This preview has intentionally blurred sections. Sign up to view the full version.
View Full DocumentThis preview has intentionally blurred sections. Sign up to view the full version.
View Full DocumentThis preview has intentionally blurred sections. Sign up to view the full version.
View Full DocumentThis preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
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 1700’s in England with the patent of Portland cement. • Reinforced concrete developed in 1850’s. • Prestressed concrete science developed in 1920’s. 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....
View
Full
Document
 Spring '10
 AmrKandile

Click to edit the document details