How to Make Adobe Bricks. The ingredients that are used to make adobe bricks couldn't be more simple: soil and water. It's cheap and can be very durable in dry climates. The only trick is making sure you have the right kind of soil.
Test the Soil
Fill a glass jar about 2/3 full with the soil you plan to use.
Add water until the jar is full and put on the lid.
Shake the jar for two full minutes.
Let the jar sit overnight.
Examine the jar the next morning. The soil will have separated into bands of sand on the bottom and clay on the top. You want the ratio of sand to clay to be roughly 70 percent sand to 30 percent clay. The sand can be less, but you want it above 50 percent.
Prepare to Make Adobe Bricks
Clear an area for the bricks to dry. Keep in mind that it can take a couple of weeks for them to dry and you want them protected from the rain.
Figure out where you're going to mix your adobe. Small amounts can be done in a wheelbarrow. You can also dig a big pit or build a pit by making a rectangular box of cinder blocks and covering it with a tarp. You can also rent a cement mixer if it's a larger project.
Make forms for the bricks. The traditional size is 4 by 10 by 14 inches and this is made with 2 by 4 studs nailed into a ladder like shape.
Make Adobe Bricks
Shovel your soil into the mixing place you have prepared. Add sand or clay if necessary.
Add water to the soil. This is not an exact science. You're basically making mud. You want it to be firm and able to hold its shape and not too watery.
Mix the adobe thoroughly. You want it to be uniform. You can use a shovel or hoe or take your shoes off and stomp on it.
Take adobe with your shovel or hand and put it in the brick forms. Be sure to fill in the corners and press it down so it's all filled. Smooth it off with the shovel, by hand or with a piece of wood.
Let the bricks dry in the forms for at least 20 minutes.
Remove the forms and let the bricks sit flat as they are for about three days.
Place the bricks on their edges.
Allow the bricks to dry thoroughly. This can take a week or more depending on the weather and your soil.