New Mexico Geological Society Annual Spring Meeting — Abstracts

In 1988, 33 commercial adobe brick producers, 28 pressed-earth-block, and two rammed-earth contractors were located in New Mexico. Extensive analyses of the materials used in earth-block production indicated that sand-and-larger grain-size materials make up from 27 to 89% of earth construction materials, whereas clay-size material varies from 1 to 15% with silt making up the remainder. The clat mineralogy of adobe soils quite variable, but commonly consists of about equal portions of expandable clay minerals (smectite and mixed-layered illite-smectite or I/S) and nonexpandable clay minerals (kaolinite, illite, and chlorite). Calcite (CaCO₃) is nearly ubiquitous, particularly in the
smaller-size fractions of adobe soils, and appears to play a far more active role in binding particles together in earth construction materials than previously considered possible.