CE 3700 Midterm
The predominant construction material in terms of volume of use - aggregates
Aggregates alone are used for ___ - road base and various types of fill
Aggregates as a binder are used for ___ - asphalt cement or Portland cement
Aggregates are classified by their ____ - 1. Source
2. Specific Gravity
3. Size
4. Petrogaphy
Petrogaphy - the description and systematic classification of rocks, aided by the
microscopic examination of thin sections
Two types of aggregates - 1. Natural Aggregates - rocks
2. Artificial - byproduct of another system
Natural Aggregates (natural gravel, natural sand) are found in nature through ____ -
quarrying, crushing, washing, sieving
Artificial Aggregate examples - 1. Blast-furnace slag (stone-like material that is by
product from the manufacture of iron)
2. Fly-ash
3. Manufactured light weight aggregate (made from expanded shale or clay)
4. Crushed waste concrete
5. Crushed bricks
Specific Gravity of Light Weight Aggregates - <2.4
Specific Gravity of Normal Weight Aggregates - 2.4 - 2.8
Specific Gravity of Heavy Weight Aggregates - >2.8
Coarse aggregate - Retained on No. 4 Sieve
Fine Aggregate - Passing No. 4 Sieve
Filler - >70% passing No. 200 Sieve
Properties of Aggregates - 1. Gradation
2. Specific Gravity
3. Absorption and Surface Moisture
, 4. Shape and Surface Textures
5. Soundness
6. Durability
Gradation is _____ - Distribution of particle size of aggregate
Gradation is determined by ____ - ASTM C 136 Sieve Analysis of Fine and Coarse
Aggregates
Wire-mesh sieves have ____ opening - square
Why is gradation used? - 1. Determine grading of materials proposed for use as
aggregate
2. Check compliance with specification requirements
Sieves at the bottom have the ____ openings - smallest
Fineness Module (FM) - measure of the gradation of the fine aggregate
Fineness Module is the sum of the _____ on the seven sieve sizes ___ - percent
retained
3/8, No. 4, No.8, No. 16, No. 30, No. 50, No. 100
Specific Gravity provides relationship between ____ - mass and volume
Specific Gravity (G) = - [Wt. of Agg.] / [Volume of Agg * unit wt of water]
Each aggregate is made of ___ - solid volume, pores (may or may not be accessible to
water)
Apparent Volume - Volume of the solid matter and the non accessible pores in the
particle
Bulk Volume - Apparent Volume plus the volume of the water absorbed into the pores
Aggregate weight varies with ____ - moisture content
Volume is determined by the ___ - volume of water it displaces
MC > Absorption : There is a ___ - free moisture condition (Free surface moisture = MC
- Absorption)
MC < Apsorption - The aggregate is in air-dry condition (Free moisture is negative)
Our aggregate blend - 64% CA, 36% FA
The predominant construction material in terms of volume of use - aggregates
Aggregates alone are used for ___ - road base and various types of fill
Aggregates as a binder are used for ___ - asphalt cement or Portland cement
Aggregates are classified by their ____ - 1. Source
2. Specific Gravity
3. Size
4. Petrogaphy
Petrogaphy - the description and systematic classification of rocks, aided by the
microscopic examination of thin sections
Two types of aggregates - 1. Natural Aggregates - rocks
2. Artificial - byproduct of another system
Natural Aggregates (natural gravel, natural sand) are found in nature through ____ -
quarrying, crushing, washing, sieving
Artificial Aggregate examples - 1. Blast-furnace slag (stone-like material that is by
product from the manufacture of iron)
2. Fly-ash
3. Manufactured light weight aggregate (made from expanded shale or clay)
4. Crushed waste concrete
5. Crushed bricks
Specific Gravity of Light Weight Aggregates - <2.4
Specific Gravity of Normal Weight Aggregates - 2.4 - 2.8
Specific Gravity of Heavy Weight Aggregates - >2.8
Coarse aggregate - Retained on No. 4 Sieve
Fine Aggregate - Passing No. 4 Sieve
Filler - >70% passing No. 200 Sieve
Properties of Aggregates - 1. Gradation
2. Specific Gravity
3. Absorption and Surface Moisture
, 4. Shape and Surface Textures
5. Soundness
6. Durability
Gradation is _____ - Distribution of particle size of aggregate
Gradation is determined by ____ - ASTM C 136 Sieve Analysis of Fine and Coarse
Aggregates
Wire-mesh sieves have ____ opening - square
Why is gradation used? - 1. Determine grading of materials proposed for use as
aggregate
2. Check compliance with specification requirements
Sieves at the bottom have the ____ openings - smallest
Fineness Module (FM) - measure of the gradation of the fine aggregate
Fineness Module is the sum of the _____ on the seven sieve sizes ___ - percent
retained
3/8, No. 4, No.8, No. 16, No. 30, No. 50, No. 100
Specific Gravity provides relationship between ____ - mass and volume
Specific Gravity (G) = - [Wt. of Agg.] / [Volume of Agg * unit wt of water]
Each aggregate is made of ___ - solid volume, pores (may or may not be accessible to
water)
Apparent Volume - Volume of the solid matter and the non accessible pores in the
particle
Bulk Volume - Apparent Volume plus the volume of the water absorbed into the pores
Aggregate weight varies with ____ - moisture content
Volume is determined by the ___ - volume of water it displaces
MC > Absorption : There is a ___ - free moisture condition (Free surface moisture = MC
- Absorption)
MC < Apsorption - The aggregate is in air-dry condition (Free moisture is negative)
Our aggregate blend - 64% CA, 36% FA
