Cement and Concrete

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Cement and Concrete

• History
• Composition
• Testing
• Key Terms

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Key TermsDesignation C 219-98

• Air-entraining hydraulic cement hydraulic
  cement containing an air entraining addition in
  such amount as to cause the product to entrain
  air in mortar within specified limits.
• Blast furnace slag nonmetallic product
  consisting essentially of silicates and
  aluminosilicates of calcium and other bases that
  is developed in a molten condition simultaneously
  with iron in a blast furnace.
• Hydration chemical reaction between hydraulic
  cement and water forming new compounds most of
  which have strength-producing properties.
• Hydraulic cement a cement that sets and hardens
  by chemical interaction with water and is capable
  of doing so under water.
• Portland cement a hydraulic cement produced by
  pulverizing portland-cement clinker and usually
  containing calcium sulfate.

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ASTM Portland Cement Types
Type Characteristics and Use
TYPE I, IA, STANDARD General Purpose, Most residential applications
TYPE II, IIA, MODIFIED Reduced heat of hydration, increased sulfate resistance
TYPE III, IIIA HIGH EARLY STRENGTH High strengths in one to three days
TYPE IV, LOW HEAT Heat during hydration kept to a minimum intended for large masses, e.g., dams
TYPE V, SULFATE RESISTANT Especially good for marine structures and soils with high alkali
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Cement

• A finely pulverized material consisting
  principally of compounds of lime, silica,
  alumina, and iron.

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Concrete

• A monolithic, ceramic product of aggregates
  bonded with cement, such as Portland or asphalt.

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Composition of Concrete

• Air-entrained Non-air-entrained
• Cement 15 15
• Water 18 21
• Air 8 3
• Fine Aggregate 28 30
• Course Aggregate 31 31
• Note All values are approximate

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Fine and Course Aggregates

• Fine aggregates stone or sand that can pass
  through a sieve with ¼ square holes.
• Course Aggregate rock or stone greater than ¼
  . Usually not larger than 1 ½

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History

• Roman Empire Colosseum and other structures
  made with a type of cement made from slaked lime
  and pozzolona (volcanic ash from Mt. Vesuvius)
  First Hydraulic Cement.
• 1756 John Smeaton discovers that cement made
  from limestone with a substantial volume of clay
  hardens under water.
• 1824 Joseph Aspdin invents Portland Cement

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Hydration

• The chemical reaction between hydraulic cement
  and water forming new compounds most of which
  have strength producing properties.

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Composition of Concrete

• 11 Cement (usually Portland)
• 16 Water
• 6 Air
• 26 Sand
• 41 Gravel or Crushed Stone

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Fiber Reinforced Concrete

• Low Fiber volume composite concrete contains
  less than 1 fiber. It is used for field
  applications involving large volumes of concrete.
  The fibers do not significantly increase the
  strength of the concrete. Low fiber volume
  concrete is used for paving roads.
• High Fiber Volume Concrete Typically used for
  thin sheets with cement mortar mix. The fiber
  volume in this mix ranges from 5 to 15.

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Fiber Reinforced Concrete

• High Fiber Volume Composite The fiber volume in
  this mix can be as high as 40. This
  significantly increases the strength and
  toughness of the mix. The reinforcement in High
  Fiber Volume Composite concrete is usually in
  sheet form. This reinforced concrete type is
  used in roof and wall panels.

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Standardized Tests of Concrete

• ASTM C-143 Slump Test
• ASTM C-39 Compressive Strength Test
• ASTM C-78 Flexural Strength Test

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ASTM C-39 Standard Test Method Compressive
Strength of Cylindrical Concrete Specimens

• Procedure
• 7.3 All test specimens for a given test age shall
  be broken within the permissable time tolerances
  prescribed as follows
• Test Age Permissible Tolerance
• 24 hours /- .5 h or 2.1
• 3 days 2 h or 2.8
• 7 days 6 h or 3.6
• 28 days 20h or 3.0
• 90 days 2 days or 2.2

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ASTM C-39 Standard Test Method Compressive
Strength of Cylindrical Concrete Specimens

• Procedure
• 8.1 If the specimen length to diameter ratio is
  less than 1.8, correct the result obtained in 8.1
  by multiplying by the appropriate correction
  factor in the following table
• L/D 1.75 1.5 1.25 1.00
• Factor 0.98 0.96 0.93 0.87

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Test Cylinders
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