Loam is part of the upper area of the solid earth‘s crust which has been transformed over millennia under the influence of weather, flora and fauna (cf. Schroder 2018: 62). During soil formation, breakdown products of inorganic and organic substances are converted and built up into new components that are characteristic for the […]
Loam is part of the upper area of the solid earth‘s crust which has been transformed over millennia under the influence of weather, flora and fauna (cf. Schroder 2018: 62). During soil formation, breakdown products of inorganic and organic substances are converted and built up into new components that are characteristic for the particular soil. While the humus-rich A-horizon forms the basis for vegetation and agriculture, suitable building soil can be taken from the lighter colored, humus-free B-horizon. There are four main types of mineral soils: gravel, sand, silt and loam. These main types of soil are mostly mixed, so loams are typical mixed-grain soils. Clay acts as a binding material between the coarse-grained components (gravel, sand, silt). Depending on the clay content, a distinction is made between cohesive and non-cohesive loam (cf. Schroder 2018: 62). Climatic regions and geological foundations determine the different composition and the resulting varying potentials of loam as a building material. But in general, loam is available almost everywhere because the formation process is similar all over the world.
Loam has always served humans as a building material.
10,000 BC, mankind‘s form of food procurement changed from hunting and gathering to agriculture and animal farming. This requires solid dwellings, constructed largely of wood, natural stone and earth. Loam is used either as a solid construction, i.e. in a load-bearing function, or as a skeleton construction in combination with wood. The construction methods depend on the climatic region and given wood resources. These methods can be traced back thousands of years in history worldwide. The first solid house constructions, were discovered by archaeologists, in southwestern Asia, in the areas of today‘s Turkey / Iran. The oldest house constructions made of loam were found in Catal Höyük, today‘s Anatolia (cf. Schroeder 2018: 2). Loam is also a widesused building material in China. Techniques such as the rammed earth construction or the construction with mud bricks have been known here for thousands of years. The Great Wall of China was partly built using loam among other materials (cf. Schroeder 2018: 4).
Another classic loam building country is Ancient Egypt.
The annual flooding of the Nile brings fertile mud, which dries to become firm and can then be processed into bricks. Egyptian representations from around 1500 BCE show the necessary steps in the production of loam bricks. The importance of this activity is additionally illustrated by symbolic images. For example, the reigning queen Hatshepsut is shown as a master builder in the production of mudstones (cf. Schroeder 2018: 5-6).
The Tower of Babel (Old Testament, Genesis 11:3) was also built from mudstones. This category of buildings included other large religious structures such as ziggurats as well. They were comparable in size and shape to the Egyptian pyramids and built in the area of today‘s Iran around 1500 B.C. The first written instructions on building with loam date to the time of Babylonian ruler Hammurabi, who lived around 1800 BCE (cf. Schroeder 2018: 6).
Various earthen building techniques were also known on the American continent, e.g. in pre-Columbian Peru.
Several million loam bricks were used for the construction of the Pyramid of the Sun in Moche (ca. 200-500 CE) (cf. Schroeder 2018: 8).
The original earthen building techniques have gotten lost over time. They have been replaced progressively by modern building materials such as concrete and cement. Even in the poorest countries of the global south, the traditional building material loam is being increasingly replaced (cf. Schroeder 2018: 10).
There are different way of how loam can be used as building material. First of all, there are different types of loam to distinguish from.
Soil can either be taken from its natural deposits or used as recycled material that has flown back into the material cycle. Depending on the mineralogical composition, this results in different plastic properties. The raw material loam can be divided into four categories: pit loam, dry loam, recycled loam and compressed loam. Pit loam, a grown geological raw material, can be taken directly from its natural deposits. It can be used in unprofessional do-it-yourself construction, but is mostly used for further processing into other building materials out of earth. Dry loam consists usually of dried pit loam, which is then ground and sold in the form of powder. Dry loam is free from gravel and sand, and it is often used for plasters. Recycled loam is obtained from demolished structures and fed back into the material cycle. Most of the time, the regained building material is crushed and ground before it is used again. Spores or artificial chemical additives reduce the reusability of loam and therefore an effort has to be made to avoid these substances. Compressed laom is a waste product that occurs primarily during gravel extraction and is available widely. For building purposes, it can only be used in tests and experiments, since so far only low stability can be achieved with it.
Normally, loam can be processed into structures that usually base on one of the following loam building techniques: Rammed earth, weller technique, straw loam and loam bricks.
Rammed earth is a technique, where loam mixed with necessary additives, such as sand and water, is introduced layer by layer, using a mobile formwork-structure that makes it possible to compact the loam by manually ramming it. A relatively high proportion of coarse grains is required to achieve a bond with the ramming technique (cf. Schroeder 2018: 177). Missing large grain sizes can be supplemented by additives. Rammed earth can be used for load-bearing and non-load-bearing components. The prefabrication of large-format up to room-high wall elements is also possible. Floors can be manufactured with this technique as well.
The weller technique describes the process, in which wet loam is mixed with straw and piled up in layers to form a wall section. A so-called set, a layer of approximately 50 to 60 cm height, is drying for several days and later carved and shaped with a spade. After another drying phase, a new set can be applied. Depending on the fiber content, when dry weller loam has a density of 1400–1700 kg / m3 (cf. Schroeder 2018: 180). Weller loam is often used to repair existing structures. Generally, it is possible to produce load-bearing and non-load-bearing walls with the weller technique, but because of the great manual effort involved, it is practiced seldom today. In contrast to rammed earth, weller loam walls are erected without formwork. The production of prefabricated loam blocks is also possible.
Straw or fiber loam is an amorphous mixture of earth, san, organic fibers and water, and has a density of 1200 to 1700 kg / m3, depending on the fiber content (cf. Schroeder 2018: 181). Soft straw, hay or other organic fibers with a length up to approx. 25 cm are suitable as organic additives. The preparation is carried out in the same way as for weller loam. This type of construction method is used as a building material in various ways e.g. for infilling timber frame constructions, beam ceilings, for plaster-like work, or for the production of loam bricks and slabs, usually used for non-load-bearing applications.
Earthen blocks, bricks or slabs can be made with all of the techniques described above. Often, loam is put into molds, dried there and later left to dry in the open air. With suitable types of loam it is possible to burn the resulting bricks at around 1000 degrees to create masonry bricks. Additional weather resistance and stronger firmness are the advantages of this material.
When working with loam the following design principles should be adhered to. Loam is susceptible to weather and generally erodes when exposed to water. This problem can be reduced by additives to the loam mass, but can never be eliminated completely. That is, why it must be structurally ensured that no water can hit the components directly, e.g. by a suitable roof overhang. As to the rest, most rules of conventional solid construction apply to loam constructions as well. Walls must be arranged in such a way that they stiffen, because in contrast to reinforced concrete walls, loam walls cannot be clamped, forming a rigid connection with another component. In addition, with loam building, the loads should be introduced into the component as flatly as possible. Openings are possible with the help of lintels.
Some advantages when building with loam include its availability as a raw material in many parts of the world. Due to the different climatic conditions and the composition of the local soil, specific building traditions and architecture, that characterize different places and represent their individual identity, have been developed. These building traditions are still valuable today as these techniques still work really well and adjust
to today’s needs. Due to its ability to absorb and release a lot of moisture, loam ensures a regulated room climate and prevents the formation of mold or excessive dryness in the rooms.
But there are also difficulties, which can arise when working with loam. The instability to weather is probably one of its biggest problems when building with loam. However, this can be compensated by appropriate construction methods. Loam elements must be protected from water or water must be kept away from it. For example, loam foundations cannot be built in areas with a lot of rainfall. Another disadvantage is its very low tensile strength, which means that loam components must be made correspondingly massive and thick in order to be stable. For this reason, other materials have to be used to support openings in loam constructions. However, this has been tried and tested to a wide extent and there are reliable solutions for most applications today.
Regarding sustainability, loam buildings can generally be advocated. The material occurs in many regions of the world, so short transport routes can be assumed. In some cases, however, local loam cannot be used for building without surcharges, as its material properties in their pure form cannot guarantee permanent weather resistance and stability. In many cases, these surcharges include cement and sand, which are emission-intensive or scarce raw materials. But Scientists continue to find more and more ways to replace conventional supplements with sustainable ones. Nevertheless, the cement content of a loam wall is much lower than that of a concrete wall. In contrast to many other building materials, loam is recyclable with low energy consumption, and if it is not returned to the material cycle, loam results in non-critical waste as it is a natural building material. Because of the relatively high mass of a loam building, there are advantages due to the heat-storing function of the material, which reduces the cooling requirements of the building. In cold locations, heating energy is saved thanks to the good insulation value of loam. Both are very important aspects of sustainability.
The indigenous population of Cuba has developed various construction techniques and vernacular huts over time. In the process, the indigenous round hut (caneyes) disappeared over the centuries. The rectangular bohios, on the other hand, became the archetype of the Cuban farmer‘s and rural worker‘s house. These are still seen in Cuba today. Single-story houses with low-pitched roofs, constructed of local building materials, are perfectly adapted to the climatic conditions of the country. Either the walls are constructed of palm wood panels or of a truss construction, made of lianas in combination with an adobe plaster. The roof covering is usually made of palm leaves, which are replaced every 5-10 years (cf. Miethig/Szerelmy 2016: 63).
In cities like Havana the bohio huts existed as well. However, these evolved into courtyard houses during the 16th century (cf. Tablada et al. 2009: 1953). The Spanish influence on the Cuban building style is very clear. Spanish builders mainly used stone and baked bricks as building materials. Not only the residential and commercial buildings, but also public and sacral buildings were constructed of them (cf. Miethig/Szerelmy 2016: 64).
In the course of the 19th and 20th century, as in most countries, the traditional, local building materials and construction techniques were increasingly replaced by the modern, industrial building materials cement and steel. However, after the revolution in 1958 and the subsequent U.S. embargo on Cuba, importing these new building materials was far too expensive (cf. Merin 2020). Due to these circumstances, one of the „largest architectural achievements of the Cuban Revolution“ (Merin 2020), the National School of Art, was built using locally produced burned bricks and terracotta tiles.
In 1961 Fidel Castro started this ambitious endeavor by stating: “Cuba will be seen as having the most beautiful academy of arts in the world.“ (Merin 2020). Three architects, Ricardo Porro, Vittorio Garatti and Roberto Gottardi, had been assigend to this project.
It had been planned on the site of a famous country club in Havana. Inspired by the catalanian vault, with its arched brick constructions as the predominant design element, the intention was to create a strong contrast to the geometric, „capitalistic‘‘ architectural forms. Five different schools were built on the site, all similar in construction and form. Adapted to the specific conditions of the site, the serpentine structure of the School of Music follows the course of the river. Various domed pavilions dominate the School of Ballet, with paths winding through them. A large amphitheater dominates the School of Dramatic Arts around which cellular inward-facing classrooms are grouped (cf. Merin 2020).
In the wake of the Cuban Missile Crisis of 1962, the enthusiasm that accompanied the design and construction of the building was curbed. Deemed as “an extravagant, unnecessary use of resources” (Merin 2020) the school was considered out of touch with the revolution. After a complete halt of construction in 1965, Castro came back to this project in later years, wanting to finish the project. Due to the ongoing financial crisis it is yet to be completed (cf. Merin 2020).
Around 70% of the Cuban surface is made up of rocks and minerals useful for producing materials such as tiles, bricks and cement.
To the northeast of Havana, the town of Guanabacoa has enough stone or clay resources for its entire area and to export and cover a good part of the capital‘s needs.
To tackle the housing crisis the authorities recommend that the population use limestone and clay as construction materials. One example of how these traditional building materials are researched and implented is the program of the National Ministry of Sugar (MINAZ). It is launching a strong housing and self-sufficiency program to attract and stabilize the necessary workforce by creating small settlements that have the conditions of a rural habitat; houses built with the materials available locally and the appropriate conditions for social life.
From March 1999, in the rural district of Crescencio Valdés of the municipality of Camajuaní, Villa Clara, Cuba, the international research project on the development of adobe and its construction technology for Cuba was carried out, developed by CIDEM (Center for Research and Development of Structures and Materials) of the Central University Marta Abreu in Las Villas, Cuba, and implemented in collaboration with MINAZ (cf. Belkis 2004).
Various analyses and studies were carried out on stabilized clay as a building material, environmental studies and bibliographic analysis on social issues and Cuban rural architecture. Subsequently, the conceptualization of the children‘s house-school and the socio-cultural center, as well as the functional program for the same, were elaborated.
article written by MARIANN BRITO GIL , JULIUS HEMPEN , JOCHEN SCHUMACHER
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AD Classics: The National Art Schools of Cuba / Ricardo Porro, Vittorio Garatti, Roberto Gottardi, in: ArchDaily, [online] https://www.archdaily.com/427268/ad-classics-the-national-art-schools-of-cuba-ricardo-porro-vittorio-garatti-robert-gattardi [18.01.2021].
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