Adobe, pressed-earth, and rammed earth industries in New Mexico

Abstract

NM continues to be the largest producer and user of adobe bricks and pressed-earth blocks in the nation. During field investigation and sampling in NM in 1987-1988, 33 commercial adobe-brick producers, 28 companies with pressed-earth-block machines, and 2 rammed-earth contractors were located. A significant number and variety of pressed-earth-block machines were in use; the gasoline- and diesel-powered machines were being made by five active NM manufacturers. In 1987, 3,124,000 adobe bricks and 642,000 pressed-earth blocks were produced. A breakdown on the types of adobe bricks produced in 1987 shows that 20 adobe-brick producers made 849,000 traditional adobe bricks, which sold for 21-40 cents per brick; 2,110,000 semistabilized adobe bricks, which sold for 30-35 cents per brick; and 165,000 stabilized adobe bricks, which sold for 59 cents per brick. The 642,000 pressed-earth blocks, largely made without stabilizers, sold for 25-35 cents per block.During sampling, various tests were made on all types of adobe bricks and pressed-earth blocks. Mineralogy and particle-size analyses of the clays and soils, performed at the NM Bureau of Mines and Mineral Resources, show that soil materials used in the adobe-brick and pressed-earth-block industries contain more sand +/- size particles than previously reported. Physical-property tests on selected adobe bricks and pressed-earth blocks, preformed at the United Nuclear Rock Mechanics Laboratory, NM Institute of Mining and Technology, show that the adobe bricks and particularly the pressed-earth blocks have high physical strength and in all cases meet or surpass the specifications and requirements of the NM Building Code.The characteristics of the soils, the techniques of production, and the examples of earth-constructed buildings that are detailed in this report show that adobe bricks, pressed-earth blocks, and rammed-earth walls make energyefficient, durable, attractive dwellings. If problems in radon-prone and seismically active areas are properly recognized and controlled, then earth-constructed buildings are no more dangerous than homes constructed with other materials.

Proceedings of the 31st Forum on the Geology of Industrial Minerals--The Borderland Forum

“…In New Mexico, clay-size particles in commercial adobe soils are the most compositionally variable. However, the clay-mineral groups in this size fraction consist of about equal parts of expandable clay minerals (smectite and mixed-layer illite/ smectite or I/S) and non-expandable clay minerals (kaolinite, illite, and chlorite), with minor quartz, calcite, and feldspar (Smith and Austin, 1989;Austin, 1994). In the arid American Southwest smectite is commonly calciumrich and the I/S is randomly interstratified.…”

“…Particle-size distribution-Adobes from some historic structures in the American Southwest and other parts of the world have clay contents from 1 to 38 wt.%, while sand-and-larger particles range from 4 to 82 wt.% in a limited number of samples (Coffman et al, 1990). The common statement by modern New Mexican adobe producers is that their soil mix is usually one-half sand and one-half "clay" or "fines" (silt and clay); however, commercial adobe soils in New Mexico range from 85 to 99 wt.% nonclay-size particles (Smith and Austin, 1989). Tests of commercially produced New Mexican adobes show that particle sizes of the soil varies widely.…”

“…Large-scale commercial adobe producers in New Mexico use adobe soils with less clay-size material than do small-scale commercial and non-commercial adobe producers. Some of the former are as low as approximately 1 wt.% clay, whereas many of the latter are between 8 and 15 wt.% (Smith and Austin, 1989). In part this is because large-scale commercial adobe producers use stabilizers that not only protect blocks from rain damage but aid in consolidation of the drying soil mix as well.…”

“…European, African, Asian, and North and South American countries contain a large number of such structures. Today, the word "adobe" is used to describe various earth building materials and techniques, usually referring to sun-dried adobe brick now used in the United States, but "adobe" is also applied to puddledadobe structures, mud-plastered logs or branches (Jacal or waddle-and-daub), pressed-earth blocks, and rammedearth walls or pisé (Ferm, 1985;Smith and Austin, 1989).…”

“…New Mexico, both historically and today, is the largest domestic producer and user of adobes. During the 1980s, 3 to 4 million adobe bricks and pressed-earth blocks were produced in New Mexico each year by about 50 commercial manufacturers (Smith and Austin, 1989). In 1994 about 3 million adobes were made commercially, as the industry became more concentrated in the hands of a few large producers (Table 1; Fig.…”