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8 Cards in this Set
- Front
- Back
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What are aggregates |
A mass of crushed stone, gravel, sand etc. |
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What are the types of aggregates |
• Lightweight aggregates e.g. thermal insulation fills in wall lightweight structural members marine and floating structures • Normal weight aggregates e.g. normal weight structural members • Heavy weight aggregates Radiation shielding, heavyweight structures such as dams |
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What is gradation and the types of grading |
The particle size distribution of the aggregate and it has effect on performance of concrete · Well graded: Aggregates containing good proportion of all sizes · Poorly graded; aggregates consist mainly of one size · Gap graded: The intermediate sizes are absent |
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What is maximum vs nominal size |
• Maximum size: smallest size through which all the aggregates will pass • Nominal size: whole number above the sieve size through which nearly all the aggregates pass |
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What is fineness modulus |
Measures the fineness or coarseness of the sand, it is the mean size of particles in the sand |
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What is the desirable shape and texture of aggregates |
· Rounded > flaky Rounded aggregates have more workability at it is cohesive and there is less friction · Textured > smooth Rough textured aggregate has stronger bonding between cement particles and aggregate, resulting in a higher compressive strength |
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Functions of fine aggregates |
· Fills the voids existing in coarse aggregates · Reduces shrinkage and cracking of concrete · Helps in hardening of cement by allowing the water through its voids · By varying proportion of sand, concrete can be prepared economically for any required strength |
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Function of coarse aggregates |
· Makes the solid and hard mass of concrete with cement and sand · Increases the crushing strength of concrete · Reduces the cost of concrete, since it occupies major volume |
