![House in Toteil 002](https://upload.wikimedia.org/wikipedia/commons/4/43/House_in_Toteil_002.jpg)
An earth structure is a building or other structure made largely from
soil
Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former te ...
. Since soil is a widely available material, it has been used in construction since prehistoric times. It may be combined with other materials, compressed and/or baked to add strength.
Soil is still an economical material for many applications, and may have low environmental impact both during and after construction.
Earth structure materials may be as simple as
mud
A MUD (; originally multi-user dungeon, with later variants multi-user dimension and multi-user domain) is a Multiplayer video game, multiplayer Time-keeping systems in games#Real-time, real-time virtual world, usually Text-based game, text-bas ...
, or mud mixed with straw to make
cob. Sturdy dwellings may be also built from
sod
Sod, also known as turf, is the upper layer of soil with the grass growing on it that is often harvested into rolls.
In Australian and British English, sod is more commonly known as ''turf'', and the word "sod" is limited mainly to agricult ...
or turf. Soil may be stabilized by the addition of lime or cement, and may be compacted into
rammed earth
Rammed earth is a technique for constructing foundations, floors, and walls using compacted natural raw materials such as earth, chalk, lime, or gravel. It is an ancient method that has been revived recently as a sustainable building method.
...
. Construction is faster with pre-formed
adobe
Adobe ( ; ) is a building material made from earth and organic materials. is Spanish for ''mudbrick''. In some English-speaking regions of Spanish heritage, such as the Southwestern United States, the term is used to refer to any kind of e ...
or
mudbrick
A mudbrick or mud-brick is an air-dried brick, made of a mixture of loam, mud, sand and water mixed with a binding material such as rice husks or straw. Mudbricks are known from 9000 BCE, though since 4000 BCE, bricks have also bee ...
s,
compressed earth block
A compressed earth block (CEB), also known as a pressed earth block or a compressed soil block, is a building material made primarily from an appropriate mix of fairly dry inorganic subsoil, non-expansive clay, sand, and aggregate. Forming compre ...
s,
earthbags or
fired clay bricks.
Types of earth structure include
earth shelters, where a dwelling is wholly or partly embedded in the ground or encased in soil. Native American
earth lodge
An earth lodge is a semi-subterranean building covered partially or completely with earth, best known from the Native American cultures of the Great Plains and Eastern Woodlands. Most earth lodges are circular in construction with a dome-like ...
s are examples.
Wattle and daub
Wattle and daub is a composite building method used for making walls and buildings, in which a woven lattice of wooden strips called wattle is daubed with a sticky material usually made of some combination of wet soil, clay, sand, animal dung a ...
houses use a "wattle" of poles interwoven with sticks to provide stability for mud walls.
Sod house
The sod house or soddy was an often used alternative to the log cabin during frontier settlement of the Great Plains of Canada and the United States in the 1800s and early 1900s. Primarily used at first for animal shelters, corrals, and fences, ...
s were built on the northwest coast of Europe, and later by European settlers on the North American prairies. Adobe or mud-brick buildings are built around the world and include houses, apartment buildings, mosques and churches.
Fujian Tulous are large fortified rammed earth buildings in southeastern
China
China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...
that shelter as many as 80 families. Other types of earth structure include mounds and pyramids used for religious purposes,
levee
A levee (), dike (American English), dyke (English in the Commonwealth of Nations, Commonwealth English), embankment, floodbank, or stop bank is a structure that is usually soil, earthen and that often runs parallel (geometry), parallel to ...
s,
mechanically stabilized earth
Mechanically stabilized earth (MSE or reinforced soil) is soil constructed with artificial reinforcing. It can be used for retaining walls, bridge abutments, seawalls, and dikes. Although the basic principles of MSE have been used throughout his ...
retaining walls, forts, trenches and
embankment dam
An embankment dam is a large artificial dam. It is typically created by the placement and compaction of a complex semi-plastic mound of various compositions of soil or rock. It has a semi-pervious waterproof natural covering for its surface and ...
s.
Soil
![SoilTexture USDA](https://upload.wikimedia.org/wikipedia/commons/a/ad/SoilTexture_USDA.svg)
Soil is created from rock that has been chemically or physically weathered, transported, deposited and precipitated.
Soil particles include
sand
Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class of s ...
,
silt
Silt is granular material of a size between sand and clay and composed mostly of broken grains of quartz. Silt may occur as a soil (often mixed with sand or clay) or as sediment mixed in suspension with water. Silt usually has a floury feel when ...
and
clay
Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4).
Clays develop plasticity when wet, due to a molecular film of water surrounding the clay par ...
. Sand particles are the largest at in diameter and clay the smallest at less than in diameter.
Both sand and silt are mostly inert rock particles, including
quartz
Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical form ...
,
calcite
Calcite is a Carbonate minerals, carbonate mineral and the most stable Polymorphism (materials science), polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on ...
,
feldspar
Feldspars are a group of rock-forming aluminium tectosilicate minerals, also containing other cations such as sodium, calcium, potassium, or barium. The most common members of the feldspar group are the ''plagioclase'' (sodium-calcium) feldsp ...
and
mica
Micas ( ) are a group of silicate minerals whose outstanding physical characteristic is that individual mica crystals can easily be split into extremely thin elastic plates. This characteristic is described as perfect basal cleavage. Mica is ...
.
Clays typically are
phyllosilicate
Silicate minerals are rock-forming minerals made up of silicate groups. They are the largest and most important class of minerals and make up approximately 90 percent of Earth's crust.
In mineralogy, silica (silicon dioxide, ) is usually consid ...
minerals with a sheet-like structure.
The very small clay particles interact with each other physically and chemically.
Even a small proportion of clay affects the physical properties of the soil much more than might be expected.
Clays such as
kaolinite
Kaolinite ( ) is a clay mineral, with the chemical composition Al2 Si2 O5( OH)4. It is an important industrial mineral. It is a layered silicate mineral, with one tetrahedral sheet of silica () linked through oxygen atoms to one octahedral ...
do not expand or contract when wetted or dried, and are useful for brick-making.
Others, such as
smectite
A smectite (from ancient Greek ''σμηκτός'' smektos 'lubricated'; ''σμηκτρίς'' smektris 'walker's earth', 'fuller's earth'; rubbing earth; earth that has the property of cleaning) is a mineral mixtures of various swelling sheet sil ...
s, expand or contract considerably when wet or dry, and are not suitable for building.
Loam
Loam (in geology and soil science) is soil composed mostly of sand (particle size > ), silt (particle size > ), and a smaller amount of clay (particle size < ). By weight, its mineral composition is about 40–40–20% concentration of sand–sil ...
is a mix of sand, silt and clay in which none predominates.
Soils are given different names depending on the relative proportions of sand, silt and clay such as "Silt Loam", "Clay Loam" and "Silty Clay".
Loam construction, the subject of this article, referred to as adobe construction when it uses unfired clay bricks, is an ancient building technology. It was used in the early civilizations of the
Mediterranean
The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on the e ...
,
Egypt
Egypt ( ar, مصر , ), officially the Arab Republic of Egypt, is a transcontinental country spanning the northeast corner of Africa and southwest corner of Asia via a land bridge formed by the Sinai Peninsula. It is bordered by the Mediter ...
and
Mesopotamia
Mesopotamia ''Mesopotamíā''; ar, بِلَاد ٱلرَّافِدَيْن or ; syc, ܐܪܡ ܢܗܪ̈ܝܢ, or , ) is a historical region of Western Asia situated within the Tigris–Euphrates river system, in the northern part of the F ...
, in the
Indus
The Indus ( ) is a transboundary river of Asia and a trans-Himalayan river of South and Central Asia. The river rises in mountain springs northeast of Mount Kailash in Western Tibet, flows northwest through the disputed region of Kashmir, ...
,
Ganges
The Ganges ( ) (in India: Ganga ( ); in Bangladesh: Padma ( )). "The Ganges Basin, known in India as the Ganga and in Bangladesh as the Padma, is an international river to which India, Bangladesh, Nepal and China are the riparian states." is ...
and
Yellow
Yellow is the color between green and orange on the spectrum of light. It is evoked by light with a dominant wavelength of roughly 575585 nm. It is a primary color in subtractive color systems, used in painting or color printing. In the R ...
river valleys, in
Central
Central is an adjective usually referring to being in the center of some place or (mathematical) object.
Central may also refer to:
Directions and generalised locations
* Central Africa, a region in the centre of Africa continent, also known as ...
and
South America
South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...
.
As of 2005 about 1.5 billion people lived in houses built of loam.
In recent years, interest in loam construction has revived in the developed world. It is seen as a way to minimize use of fossil fuels and pollution, particularly carbon dioxide, during manufacture, and to create a comfortable living environment through the high mass and high absorption of the material.
The two main technologies are stamped or rammed earth, clay or loam, called ''pise de terre'' in French, and
adobe
Adobe ( ; ) is a building material made from earth and organic materials. is Spanish for ''mudbrick''. In some English-speaking regions of Spanish heritage, such as the Southwestern United States, the term is used to refer to any kind of e ...
, typically using sun-dried bricks made of a mud and straw mixture.
Materials
![Mud houses are commonly found in various regions of Afghanistan](https://upload.wikimedia.org/wikipedia/commons/b/ba/Mud_houses_are_commonly_found_in_various_regions_of_Afghanistan..jpg)
Earth usually requires some sort of processing for use in construction. It may be combined with water to make
mud
A MUD (; originally multi-user dungeon, with later variants multi-user dimension and multi-user domain) is a Multiplayer video game, multiplayer Time-keeping systems in games#Real-time, real-time virtual world, usually Text-based game, text-bas ...
, straw may be added, some form of stabilizing material such as lime or cement may be used to harden the earth, and the earth may be compacted to increase strength.
Mud
Coursed mud construction is one of the oldest approaches to building walls. Moist mud is formed by hand to make the base of a wall, and allowed to dry. More mud is added and allowed to dry to form successive courses until the wall is complete. With puddled mud, a hand-made mud form is filled with wetter mud and allowed to dry.
In Iran, puddled mud walls are called ''chine'' construction. Each course is about thick, and about high. Typically the technique is used for garden walls but not for house construction, presumably because of concern about the strength of walls made in this way.
A disadvantage to the approach is that a lot of time can be spent waiting for each course to dry.
Another technique, used in areas where wood is plentiful, is to build a wood-frame house and to infill it with mud, primarily to provide insulation. In parts of
England
England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe b ...
a similar technique was used with cob.
Cob
Cob, sometimes referred to as "monolithic adobe", is a
natural building
A natural building involves a range of building systems and materials that place major emphasis on sustainability. Ways of achieving sustainability through natural building focus on durability and the use of minimally processed, plentiful or renew ...
material made from soil that includes clay, sand or small stones and an organic material such as
straw
Straw is an agricultural byproduct consisting of the dry stalks of cereal plants after the grain and chaff have been removed. It makes up about half of the yield of cereal crops such as barley, oats, rice, rye and wheat. It has a number ...
. Cob walls are usually built up in courses, have no mortar joints and need 30% or more clay in the soil. Cob can be used as in-fill in post-and-beam buildings, but is often used for load bearing walls, and can bear up to two stories. A cob wall should be at least thick, and the ratio of width to height should be no more than one to ten. It will typically be plastered inside and out with a mix of lime, soil and sand. Cob is fireproof, and its thermal mass helps stabilize indoor temperatures.
Tests have shown that cob has some resistance to seismic activity. However, building codes in the developed world may not recognize cob as an approved material.
Sod or turf
![Sod House Detail (4245555122)](https://upload.wikimedia.org/wikipedia/commons/5/50/Sod_House_Detail_%284245555122%29.jpg)
Cut
sod
Sod, also known as turf, is the upper layer of soil with the grass growing on it that is often harvested into rolls.
In Australian and British English, sod is more commonly known as ''turf'', and the word "sod" is limited mainly to agricult ...
bricks, called ''terrone'' in Spanish, can be used to make tough and durable walls. The sod is cut from soil that has a heavy mat of grass roots, which may be found in river bottom lands. It is stood on edge to dry before being used in construction.
European settlers on the North American Prairies found that the sod least likely to deteriorate due to freezing or rain came from dried sloughs. Turf was once extensively used for the walls of houses in Ireland, Scotland and Iceland, where some turf houses may still be found. A turf house may last fifty years or longer if well-maintained in a cold climate.
The Icelanders find that the best quality turf is the ''Strengur'', the top of the grass turf.
Stabilized earth
Clay is usually hard and strong when dry, but becomes very soft when it absorbs water. The dry clay helps hold an earth wall together, but if the wall is directly exposed to rain, or to water leaking down from the roof, it may become saturated.
Earth may be "stabilized" to make it more weather resistant. The practice of stabilizing earth by adding burnt lime is centuries old.
Portland cement
Portland cement is the most common type of cement in general use around the world as a basic ingredient of concrete, mortar, stucco, and non-specialty grout. It was developed from other types of hydraulic lime in England in the early 19th c ...
or
bitumen
Asphalt, also known as bitumen (, ), is a sticky, black, highly viscous liquid or semi-solid form of petroleum. It may be found in natural deposits or may be a refined product, and is classed as a pitch. Before the 20th century, the term a ...
may also be added to earth intended for construction which adds strength, although the stabilized earth is not as strong as fired clay or concrete. Mixtures of cement and lime, or
pozzolana
Pozzolana or pozzuolana ( , ), also known as pozzolanic ash ( la, pulvis puteolanus), is a natural siliceous or siliceous- aluminous material which reacts with calcium hydroxide in the presence of water at room temperature (cf. pozzolanic reactio ...
and lime, may also be used for stabilization.
Preferably the sand content of the soil will be 65% – 75%. Soils with low clay content, or with no more than 15% non-expansive clay, are suitable for stabilized earth. The clay percentage may be reduced by adding sand, if available.
If there is more than 15% clay it may take more than 10% cement to stabilize the soil, which adds to the cost.
If earth contains little clay and holds 10% or more cement, it is in effect concrete.
Cement is not particularly environmentally friendly, since the manufacturing process generates large amounts of carbon dioxide.
Low-density stabilized earth will be porous and weak. The earth must therefore be compacted either by a machine that makes blocks or within the wall using the "rammed earth" technique.
Rammed earth
![Alte Schule Bonbaden 1](https://upload.wikimedia.org/wikipedia/commons/f/fe/Alte_Schule_Bonbaden_1.jpg)
Rammed earth is a technique for building walls using natural raw materials such as earth,
chalk
Chalk is a soft, white, porous, sedimentary carbonate rock. It is a form of limestone composed of the mineral calcite and originally formed deep under the sea by the compression of microscopic plankton that had settled to the sea floor. Chalk ...
,
lime
Lime commonly refers to:
* Lime (fruit), a green citrus fruit
* Lime (material), inorganic materials containing calcium, usually calcium oxide or calcium hydroxide
* Lime (color), a color between yellow and green
Lime may also refer to:
Botany ...
or
gravel
Gravel is a loose aggregation of rock fragments. Gravel occurs naturally throughout the world as a result of sedimentary and erosive geologic processes; it is also produced in large quantities commercially as crushed stone.
Gravel is classifi ...
.
A rammed earth wall is built by placing damp soil in a temporary form. The soil is manually or mechanically compacted and then the form is removed.
Rammed earth is generally made without much water, and so does not need much time to dry as the building rises. It is susceptible to moisture, so must be laid on a course that stops rising dampness, must be roofed or covered to keep out water from above, and may need protection through some sort of plaster, paint or sheathing.
In China, rammed earth walls were built by the
Longshan people in 2600–1900 BC, during the period when cities first appeared in the region. Thick sloping walls made of rammed earth became a characteristic of traditional Buddhist monasteries throughout the Himalayas and became very common in northern Indian areas such as
Sikkim
Sikkim (; ) is a state in Northeastern India. It borders the Tibet Autonomous Region of China in the north and northeast, Bhutan in the east, Province No. 1 of Nepal in the west and West Bengal in the south. Sikkim is also close to the Siligur ...
. The technique spread to the Middle East, and to North Africa, and the city of
Carthage
Carthage was the capital city of Ancient Carthage, on the eastern side of the Lake of Tunis in what is now Tunisia. Carthage was one of the most important trading hubs of the Ancient Mediterranean and one of the most affluent cities of the classi ...
was built of rammed earth. From there the technology was brought to Europe by the Romans.
Rammed earth structures may be long lasting. Most of the
Great Wall of China
The Great Wall of China (, literally "ten thousand ''li'' wall") is a series of fortifications that were built across the historical northern borders of ancient Chinese states and Imperial China as protection against various nomadic grou ...
was made from rammed earth, as was the
Alhambra
The Alhambra (, ; ar, الْحَمْرَاء, Al-Ḥamrāʾ, , ) is a palace and fortress complex located in Granada, Andalusia, Spain. It is one of the most famous monuments of Islamic architecture and one of the best-preserved palaces of the ...
in the
Kingdom of Granada
)
, common_languages = Official language:Classical ArabicOther languages: Andalusi Arabic, Mozarabic, Berber, Ladino
, capital = Granada
, religion = Majority religion:Sunni IslamMinority religions:Roman C ...
. In Northern Europe there are rammed earth buildings up to seven stories high and two hundred years old.
Concrete
The Romans made durable concrete strong enough for load-bearing walls. Roman concrete contains a rubble of broken bricks and rocks set in mortar. The mortar included lime and ''pozzolana'', a volcanic material that contributed significantly to its strength. Roman concrete structures such as the
Colosseum
The Colosseum ( ; it, Colosseo ) is an oval amphitheatre in the centre of the city of Rome, Italy, just east of the Roman Forum. It is the largest ancient amphitheatre ever built, and is still the largest standing amphitheatre in the world to ...
, completed in 80 AD, still stand.
Their longevity may be explained by the fact that the builders used a relatively dry mix of mortar and aggregate and compacted it by pounding it down to eliminate air pockets. Although derived from earth products, concrete structures would not usually be considered earth structures.
Building units
Mud brick or adobe brick
![Working mudbrick press 5](https://upload.wikimedia.org/wikipedia/commons/6/65/Working_mudbrick_press_5.jpg)
Mudbricks or Adobe bricks are preformed modular masonry units of sun-dried mud that were invented at different times in different parts of the world as civilization developed. Construction with bricks avoids the delays while each course of puddled mud dries. Wall murals show that adobe production techniques were highly advanced in Egypt by 2500 BC.
Adobe construction is common throughout much of Africa today.
Adobe bricks are traditionally made from sand and clay mixed with water to a plastic consistency, with straw or grass as a binder.
The mud is prepared, placed in wooden forms, tamped and leveled, and then turned out of the mold to dry for several days.
The bricks are then stood on end to air-cure for a month or more.
In the southwest United States and Mexico adobe buildings had massive walls and were rarely more than two stories high.
Adobe mission churches were never more than about .
Since adobe surfaces are fragile, coatings are used to protect them.
These coatings, periodically renewed, have included mud plaster, lime plaster, whitewash or stucco.
Adobe walls were historically made by laying the bricks with mud mortar, which swells and shrinks at the same rate as the bricks when wetted or dried, heated or cooled. Modern adobe may be stabilized with cement and bonded with cement mortars, but cement mortars will cause unstabilized adobe bricks to deteriorate due to the different rates of thermal expansion and contraction.
Compressed earth block
Compressed earth block
A compressed earth block (CEB), also known as a pressed earth block or a compressed soil block, is a building material made primarily from an appropriate mix of fairly dry inorganic subsoil, non-expansive clay, sand, and aggregate. Forming compre ...
s (CEB) were traditionally made by using a stick to ram soil into a wooden mold. Today they are usually made from subsoil compressed in a hand-operated or powered machine. In the developing world, manual machines can be a cost-effective solution for making uniform building blocks, while the more complex and expensive motorized machines are less likely to be appropriate.
Although labor-intensive, CEB construction avoids the cost of buying and transporting materials.
Block-making machines may form blocks that have interlocking shapes to reduce the requirement for mortar.
The block may have holes or grooves so rods such as bamboo can be inserted to improve earthquake resistance.
Suitable earth must be used, with enough clay to hold the block together and resist erosion, but not too much expansive clay.
When the block has been made from stabilized earth, which contains cement, the concrete must be given perhaps three weeks to cure.
During this time the blocks should be stacked and kept from drying out by sprinkling water over them.
This may be a problem in hot, dry climates where water is scarce.
Closely stacking the blocks and covering them with a polythene sheet may help reduce water loss.
Earthbags
Earthbag construction
Earthbag construction is an inexpensive building method using mostly local soil to create structures which are both strong and can be quickly built.
Earthbag development
Features
It is also natural building technique developed from historic mi ...
is a
natural building
A natural building involves a range of building systems and materials that place major emphasis on sustainability. Ways of achieving sustainability through natural building focus on durability and the use of minimally processed, plentiful or renew ...
technique that has evolved from historic military construction techniques for
bunker
A bunker is a defensive military fortification designed to protect people and valued materials from falling bombs, artillery, or other attacks. Bunkers are almost always underground, in contrast to blockhouses which are mostly above ground. ...
s.
Local subsoil of almost any composition can be used, although an adobe mix would be preferable.
The soil is moistened so it will compact into a stable structure when packed into woven polypropylene or burlap sacks or tubes. Plastic mesh is sometimes used. Polypropylene (pp) sacks are most common, since they are durable when covered, cheap, and widely available.
The bags are laid in courses, with barbed wire between each course to prevent slipping. Each course is tamped after it is laid.
The structure in pp bags is similar to adobe but more flexible. With mesh tubing the structure is like rammed earth.
Earthbags may be used to make dome-shaped or vertical wall buildings. With soil stabilization they may also be used for retaining walls.
Fired clay brick
![English Bond - geograph](https://upload.wikimedia.org/wikipedia/commons/c/c0/English_Bond_-_geograph.org.uk_-_702506.jpg)
The technique of firing clay
brick
A brick is a type of block used to build walls, pavements and other elements in masonry construction. Properly, the term ''brick'' denotes a block composed of dried clay, but is now also used informally to denote other chemically cured cons ...
s in a kiln dates to about 3500 BC.
Fired bricks were being used to build durable masonry across Europe, Asia and North Africa by 1200 BC and still remain an important building material. Modern fired clay bricks are formed from clays or shales, shaped and then fired in a kiln for 8–12 hours at a temperature of 900–1150 °C.
The result is a
ceramic
A ceramic is any of the various hard, brittle, heat-resistant and corrosion-resistant materials made by shaping and then firing an inorganic, nonmetallic material, such as clay, at a high temperature. Common examples are earthenware, porcelain ...
that is mainly composed of silica and alumina, with other ingredients such as quartz sand. The porosity of the brick depends on the materials and on the firing temperature and duration. The bricks may vary in color depending on the amount of iron and calcium carbonate in the materials used, and the amount of oxygen in the kiln.
Bricks may decay due to crystallization of salts on the brick or in its pores, from frost action and from acidic gases.
Bricks are laid in courses bonded with mortar, a combination of Portland cement, lime and sand.
A wall that is
one brick thick will include stretcher bricks with their long, narrow side exposed and header bricks crossing from side to side.
There are various
brickwork
Brickwork is masonry produced by a bricklayer, using bricks and mortar. Typically, rows of bricks called '' courses'' are laid on top of one another to build up a structure such as a brick wall.
Bricks may be differentiated from blocks by s ...
"bonds", or patterns of stretchers and headers, including the English, Dutch and Flemish bonds.
Examples
Earth sheltering
Earth sheltering
An earth shelter, also called an earth house, earth bermed house, or underground house, is a structure (usually a house) with earth (soil) against the walls, on the roof, or that is entirely buried underground.
Earth acts as thermal mass, making ...
has been used for thousands of years to make energy-efficient dwellings.
There are various configurations. At one extreme, an earth sheltered dwelling is completely underground, with perhaps an open courtyard to provide air and light.
An
earth house
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surface ...
may be set into a slope, with windows or door openings in one or more of its sides, or the building may be on ground level, but with earth mounded against the walls, and perhaps with an earth roof.
Pit houses made by
Hohokam
Hohokam () was a culture in the North American Southwest in what is now part of Arizona, United States, and Sonora, Mexico. It existed between 300 and 1500 AD, with cultural precursors possibly as early as 300 BC. Archaeologists disagree about ...
farmers between 100 and 900 AD, in what is now the southwest of the US, were bermed structures, partially embedded in south-facing slopes. Their successful design was used for hundreds of years.
At
Matmata, Tunisia
Matmata ( ar, مطماطة '; Berber: ⵎⴰⵜⵎⴰⵜⴰ) is a small Berber speaking town in southern Tunisia. Some of the local Berber residents live in traditional underground "troglodyte" structures. In 2004 it had a population of 2,116 ...
, most of the ancient homes were built below ground level, and surrounded courtyards about square.
The homes were reached through tunnels. Other examples of subterranean, semi-subterranean or cliff-based dwellings in both hot and cold climates are found in Turkey, northern China and the Himalayas, and the southwest USA. A number of Buddhist monasteries built from earth and other materials into cliff sides or caves in Himalayan areas such as
Tibet
Tibet (; ''Böd''; ) is a region in East Asia, covering much of the Tibetan Plateau and spanning about . It is the traditional homeland of the Tibetan people. Also resident on the plateau are some other ethnic groups such as Monpa people, ...
,
Bhutan
Bhutan (; dz, འབྲུག་ཡུལ་, Druk Yul ), officially the Kingdom of Bhutan,), is a landlocked country in South Asia. It is situated in the Eastern Himalayas, between China in the north and India in the south. A mountainous ...
,
Nepal
Nepal (; ne, नेपाल ), formerly the Federal Democratic Republic of Nepal ( ne,
सङ्घीय लोकतान्त्रिक गणतन्त्र नेपाल ), is a landlocked country in South Asia. It is mai ...
and northern India are often perilously placed. Starting in the 1970s, interest in the technique has revived in developed countries. By setting an earth house into the ground, the house will be cooler in the warm season and warmer in the cool season.
Native American earth lodge
An
earth lodge
An earth lodge is a semi-subterranean building covered partially or completely with earth, best known from the Native American cultures of the Great Plains and Eastern Woodlands. Most earth lodges are circular in construction with a dome-like ...
is a circular building made by some of the
Native Americans of North America.
They have wood post and beam construction and are dome-shaped.
A typical structure would have four or more central posts planted in the ground and connected at the top by cross beams. The smoke hole would be left open in the center. Around the central structure there was a larger ring of shorter posts, also connected by cross beams. Rafters radiated from the central cross beams to the outside cross beams, and then split planks or beams formed the slanting or vertical side walls.
The structure was covered by sticks and brush or grass, covered in turn by a heavy layer of earth or
sod
Sod, also known as turf, is the upper layer of soil with the grass growing on it that is often harvested into rolls.
In Australian and British English, sod is more commonly known as ''turf'', and the word "sod" is limited mainly to agricult ...
.
Some groups plastered the whole structure with mud, which dried to form a shell.
Wattle and daub
Wattle and daub
Wattle and daub is a composite building method used for making walls and buildings, in which a woven lattice of wooden strips called wattle is daubed with a sticky material usually made of some combination of wet soil, clay, sand, animal dung a ...
is an old building technique in which vines or smaller sticks are interwoven between upright poles, and then mud mixed with straw and grass is plastered over the wall.
The technique is found around the world, from the Nile Delta to Japan, where bamboo was used to make the wattle.
In
Cahokia
The Cahokia Mounds State Historic Site ( 11 MS 2) is the site of a pre-Columbian Native American city (which existed 1050–1350 CE) directly across the Mississippi River from modern St. Louis, Missouri. This historic park lies in south-w ...
, now in Illinois, USA, wattle and daub houses were built with the floor lowered by below the ground.
A variant of the technique is called ''bajareque'' in
Colombia
Colombia (, ; ), officially the Republic of Colombia, is a country in South America with insular regions in North America—near Nicaragua's Caribbean coast—as well as in the Pacific Ocean. The Colombian mainland is bordered by the Car ...
.
In prehistoric Britain simple circular wattle and daub shelters were built wherever adequate clay was available.
Wattle and daub is still found as the panels in timber-framed buildings. Generally the walls are not structural, and in interior use the technique in the developed world was replaced by lath and plaster, and then by
gypsum wallboard.
Prairie sod house
![Omer Kem's sod house](https://upload.wikimedia.org/wikipedia/commons/7/72/Omer_Kem%27s_sod_house.jpg)
European pioneer farmers in the prairies of North America, where there is no wood for construction, often made their first home in a dug-out cave in the side of a hill or ravine, with a covering over the entrance. When they had time, they would build a
sod house
The sod house or soddy was an often used alternative to the log cabin during frontier settlement of the Great Plains of Canada and the United States in the 1800s and early 1900s. Primarily used at first for animal shelters, corrals, and fences, ...
. The farmer would use a plow to cut the sod into bricks , which were then piled up to form the walls.
The sod strips were piled grass-side down, staggered in the same way as brickwork, in three side-by-side rows, resulting in a wall over thick. The sod wall was built around door and window frames, and the corners of the wall were secured by rods driven vertically through them. The roof was made with poles or brush, covered with prairie grass, and then sealed with a layer of sod.
Sod houses were strong and often lasted many years, but they were damp and dirty unless the interior walls were plastered.
The roofs tended to leak, and sometimes collapsed in a rainstorm.
Mud brick buildings
There are innumerable examples of mud brick or adobe building around the world. The walled city of
Shibam
Shibam Hadramawt ( ar, شِبَام حَضْرَمَوْت, Shibām Ḥaḍramawt) is a town in Yemen. With about 7,000 inhabitants, it is the seat of the District of Shibam in the Governorate of Hadhramaut. Known for its mudbrick-made high-r ...
in Yemen, designated a World Heritage Site in 1982, is known for its ten-story unreinforced mud-brick buildings.
The
Djinguereber Mosque
The Djinguereber Mosque ( ar, مسجد دجينجيربر) in Timbuktu, Mali is a famous learning center of Mali built in 1327, and cited as Djingareyber or Djingarey Ber in various languages. Its design is accredited to Abu Ishaq Al Sahili ...
of
Timbuktu
Timbuktu ( ; french: Tombouctou;
Koyra Chiini: ); tmh, label=Tuareg, script=Tfng, ⵜⵏⴱⴾⵜ, Tin Buqt a city in Mali, situated north of the Niger River. The town is the capital of the Tombouctou Region, one of the eight administrativ ...
, Mali, was first built at the start of the 14th century AD (8th century AH) from round mud bricks and a stone-mud mixture, and was rebuilt several times afterwards, steadily growing in size.
Further south in Mali, the
Great Mosque
A congregational mosque or Friday mosque (, ''masjid jāmi‘'', or simply: , ''jāmi‘''; ), or sometimes great mosque or grand mosque (, ''jāmi‘ kabir''; ), is a mosque for hosting the Friday noon prayers known as ''jumu'ah''.*
*
*
*
*
*
*
...
of
Djenné
Djenné ( Bambara: ߘߖߋߣߣߋ tr. Djenne; also known as Djénné, Jenné and Jenne) is a Songhai people town and an urban commune in the Inland Niger Delta region of central Mali. The town is the administrative centre of the Djenné Cercle, on ...
, a dramatic example of Sahel mudbrick architecture. was built in 1907, based on the design of an earlier Great Mosque first built on the site in 1280. Mudbrick requires maintenance, and the fundamentalist ruler
Seku Amadu
Sheikhu Ahmadu ( ar-at, شيخ أحمد بن محمّد لبّو, Shaykh Aḥmadu bin Muḥammadu Lobbo; ff, Seeku Aamadu ; ) (c. 1776 – 20 April 1845) was the Fulbe founder of the Massina Empire (Diina of Hamdullahi) in the Inner Niger D ...
had let the previous mosque collapse.
The
Casa Grande Ruins, now a national monument in Arizona protected by a modern roof, is a massive four-story adobe structure built by Hohokam people between 1200 and 1450 AD.
The first European to record the great house was a Jesuit priest, Father
Eusebio Kino
Eusebio Francisco Kino ( it, Eusebio Francesco Chini, es, Eusebio Francisco Kino; 10 August 1645 – 15 March 1711), often referred to as Father Kino, was a Tyrolean Jesuit, missionary, geographer, explorer, cartographer and astronomer born i ...
, who visited the site in 1694.
At that time it had long been abandoned.
By the time a temporary roof was installed in 1903 the adobe building had been standing empty and unmaintained for hundreds of years.
Huaca de la Luna
Huaca de la Luna ("Temple or Shrine of the Moon") is a large adobe
Adobe ( ; ) is a building material made from earth and organic materials. is Spanish for ''mudbrick''. In some English-speaking regions of Spanish heritage, such a ...
in what is now northern Peru is a large adobe temple built by the
Moche people. The building went through a series of construction phases, growing eventually to a height of about , with three main platforms, four plazas and many smaller rooms and enclosures. The walls were covered by striking multi-colored murals and friezes; those visible today date from about 400–610 AD.
File:Shibam2.JPG, High-rise mud brick buildings in Shibam
Shibam Hadramawt ( ar, شِبَام حَضْرَمَوْت, Shibām Ḥaḍramawt) is a town in Yemen. With about 7,000 inhabitants, it is the seat of the District of Shibam in the Governorate of Hadhramaut. Known for its mudbrick-made high-r ...
File:Donkeys, Timbuktu.jpg, Mud wall and mosque in Timbuktu
Timbuktu ( ; french: Tombouctou;
Koyra Chiini: ); tmh, label=Tuareg, script=Tfng, ⵜⵏⴱⴾⵜ, Tin Buqt a city in Mali, situated north of the Niger River. The town is the capital of the Tombouctou Region, one of the eight administrativ ...
File:Tellem Dwelling Bandiagara Escarpment Mali.jpg, Old mud dwellings and modern mud mosque in Mali
Mali (; ), officially the Republic of Mali,, , ff, 𞤈𞤫𞤲𞥆𞤣𞤢𞥄𞤲𞤣𞤭 𞤃𞤢𞥄𞤤𞤭, Renndaandi Maali, italics=no, ar, جمهورية مالي, Jumhūriyyāt Mālī is a landlocked country in West Africa. Mali ...
File:La grande mosquée-1, Djenné, Mali au petit matin. Date du cliché 27-12-1972.jpg, Great Mosque of Djenné
Djenné ( Bambara: ߘߖߋߣߣߋ tr. Djenne; also known as Djénné, Jenné and Jenne) is a Songhai people town and an urban commune in the Inland Niger Delta region of central Mali. The town is the administrative centre of the Djenné Cercle, on ...
, Mali, in 1972
File:Casa grande 2003.jpg, Casa Grande Ruins National Monument
Casa Grande Ruins National Monument ( ood, Siwañ Waʼa Ki: or ''Sivan Vahki''), in Coolidge, Arizona, just north-east of the city of Casa Grande, preserves a group of Hohokam structures dating to the Classic Period ().
History of the area
Th ...
in Arizona
File:Taos mission church.jpg, San Francisco de Asis Mission Church at Ranchos de Taos, New Mexico
File:Huaca 58.jpg, Interior of Huaca de la Luna
Huaca de la Luna ("Temple or Shrine of the Moon") is a large adobe
Adobe ( ; ) is a building material made from earth and organic materials. is Spanish for ''mudbrick''. In some English-speaking regions of Spanish heritage, such a ...
, Trujillo, Peru
File:Artistic mud house at shantiniketan.JPG, Art on an adobe building at Shantiniketan University, Bolpur
Bolpur is a city and a municipality in Birbhum district in the state of West Bengal, India. It is the headquarters of the Bolpur subdivision. Bolpur municipal area includes Santiniketan, Sriniketan and Prantik. The city is known as a Cultural a ...
, West Bengal
Toulous
![Snail pit tulou](https://upload.wikimedia.org/wikipedia/commons/4/45/Snail_pit_tulou.jpg)
A
Fujian Tulou is a type of rural dwelling of the
Hakka people
The Hakka (), sometimes also referred to as Hakka Han, or Hakka Chinese, or Hakkas are a Han Chinese subgroup whose ancestral homes are chiefly in the Hakka-speaking provincial areas of Guangdong, Fujian, Jiangxi, Guangxi, Sichuan, Hunan, Zhe ...
in the mountainous areas in southeastern
Fujian
Fujian (; alternately romanized as Fukien or Hokkien) is a province on the southeastern coast of China. Fujian is bordered by Zhejiang to the north, Jiangxi to the west, Guangdong to the south, and the Taiwan Strait to the east. Its capi ...
, China.
They were mostly built between the 13th and the 20th centuries.
A tulou is a large, enclosed and fortified earth building, rectangular or circular, with very thick load-bearing
rammed earth
Rammed earth is a technique for constructing foundations, floors, and walls using compacted natural raw materials such as earth, chalk, lime, or gravel. It is an ancient method that has been revived recently as a sustainable building method.
...
walls between three and five stories high.
A toulou might house up to 80 families. Smaller interior buildings are often enclosed by these huge peripheral walls which can contain halls, storehouses, wells and living areas.
The structure resembles a small fortified city.
The walls are formed by compacting earth mixed with stone, bamboo, wood and other readily available materials, and are to thick.
The result is a well-lit, well-ventilated, windproof and earthquake-proof building that is warm in winter and cool in summer.
Mounds and pyramids
Ziggurat
A ziggurat (; Cuneiform: 𒅆𒂍𒉪, Akkadian: ', D-stem of ' 'to protrude, to build high', cognate with other Semitic languages like Hebrew ''zaqar'' (זָקַר) 'protrude') is a type of massive structure built in ancient Mesopotamia. It has ...
s were elevated temples constructed by the
Sumer
Sumer () is the earliest known civilization in the historical region of southern Mesopotamia (south-central Iraq), emerging during the Chalcolithic and early Bronze Ages between the sixth and fifth millennium BC. It is one of the cradles of c ...
ians between the end of the 4th millennium BC and the 2nd millennium BC, rising in a series of terraces to a temple up to above ground level. The
Ziggurat of Ur
The Ziggurat (or Great Ziggurat) of Ur ( Sumerian: "Etemenniguru", meaning "temple whose foundation creates aura") is a Neo-Sumerian ziggurat in what was the city of Ur near Nasiriyah, in present-day Dhi Qar Province, Iraq. The structure wa ...
contained about three million bricks, none more than in length, so construction would have been a huge project.
The largest ziggurat was in Babylon, and is thought by some to be the
Tower of Babel
The Tower of Babel ( he, , ''Mīgdal Bāḇel'') narrative in Genesis 11:1–9 is an origin myth meant to explain why the world's peoples speak different languages.
According to the story, a united human race speaking a single language and mi ...
mentioned in the
Bible
The Bible (from Koine Greek , , 'the books') is a collection of religious texts or scriptures that are held to be sacred in Christianity, Judaism, Samaritanism, and many other religions. The Bible is an anthologya compilation of texts of a ...
. It was destroyed by
Alexander the Great
Alexander III of Macedon ( grc, wikt:Ἀλέξανδρος, Ἀλέξανδρος, Alexandros; 20/21 July 356 BC – 10/11 June 323 BC), commonly known as Alexander the Great, was a king of the Ancient Greece, ancient Greek kingdom of Maced ...
and only the foundations remain, but originally it stood high on a base about square.
Sun-dried bricks were used for the interior and kiln-fired bricks for the facing.
The bricks were held together by clay or bitumen.
Many pre-Columbian Native American societies of ancient North America built large
pyramid
A pyramid (from el, πυραμίς ') is a structure whose outer surfaces are triangular and converge to a single step at the top, making the shape roughly a pyramid in the geometric sense. The base of a pyramid can be trilateral, quadrilat ...
al earth structures known as
platform mound
Platform may refer to:
Technology
* Computing platform, a framework on which applications may be run
* Platform game, a genre of video games
* Car platform, a set of components shared by several vehicle models
* Weapons platform, a system or ...
s. Among the largest and best-known of these structures is
Monks Mound
Monks Mound is the largest Pre-Columbian earthwork in the Americas and the largest pyramid north of Mesoamerica. The beginning of its construction dates from 900–955 CE. Located at the Cahokia Mounds UNESCO World Heritage Site near Collinsvil ...
at the site of
Cahokia
The Cahokia Mounds State Historic Site ( 11 MS 2) is the site of a pre-Columbian Native American city (which existed 1050–1350 CE) directly across the Mississippi River from modern St. Louis, Missouri. This historic park lies in south-w ...
in what became Illinois, completed around 1100 AD, which has a base larger than that of the Great Pyramid at Giza. Many of the mounds underwent multiple episodes of mound construction at periodic intervals, some becoming quite large. They are believed to have played a central role in the mound-building peoples' religious life and documented uses include semi-public
chief
Chief may refer to:
Title or rank
Military and law enforcement
* Chief master sergeant, the ninth, and highest, enlisted rank in the U.S. Air Force and U.S. Space Force
* Chief of police, the head of a police department
* Chief of the boa ...
's house platforms, public
temple
A temple (from the Latin ) is a building reserved for spiritual rituals and activities such as prayer and sacrifice. Religions which erect temples include Christianity (whose temples are typically called churches), Hinduism (whose temples ...
platforms,
mortuary
A morgue or mortuary (in a hospital or elsewhere) is a place used for the storage of human corpses awaiting identification (ID), removal for autopsy, respectful burial, cremation or other methods of disposal. In modern times, corpses have cus ...
platforms,
charnel house
A charnel house is a vault or building where human skeletal remains are stored. They are often built near churches for depositing bones that are unearthed while digging graves. The term can also be used more generally as a description of a pla ...
platforms,
earth lodge
An earth lodge is a semi-subterranean building covered partially or completely with earth, best known from the Native American cultures of the Great Plains and Eastern Woodlands. Most earth lodges are circular in construction with a dome-like ...
/town house platforms, residence platforms, square ground and rotunda platforms, and dance platforms.
The
Pyramid of the Sun
The Pyramid of the Sun is the largest building in Teotihuacan, and one of the largest in Mesoamerica. It is believed to have been constructed about 200 AD. Found along the Avenue of the Dead, in between the Pyramid of the Moon and the Ciudadela ...
in
Teotihuacan
Teotihuacan (Spanish language, Spanish: ''Teotihuacán'') (; ) is an ancient Mesoamerican city located in a sub-valley of the Valley of Mexico, which is located in the State of Mexico, northeast of modern-day Mexico City. Teotihuacan is ...
, Mexico, was started in 100 AD.
The stone-faced structure contains two million tons of rammed earth.
Earthworks
Earthworks
Earthworks may refer to:
Construction
*Earthworks (archaeology), human-made constructions that modify the land contour
* Earthworks (engineering), civil engineering works created by moving or processing quantities of soil
*Earthworks (military), m ...
are engineering works created through moving or processing quantities of soil or unformed rock.
The material may be moved to another location and formed into a desired shape for a purpose.
Levee
A levee (), dike (American English), dyke (English in the Commonwealth of Nations, Commonwealth English), embankment, floodbank, or stop bank is a structure that is usually soil, earthen and that often runs parallel (geometry), parallel to ...
s, embankments and dams are types of earthwork.
A levee, floodbank or stopbank is an elongated natural ridge or artificially constructed
dirt fill wall that regulates water levels. It is usually earthen and often runs parallel to the course of a river in its
floodplain
A floodplain or flood plain or bottomlands is an area of land adjacent to a river which stretches from the banks of its channel to the base of the enclosing valley walls, and which experiences flooding during periods of high discharge.Goudi ...
or along low-lying coastlines.
Mechanically stabilized earth
Mechanically stabilized earth (MSE or reinforced soil) is soil constructed with artificial reinforcing. It can be used for retaining walls, bridge abutments, seawalls, and dikes. Although the basic principles of MSE have been used throughout his ...
(MSE) retaining walls may be used for embankments.
MSE walls combine a concrete leveling pad, wall facing panels, coping, soil reinforcement and select backfill.
A variety of designs of wall facing panels may be used.
After the leveling pad has been laid and the first row of panels has been placed and braced, the first layer of earth backfill is brought in behind the wall and compacted.
The first set of reinforcements is then laid over the earth.
The reinforcements, which may be tensioned polymer or galvanized metal strips or grids, are attached to the facing panels.
This process is repeated with successive layers of panels, earth and reinforcements.
The panels are thus tied into the earth embankment to make a stable structure with balanced stresses.
Although construction using the basic principles of MSE has a long history, MSE was developed in its current form in the 1960s. The reinforcing elements used can vary but include
steel
Steel is an alloy made up of iron with added carbon to improve its strength and fracture resistance compared to other forms of iron. Many other elements may be present or added. Stainless steels that are corrosion- and oxidation-resistant ty ...
and
geosynthetic
Geosynthetics are synthetic products used to stabilize terrain. They are generally polymeric products used to solve civil engineering problems. This includes eight main product categories: geotextiles, geogrids, geonets, geomembranes, geosyntheti ...
s. The term MSE is usually used in the US to distinguish it from "Reinforced Earth", a trade name of the Reinforced Earth Company, but elsewhere Reinforced Soil is the generally accepted term. MSE construction is relatively fast and inexpensive, and although labor-intensive, it does not demand high levels of skill. It is therefore suitable for developing as well as developed countries.
Forts and trenches
![Soldiers in trench](https://upload.wikimedia.org/wikipedia/commons/2/20/Soldiers_in_trench.jpg)
Earth has been used to construct fortifications for thousands of years, including strongholds and walls, often protected by ditches.
Aerial photography in Europe has revealed traces of earth fortifications from the Roman era, and later medieval times.
Offa's Dyke
Offa's Dyke ( cy, Clawdd Offa) is a large linear earthwork that roughly follows the border between England and Wales. The structure is named after Offa, the Anglo-Saxon king of Mercia from AD 757 until 796, who is traditionally believed to h ...
is a huge earthwork that stretches along the disputed border between England and Wales.
Little is known about the period or the builder, King
Offa of Mercia
Offa (died 29 July 796 AD) was List of monarchs of Mercia, King of Mercia, a kingdom of History of Anglo-Saxon England, Anglo-Saxon England, from 757 until his death. The son of Thingfrith and a descendant of Eowa of Mercia, Eowa, Offa came to ...
, who died in 796 AD.
An early timber and earth fortification might later be succeeded by a brick or stone structure on the same site.
Trenches were used by besieging forces to approach a fortification while protected from missiles.
Sappers would build "saps", or trenches, that zig-zagged towards the fortress being attacked.
They piled the excavated dirt to make a protective wall or gabion. The combined trench depth and gabion height might be .
Sometimes the sap was a tunnel, dug several feet below the surface. Sappers were highly skilled and highly paid due to the extreme danger of their work.
In the
American Civil War
The American Civil War (April 12, 1861 – May 26, 1865; also known by other names) was a civil war in the United States. It was fought between the Union ("the North") and the Confederacy ("the South"), the latter formed by states th ...
(1861−1865) trenches were used for defensive positions throughout the struggle, but played an increasingly important role in the campaigns of the last two years.
Military earthworks perhaps culminated in the vast network of trenches built during
World War I
World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fightin ...
(1914−1918) that stretched from
Switzerland
). Swiss law does not designate a ''capital'' as such, but the federal parliament and government are installed in Bern, while other federal institutions, such as the federal courts, are in other cities (Bellinzona, Lausanne, Luzern, Neuchâtel ...
to the
North Sea
The North Sea lies between Great Britain, Norway, Denmark, Germany, the Netherlands and Belgium. An epeiric sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the Norwegian S ...
by the end of 1914.
The two lines of trenches faced each other, manned by soldiers living in appalling conditions of cold, damp and filth.
Conditions were worst in the Allied trenches. The Germans were more willing to accept the trenches as long-term positions, and used concrete blocks to build secure shelters deep underground, often with electrical lighting and heating.
Embankment dams
An
embankment dam
An embankment dam is a large artificial dam. It is typically created by the placement and compaction of a complex semi-plastic mound of various compositions of soil or rock. It has a semi-pervious waterproof natural covering for its surface and ...
is a massive artificial
water barrier. It is typically created by the emplacement and
compaction of a complex semi-
plastic
Plastics are a wide range of synthetic or semi-synthetic materials that use polymers as a main ingredient. Their plasticity makes it possible for plastics to be moulded, extruded or pressed into solid objects of various shapes. This adaptab ...
mound of various compositions of soil, sand, clay and/or rock. It has a semi-permanent natural waterproof covering for its surface, and a dense, waterproof core. This makes such a dam impervious to surface or
seepage
Soil mechanics is a branch of soil physics and applied mechanics that describes the behavior of soils. It differs from fluid mechanics and solid mechanics in the sense that soils consist of a heterogeneous mixture of fluids (usually air and wat ...
erosion
Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is distin ...
.
The force of the impoundment creates a downward thrust upon the mass of the dam, greatly increasing the weight of the dam on its foundation. This added force effectively seals and makes waterproof the underlying foundation of the dam, at the interface between the dam and its
stream bed
A stream bed or streambed is the bottom of a stream or river (bathymetry) or the physical confine of the normal water flow (Channel (geography), channel). The lateral confines or channel margins are known as the stream Bank (geography), banks ...
.
Such a dam is composed of fragmented independent material particles.
The friction and interaction of particles binds the particles together into a stable mass rather than by the use of a cementing substance.
The
Syncrude Mildred Lake Tailings Dyke in
Alberta
Alberta ( ) is one of the thirteen provinces and territories of Canada. It is part of Western Canada and is one of the three prairie provinces. Alberta is bordered by British Columbia to the west, Saskatchewan to the east, the Northwest Ter ...
, Canada, is an embankment dam about long and from high. By volume of fill, as of 2001 it was believed to be the largest earth structure in the world.
Structural Issues
Designing for Earthquakes
Regions with low seismic risk are safe for most earth buildings, but historic construction techniques often cannot resist even medium earthquake levels effectively because of earthen buildings' three highly undesirable qualities as a seismic building material: being relatively 'weak, heavy and brittle'. However, earthen buildings can be built to resist seismic loads.
Key factors to improved seismic performance are soil strength, construction quality, robust layout and seismic reinforcement.
Stronger soils make stronger walls. Adobe builders can test cured blocks for strength by dropping from a specific height or by breaking them with a lever. Builders using immediate techniques like earthbag, cob, or rammed earth may prefer approximate crushing tests on smaller samples that can be oven-dried and crushed under a small lever.
Builders must understand construction processes and be able to produce consistent quality for strong buildings.
Robust layout means buildings more square than elongated, and symmetrical not L-shaped, as well as no 'soft' first stories (stories with large windows, buildings on unbraced columns). New Zealand's earthen building guidelines check for enough bracing wall length in each of the two principal directions, based on wall thickness, story height, bracing wall spacing, and the roof, loft and second story weight above earthen walls.
Seismic-Resistant Construction Techniques
Building techniques that are more ductile than brittle, like the
contained earth
Contained earth (CE) is a structurally designed natural building material that combines containment, inexpensive reinforcement, and strongly cohesive earthen walls. CE is earthbag construction that can be calibrated for several seismic risk levels ...
type of earthbag, or tire walls of
earthships
An Earthship is a style of architecture developed in the late 20th century to early 21st century by architect Michael Reynolds. Earthships are designed to behave as passive solar earth shelters made of both natural and upcycled materials such ...
, may better avoid collapse than brittle unreinforced earth. Contained gravel base courses may add
base isolation
Seismic base isolation, also known as base isolation, or base isolation system, is one of the most popular means of protecting a structure against earthquake forces. It is a collection of structural elements which should substantially decoup ...
potential.
Wall containment can be added to techniques like adobe to resist loss of material that leads to collapse. Confined masonry is effective for adobe against quake forces of 0.3 g may be useful with earthen masonry.
Many types of reinforcement can increase wall strength, such as plastic or wire mesh and reinforcing rods of steel or fiberglass or bamboo. Earth resists compression well but is weak when twisted. Tensile reinforcement must span potential damage points and be well-anchored to increase out-of-plane stability. Bond beams at wall tops are vital and must be well attached to walls.
Builders should be aware that organic reinforcements embedded in walls may be destroyed before the building is retired. Attachment details of reinforcement are critical to resist higher forces. Best adobe shear strength came from horizontal reinforcement attached directly to vertical rebar spanning from footing to bond beam.
Interlaced wood in earthen walls reduces quake damage if wood is not damaged by dry rot or insects. Timberlacing includes finely webbed Dhajji, and other types.
[Langenbach, Rudolp]
Earthquake Resistant Traditional Construction is not an Oxymoron
Bhutan International Conference on Disaster Management and Cultural Heritage, 12–14 December 2010
See also
![Mud house](https://upload.wikimedia.org/wikipedia/commons/7/7e/Mud_house.JPG)
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* , sometimes considered earthen architecture
*
* , Chinese cave dwellings
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{{good article
Construction
Building materials
Sustainable building
Appropriate technology
Natural materials
Soil
Sustainable architecture
Buildings and structures by type
Earthworks (engineering)