Before ready-made bricks and cinder blocks were available for purchase at your local hardware store, people from many parts of the world were creating structures out of adobe, and the eco-friendly practice can still be seen today. Also known as mud bricks, adobe bricks are a cost-effective way to use the resources around you to create anything from a fun craft project to a sturdy home or garage-type building. Naturally fire and water resistant, non-toxic, biodegradable and easily cut to size, these building materials come with many advantages and are as affordable as they are easy to create.
Before You Get Started
Like any strong material, your bricks will require the right components before you can start building them, the most important being good soil. If you're looking to create adobe bricks for a fun project, any dry dirt will do. To create a stable structure, however, you'll need to find soil containing just the right amount of clay to allow for optimum durability. Soil containing anywhere between 25 and 45 percent clay will work best and meets U.S. Building Code requirements. You can test your soil by placing about a half cup of loose dirt in a large mason jar. Add water and a spoonful of water softener, give it a shake and let sit for one day. After shaking again for five minutes, any amount of unsettled material will represent the clay found in your soil.
After you've found your soil you'll need a good amount of straw or grass (pine needles work well, too), water, a large bowl or bucket for mixing and lots and lots of sunlight.
Finally, you'll need a form to help shape your adobe bricks. An easy way to create multiple molds is by building your own forms out of wood or metal. Once constructed, this DIY mold will resemble a ladder laid down on its side, with an open top for pouring as much mud as needed to fill. For small projects, like children's crafts, you can use a basic paper milk carton by laying the carton on its side and cutting a side off to allow an easy pouring of mud. Once dried, simply cut the paper mold form away from the brick.
How to Build Your Bricks
After your molds are formed and set in place on a flat surface, mix soil and water in a large receptacle until a wet, thick mud is formed. Next, add in your sand. This will work as a filler in your mud mixture and helps lower the clay content of soil if you find it is too rich (just take care to stay away from beach sand, which is too salty.) Your straw (or grass or pine) material is added next, which works to bind the mud material and prevents bricks from cracking while they dry. Be sure to mix all ingredients well before pouring into your molds.
After filling your brick forms, allow them to bake in sunlight for about three to five days, taking care to cover them if cracking appears. After they've dried, carefully remove them from your molds and allow them to dry for an additional few days before testing for strength and moving on with your project.
A Few Things to Keep in Mind
After you've created your bricks, you'll want to test them for durability if you're planning to create any type of weight bearing structure out of them. To test, simply drop one or two from a few feet off the ground. If they shatter, the sand content is likely too high, so opt for less in your next batch. If your bricks have cracked once dried, you probably have too much clay in your soil, so keep playing around with different soil types and mixing ratios until you've found the right fit to create sturdy bricks. If your mud mix seems too wet, rest your forms on a layer of newspaper to absorb unnecessary moisture.