Making Compressed Earth Blocks

Earthen Architecture With CEBs

man in t-shirt and dust mask watching blocks roll along conveytor belt
Compressed Earth Building Blocks Coming Off the Line. Jackie Craven

CEB or compressed earth block is a natural building material that won't burn, rot, or waste energy in hot or cold climates. The process of making and using bricks made of earth is part of sustainable development and regenerative design, a steadfast belief that "all people can live in a mutually enhancing relationship with the earth."  In 2003, green building professionals were called to Mexico's Baja California Sur to create the building blocks for a new urbanist resort community called the Villages of Loreto Bay. This is the story of how a group of visionary developers made building materials on site and constructed a village with blocks of compressed earth.

Earth: The Magic Building Material

white man, long hair, gesturing with water bottle in a sandy, mountainous environment
Jim Hallock, Director of Earth Block Operations at The Villages of Loreto Bay. Jackie Craven

When his wife developed chemical sensitivities, builder Jim Hallock searched for ways to construct with nontoxic materials. The answer was under his feet — dirt.

"Earthen walls have always been the best," Hallock said at the Mexican facility near the Gulf of California. As Earth Block Operations Director, Hallock oversaw production of compressed earth blocks for construction of the Villages of Loreto Bay. CEBs were chosen for the new resort community because they can be made economically from local materials. The blocks are also energy efficient and durable. "Bugs don't eat them and they don't burn," Hallock said.

An added benefit — CEBs are entirely natural. Unlike modern adobe blocks, the CEBs don't use asphalt or other potentially toxic additives.

Hallock's company, Earth Block International, has developed an especially efficient and affordable process for earth block production. Hallock estimated that his temporary plant in Loreto Bay had the capacity to produce 9,000 CEBs a day, and that 5,000 blocks are enough to build the exterior walls for a 1,500 square-foot home.

Sift the Clay

angled screens attached to metal posts set in mounds of sand
Before Making the Compressed Earth Blocks, the Clay Must Be Sifted. Jackie Craven

The soil itself is the most important ingredient in earth block construction.

Jim Hallock knew that the soil at the Baja, Mexico site would lend itself to CEB construction because of its rich clay deposits. If you scoop up a soil sample here, you'll notice that you can easily form it into a firm ball that will dry hard.

Before manufacturing the compressed earth blocks, the clay content must be drawn from the soil. A backhoe mines the earth from surrounding hills at the Loreto Bay, Mexico plant. Then the soil is sifted through a 3/8 wire mesh. Larger rocks were saved to use in landscape design in the new Loreto Bay neighborhoods.

Stabilize the Clay

man in jeans without shirt, red scarf under hat, works a small, round, cement-mixer-type machine
he Mortar Is Mixed at the Building Site. Jackie Craven

Earth blocks are sometimes called  Compressed Stabilized Earth Blocks (CSEBs). Although clay is essential in earth block construction, blocks that contain too much clay may crack. In many parts of the world, builders use Portland cement to stabilize the clay. At Loreto Bay, Hallock used freshly-mined lime as a stabilizer. A CSEB can spend a year in a bucket of water and come out structurally undamaged — the stabalized block will be completely absorbed with water, but it will look like a building block.

"Lime is forgiving and lime is self-healing." Hallock credits lime for the endurance of the centuries-old Tower of Pisa in Italy and the ancient aqueducts of Rome.

The lime used to stabilize the clay must be fresh, Hallock said. Lime that has turned gray is old. It has absorbed humidity and won't be as effective.

The exact recipe used to manufacture CEBs will depend on the soil composition of the region. In Baja California, Sur, Mexico, the Loreto Bay plant combined 65 percent clay, 30 percent sand, and 5 percent lime.

These ingredients are placed in a large concrete batch mixer that spins at 250 revolutions per minute. The more thoroughly the ingredients are mixed, the less need there is for stabilizer.

Later, a smaller mixer was used to combine the mortar, which is also stabilized with lime.

Compress the Mixture

blue machine with large metal container of sand on the top
Earth Block Compressor. Jackie Craven

A tractor removes the earth mixture and places it into a high-pressure hydraulic ram. This compressed earth block machine, the AECT 3500, can make 380 blocks in an hour.

The large compression machine used at the Loreto building project was manufactured by the Texas-based Advanced Earthen Construction Technologies (AECT). Its founder, Lawrence Jetter, has been making the machinery for CEBs since the 1980s. They are used around the world and are particularly useful in remote areas.

The machines used to build the Villages of Loreto Bay in Mexico made 9000 blocks a day and eventually pressed out 2 million lime-stabalized blocks. Oil is also saved because each hydraulic ram machine consumes only about 10 diesel gallons of fuel a day.

Local Materials, Local Workers

man in t-shirt, cap, and surgical mask examines earth block on a conveyor roller
The Earthen Mixture Is Compressed Into Building Blocks. Jackie Craven

A standard CEB is 4 inches thick, 14 inches long, and 10 inches wide. Each block weighs about 40 pounds. The fact that compressed earth blocks are uniform in size saves time during the construction process. They can be stacked with little or no mortar.

The plant employed 16 workers: 13 to run the equipment, and three night watchmen. All were local to Loreto, Mexico.

Using local materials and hiring local laborers were part of the philosophies behind the building of this community in Loreto Bay. Hallock uses the United Nations' long held belief in sustainable development, "to ensure that it meets the needs of the present without compromising the ability of future generations to meet their own needs." As such, sustainable building should give all people "the opportunity to fulfil their aspirations for a better life."

Let the Earth Cure

man in white t-shirt using plastic wrap to cover a pallet of blocks at a compression station under a tent-like cover
the Compressed Earth Blocks Are Wrapped in Plastic. Jackie Craven

Earth blocks could be used immediately after they are compressed in the high-pressure hydraulic ram. However, the blocks will shrink slightly as they dry, so they are cured.

The Loreto Bay plant had three compression machines at three production stations. At each station, workers set the newly made earth blocks on pallets. The blocks were wrapped tightly in plastic to preserve the moisture.

"Clay and lime must dance together for a month, then they can never divorce," said Jim Hallock. The month-long curing process helps strengthen the blocks.

Stack the Blocks

construction of residence using earth blocks and cement blocks
Mortar Should Be Used Sparingly on CEBs. Jackie Craven

CEBs can be stacked in a variety of ways. For best adhesion, the masons used thin mortar joints. Hallock recommended using a clay and lime mortar, or slurry, mixed to a milkshake consistency.

Working very quickly, the masons apply a thin but complete layer to the lower course of the blocks. The slurry would still be moist when the masons lay the next course of blocks. Because it's made from the same ingredients as the CEBs, the moist slurry formed a tight molecular bond with the blocks.

Reinforce the Blocks

man in hard hat on scaffolding working on earth block wall
Steel Rods and Chicken Wire Reinforce the Walls. Jackie Craven

Compressed earth blocks are much stronger than concrete mason's blocks. The cured CEBs produced in Loreto Bay have a load-bearing capacity of 1,500 PSI (pounds per square inch). This ranking far exceeds Uniform Building Code, Mexican Building Code, and HUD requirements.

However, CEBs are also thicker and heavier than concrete mason's blocks. Once the earth blocks have been plastered, these walls are sixteen inches thick. So, to conserve on square footage and to expedite the construction process, builders in Loreto Bay used lighter mason's blocks for the interior walls.

Steel rods extending through the mason's blocks provided added strength. The compressed earth blocks were wrapped with chicken wire and securely anchored to the interior walls.

Parge the Walls

two workmen applying a layer of plaster with trowels
The Earth Block Walls Are Parged With Lime Plaster. Jackie Craven

Both interior and exterior walls were parged — coated with lime-based plaster. The plaster is not cement-based stucco that doesn't breath. The idea of CEB construction is to build breathable walls that regulate interior temperatures, continually absorbing and releasing water vapor and heat. Like the slurry used to mortar the joints, the plaster used for parging bonds with the compressed earth blocks.

Add Color

street photo of colorful earthen buildings in a Spanish style
Homes in the Villages of Loreto Bay Are Finished With Organic Mineral Oxide Pigments That Bond With the Lime Plaster. Jackie Craven

The Founders' Neighborhood at Loreto Bay, Mexico was the first to be completed. The compressed earth block walls were reinforced with wire and parged with plaster. The houses appear to be attached, but there is actually a two-inch space between facing walls. Recycled styrofoam fills the gap.

The plaster-coated earth blocks were colored with a lime-based finish. Tinted with mineral oxide pigments, the finish produces no toxic fumes and the colors do not fade.

Many people think that adobe and earth block construction are only suitable for a warm, dry climate. Not true, says Jim Hallock. The hydraulic press machines make producing compressed earth blocks efficient and affordable. "This technology can be used anywhere there's clay," Hallock said.

The Auroville Earth Institute (AVEI) in India and Paolo Lugari's ecovillage of Las Gaviotas in Colombia, South America were both influences on Hallock's life path and regenerative vision.

In time, Hallock hopes that the market will expand, providing the economical, energy-efficient CEBs to other parts of Mexico and throughout the world.

"Regenerative practitioners do not think about what they are designing as an end product," write the Regenesis Group, authors of Regenerative Development and Design. "They think about it as the beginning of a process."

Sources

  • Hallock, Jim. Compressed Earth Blocks: Why and How, Here and There, May 7, 2015, https://www.youtube.com/watch?v=IuQB3x4ZNeA
  • United Nations. Our Common Future, March 20, 1987, http://www.un-documents.net/our-common-future.pdf
  • As is common in the travel industry, the writer was provided with complimentary accommodation for the purpose of researching this article. While it has not influenced this article, ThoughtCo / Dotfash believe in full disclosure of all potential conflicts of interest. For more information, see our ethics policy.