Concrete

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Concrete is one of the most popular materials used for buildings because of its resistance and fire-and-waterproof properties. Since concrete has a great plasticity, there are many construction methods that use this material in different ways. ======

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 The following page is dedicated to the studies of concrete as a construction material obtained from the experiment results of the Materials Lab, the information given in audio and readings and web research. There are also posted asigments that will help understand and illustrate the differences between some concrete-construction methods. ======

Concrete is a construction material that comes from a combination of cement, water and small stones and comes to be cheaper than iron and steel and doesn't need to be fused with other materials. Concrete has been used since ancient times by the Egyptians but the Romans were the ones that exploited its abilities to create architectural icons in history.

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 As a property, concrete is naturally fire-and-weather proof and moderatly light (this feature depends mostly of the weight of the cement and stones). Concrete is poured in liquid state, into the form desired and then it hardens in a short period of time. ======

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 The strengh of concrete remains in the compression it can support, that's why it's used to create floor panels and deck supports. ======

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 Concrete has disadvantages as well: It doens't have enough tensile strengh and weakens with large changes in temperature, but with the invention of reinforced concrete, the tensile force of the steel is blended with the compressive force of concrete to create a limitless amount of constructions such as sewerage systems, foundations (since concrete is waterproof), bridges, arches, pipes, girders… ======

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 Nowadays, there are many construction methods that apply concrete as their main material such as precast-concrete, tilt wall concrete and prestressed concrete constructions. ======

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**Concrete**  is a manufactured mixture of cement and water, with aggregates of sand and stones, which hardens rapidly by chemical combination to a stonelike, water-and-fire-resisting solid ======

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**Pozzolana**  is a volcanic-ash cement used by the ancient Romans to fabricate concrete. ======

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**Reinforced concrete**  is a construction material to make large variety of construction members that was invented by Joseph Monier wih the purpose of adding the tensile strengh of steel to the compressive strengh of mass concrete by embedding the metal and shaping it into the desired form befored pouring the concrete in it. ======

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**Concrete-shell construction**  is a building method that permits the erection of vast vaults and domes with a concrete and steel content so reduced that the thickness is comparatively less than that of an eggshell. ======

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**Precast-concrete construction** <span style="font-family: Tahoma,Geneva,sans-serif; font-size: 12.1pt;"> is a building method that employs construction members prefabricated under optimal factory conditions to increase waterproofing and solidity, to decrease time and cost in eretion, and to reduce expansion and contractions. ======

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<span style="color: #800080; font-family: Tahoma,Geneva,sans-serif; font-size: 11pt;">**Prestressed concrete** <span style="font-family: Tahoma,Geneva,sans-serif; font-size: 11pt;"> is a construction method that provides bearing stressed members into which reinforcement is set under tension to produce a live force to resist a particular load. It is mostly used to create bridge supports and girders. ======

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<span style="font-family: Tahoma,Geneva,sans-serif; font-size: 110%;">**<span style="color: #5b0ea4; font-family: Tahoma,Geneva,sans-serif; font-size: 12.1pt;">Differences between Tiltwall construction, tilt-up construction and precast concrete construction. ** =====

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<span style="font-family: Tahoma,Geneva,sans-serif; font-size: 12.1pt;">Tilt-up wall and tiltwall are two terms used to describe the same process. The wall panels are created at the jobsite by pouring the material (concrete) into molds assembled at the same place. Once dried, the panels are tilted up to their corresponding position to erect the walls of the new building. Therefore, no transportation is need. The biggest problem of this construction method is that the assembly of the panels is completly exposed to weather conditions (this is the reason why this type of construction is popular at southern regions). The main difference in the design of houses assembled by tilt-up constrcution in southern and northern regions is the size of the walls. ======

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<span style="font-family: Tahoma,Geneva,sans-serif; font-size: 12.1pt;">In comparisson with the precast concrete construction, this method has a way to solve the exposure of the concrete panels to the weather conditions. Instead of making the panels at the construction site, the panels are manufactured in a large facility close enough to the jobsite to short the transportation time and costs. The manufacturing facility provides protection from the weather and a product of better quality. On the other hand, the transportation of the precast panels becomes the biggest disadvantage of this construction method because the size of the walls shall be limited to be carried by trucks. ======

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<span style="font-family: Tahoma,Geneva,sans-serif; font-size: 12.1pt;">In conclusion, tilt-up and tilt wall constructions are two different names for the same method of construction using concrete. The main difference between tilt wall and precast concrete construction is the assembly and fabrication of the concrete panels. While tilt-up method creates the panels at the place of construction, the precast concrete method manufactures the panels in a facility from where they'll be transported. ======

<span style="color: #2829a9; font-family: Tahoma,Geneva,sans-serif; font-size: 140%;">**Illustrations and diagrams**