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Unformatted text preview: C E M 6 2 C o n s t r u c t i o n M e t h o d s CEM 602 Construction Methods Lecture 14 Concrete Construction 1 L e c t u r e 1 4 C o n c r e t e C o n s t r u c t i o n C E M 6 2 C o n s t r u c t i o n M e t h o d s Background 2 L e c t u r e 1 4 C o n c r e t e C o n s t r u c t i o n C E M 6 2 C o n s t r u c t i o n M e t h o d s History of Concrete Predecessor of Portland cement was discovered by the Romans in ancient times. Knowledge was lost after the fall of the Roman Empire. Concrete was rediscovered in 1700s in England with the patent of Portland cement. Reinforced concrete developed in 1850s. Prestressed concrete science developed in 1920s. L e c t u r e 1 4 C o n c r e t e C o n s t r u c t i o n 3 C E M 6 2 C o n s t r u c t i o n M e t h o d s Cement and Concrete Concrete consists of Portland cement Aggregates: fine and coarse Water Concrete chemically hardens through a process called hydration. Hydration creates heat as a byproduct. Concrete does NOT dry concrete cures! L e c t u r e 1 4 C o n c r e t e C o n s t r u c t i o n 4 C E M 6 2 C o n s t r u c t i o n M e t h o d s Types of Cement I Normal (common) IA Normal, airentraining (air) II Moderate resistance to sulfate attack (water) IIA Type II with air III High early strength (precast or fast construction) IIIA Type III with air IV Low heat of hydration (used in dams) L e c t u r e 1 4 C o n c r e t e C o n s t r u c t i o n 5 C E M 6 2 C o n s t r u c t i o n M e t h o d s Airentrainment Microscopic bubbles in concrete Enhances resistance to freezethaw action Used in pavements Used in foundations Used where concrete will be exposed to the weather L e c t u r e 1 4 C o n c r e t e C o n s t r u c t i o n 6 C E M 6 2 C o n s t r u c t i o n M e t h o d s Aggregate and Water Must not contain dirt or chemicals hazardous to the hydration process or reinforcing. Must be small enough to fit between reinforcing. Should be wellgraded. Strength of concrete is affected by aggregate strength....
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 Spring '10
 AmrKandile

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