I f the PI value content range from liquid limit (LL) to the plastic limit (PL). Soil sample was obtained from a site in front of the Federal polytechnic Ado-Ekiti, in Nigeria. The basic ingredients of cob are soil, sand and straw. High moisture content will also affect and eventually reduce the durability of straw, leading to a greater potential loss in strength for cob with higher straw content. As cob is strong in terms of load-bearing, two-storey buildings are possible. Get the Firefox add-on to access 20,000 definitions direct from any website, Share your construction industry knowledge, Unfired clay masonry: An introduction to low-impact building materials, https://www.designingbuildings.co.uk/wiki/Cob_building. While the term English term "cob" was first recorded in Cornwall in 1602, mud and straw construction has been used worldwide in a variety of forms under a variety of names.… You can find out about our cookies and how to disable cookies in our Privacy Policy. 1. The general trend is an increase in strength due to a reduction in moisture from 9:00 to 17:00 hours, that means COB is 17:00. The oldest cob house still standing is 10,000 years old. Production of Cob: The production of cob involved three stages. The owner-builder can take great satisfaction in supplying the labor, building little by little in leisure time, or inviting friends to share the excitement of hand-sculpting a whole house. They were air dried for 28 days and frequent weight and size measurements were taken. The soil sample used was obtained from a site in … ESPD digital implementation and name change anticipated post-Brexit. One of the advantages of using cob is that the walls can be built up to any shape required, making it very flexible in terms of design. If too much straw is added, the extra water needed also leads to increased volume changes during drying however the straw reduces the size of cracks. The straw does not appear to affect the rate of drying as can be seen in Fig. Cob is an ancient technique of building, which is a combination of sand and clay, mixed with straw and water. Due to the locality in which the study was conducted and the comparatively availability of rice in most areas, it was most reasonable to use rice straw for this testing programme. Fig. The term building material refers to any material used in the process of any civil engineering construction work. In climates that benefit by some insulation, cob’s sister, strawbale construction, can be an excellent choice. Cob Houses Are Healthy. At Cob Cottage Company we have found that many visitors have similar questions about cob. The mixes that contained the most straw and required the most water to provide a suitable mix tended to shrink the most. Chemical erosion of rock material produces the “binder fraction. COB Stands For: All acronyms (308) Airports & Locations (1) Business & Finance (18) Common (2) Government & Military … m-2 irrespective of straw content. silt and clay. Close of Business. Cob construction is a very effective and efficient means for building a cozy cocoon and healthy home. engineering, building. Straw is in most countries a waste product, much of which is burned in the field. Whatever was used, it will surely need to be resealed every few years in a rainy environment. 4, there is possibility of a lower characteristic compressive strength below 4% moisture content. The full length of it means “close of business” and it represents the time when you are supposed to go home from work. is less than about 10%, the soil may not be sufficiently clayey to give adequate In the construction of Cob, the straw of a grain producing plant is used. Cob houses are made of clay-like lumps of soil, sand, and straw. Usually referring to a 5:00PM deadline. It is one of many methods for building with raw earth. Cob walls are traditionally left bare or rendered with lime to allow them to dry out naturally after becoming wet. cob wall "A wall formed of unburnt clay mixed with chopped straw, gravel, and occasionally with layers of long straw, in which the straw acts as a bond"- Dictionary of Architecture and Construction, Cyril M. Harris, ed., McGraw- Hill, 1975, p. 111. The straw provided significant tensile strength. Several of these specimens were trimmed and then centrally loaded at one end via a 38 mm diameter steel disc. Michael G. Smith has a background in environmental engineering, ecology, and sustainable resource management. Clay soils require the addition of more sand than do silty soils, but the overall quantities of sand and straw needed for a modest cob building are surprisingly small. COB. For example, traditional English cob, which was used up until the 1800s when it began to be replaced by more modern construction methods, was a mixture of clay-based subsoil, sand, straw and water. Rate of drying, shrinkage and cracking: The drying rates for the parts specimens are shown in Fig. 2. Guidance from the Government for the construction sector. Here are 9 tips for getting building approval for your cob house construction. WHAT IS THE MEANING OF COB AND EOD? Cob-builders are not getting a consumer product instantly off the shelf. Below a moisture content of about Depending on the contents of the subsoil, sand or clay can be added to achieve the best possible mixture for building. A plaster made of lime and sand may be used to windproof the exterior walls from wind damage (Michael, 2000). It is a well known fact that, when the moisture content of clayey soils increase, they become weaker. Learn more. Cob is a very old method of building with earth and straw or other fibers. Cob building - Designing Buildings Wiki - Share your construction industry knowledge. Cob construction is attractive to many, due to its sculptural possibilities. Cob - Unburned clay mixed with straw. An earthen floor for solar mass and economy of construction An interior cob bench for built-in seating and rocket mass heater . Sometimes just doing one of these things can be enough to help. The present study looks into some properties of Cob as a building material. They are spending time, crafting their building, taking great pride in their work. For the part 2, 14 similar specimens were prepared with a straw content of 1.5%. Unlike straw bale and adobe construction, cob building does not use dried bricks or blocks.Instead, wall surfaces are built up with lumps of damp cob mixture, compressed, and sculpted into smooth, sinuous forms. Engineering COB abbreviation meaning defined here. How Do You Make Cob?. Clear over Base. storeys high. 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