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Earth Materials Contents:

CSI NUMBERS
DEFINITION
CONSIDERATIONS
COMMERCIAL STATUS
IMPLEMENTATION ISSUES
GUIDELINES

RESOURCES

CSI Numbers

DEFINITIONS:

The type of materials available locally will of course vary depending upon the conditions in the area of the building site.

In Austin, indigenous stone is stone from central Texas, such as limestone, marble, granite, and sandstone. It mat be cut in quarries or removed from the surface of the ground (flag and fieldstone). Ideally, stone from the building site can be utilized. Depending on the stone type, it can be used for structural block, facing block, pavers, and crushed stone.

Most brick plants are located near the clay source they use to make brick. Bricks are molded and baked blocks of clay. Brick products come in many forms, including structural brick, face brick, roof tile, structural tile, paving brick, and floor tile.

Caliche is a soft limestone material which is mined from areas with calcium-carbonate soils and limestone bedrock. It is best known as a road bed material, but it can be processed into an unfired building block, stabilized with an additive such as cement. Other earth materials include soil blocks typically stabilized with a cement additive and produced with forms or compression.

Rammed Earth consists of walls made from moist, sandy soil, or stabilized soil, which is tamped into form work. Walls are a minimum of 12" thick. Soils should contain about 30% clay and 70% sand.

CONSIDERATIONS:

The use of locally available and indigenous earth materials has several advantages in terms of sustainability. They are:

Care must be taken to ensure that non-renewable earth materials are not over-extracted. Ecological balance within the region needs to be maintained while efficiently utilizing its resources. Many local suppliers carry materials that have been shipped in from out of the area, so it is important to ask for locally produced/quarried materials.

Both brick and stone materials are aesthetically pleasing, durable, and low maintenance. Exterior walls weather well, eliminating the need for constant refinishing and sealing. Interior use of brick and stone can also provide excellent thermal mass, or be used to provide radiant heat. Some stone and brick makes an ideal flooring or exterior paving material, cool in summer and possessing good thermal properties for passive solar heating. Caliche block has been produced for applications similar to stone and brick mentioned above. Caliche or earth material block has special structural and finishing characteristics.

Rammed earth is more often considered for use in walls, although it can also be used for floors. Rammed earth and caliche block can be used for structural walls, and offer great potential as low-cost material alternatives with low embodied energy. In addition, such materials are fireproof.

Caliche block and rammed earth can be produced on-site. It is very important to have soils tested for construction material use. Some soils, such as highly expansive or bentonite soils, are not suitable for structural use. Testing labs are available in most areas to determine material suitability for structural use and meeting codes.

Soils for traditional adobe construction are not found in the Austin area, but other soils for earth building options are available. Travis county and surrounding areas have a high percentage of soils suitable for ramming, approximately 19,610 acres, according to the US. Department of Agriculture. Caliche is also abundant in Austin, covering 14 % of our geographic area, and is readily available locally at nine different pits.

Commercial
Status		 Implementation
Issues
technology suppliers cost financing public regulatory
F
O
U
N
D
A
T
I
O
N		 Stone RED green yellow green green RED
Brick red Green yellow Green Green red
Caliche red black Green Green red black
F
L
O
O
R		 Stone Green Green yellow Green Green Green
Brick Green Green yellow Green Green Green
Caliche yellow black Green Green yellow Green
W
A
L
L

(A)
 Stone Green Green Green Green Green Green
Brick Green Green Green Green Green Green
Caliche red black Green red yellow black
W
A
L
L

(B)		 Stone Green Green yellow Green Green Green
Brick Green Green yellow Green Green Green
Rammed Earth red black yellow red red black

Legend
green Satisfactory
yellow Satisfactory in most conditions
red Satisfactory in Limited Conditions
black Unsatisfactory or Difficult

COMMERCIAL STATUS

TECHNOLOGY:

Stone cutting, brick production and masonry techniques are mature technologies. Rammed earth and caliche block construction are not well known by most builders and architects today, although there are some architects and builders who are experienced with these materials. Compressed soil block technology is available in Austin.

SUPPLIERS:

There are numerous suppliers of indigenous stone and local brick in the central Texas region. Caliche block and rammed earth are not available commercially, but can be created on site. There are contractors who can provide machinery for manufacturing compressed soil block, although it is not commercially available.

COST:

Brick: approximately $2.00 per square foot (4 inch material) and up depending on thickness. Stone: $4.00 to $15.00 per square foot (material) depending on type. Compressed soil block: approximately $1.80 per square foot (9 inches thick). Earth block made from labor intensive methods cost significantly less.

IMPLEMENTATION ISSUES

FINANCING:

Stone and brick materials do not pose a problem for lending institutions, and are often valued positively for increased property value and fire rating. Rammed earth, compressed soil block, and caliche block may pose problems for traditional financing. Proper testing and building code compliance will assist lenders in accepting their products.

PUBLIC ACCEPTANCE:

Stone and brick construction are considered desirable, although their use for interior thermal mass is not common in our area. Rammed earth and caliche block are little known, and may not currently receive wide public acceptance.

REGULATORY:

In structural applications, materials must be rated for appropriate load requirements. Unfired caliche blocks can easily pass Unified Building Code standards for compression with an average of 960 p.s.i. Rammed earth and caliche block construction will require a building code review if used structurally. Regulatory acceptance will be based on precedents for the material as accepted in other jurisdictions and/or upon independent tests that demonstrate methods and performance required by code for masonry materials are satisfied.

GUIDELINES

RESOURCES

PROFESSIONAL ASSISTANCE
Stone and Brick:

See "Engineers-Structural," "Engineers-Foundation" and "Mason Contractors" in the Yellow pages.

Soil Materials:
See "Laboratories-Testing" in the Yellow Pages.

ARCHITECTS AND BUILDERS

COMPONENTS / MATERIALS / SYSTEMS
See "Stone-Natural" ,"Limestone", "Brick" ,"Granite", "Sand & Gravel" in the Austin area Yellow Pages

For used brick, see "Recycled Building Materials "in Yellow Pages

Soil Materials:

Caliche (caliche pits):

GENERAL ASSISTANCE
Brick:

Soil Materials:

Publications:

NET RESOURCES

Websites:

Newsgroup:

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