Properties of Fresh Concrete

Properties of Fresh Concrete

Workability

• Definition: The ease with which concrete can be mixed, placed, and finished.
• Factors Influencing Workability:
  • Water content
  • Mix proportions
  • Aggregate characteristics
  • Admixtures

Consistency

• Definition: A measure of the fluidity or wetness of concrete.
• Testing: Slump test is commonly used to assess consistency.

Plasticity

• Definition: The ability of fresh concrete to flow and be molded without segregation.

Cohesiveness

• Definition: The ability of concrete to hold all ingredients together without separation or bleeding.

Setting Time

• Initial Setting: Time taken for concrete to start hardening.
• Final Setting: Time taken for concrete to completely harden.
• Factors Affecting Setting Time:
  • Ambient temperature
  • Cement type
  • Mixing water

Temperature Effects

• Higher Temperatures: Accelerate setting and can result in quick loss of workability.
• Lower Temperatures: Slow down setting and can delay construction schedules.

Compaction

• Importance: Ensures removal of entrapped air and achieves the desired density.
• Method: Can be achieved using mechanical vibrations.

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These notes cover the critical properties that define the behavior and quality of fresh concrete. Understanding these properties is essential for ensuring successful concrete placement and durability.