1180095 634511533955941250
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CIVIL ENGG

CIVIL ENGG

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1180095 634511533955941250 1180095 634511533955941250 Presentation Transcript

  • Presented By- PARTH DANANI (3rd sem, Civil Engineering)
  • Developing and maintaining world’s infrastructure to meet the future needs of industrialized and developing countries is necessary to economically grow and improve the quality of life. The quality and performance of concrete plays a key role for most of infrastructure including commercial, industrial, residential and military structures, dams, power plants. Concrete is the single largest manufactured material in the world and accounts for more than 6 billion metric tons of materials annually. Initial and life-cycle costs play a major role in today’s infrastructure development. There have been number of notable advancements made in concrete technology in the last fifty years.
  •  What is Concrete  History of concrete  Composition of concrete  What is Cement  Function  Portland cement  Manufacturing of cement  Uses  Conclusion
  • Concrete is comprised of Portland cement, fine aggregate, coarse aggregate, water, pozzolans, and air. Portland cement got its name when it was first used in the early nineteenth century in England, because its product resembled building stone from the isle of Portland off the British coast. Portland cement is made by grinding a calcareous material, such as limestone or shell, with an argillaceous (clayish) material such as clay, shale or blast furnace slag. These two finely ground materials are heated in a giant rotary furnace to the point where they begin to fuse. The resulting product is called a clinker. The clinker is cooled and reground to a fine powder to form Portland cement.
  • 1824—Portland Cement Invented Joseph Aspdin of England is credited with the invention of modern portland cement. He named his cement portland, after a rock quary that produced very strong stone. HISTORY OF CONCRETE
  • 1992—Tallest Concrete Building The tallest reinforced concrete building was built in Chicago, Illinois. The 65-story building is known only by its street address.
  • Concrete Composition= • 25-40% cement (absolute volume of cement = 7-15% ; water = 14-21%) • Up to 8% air (depending on top size of coarse aggregate) • Thus composition of concrete= cement+ sand+ aggregates+ water+ admixtures+ air
  • Therefore: Aggregates make up 60-75% of total volume of concrete.
  • What is an AGGREGATE?
  • Aggregate: the inert filler materials, such as sand or stone, used in making concrete
  • Physical Properties of Aggregates: 1.Unit Weight and Voids 2. Specific Gravity 3. Particle Shape and Surface Texture 4. Shrinkage of Aggregates 5. Absorption and Surface Moisture 6. Resistance to Freezing and Thawing
  • Although the terms ―cement‖ and ―concrete‖ are often used interchangeably, cement is actually an ingredient of concrete. Cements are binding agents in concretes and mortars. Concrete is an artificial rock-like material, basically a mixture of coarse aggregate (gravel or crushed stone), fine aggregate (sand), cement, air, and water. The term portland cement is a general term used to describe a variety of cements used today. Portland cements are hydraulic cements, which means they will set and harden by reacting chemically with water through hydration.
  •  Material with adhesive and cohesive properties  Any material that binds or unites - essentially like glue
  • Definition: “Cement is a crystalline compound of calcium silicates and other calcium compounds having hydraulic properties” (Macfadyen, 2006).
  •  to bind the sand and coarse aggregate together  to fill voids in between sand and coarse aggregate particle  to form a compact mass
  •  Chemical composition of Portland Cement: a) Tricalcium Silicate (50%) b) Dicalcium Silicate (25%) c) Tricalcium Aluminate (10%) d) Tetracalcium Aluminoferrite (10%) e) Gypsum (5%)
  • Clinker compounds in Type I portland cement
  •  Hardens rapidly and largely responsible for initial set & early strength  The increase in percentage of this compound will cause the early strength of Portland Cement to be higher.  A bigger percentage of this compound will produces higher heat of hydration and accounts for faster gain in strength.
  •  Hardens slowly  It effects on strength increases occurs at ages beyond one week .  Responsible for long term strength
  •  Contributes to strength development in the first few days because it is the first compound to hydrate .  It turns out higher heat of hydration and contributes to faster gain in strength.  But it results in poor sulfate resitance and increases the volumetric shrinkage upon drying.
  •  Assist in the manufacture of Portland Cement by allowing lower clinkering temperature.  Also act as a filler  Contributes very little strength of concrete eventhough it hydrates very rapidly.  Also responsible for grey colour of Ordinary Portland Cement
  •  The 3 primary constituents of the raw materials used in the manufacture of Portland Cement are: a) Lime b) Silica c) Alumina  Lime is derived from limestone or chalk  Silica & Alumina from clay, shale or bauxite
  •  There are 2 chief aspects of the manufacturing process: First To produce a finely divided mixture of raw materials – chalk / limestone and clay / shale Second To heat this mixture to produce chemical composition  There 2 main process that can be used in manufacturing of Portland Cement that is i) wet process ii) dry process
  •  Raw materials are homogenized by crushing, grinding and blending so that approximately 80% of the raw material pass a No.200 sieve.  The mix will be turned into form of slurry by adding 30 - 40% of water.  It is then heated to about 2750ºF (1510ºC) in horizontal revolving kilns (76-153m length and 3.6-4.8m in diameter.
  •  Natural gas, petroluem or coal are used for burning. High fuel requirement may make it uneconomical compared to dry process.
  •  Raw materials are homogenized by crushing, grinding and blending so that approximately 80% of the raw material pass a No.200 sieve.  Mixture is fed into kiln & burned in a dry state  This process provides considerable savings in fuel consumption and water usage but the process is dustier compared to wet process that is more efficient than grinding.
  •  In the kiln, water from the raw material is driven off and limestone is decomposed into lime and Carbon Dioxide. limestone lime + Carbon Dioxide  In the burning zone, portion of the kiln, silica and alumina from the clay undergo a solid state chemical reaction with lime to produce calcium aluminate. silica & alumina + lime calcium aluminate
  •  The rotation and shape of kiln allow the blend to flow down the kiln, submitting it to gradually increasing temperature.  As the material moves through hotter regions in the kiln, calcium silicates are formed  These products, that are black or greenish black in color are in the form of small pellets, called cement clinkers  Cement clinkers are hard, irregular and ball shaped particles about 18mm in diameter.
  • Uses Main use is in the fabrication of concrete and mortars Modern uses Building (floors, beams, columns, roofing, piles, bricks, mortar, panels, plaster) Transport (roads, pathways, crossings, bridges, viaducts, tunnels, parking, etc.) Water (pipes, drains, canals, dams, tanks, pools, etc.) Civil (piers, docks, retaining walls, silos, warehousing, poles, pylons, fencing) Agriculture (buildings, processing, housing, irrigation) USES
  • Significant advances have been made in concrete technology during the last fifty years. This paper has highlighted some of the significant advancements in technologies and their effect on the design and preservation of infrastructure. While it is not the definitive state-of-practice for design and preservation, it does bring to the forefront some of the technologies that are being considered by professionals. As with all new technologies, long term performance monitoring identifying both successes and failures, will prove to be invaluable for advancing the concept of long-life pavements. Some of the successful examples are discussed in this paper. Many of the innovations have been incorporated in the routine practice.