 2009). In Section G, a mineral soil is specified, suggesting a material
free from any organic constituent. Due to weaker strength and higher compressibility,
organic soils containing roots, moss, sticks, leaves, etc. are not suitable for SCEB
production (Coduto 1999). As the organic material breaks down, it is possible that it
creates additional void space within the block, allowing for water seepage and
augmenting freeze/thaw effects. Excessive organic material content may be the result of
improper mining techniques, such as not removing enough of the top-layer of earth on-
site.
The shape and angularity of the aggregate material (silt, sand and gravel) can vary
from very angular to well-rounded. The more angular particles are, the more difficult it
is for particles to move past each other when loaded. This effect creates a matrix of
particles capable of increased shear strength and therefore better performance when
subjected to loads (Coduto 1999).
The initial moisture content of the soil is determined. The moisture content is the
ratio of water mass to solid (dry soil) mass. Samples are generally collected and
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