SEMINAR REPORT OF NATURAL BUILDING MATERIALS

ABSTRACT

Building materials can be generally categorized into two sources, natural and synthetic. Natural building materials are those that are unprocessed or minimally processed by industry, such as lumber or glass.
Mud, stone, and fibrous plants are the most basic building materials, aside from tents made of flexible materials such as cloth or skins. People all over the world have used these three materials together to create homes to suit their local weather conditions. In general stone and/or brush are used as basic structural components in these buildings, while mud is used to fill in the space between, acting as a type of concrete and insulation.
A basic example is wattle and daub mostly used as permanent housing in tropical countries or as summer structures by ancient northern people. Other examples are brush structures, rock structures, wooden structures, Thatch structures, Mud and clay structures, Ice structures, etc.   





INTRODUCTION

Building material is any material which is used for a construction purpose. Many naturally occurring substances, such as clay, sand, wood and rocks, even twigs and leaves have been used to construct buildings. Using natural building materials lowers the cost of construction, enabling anyone to build and afford their own Eco-friendly home. Natural materials have been the number one preference of home-builders since the beginning of human history. The reason they used natural materials is because there are so many benefits. First of all, most of the materials are dirt cheap: sand from nearby streams or river beds, straw bales from local farmers, clay free for the digging and so on. Natural building materials such as earth, stone and straw are sustainable, safe, nontoxic, and easy to work with, and only require minimal tools and basic skills. And as far as beauty, there's no comparison. A home built of natural materials is more like a work of art that's personalized to match your lifestyle and needs.
Apart from naturally occurring materials, many man-made products are in use, some more and some less synthetic. The manufacture of building materials is an established industry in many countries and the use of these materials is typically segmented into specific specialty trades, such as carpentry, plumbing, roofing and insulation work. This reference deals with habitats and structures including homes.

CONSTRUCTION WITH NATURAL MATERIALS

1.WATTLE AND DAUB

Wattle and daub is a building material used for making walls, 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 and straw. Wattle and daub has been used for at least 6,000 years, and is still an important construction material in many parts of the world. Many historic buildings include wattle and daub construction, and the technique is becoming popular again in more developed areas as a low-impact sustainable building technique.

CONSTRUCTION

The wattle is made by weaving thin branches (either whole or more usually split) or slats between upright stakes. The wattle may be made as loose panels, slotted between timbers framing to make infill panels, or it may be made in place to form the whole of a wall.

Daub is generally created from a mixture of certain ingredients from three categories: binders, aggregates and reinforcement. Binders hold the mix together and can include clay, lime, chalk dust and limestone dust. Aggregates give the mix its bulk and dimensional stability through materials such as earth, sand, crushed chalk and crushed stone. Reinforcement is provided by straw, hair, hay or other fibrous materials, and helps to hold the mix together as well as to control shrinkage and provide flexibility. The daub may be mixed by hand, or by treading – either by humans or livestock. It is then applied to the wattle and allowed to dry, and often then whitewashed to increase its resistance to rain.

This process is similar in modern architecture to lath and plaster, a common building material for wall and ceiling surfaces, in which a series of nailed wooden strips are covered with plaster smoothed into a flat surface. In some regions this building method has itself been overtaken by drywall construction using plasterboard sheets.

WATTLE &DAUB HOUSE USED BY AMERICAN INDIANS DURING MISSISSIPPIAN PERIOD.

The wattle and daub technique was used already in the Neolithic. It was common for houses of the Linearbandkeramic and Rössen cultures of Central Europe, but is also found in Western Asia as well as in North America (Mississippian Culture) and South America (Brazil). Its usage dates back at least 6000 years. There are suggestions that construction techniques such as lath and plaster and even cob may have evolved from the practicality of wattle and daub. Fragments from prehistoric wattle and daub buildings have been found in Africa, Europe, Mesoamerica and North America Shaffer, G.D.

2.MUD AND CLAY

The amount of each material used leads to different styles of buildings. The deciding factor is usually connected with the quality of the soil being used. Larger amounts of clay usually mean using the cob/adobe style, while low clay soil is usually associated with sod building. The other main ingredients include more or less sand/gravel and straw/grasses. Rammed earth is both an old and newer take on creating walls, once made by compacting clay soils between planks by hand; now forms and mechanical pneumatic compressors are used.

Earthen walls change temperature slowly, so artificially rising or lowering the temperature can use more resources than in say a wood built house, but the heat/coolness stays longer.

Peoples building with mostly dirt and clay, such as cob, sod, and adobe, resulted in homes that have been built for centuries in western and northern Europe as well as the rest of the world, and continue to be built, though on a smaller scale. Some of these buildings have remained habitable for hundreds of year.


ADVANTAGES&DISADVANTAGES

  ADVANTAGE:
Wattle & Daub is elegant and fine for Seismic Zones

DISADVANTAGE

Wattle and daub is vulnerable to damp. If not kept dry, wattles have a tendency to rot, or be attacked by beetles causing the daub to crack or become loose due to becoming exposed to moisture and frost. This factor caused wattle and daub structures to be draughty and required constant repair of the panels

CITADEL & MUD CITY OF BAM

Located in south-eastern Iran, 200 kilometers south of Kerman, the ruined city of Arg-e-Bam is made entirely of mud bricks, clay, straw and the trunks of palm trees. The city was originally founded during the Sassanian period (224-637 AD) and while some of the surviving structures date from before the 12th century, most of what remains was built during the Safavid period (1502-1722). During Safavid times, the city occupied six square kilometers, was surrounded by a rampart with 38 towers, and had between 9000 and 13,000 inhabitants. Bam declined in importance following an invasion by Afghans in 1722 and another by invaders from the region of Shiraz in 1810. The city was used as a barracks for the army until 1932 and then completely abandoned. Intensive restoration work began in 1953 and continues today.

CONSTRUCTION

The main entry portal of the citadel is found along the third wall, just north of the middle-class neighborhood (shahrestan) and east of the military stables which are encircled by the "second" wall. Entering through this portal, one continues north up a steep incline to the gateway in the "fourth" wall. Turning to the west from this gateway, one enters the two-level military barracks, with the 31.5 meter deep well in its southeast corner. The barracks, also called the armory, were used for artillery storage. Proceeding south from the barracks, one enters the military stables with its rock-lined well (28 meters deep, also in its southeast corner). One of the largest structures in the complex, the stable measures 60 x 70 meters, and dates from the Mughal period (1220-1380). The stable courtyard is lined with mangers, and the stables themselves are topped by a total of 46 domes.

ADVANTAGES&DISADVANTAGES

  ADVANTAGES
Clay is very good at keeping temperatures at a constant level.
Clay holds heat or cold, releasing it over a period of time like stone.
The use of mud in building provides a good acoustic and insulation.


DISADVANTAGES.
Buildings that incorporate the use of clay are particularly vulnerable to deterioration and deserving of care and maintenance.
It requires excessive dependence on manual labour (“work intensive").


3.ROCK

Rock structures have existed for as long as history can recall. It is the longest lasting building material available, and is usually readily available. There are many types of rock throughout the world all with differing attributes that make them better or worse for particular uses. Rock is a very dense material so it gives a lot of protection too, its main draw-back as a material is its weight and awkwardness. Its energy density is also considered a big draw-back, as stone is hard to keep warm without using large amounts of heating resources.

Dry-stone walls have been built for as long as humans have put one stone on top of another. Eventually different forms of mortar were used to hold the stones together, cement being the most commonplace now.

The granite-strewn uplands of Dartmoor National Park, United Kingdom, for example, provided ample resources for early settlers. Circular huts were constructed from loose granite rocks throughout the Neolithic and early Bronze Age, and the remains of an estimated 5,000 can still be seen today. Granite continued to be used throughout the medieval period and into modern times. Slate is another stone type, commonly used as roofing material in the United Kingdom and other parts of the world where it is found.

Mostly stone buildings can be seen in most major cities, some civilizations built entirely with stone such as the Pyramids in Egypt, the Aztec pyramids and the remains of the Inca civilization. Example for rock structure is Dartmoor longhouse in the south west of the United Kingdom

DARTMOOR LONGHOUSE

The Dartmoor longhouse is a type of traditional home, found on the high ground of Dartmoor, in the south west of the United Kingdom. The earliest are thought to have been built in the 13th century, and they continued to be constructed throughout the medieval period, using local granite. Many longhouses are still inhabited today (although obviously adapted over the centuries), while others have been converted into farm buildings.

CONSTRUCTION
The Dartmoor longhouse consists of a long, single-storey granite structure, with a central 'cross-passage' dividing it into two rooms, one to the left of the cross-passage and the other to the right. The one at the higher end of the building was occupied by the human inhabitants; their animals were kept in the other, especially during the cold winter months. The animal quarters were called the 'shippon' or 'shippen'; a word still used by many locals to describe a farm building used for livestock. They sheltered both people and cattle under a single roof. These single storey stone-built houses were, as their name suggests, long rectangular structures, built into a hill slope and essentially divided into two by opposing doors about halfway down their long sides, thus creating a passage across the width of the building. On the lower side of this cross passage was the area given over to the shelter of cattle, known as a shippon; the excavations revealed a drain running down the center of the shippon, exiting through a hole in the end wall - and the location of wooden posts just inside the long, side walls. The cattle would thus have been tethered with their faces to the long walls and their rear ends over the drain. The higher end of the longhouse, that occupied by people, was usually divided into two unequal halves; the larger room, next to the cross passage, contained a hearthstone on which an open fire would have burned; the smaller room, buried into the hillside and known as the inner room, was unheated and its purpose remains unclear. The construction of these longhouses has been dated to about AD1250 and they probably went out of use around AD1400.

4. THATCH


Thatch is one of the oldest of building materials known; grass is a good insulator and easily harvested. Many African tribes have lived in homes made completely of grasses year round. In Europe, thatch roofs on homes were once prevalent but the material fell out of favour as industrialization and improved transport increased the availability of other materials. Today, though, the practice is undergoing a revival. In the Netherlands, for instance, many new buildings have thatched roofs with special ridge tiles on top.

THE CHIEF’S HOUSE ON SAN LUIS

The chief’s house was equally impressive at 70 feet in diameter (typical Apalachee houses measured between 18-24 feet in diameter).  The chief’s house was a round, pole and thatch building. It contained a single row of sleeping benches around the wall and a central hearth.

CONSTRUCTION
The grass after removing the leaf growth from the lower two thirds of the stalks is remade into bundles. It is butted against a butting board, or on level ground, to ensure that the butt end is even and that any sharp ends are blunted.. The grass is used in bundles as cut and laid on the roof with the butt end lowest. As each bundle is laid on the roof the Thatcher cuts through the twisted grass or twine that secures it.  Then the first bundle on the corner is laid, at an angle of at least 45°, thus exposing the butt end at the eaves and at the verge. Each bundle in the first course at eaves level is secured to the second batten with tarred sisal cord ¬thatching twine at 75 mm intervals. The thatch is laid, two bundles thick, to a total minimum thickness of 150mm. Each successive layer conceals the poplar stick or wire that secures the previous layer. As thatching proceeds a layer of selected stems is spread evenly on the roof battens to a thickness of about 12mm. This gives a neat appearance inside the roof. On top of this layer a laminated foil of aluminum and building paper reinforced with fiberglass is laid as a protection against fire. Thatching then proceeds, course by course, to the ridge level until complete.
ADVANTAGES
A thatched roof will normally last for about 25-30 years if properly laid.
      DISADVANTAGES
 A disadvantage of using such a ridge is that it will require renewal every 4-6 years.
As maintenance of a thatched roof invariably results in dust and pieces of straw being dislodged from the roof, led for other building purposes.

5. BRUSH

Brush structures are built entirely from plant parts and are generally found in tropical and sub-tropical areas, such as rain forests, where very large leaves can be used in the building. Native Americans often built brush structures for resting and living in, too. These are built mostly with branches, twigs and leaves, and bark, similar to a beaver's lodge. These were variously named wikiups, lean-tos, and so forth. An example of brush structure is Hut of Toda tribe (Nilgiris, India).


TODA TRIBAL HUT


The Toda people are a small pastoral tribe of less than 1,000 people who reside in the Nilgiri hills of Southern India. Shown here is a typical Toda hut, about 3 m (10 ft.) high, 5.5 m (18 ft.) long and 2.7 m (9 ft.) wide. They are built of bamboo fastened with rattan and thatched. The hut has only a tiny (about 0.9 x 0.9 m, 3 x 3 ft.) entrance at the front, which serves as protection from wild animals.

CONSTRUCTION
The Toda huts, of an oval, pent-shaped construction, are usually 10 feet (3 m) high, 18 feet (5.5 m) long and 9 feet (2.7 m) wide. They are built of bamboo fastened with rattan and thatched. Each hut is enclosed within a wall of loose stones. The front and back of the hut are usually made of dressed stones (mostly granite). Hut has only a tiny entrance at the front – about 3 feet (90 cm) wide, 3 feet (90 cm) tall. This unusually small entrance is a means of protection from wild animals. The front portion of the hut is decorated with the Toda art forms, a kind of rock mural painting. Thicker bamboo canes are arched to give the hut its basic pent shape. Thinner bamboo canes are tied close and parallel to each other over this frame. Dried grass is stacked over this as thatch.



ADVANTAGES
Its construction is very economical.
DISADVANTAGES
It requires constant maintenance.

6. ICE

Ice was used by the Inuit for igloos, but has also been used for ice hotels as a tourist attraction in northern areas that might not otherwise see many winter tourists.

IGLOOS

An igloo or snow house is a type of shelter built out of snow, originally built by the Inuit. Iglu is the Inuit word for a house or home built out of any material, and is not restricted exclusively to snow houses, but includes traditional tents, sod houses, homes constructed of driftwood and modern buildings. Outside of Inuit society, however, "igloo" refers exclusively to shelters constructed out of blocks of compacted snow, generally in the form of a dome.

Although igloos are usually associated with all Inuit, they were predominantly constructed by people of Canada's Central Arctic and Greenland's Thule area. Other Inuit people tended to use snow to insulate their houses, which were constructed from whalebone and hides. Snow is used because the air pockets trapped in it make it an insulator. On the outside, temperatures may be as low as −45 °C (−49.0 °F), but on the inside the temperature may range from −7 °C (19 °F) to 16 °C (61 °F) when warmed by body heat alone.

TRADITIONAL TYPES OF IGLOOS

There are three traditional types of igloos, all of different sizes and all used for different purposes.

* The smallest was constructed as a temporary shelter, usually only used for one or two nights. These were built and used during hunting trips, often on open sea ice.
* The next in size was the semi-permanent, intermediate-sized family dwelling. This was usually a single room dwelling that housed one or two families. Often there were several of these in a small area, which formed an Inuit village.
* The largest of the igloos was normally built in groups of two. One of the buildings was a temporary structure built for special occasions, the other built nearby for living. These might have had up to five rooms and housed up to 20 people. A large igloo might have been constructed from several smaller igloos attached by their tunnels, giving common access to the outside. These were used to hold community feasts and traditional dances.

CONSTRUCTION

The snow used to build an igloo must have sufficient structural strength to be cut and stacked in the appropriate manner. The best snow to use for this purpose is snow which has been blown by wind, which can serve to compact and interlock the ice crystals. The hole left in the snow where the blocks are cut from is usually used as the lower half of the shelter. Sometimes, a short tunnel is constructed at the entrance to reduce wind and heat loss when the door is opened. Due to snow's excellent insulating properties, inhabited igloos are surprisingly comfortable and warm inside. In some cases a single block of ice is inserted to allow light into the igloo.

Architecturally, the igloo is unique in that it is a dome that can be raised out of independent blocks leaning on each other and polished to fit without an additional supporting structure during construction. The igloo, if correctly built, will support the weight of a person standing on the roof. Also, in the traditional Inuit igloo the heat from the kudlik (qulliq) (stone lamp) causes the interior to melt slightly. This melting and refreezing builds up a layer of ice that contributes to the strength of the igloo.

The sleeping platform is a raised area. Because warmer air rises and cooler air settles, the entrance area acts as a cold trap whereas the sleeping area will hold whatever heat is generated by a stove, lamp or body heat.

The Central Inuit, especially those around the Davis Strait, lined the living area with skin, which could increase the temperature within from around 2 °C (36 °F) to 10–20 °C (50–68 °F).

ICE HOTELS

An ice hotel is a temporary hotel made up of snow, sculpted blocks of ice, and some steel framing. They are promoted by their sponsors and have special features for travellers who are interested in novelties and unusual environments, and thus are in the class of destination hotels. Their lobbies are often filled with ice sculptures, and food and beverages are specially chosen for the circumstances.

All of the ice hotels are reconstructed every year, and are dependent upon constant sub-freezing temperatures during construction and operation. The walls, fixtures, and fittings are made entirely of ice, and are held together using a substance known as snice, which takes the place of mortar in a traditional brick-built hotel.

ADVANTAGES
IGLOO can provide complete protection from extreme weather.


DISADVANTAGES
IGLOO can take 2-5 hours to build, difficult for the inexperienced.
The main disadvantage of ice structure is it melts away in the summer.

7. WOOD

Wood is a product of trees, and sometimes other fibrous plants, used for construction purposes when cut or pressed into lumber and timber, such as boards, planks and similar materials. It is a generic building material and is used in building just about any type of structure in most climates. Wood can be very flexible under loads, keeping strength while bending, and is incredibly strong when compressed vertically. There are many differing qualities to the different types of wood, even among same tree species. This means specific species are better for various uses than others. And growing conditions are important for deciding quality.

Historically, wood for building large structures was used in its unprocessed form as logs. The trees were just cut to the needed length, sometimes stripped of bark, and then notched or lashed into place.

In earlier times, and in some parts of the world, many country homes or communities had a personal wood-lot from which the family or community would grow and harvest trees to build with. These lots would be tended to like a garden.

With the invention of mechanizing saws came the mass production of dimensional lumber. This made buildings quicker to put up and more uniform. Thus the modern western style home was made.

KIZHI WOODEN CHURCH, RUSSIA

Russia's wooden churches often perched on hilltops, overlooking the forests and villages. Although the walls were crudely constructed of rough-hewn logs, the roofs were often complex. Onion shaped domes, symbolizing heaven in the Russian Orthodox tradition, were covered with wooden shingles. The onion domes reflected Byzantine design ideas and were strictly decorative. They were constructed of wood framing and served no structural function.
Located at the northern end of Lake Onega near St. Petersburg, the island of Kizhi (also spelled "Kishi" or "Kiszhi") is famous for its remarkable array of wooden churches. Early mention of the Kizhi settlements are found in chronicles from the 14th and 15th century. In 1960, Kizhi became home to an open-air museum for the preservation of Russia's wooden architecture. Restoration work was supervised by the Russian architect, Dr. A. Opolovnikov.

CONSTRUCTION
The wooden Cathedral is large. It Is 65.72 meters long, 18.72 meters broad and 25.82 meters at the transept. A daring enterprise for that time. The most interesting aspect is the use of wood for construction and decoration, including greenheart for the construction and cedar for the interior.
ADVANTAGES
Log houses are known as prestigious, eco – friendly and healthy houses.
Resin marks that remain in the log’s structure have a benefice impact on the respiratory system of those who inhabit these types of houses.
Logs help keep a balance of the moisture in the house, thus, if it raises, the walls begin to absorb it. If the environment becomes too dry, then the wood will restore the humidity. Contrary to other types of houses, the air from wooden constructions never gets too dry.
Wood’s ability to retain and restore humidity helps maintain a constant temperature indoors.
The logs from the house’s structure “breathe” thus; there is no need for an air conditioning system, the house already having a natural ventilation system.
There is no dust in log houses. Wood’s electrostatic properties don’t allow the formation and accumulation of dust in the rooms.
Wood is a sustainable building material. Put together in a correct manner, they can last for centuries. In Siberia and other Scandinavian countries there are wooden houses for 600 years, in perfect condition.
Developed using modern technologies, their sustainability can raise considerably.
Wooden walls have isolative proprieties. In Siberia, where temperatures drop below 40 degrees in winter, not long ago, people lived in wood houses with walls 25-30cm thick. A wall this thick has a isolative capacity equal to that of a concrete wall. The walls keep the warmth and distribute in gradually around the house. Thus, the room’s temperature is the same as that of the wall’s. This creates comfort in this type of houses.
Dry wood is a good sound isolator. Its physical properties ensure good sound absorption and prevent its distribution. Wood is also known for its ability to absorb and minimise vibration.

DISADVANTAGES

One of the substantial problem, and one of the worst for log homes, is that they are ideal places for a number of insects to make their homes, raise their young, and feed on the wood pulp. Termites are always a threat, and can cause severe damage to logs prior to their discovery.
Moisture can affect log homes in two ways---the first from moisture build-up, and the second from the wood drying out. Moisture can easily be trapped in the wood if a finish is applied to wet logs, halting the ability for the wood to breathe properly. Splits or cracks can also trap water from rain or sprinklers and lead to decay and rot. When logs dry out due to lack of proper protective sealant, the logs can shrink, warp and twist, and allow small gaps to form in the walls around doors, windows and other seams.
Log homes require more maintenance and upkeep than other home types. Finishes and sealants need to be regularly applied to the wood to fight moisture buildup, prevent the wood from drying out, and guard against decay or splitting. The constant need to apply new coats of stain and sealant can become pricey over time, adding much expense to an already costly investment.

8.RAMMED EARTH

Rammed earth is an earth-based wall system made of compacted gravel, sand, and clay; that is extremely strong and durable. Quality rammed earth walls are dense, solid, and stone-like with great environmental benefits and superior low maintenance characteristics. As an option depending on climate or seismic concerns rigid insulation can be placed inside the wall as well as steel reinforcement. Rammed earth has been used for around 10,000 years in all types of buildings from low rise to high-rise and from small huts to palaces.
Rammed earth walls are formed in place by pounding damp sub-soil (gravel, sand, and clay) into movable, reusable forms with manual or machine-powered tampers. A mixture of around 70% aggregate (gravel, sand) and 30% clay is optimal. Cement may be added if the mix requires it or pigmentation to achieve the desired colour. Around 5-10 inches of mixed damp sub-soil are placed inside the forms and pounded to total compaction and the process is repeated until the desired height is achieved. What is left after the forms are removed is a wall that is structural and can last over 1000 years.

ADVANTAGES&DISADVANTAGES

ADVANTAGES
It is a perfect choice for every weather: Due to the thickness of the wall and the characteristics of rammed earth, it provides protection to extreme weathers. It stays cool in summer and warm in winters, perfect to reduce your electricity bills.
Proof against flames of fire: The materials in rammed earth are completely fir proof. And, if you combine it with a steel roof, the protection against the fire is 100%
Will not be eaten by termites: There is no material used on which termites can feed.
Soundproofing: The qualities or rammed earth cut out all the noises that come un-invited into your homes.
It provides strength: It is strong, which explains why some parts of Great Wall of China were built in rammed earth.
Requires less maintenance: There is never a need to re-do the rammed earth walls in any way, as it has the inherent quality of water resistance.
It is programmed to bear load: It is capable of bearing load and you can envision number of features and floors when you are planning on a rammed earth house.
Disaster proof: It is ideal for cyclone prone areas, and earthquake zones also have a place for these types of housing.
Humidity Controller: It controls humidity where walls contain clay exposed to internal space. It is successful in controlling humidity till 40%-60%.
Economically feasible: The material is naturally available and does not also involve the cost of plastering, tiling etc.
Variety: It provides for variety in the look and the fell of the house, due to the usage of a different material.
DISADVANTAGES
We cannot create sculptural shaped walls as you would be able to with other materials.
The material stays warm in winters, but in severely cold climates you will need an insulating layer like a foam layering.
Though not involving the costs of other materials, it will add up the costs of intensive labouring processes that it requires, due to the extent of details and technicalities one has to pay attention to.
Designing a Rammed Earth Home
Preparing the material: The right type of soil is needed. It needs to be sandy between 50%-75%. Too much clay should not be used as the wall can shrink and crack. Sieve the soil selected to separate other impurities like leaves; stones etc. spread a cover on the material, as it will prevent it from precipitation. If the soil will contain more than 10% moisture, it will puddle. To test it, make a ball of the material and drop it, when you do so it should hold its shape. If you have kept your material homogeneous by following the above steps, the turn is to change the material into sandstone with the help of pressure.
Build the Foundation: Lay the foundation carefully and properly so that the walls have a strong base to stand on.
Then is the turn to ram the earth for the walls: 3-10% of Portland cement is mixed with the material for stabilization. The wall depths will be from 18 to 36 inches. However in two story buildings the first story walls are wider. Walls will definitely include a framework as well.
After the walls, the turn is to lay the roof

9. ADOBE

Adobe is one of the oldest building materials in use. It is basically just dirt that has been moistened with water, sometimes with chopped straw or other fibers added for strength, and then allowed to dry in the desired shape. Commonly adobe is shaped into uniform blocks that can be stacked like bricks to form walls, but it can also be simply piled up over time to create a structure. The best adobe soil will have between 15% and 30% clay in it to bind the material together, with the rest being mostly sand or larger aggregate. Too much clay will shrink and crack excessively; too little will allow fragmentation. Sometimes adobe is stabilized with a small amount of cement or asphalt emulsion added to keep it intact where it will be subject to excessive weather. Adobe blocks can be formed either by pouring it into moulds and allowing it to dry or it can press into blocks with a hydraulic or leverage press. Adobe can also be used for floors that have resilience and beauty, coloured with a thin slip of clay and polished with natural oil.
Adobe buildings that have substantial eaves to protect the walls and foundations to keep the adobe off the ground will require less maintenance than if the walls are left unprotected. Some adobe buildings have been plastered with Portland cement on the outside in an attempt to protect the adobe, but this practice has led to failures when moisture finds a way through a crack in the cement and then can't readily evaporate. When adobe is used as an exterior plaster it is either stabilized or re plastered on a regular basis.

Construction
It has a rectangular plan, single door, and small lateral windows are predominant. Quality of construction in urban areas is generally superior to that in rural areas. The foundation, if present, is made of medium to-large stones joined with mud or coarse mortar. Walls are made with adobe blocks joined with mud mortar. Sometimes straw or wheat husk is added to the soil used to make the blocks and mortar. The size of adobe blocks varies from region to region. In traditional constructions, wall thickness depends on the weather conditions of the region. Thus, in coastal areas with a mild climate, walls are thinner than in the cold highlands or in the hottest deserts. The roof is made of wood joists (usually from locally available tree trunks) resting directly on the walls or supported inside indentations on top of the walls. Roof covering may be corrugated zinc sheets or clay tiles, depending on the economic situation of the owner and the cultural inclinations of the region. A traditional adobe house that exhibits good seismic behaviour is the bhonga type.
ADVANTAGES
Adobe is a good thermal mass material, holding heat and cool well.
ADOBE or SUN DRIED BRICKS can easily cope with two storey houses.
DISADVANTAGES
It does not insulate very well, so walls made of adobe need some means of providing insulation to maintain comfort in the building. Sometimes this is accomplished by creating a double wall, with an air space, or some other insulation in between. Another approach is placing insulating materials on the outside.

Comments 1 comment

Anadirunika 3 years ago

Эргономичность. Под этим непонятным русскому слуху словом понимается всего лишь удобность мобильного телефона, да и любого другого устройства для пользователя. Хотя подоплека, конечно, более сложная, чем простое удобство. Есть такая наука – эргономика, которая занимается изучением затрат энергии человеческого тела при определенных движениях по управлению техническими средствами. На практике это выглядит следующим образом: покупая дешевый телефон, производители которого поскупились при разработке на расчеты эргономики, вы рискуете затратить на несколько движений пальцами больше, чем обладатель досконально проработанного аппарата для доступа к одной и той же функции. Это не раздражает только в одном случае, когда вы носите телефон в роли украшения. Если же вы решите воспользоваться им по назначению, может оказаться что поиск в ваших контактах организован не очень удачно, и пока вы будете искать нужного вам абонента перебирая клавишами меню одного за другим, может оказаться что звонить ему уже и незачем.

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