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Cement

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Cement is a binding agent that sets and hardens after mixing with water. Romans first developed hydraulic cement by mixing volcanic ash with lime. Portland cement, the most common type today, was invented in 1824 and consists of calcium silicates and other compounds. It is produced through a process of grinding raw materials like limestone and clay, heating the mixture in a kiln to form clinker, then grinding the clinker with gypsum. The clinker compounds hydrate and harden when mixed with water. Cement is primarily used to bind sand, gravel and water into concrete for construction applications.

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CEMENT
INTRODUCTION Definition: “Cement is a crystalline compound of calcium silicates and other calcium compounds having hydraulic properties. or Material with adhesive and cohesive properties Any material that binds or unites - essentially like glue
History Lime and clay have been used as cementing material on constructions through many centuries. Romans are commonly given the credit for the development of hydraulic cement, the most significant incorporation of the Roman’s was the use of pozzolan-lime cement by mixing volcanic ash from the Mt. Vesuvius with lime. Best know surviving example is the Pantheon in Rome In 1824 Joseph Aspdin from England invented the Portland cement (http://www.holcim.com/NZ/EN/id/71772/mod/gnm20/page/editorial.htm) (http://pubs.usgs.gov/of/2005/1152/2005-1152.pdf) http://www.artchive.com/artchive/r/roman/roman_pantheon.jpg
FUNCTION OF CEMENT  To bind the sand and coarse aggregate together  To fill voids in between sand and coarse aggregate particle  To form a compact mass
Types of Cement  2 types of cement normally used in building industry are as follows: a) Hydraulic Cement b) Nonhydraulic Cement
Hydraulic Cement Hydraulic Cement sets and hardens by action of water. Such as Portland Cement In other words it means that hydraulic cement are: “ Any cements that turns into a solid product in the presence of water (as well as air) resulting in a material that does not disintegrate in water.”
Most common Hydraulic Cement is Portland Cement
Nonhydraulic Cement  Any cement that does not require water to transform it into a solid product.  2 common Nonhydraulic Cement are a) Lime - derived from limestone / chalk b) Gypsum
Cements are considered hydraulic because of their ability to set and harden under or with excess water through the hydration of the cement’s chemical compounds or minerals There are two types: Those that activate with the addition of water And pozzolanic that develop hydraulic properties when the interact with hydrated lime Ca(OH)2 Pozzolanic: any siliceous material that develops hydraulic cementitious properties when interacted with hydrated lime. HYDRAULIC CEMENTS: Hydraulic lime: Only used in specialized mortars. Made from calcination of clay- rich limestones. Natural cements: Misleadingly called Roman. It is made from argillaceous limestones or interbedded limestone and clay or shale, with few raw materials. Because they were found to be inferior to portland, most plants switched. ) Types of Cement
Portland cement: Artificial cement. Made by the mixing clinker with gypsum in a 95:5 ratio. Portland-limestone cements: Large amounts (6% to 35%) of ground limestone have been added as a filler to a portland cement base. Blended cements: Mix of portland cement with one or more SCM (supplementary cemetitious materials) like pozzolanic additives. Pozzolan-lime cements: Original Roman cements. Only a small quantity is manufactured in the U.S. Mix of pozzolans with lime. Masonry cements: Portland cement where other materials have been added primarily to impart plasticity. Aluminous cements: Limestones and bauxite are the main raw materials. Used for refractory applications (such as cementing furnace bricks) and certain applications where rapid hardening is required. It is more expensive than portland. There is only one producing facility in the U.S. ).
PORTLAND CEMENT  Chemical composition of Portland Cement: a) Tricalcium Silicate (50%) b) Dicalcium Silicate (25%) c) Tricalcium Aluminates (10%) d) Tetra calcium Aluminoferrite (10%) e) Gypsum (5%)
FUNCTION :TRICALCIUM SILICATE  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.
FUNCTION :DICALCIUM SILICATE  Hardens slowly  It effects on strength increases occurs at ages beyond one week .  Responsible for long term strength
FUNCTION :TRICALCIUM ALUMINATE  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.
 Cements with low Tricalcium Aluminates contents usually generate less heat, develop higher strengths and show greater resistance to sulfate attacks.  It has high heat generation and reactive with soils and water containing moderate to high sulfate concentrations so it’s least desirable.
MANUFACTURING OF 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
WET 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.
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 DRY PROCES & WET PROCESS
 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.
CEMENT CLINKERS
 The cement clinkers are cooled to about 150ºF (51ºC) and stored in clinker silos.  When needed, clinker are mixed with 2-5% gypsum to retard the setting time of cement when it is mixed with water.  Then, it is grounded to a fine powder and then the cement is stored in storage bins or cement silos or bagged.  Cement bags should be stored on pallets in a dry place.
KILN
GEOLOGY (RAW MATERIALS) The fundamental chemical compounds to produce cement clinker are: Lime (CaO) Silica (SiO2) Alumina (Al2O3) Iron Oxide (Fe2O3) ( Fly ash: by-product of burning finely grounded coal either for industrial application or in the production of electricity Raw materials used in the production of clinker cement
Clinker compounds in Type I portland cement
Sedimentary deposits of marine origin (limestone) Marble (metamorphosed limestone) Chalk Marl Coral Aragonite Oyster and clam shells Travertine Tuff LIMESTONES Originate from the biological deposition of shells and skeletons of plants and animals. Massive beds accumulated over millions of years. In the cement industry limestone includes calcium carbonate and magnesium carbonate. Most industrial quality limestones is of biological origin. The ideal cement rock 77 to 78% CaCO3, 14% SiO2, 2.5% Al2O3, and 1.75% FeO3. Limestone with lower content of CaCO3 and higher content of alkalis and magnesia requires blending with high grade limestone SOURCES OF CaCO3
Argillaceous mineral resources: Clay and shale for alumina and silica Iron ore for iron Other natural sources of silica are and alumina are: Loess, silt, sandstone, volcanic ash, diaspore, diatomite, bauxite Shales, mudstones, and sandstones are typically interbedded with the limestone and were deposited as the inland waters and oceans covered the land masses. Clays are typically younger surface deposits SOURCES OF ARGILLACEOUS MINERALS (
Limestone deposits are mainly extracted by bench mining in which holes are charged with ammonium nitrate and fuel oil explosive and blasted The rock is excavated with front end loaders (10 m3 capacity) and loaded into 70 to 90 tons haul trucks and then transported to the primary crusher Marl and chalk normally do not require blasting. A trend is to use in pit moveable primary crushers and belt conveyors to transport the rock to a fixed secondary crusher, thereby reducing the number of trucks and haulage distance Underground mining of limestones is not typical, in the U.S one plant obtains its limestone from underground operation, using room and pillar mining method. Clay and shale normally extracted using front end loaders and loaded into haul trucks. When they occur as overburden the clays and shales not used are stored and often reused for reclamation in the mined out areas of the quarry MINING METHODS
PROCESSING
(Macfadyen, 2006)
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 (http://pubs.usgs.gov/of/2005/1152/2005-1152.pdf) (http://www.holcim.com/NZ/EN/id/71772/mod/gnm20/page/editorial. html) (http://en.wikipedia.org/wiki/Mortar_%28masonry%29) http://www.wpclipart.com/working/construction/concrete_block.png http://irandaily.ir/1383/2116/html/005991.jpg
SUBSTITUTES It competes in the construction industry with concrete substitutes: Alumina Asphalt Clay brick Fiberglass Glass Steel Stone Wood Some materials like fly ash and ground granulated furnace slugs have good hydraulic properties and are being used as partial substitutes for Portland cement in some concrete applications

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Cement

  • 2. INTRODUCTION Definition: “Cement is a crystalline compound of calcium silicates and other calcium compounds having hydraulic properties. or Material with adhesive and cohesive properties Any material that binds or unites - essentially like glue
  • 3. History Lime and clay have been used as cementing material on constructions through many centuries. Romans are commonly given the credit for the development of hydraulic cement, the most significant incorporation of the Roman’s was the use of pozzolan-lime cement by mixing volcanic ash from the Mt. Vesuvius with lime. Best know surviving example is the Pantheon in Rome In 1824 Joseph Aspdin from England invented the Portland cement (http://www.holcim.com/NZ/EN/id/71772/mod/gnm20/page/editorial.htm) (http://pubs.usgs.gov/of/2005/1152/2005-1152.pdf) http://www.artchive.com/artchive/r/roman/roman_pantheon.jpg
  • 4. FUNCTION OF CEMENT  To bind the sand and coarse aggregate together  To fill voids in between sand and coarse aggregate particle  To form a compact mass
  • 5. Types of Cement  2 types of cement normally used in building industry are as follows: a) Hydraulic Cement b) Nonhydraulic Cement
  • 6. Hydraulic Cement Hydraulic Cement sets and hardens by action of water. Such as Portland Cement In other words it means that hydraulic cement are: “ Any cements that turns into a solid product in the presence of water (as well as air) resulting in a material that does not disintegrate in water.”
  • 7. Most common Hydraulic Cement is Portland Cement
  • 8. Nonhydraulic Cement  Any cement that does not require water to transform it into a solid product.  2 common Nonhydraulic Cement are a) Lime - derived from limestone / chalk b) Gypsum
  • 9. Cements are considered hydraulic because of their ability to set and harden under or with excess water through the hydration of the cement’s chemical compounds or minerals There are two types: Those that activate with the addition of water And pozzolanic that develop hydraulic properties when the interact with hydrated lime Ca(OH)2 Pozzolanic: any siliceous material that develops hydraulic cementitious properties when interacted with hydrated lime. HYDRAULIC CEMENTS: Hydraulic lime: Only used in specialized mortars. Made from calcination of clay- rich limestones. Natural cements: Misleadingly called Roman. It is made from argillaceous limestones or interbedded limestone and clay or shale, with few raw materials. Because they were found to be inferior to portland, most plants switched. ) Types of Cement
  • 10. Portland cement: Artificial cement. Made by the mixing clinker with gypsum in a 95:5 ratio. Portland-limestone cements: Large amounts (6% to 35%) of ground limestone have been added as a filler to a portland cement base. Blended cements: Mix of portland cement with one or more SCM (supplementary cemetitious materials) like pozzolanic additives. Pozzolan-lime cements: Original Roman cements. Only a small quantity is manufactured in the U.S. Mix of pozzolans with lime. Masonry cements: Portland cement where other materials have been added primarily to impart plasticity. Aluminous cements: Limestones and bauxite are the main raw materials. Used for refractory applications (such as cementing furnace bricks) and certain applications where rapid hardening is required. It is more expensive than portland. There is only one producing facility in the U.S. ).
  • 11. PORTLAND CEMENT  Chemical composition of Portland Cement: a) Tricalcium Silicate (50%) b) Dicalcium Silicate (25%) c) Tricalcium Aluminates (10%) d) Tetra calcium Aluminoferrite (10%) e) Gypsum (5%)
  • 12. FUNCTION :TRICALCIUM SILICATE  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.
  • 13. FUNCTION :DICALCIUM SILICATE  Hardens slowly  It effects on strength increases occurs at ages beyond one week .  Responsible for long term strength
  • 14. FUNCTION :TRICALCIUM ALUMINATE  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.
  • 15.  Cements with low Tricalcium Aluminates contents usually generate less heat, develop higher strengths and show greater resistance to sulfate attacks.  It has high heat generation and reactive with soils and water containing moderate to high sulfate concentrations so it’s least desirable.
  • 16. MANUFACTURING OF 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
  • 17. 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
  • 18. WET 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.
  • 19. 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.
  • 20.  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 DRY PROCES & WET PROCESS
  • 21.  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.
  • 23.  The cement clinkers are cooled to about 150ºF (51ºC) and stored in clinker silos.  When needed, clinker are mixed with 2-5% gypsum to retard the setting time of cement when it is mixed with water.  Then, it is grounded to a fine powder and then the cement is stored in storage bins or cement silos or bagged.  Cement bags should be stored on pallets in a dry place.
  • 24. KILN
  • 25. GEOLOGY (RAW MATERIALS) The fundamental chemical compounds to produce cement clinker are: Lime (CaO) Silica (SiO2) Alumina (Al2O3) Iron Oxide (Fe2O3) ( Fly ash: by-product of burning finely grounded coal either for industrial application or in the production of electricity Raw materials used in the production of clinker cement
  • 26. Clinker compounds in Type I portland cement
  • 27. Sedimentary deposits of marine origin (limestone) Marble (metamorphosed limestone) Chalk Marl Coral Aragonite Oyster and clam shells Travertine Tuff LIMESTONES Originate from the biological deposition of shells and skeletons of plants and animals. Massive beds accumulated over millions of years. In the cement industry limestone includes calcium carbonate and magnesium carbonate. Most industrial quality limestones is of biological origin. The ideal cement rock 77 to 78% CaCO3, 14% SiO2, 2.5% Al2O3, and 1.75% FeO3. Limestone with lower content of CaCO3 and higher content of alkalis and magnesia requires blending with high grade limestone SOURCES OF CaCO3
  • 28. Argillaceous mineral resources: Clay and shale for alumina and silica Iron ore for iron Other natural sources of silica are and alumina are: Loess, silt, sandstone, volcanic ash, diaspore, diatomite, bauxite Shales, mudstones, and sandstones are typically interbedded with the limestone and were deposited as the inland waters and oceans covered the land masses. Clays are typically younger surface deposits SOURCES OF ARGILLACEOUS MINERALS (
  • 29. Limestone deposits are mainly extracted by bench mining in which holes are charged with ammonium nitrate and fuel oil explosive and blasted The rock is excavated with front end loaders (10 m3 capacity) and loaded into 70 to 90 tons haul trucks and then transported to the primary crusher Marl and chalk normally do not require blasting. A trend is to use in pit moveable primary crushers and belt conveyors to transport the rock to a fixed secondary crusher, thereby reducing the number of trucks and haulage distance Underground mining of limestones is not typical, in the U.S one plant obtains its limestone from underground operation, using room and pillar mining method. Clay and shale normally extracted using front end loaders and loaded into haul trucks. When they occur as overburden the clays and shales not used are stored and often reused for reclamation in the mined out areas of the quarry MINING METHODS
  • 32. 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 (http://pubs.usgs.gov/of/2005/1152/2005-1152.pdf) (http://www.holcim.com/NZ/EN/id/71772/mod/gnm20/page/editorial. html) (http://en.wikipedia.org/wiki/Mortar_%28masonry%29) http://www.wpclipart.com/working/construction/concrete_block.png http://irandaily.ir/1383/2116/html/005991.jpg
  • 33. SUBSTITUTES It competes in the construction industry with concrete substitutes: Alumina Asphalt Clay brick Fiberglass Glass Steel Stone Wood Some materials like fly ash and ground granulated furnace slugs have good hydraulic properties and are being used as partial substitutes for Portland cement in some concrete applications