Adobe

Adobe is a building material made from loam and organic materials. The word "adobe" actually means mudbrick in Spanish. This material has been used for thousands of years and is one of the earliest building materials known to people. You can find adobe buildings all around the world.

In places with Spanish history, like the Southwestern United States, the word adobe can describe any kind of building made from earth. These buildings look a lot like others made from cob or rammed earth. Adobe buildings have been around since before 5,100 BP, which means they have a very long history.

Description

Adobe bricks are small, rectangular blocks that dry quickly in the air without breaking. They are made from a mix of soil and other natural materials, and can be stuck together with more of this mix to build structures. There isn’t one set size for these bricks—they come in different shapes and sizes depending on where and when they are made. Some common sizes are about 20 cm by 10 cm by 30 cm, weighing around 10 kg, while others can be larger, up to about 45 kg. When bricks get too heavy, it’s easier to pack the material directly into place, a method called rammed earth.

Strength

In dry places, buildings made from adobe can last a very long time and some are among the oldest in the world. These buildings stay cool or warm better than others because of their thickness. However, they can be damaged during earthquakes unless they are made stronger. Big earthquakes that hurt many adobe buildings happened in 1976 Guatemala earthquake, the 2003 Bam earthquake, and the 2010 Chile earthquake.

Distribution

Buildings made from sun-dried earth can be found all around the world, like in the Middle East, Western Asia, North Africa, West Africa, South America, and parts of the United States and Europe. People in places like the Southwestern United States, Mesoamerica, and the Andes have used adobe for thousands of years. The Puebloan peoples made their homes with their hands or baskets full of adobe before the Spanish showed them how to make bricks. Adobe bricks were also used in Spain starting from the Late Bronze and Iron Ages. Adobe is popular because it is easy to make and affordable.

Etymology

The word adobe has been used for about 4,000 years with little change in how we say it or what it means. It started in Middle Egyptian around 2000 BC as a word for "mud brick." Over time, the word moved through Late Egyptian and Coptic, then into Arabic, and finally into Old Spanish language. English took the word from Spanish in the early 1700s, still meaning a type of mud brick.

Today, in English, adobe can also describe a style of building common in dry places in North America, like in New Mexico, no matter the building method.

Composition

An adobe brick is made from earth mixed with water and natural materials like straw or dung. The soil usually includes sand, silt, and clay. Straw helps the brick stay together and dry evenly, stopping it from cracking. Dung can do the same thing. The best soil for making adobe has about 15% clay, 10–30% silt, and 55–75% fine sand. Sometimes modern adobe is made stronger with special materials.

Material properties

Adobe walls can hold up their own weight because they push down into the foundation. This means the adobe needs to be strong enough to stay standing. In the United States, rules say adobe blocks must be strong enough to handle certain forces, like from earthquakes.

Adobe is also a good material for keeping buildings comfortable. Because the walls are thick, they can store heat. On hot days, the walls slowly warm up from the sun and air outside. After the sun goes down, the walls keep releasing heat inside for several hours. This helps keep the inside temperature steady, which is why people have used adobe for a long time.

Uses

Adobe bricks are made by pressing a mix of mud into a wooden frame. In North America, these bricks are usually about 25 by 36 cm (10 by 14 in) in size. After placing the mixture in the frame, it is removed once the bricks start to set. They are then turned on their edge to dry completely. Drying them slowly in the shade helps prevent cracking.

This same mud mixture, without straw, is used to make mortar and plaster for walls. Some cultures added lime-based cement to the plaster to help protect it from rain. Adobe bricks can be shaped in many ways, as long as they dry evenly and have materials like straw or cement mixed in to make them stronger. Builders often test the soil first to make sure it has the right mix of sand and clay for strong bricks.

Adobe walls need strong support because they are very heavy. Builders often use deep footings and add steel reinforcement to help the walls stay steady. Adobe walls usually are not built higher than two stories because they do not support much weight. When making windows or doors, a lintel is placed above to hold the bricks in place. Wooden or concrete beams are placed on top of the walls to help support the roof.

Adobe roofs are made using a mix of soil, water, sand, and organic materials pressed into wooden forms to create bricks. These bricks are then laid on a framework of wood or metal beams. In dry climates, traditional flat adobe roofs are still used. Heavy wooden beams called vigas are placed on top of the walls, with smaller beams called latillas on top of them. Brush is laid over the latillas, and then the adobe bricks are applied. Over time, the roof may need to be reshaped and weeds removed to keep it in good condition. Adobe roofs can be fire-proof depending on the materials used.

Adobe around the world

The biggest building ever made from adobe is the Arg-é Bam, built by the Achaemenid Empire. Other huge adobe buildings include the Huaca del Sol in Peru, which has 100 million bricks, and the ciudellas of Chan Chan and Tambo Colorado, both also in Peru.

Adobe buildings are still being made today in many places. Examples include houses in Kyrgyzstan, Romania, and Sa'dah, Yemen. There are also famous adobe sites like the Poeh Museum in New Mexico, US, and the Taos Pueblo in Santa Fe, New Mexico. The Great Mosque of Djenné in Mali is made from a type of adobe called banco.