Sunday, October 6, 2019

Manufacturing process of concrete Research Paper

Manufacturing process of concrete - Research Paper Example Earlier clay was also used as bonding material to prepare the concrete by the Assyrians and Babylonian. The Egyptians introduced the use of lime and gypsum cement to make concrete. In 1756, the first modern concrete was invented by the British engineer John Smeaton. He used pebbles as coarse aggregate substances and mixing powered bricks in to the cement for the formation of concrete. In 1984, English inventor by Joseph Aspdin first time made the Portland cement that still play major role in the composition of modern day concrete. It is believed that the invention of Portland cement is the first and major landmark achieved in the history of modern concrete because it was the first true artificial cement produced by burning of limestone and clay together (Stella, 1996). Due to burning some chemical changes occurred in the properties of limestone and clay and their combination become stronger cement as compared with that produced with the plain crushed limestone. Along with cement aggr egates are also used in the composition of concrete like sand, crushed stones, slag and ashes etc. Along with time several new materials were added as aggregate to bring variations in concrete. For instance, the reinforced concrete or Ferro-concrete was introduced in which metal like steel is imbedded. This concrete was invented in 1849 by a Parisian gardener Joseph Moneir. He made several garden pots and tubs with the concrete in which he used meshed iron as aggregate. His invention was exhibit in 1867 in Paris Exposition in which he not only show the use of reinforced concrete for making tubs and pots but also for the construction of railways, pipes, bridges and arches (Robert and Hutchinson, 1999). The invention o f the reinforced concrete was another important... After mixing the material is transported to the site where the concrete is placed and compacted. This process occurs just after the mixing process in order to avoid the separation of any ingredient from the mixture and to prevent the entrance of air bubbles into the mixture. An internal or external vibrator is used for compacting of the concrete or it is also done with the help of vibrating tables in which there are two shafts rotating in opposite directions for creating vertical vibration.   After placement, the concrete is cured so that it could be prevented from drying too fast (Neville and Brooks, 1987). The moisture level at the time of hardening of the concrete determines the durability and strength of the concrete. When the concrete dries it decreases in size because the cement solidifies and reduces the size of the concrete. The concrete becomes week if the concrete is prevented from contracting and tensile stresses also develop in the concrete so the concrete is kept damp for several days when it is set for hardening. After curing the necessary quality assurance checks and tests are conducted using quality assurance charts and other tools that assure the strength of the concrete before it is used for the construction purpose (Lancaster, 2005).   Properties of concreteThe concrete could be examined according to its properties including strength, elasticity, tension and shrinkage cracking and expansion and shrinkage.   The simple tensile strength of concrete is usually around 10-15 percent.

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