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An earth structure is a building or other structure made largely from soil. 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, or mud mixed with straw to make cob. Sturdy dwellings may be also built from sod or turf. Soil may be stabilized by the addition of lime or cement, and may be compacted into rammed earth. Construction is faster with pre-formed adobe or mudbricks, compressed earth blocks, 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 lodges are examples. Wattle and daub houses use a "wattle" of poles interwoven with sticks to provide stability for mud walls. Sod houses 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 that shelter as many as 80 families. Other types of earth structure include mounds and pyramids used for religious purposes, levees, mechanically stabilized earth retaining walls, forts, trenches and embankment dams. ==Soil== Soil is created from rock that has been chemically or physically weathered, transported, deposited and precipitated. Soil particles include sand, silt and clay. 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, calcite, feldspar and mica. Clays typically are phyllosilicate 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 do not expand or contract when wetted or dried, and are useful for brick-making. Others, such as smectites, expand or contract considerably when wet or dry, and are not suitable for building. Loam 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, Egypt and Mesopotamia, in the Indus, Ganges and Yellow river valleys, in Central and South America. 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, typically using sun-dried bricks made of a mud and straw mixture. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Earth structure」の詳細全文を読む スポンサード リンク
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