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Rammed Earth Theory in Earth Architecture

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Rammed Earth Theory in Earth Architecture Vol. 9(3), pp. 432-435, 16 January, 2014 DOI: 10.5897/AJARx11.070 African Journal of Agricultural ISSN 1991-637X ©2014 Academic Journals Research http://www.academicjournals.org/AJAR Review Rammed earth theory in earth architecture Hamed Niroumand*, M. F. M. Zain and Maslina Jamil Department of Architecture, Faculty of Engineering, National University of Malaysia (UKM), Malaysia. Accepted 14 May, 2013 Rammed earth is a method of building walls whereby a mixture of earth is compacted in layers between forms. The soil mix needs to be carefully balanced between clay, sand and aggregate. The clay and moisture content of rammed earth is relatively low compared to that used for mud brick or other earth building methods. The use of rammed earth is a fascinating fusion of modern technology, ancient knowledge, and innovative construction techniques, and is increasingly attracting attention. It’s a sustainable building materials and natural building methods. Once a building is obsolete, it returns to earth. The paper presents rammed system based on physical and construction characteristics. Key words: Earth architecture, rammed earth, sustainable, construction. INTRODUCTION Rammed earth is a technique for building walls using the incombustible, thermally massive, strong, and durable. raw materials of earth, chalk, lime and gravel. Rammed They can be labor-intensive to construct without earth is a structural wall system built of natural mineral machinery, however, and they are susceptible to water soils compacted in thin layers within sturdy formwork. damage if inadequately protected or maintained. Building The strength and durability of the wall are results from the a rammed earth wall involves compressing a damp densification of a clay, sand and gravel matrix. The mass mixture of earth that has suitable proportions of sand, of the wall provides superior thermal and acoustic gravel and clay into an externally supported frame or properties. It is an ancient building method that has seen mould, creating either a solid wall of earth or individual a revival in recent years as people seek more sustainable blocks. Historically, such additives as lime or animal building materials and natural building methods. A natural blood were used to stabilize the material, whilst modern building involves a range of building systems and construction uses lime, cement or asphalt emulsions. materials that place major emphasis on sustainability. Some modern builders also add colored oxides or other Ways of achieving sustainability through natural building items, such as bottles or pieces of timber, to add variety focus on durability and the use of minimally processed, to the structure. The construction of an entire wall begins plentiful or renewable resources, as well as those that, with a temporary frame, usually made of wood or while recycled or salvaged, produce healthy living plywood, to act as a mould for the desired shape and environments and maintain indoor air quality. Natural dimensions of each wall section. The form must be sturdy building tends to rely on human labor, more than and well braced, and the 2 opposing wall faces clamped technology. It depends on "local ecology, geology and together, to prevent bulging or deformation from the large climate; on the character of the particular building site, compression forces involved. Damp material is poured in and on the needs and personalities of the builders and to a depth of 10 to 25 cm and then compacted to around users". Rammed-earth walls are simple to construct, 50% of its original height. The material is compressed *Corresponding author. E-mail: [email protected]. Niroumand et al. 433 iteratively, in batches, gradually building the wall up to the where unclad walls containing clay are exposed to an top of the frame. Tamping was historically done by hand internal space. Humidity is held between 40 and 60%, the with a long ramming pole, and was very labor-intensive; ideal range for asthma sufferers and for the storage of modern construction can be made more efficient by such susceptible items as books. The material mass and employing pneumatically powered tampers. Once a wall is clay content of rammed earth allows the building to complete, it is strong enough that the frames can be "breathe" more than concrete structures do, avoiding removed immediately. This is necessary if a surface condensation issues without significant heat loss. Surface texture will be applied, since the walls become too hard to detail of a rammed earth wall; apart from the patches of work after about an hour. Construction is best done in damage, the surface shows regular horizontal lines from warm weather so that the walls can dry and harden. The the wooden formwork used in constructing the wall and compression strength of the rammed earth increases as it subtler horizontal strata from successive layers of cures; it takes some time to dry out, as much as 2 years compacted earth (Figure 2). for complete curing. Exposed walls should be sealed to prevent water damage. In modern variations of the method, rammed earth walls are constructed on top of Environmental aspects and sustainability conventional footings or a reinforced concrete slab base. Where blocks made of rammed earth are used, they are Sustainable architecture is a general term that describes generally stacked like regular blocks but are bonded environmentally conscious design techniques in the field together with thin mud slurry instead of cement. Special of architecture. Sustainable architecture is framed by the machines, usually powered by small engines and often larger discussion of sustainability and the pressing portable, are used to compress the earth into blocks economic and political issues of our world. In the broad (Figure 1). context, sustainable architecture seeks to minimize the negative environmental impact of buildings by enhancing efficiency and moderation in the use of materials, energy, Characteristics and development space (Niroumand et al., 2011). Most simply, the idea of sustainability, or ecological design, is to The compressive strength of rammed earth can be up to ensure that our actions and decisions today do not inhibit 4.3 MPa. This is less than that of concrete, but more than the opportunities of future generations. Some examples of strong enough for use in domestic buildings. Indeed, sustainable building materials include recycled denim or properly built rammed earth can withstand loads for blown-in fiber glass insulation, sustainably harvested thousands of years, as many still-standing ancient wood, Linoleum, sheep wool, concrete, panels made from structures around the world attest. Rammed earth using paper flakes, baked earth, rammed earth, clay, rebar, wood or bamboo reinforcement can prevent failure vermiculite, flax linen, sisal, see grass, cork, expanded caused by earthquakes or heavy storms. Adding cement clay grains, coconut, wood fiber plates, calcium sand to clay-poor soil mixtures can also increase a structure's stone, locally obtained stone and rock, and bamboo, load-bearing capacity. Soil is a widely available, low-cost which is one of the strongest and fastest growing woody and sustainable resource, and utilizing it in construction plants, and non-toxic glues and paints (Minke, 2006). has minimal environmental impact. This makes rammed- Because rammed earth structures use locally available earth construction highly affordable and viable for low- materials, they usually have low embodied energy and income builders. Unskilled labor can do most of the generate very little waste. The soils used are typically sub necessary work, and today more than 30% of the world's soils low in clay (between 5 and 15%), the topsoil being population uses earth as a building material. retained for agricultural use. Where soil excavated in Rammed earth has been used around the world in a preparing the building's foundation can be used, the cost wide range of climatic conditions, from wet Northern and energy consumption for transportation are minimal. Europe to dry regions in Africa. While the cost of material Rammed earth buildings reduce the need for lumber is low, rammed-earth construction without mechanical because the formwork is removable and can be tools can be very time-consuming, however, with a repeatedly reused (Jaquin et al., 2008). When cement is mechanical tamper and prefabricated form work, it can used in the earth mixture, sustainable benefits such as low take as little as 2 to 3 days to construct the walls for a 200 embodied energy and humidity control will not be realized. to 220 m2 house. One of the significant benefits of Manufacture of the cement itself adds to the global carbon rammed earth is its high thermal mass; like brick or dioxide burden at a rate of 1.25 tons per ton of cement concrete construction, it can absorb heat during the day produced. Partial substitution of cement with alternatives and release it at night. This moderates daily temperature such as ground granulated blast furnace slag has not variations and reduces the need for air conditioning and been shown to be effective, and raises further heating. It often requires thermal insulation in colder sustainability questions. Rammed earth can contribute to climates, again like brick and concrete, and must be the overall energy-efficiency of buildings. The density, protected from heavy rain and insulated with vapor thickness and thermal conductivity of rammed earth make barriers. Rammed earth can effectively control humidity it a particularly suitable material for passive solar heating. 434 Afr. J. Agric. Res. Figure 1. Construction Steps of Rammed Earth (Gunzelmann, 2008). Figure 2. Rammed Earth in Practice (Lennart and James, 1998). Warmth takes almost 12 h to work its way through a wall maintenance; fire proofing, load bearing and pest 35 cm thick. Rammed earth housing has been shown to deterrence (Niroumand et al., 2011). The external walls of resolve problems with homelessness caused by otherwise rammed earth buildings are a minimum of 300mm thick, high building costs, also to help address the ecological providing excellent protection from extremes in climate.
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