brief History of adobe brick
Adobe brick (or mud brick) building is an ancient building techniques that are popular in the Americas and the Middle East. The word adobe in Spanish is a derivation from Arabic word 'al-tob', which means brick. Moorish architecture are famed for their adobe building architecture, and some of their buildings that dated back 900 years ago are still being used these days. Adobe bricks are made of earth with a high content of clay and straw. If produced manually the earth mix is cast in open moulds onto the ground and then left to dry out. Adobe bricks are only sun-dried, and not kiln-fired. Its application in construction is fairly simple, they are laid up into a wall using an earth mortar. Before drying out, the finished walls are smoothed down. Often a clay render is applied as a surface coating. This type of construction are more commonly found in dry regions, such as South America, Mexico, Middle East and most parts of South Asia.
advantages of adobe brick
Apart from the simplicity of making and using it, there are many advantages of using adobe brick in construction.
- it uses natural and readily available material that can be found around you.
- adobe bricks are a fireproof, durable yet biodegradable, non-toxic building material which provide sufficient thermal mass to buildings to ensure excellent thermal performance.
- it has low sound transmission levels through walls and a general feeling of solidity and security.
- no costly tools or equipment are necessary and the essential know-how can be easily acquired on a training workshop and through hands-on experiences, or by a simple search on the Internet.
- risk of extensive shrinkage and cracking, which would otherwise occur in soils of high clay content in a large monolithic wall, is prevented, as the brick are dried totally before being use.
- it can be cast from a wider range of soils and can cope with a higher clay content and is suitable for in-situ techniques.
- due to the production process and the nature of clay, adobe bricks have good water resistance. nevertheless it is very important to provide adequate weather protection of the earth walls, especially in exposed situations.
- small Adobe units provide great flexibility in the design and construction of earth buildings. Adobe bricks can be easily cut for fitting and can be provided with holes for reinforcing and services.
- Many people find the pattern and texture of Adobe walls very attractive.
Making adobe brick
Adobe brick is a simple technology that requires only the mix of native soil, clay, sand and additional organic matter such as dried grass or straw. Desirable native soils for brickmaking are those classified as loamy sands, sandy loams, or sandy clay loams. There are three important points to remember about these soil descriptions:
- clay content shall not exceed 30 percent, or roughly one-third of the ingredients, and the major portion of each mix (never less than 50 percent) is sand.
- if you cannot classify the soil yourself, seek guidance from someone with soil classification experience.
- if you cannot classify the soil or get it classified, make a trial batch of bricks from your soil at least six months before you begin production for your building project.
Doing a soil test is a good idea to start making adobe brick. Fill a container about 2/3 full of soil. Add water until the jar is full, and stir it for about 2 minutes. Set the container down and let it sit overnight. When you check the content, the soil should be broken up into two distinct bands of dirt. The sand should be settled on the bottom with the clay on the top. There should be more sand than clay. A ratio of about 70 percent sand to 30 percent clay is ideal for making adobe brick. This kind of soil is usally available on the top or a side of a natural hill.
Making adobe brick is a simple yet effective technology. After identifying the soil to use, it is only a matter of mixing the soil with water and some fibres for strength. Mix the element on a waterproof tarp until the mixture turns doughy and mud-like. We trample the mixture, and then we add dried straw or hay. It is also common to dig a small square on the ground to do the mixing.The photo here shows the texture of our mix.
The next step is to mold the mixture into brick shape. We uses 2x4 wood to build a brick form. Cut two pieces to 5 feet in length. Cut the other 2x4s down to 14-inch lengths. Nail these to the 5-foot pieces every 10 inches to create a structure that looks like a ladder. Fill the inside of the form with the adobe mix, be sure to press it as hard as you can to squeeze out excessive liquid. Fill each form completely and level it off with a shovel. Let the brick set and then remove the form, repeat the process until you get your desired amount of brick.
The next step after molding the brick is to give it time. Leave the brick to dry without moving it. When the edges turn white, you may turn the brick on the other side to let it completely dry. It is important to leave the brick to dry completely as wet/moist brick will have less structural strength. Be patient as this process could take more than 3 weeks depending on your local climate and temperature. The adobe brick are ready to be utilize when it is completely dry and solid.
point to note on adobe brick
- Clay holds your bricks together just like the cement in a concrete block. It contains primarily an aluminum salt and is made up of extremely fine particles. There are several different kinds of clay, but you can use any one of them for making bricks.
- Straw, the third ingredient, doesn't add strength but binds a brick together and allows it to shrink without cracking.
- Emulsified asphalt, or construction lime powder can be added in the mix to make a waterproof adobe brick.
- It might take three or four tries to find the right dirt mixture, or you might stumble upon a working source of dirt the first time you look. Remember that you will need a large pile of dirt for a modest sized building.