Podcast
Questions and Answers
What property of wet concrete indicates its ability to hold together without segregation?
What property of wet concrete indicates its ability to hold together without segregation?
- Cohesion (correct)
- Bleeding
- Workability
- Plasticity
What is typically the primary factor affecting the consistency of wet concrete?
What is typically the primary factor affecting the consistency of wet concrete?
- Ambient temperature
- Type of cement used
- Aggregate size
- Water-to-cement ratio (correct)
Which of the following properties of hardened concrete is most critical for ensuring resistance to cracking?
Which of the following properties of hardened concrete is most critical for ensuring resistance to cracking?
- Shrinkage (correct)
- Compressive strength
- Durability
- Density
Which property of hardened concrete typically has a lower value than its compressive strength?
Which property of hardened concrete typically has a lower value than its compressive strength?
In the context of wet concrete, what does bleeding refer to?
In the context of wet concrete, what does bleeding refer to?
What is the typical initial setting time range for concrete before it transitions to a stiffened state?
What is the typical initial setting time range for concrete before it transitions to a stiffened state?
Which characteristic of hardened concrete is crucial for applications requiring substantial load-bearing?
Which characteristic of hardened concrete is crucial for applications requiring substantial load-bearing?
What does a low permeability in hardened concrete indicate?
What does a low permeability in hardened concrete indicate?
Flashcards
Workability of Wet Concrete
Workability of Wet Concrete
The ease with which fresh concrete can be mixed, placed, compacted, and finished, measured by a slump test.
Consistency of Wet Concrete
Consistency of Wet Concrete
The ability of fresh concrete to flow, determined by the water-to-cement ratio.
Bleeding of Wet Concrete
Bleeding of Wet Concrete
The tendency of water to separate from the concrete mix, potentially weakening the surface layer.
Setting Time of Concrete
Setting Time of Concrete
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Compressive Strength of Hardened Concrete
Compressive Strength of Hardened Concrete
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Durability of Hardened Concrete
Durability of Hardened Concrete
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Shrinkage of Hardened Concrete
Shrinkage of Hardened Concrete
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Tensile Strength of Hardened Concrete
Tensile Strength of Hardened Concrete
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Study Notes
Properties of Wet Concrete (Plastic State)
- Workability: Ease of mixing, placing, compacting, and finishing; measured by the slump test
- Consistency: Concrete's fluidity; influenced by the water-to-cement ratio
- Cohesion: Holding together of mix components, assuring uniformity in strength and durability
- Plasticity: Moldability and shapeable-ness of the concrete
- Bleeding: Separation of water from the mix; excessive bleeding weakens surface
- Setting Time: Time for concrete to transition from plastic to stiffened; initial setting usually 30 minutes to 2 hours, mix dependent
- Air Content: Entrapped or purposeful air affects durability and workability
Properties of Hardened Concrete
- Compressive Strength: Ability to withstand heavy loads, typically measured at 28 days; depends on mix design, curing, and compaction
- Durability: Resistance to weather, chemicals, abrasion, and freeze-thaw cycles
- Tensile Strength: Resistance to tension, typically lower than compressive strength; reinforcement often used
- Permeability: Low permeability resists water penetration; enhances durability
- Shrinkage: Volume reduction due to moisture loss during curing; excessive shrinkage causes cracking
- Modulus of Elasticity: Indicates hardened concrete's stiffness under load
- Density: Depends on the mix design; typical density is around 2400 kg/m³ for normal-weight concrete
- Fire Resistance: Non-combustible; excellent fire resistance
- Surface Hardness: Important for applications needing abrasion resistance, such as floors and pavements
- Creep: Gradual deformation under sustained load over time
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