Aggregate is a collective term for materials like sand, gravel, and crushed stone that are used with a binding medium like cement or asphalt to form construction materials. Aggregates can be natural or manufactured. Fine aggregates pass through a 4.75 mm sieve while coarse aggregates are retained on the sieve. Common types of fine aggregates are natural sand, crushed stone sand, and crushed gravel sand. Common types of coarse aggregates include crushed gravel, uncrushed gravel, and partially crushed gravel. The proportion of fine and coarse aggregates in concrete is estimated using methods that account for the volumes and specific gravities of cement, water, and chemical admixtures.

1. AGGREGATES
Aggregate is a collective term for the mineral materials such as
sand, gravel and crushed stone that
are used with a binding medium (such as water, bitumen, portland
cement, lime, etc.) to form
compound materials (such as asphalt concrete and portland
cement concrete). Aggregates can either be natural or
manufactured.

2. FINE AGGREGATES
• The aggregates which passes through a 4.75
mm IS sieve.
• Sand is generally considered to have a lower
size limit of about 0.07
• Material between 0.06 mm and 0.00 mm is
classified as silt
• Other left particles are called as clay

3. TYPES OF FINE AGGREGATES:-
1. Natural sand
2. Crushed stone sand
3. Crushed gravel sand

4. COARSE AGGREGATES
• The aggregates which are retained on the 4.75
mm IS sieve
• They contain only that much of fine material
as is permitted by the specifications

5. TYPES OF COARSE AGGREGATES:-
1.Crushed gravel
2.Uncrushed gravel
3.Partially crushed gravel

6. ESTIMATION OF COARSE AGGREGATE
PROPORTION:-

7. Estimation of Fine Aggregate
Proportion
Estimation of Fine Aggregate Proportion
With the completion of procedure given in 4.4, all the ingredients have
been estimated except the coarse
and fine aggregate content. These quantities are
determined by finding out the absolute volume of cementitious
material, water and the chemical admixture; by dividing their mass by
their respective specific gravity, multiplying by III 000 and subtracting
the result of their summation from unit volume. The values so
obtained are divided into Coarse and Fine Aggregate fractions by
volume in accordance with coarse aggregate proportion already
determined in 4.4. The coarse and fine aggregate
contents are then determined by multiplying with their respective
specific gravities and multiplying by
1000.

8. Volume of coarse aggregate is required to be
increased
to decrease the fine aggregate content and vice
versa at the rate of -/+ 0.01 for every ± 0.05
change in water-cement ratio

9. In 1925, Duff Abrams introduced the concept of fineness modulus (FM) for estimating the
proportions of fine and course aggregates in concrete mixtures. The premise: "aggregate of
the same fineness modulus will require the same quantity of water to produce a mix of the
same consistency and give a concrete of the same strength." Before calculating FM, lab
technicians perform a sieve analysis to determine the particle size distribution, or grading, of
the aggregate sample. FM is the sum of the total percentages retained on each specified sieve
divided by 100. ASTM C 33 requires the FM of fine aggregate to be between 2.3 and 3.1. The
higher the FM, the coarser the aggregate. Fine aggregate affects many concrete properties,
including workability and finishability. Usually, a lower FM results in more paste, making
concrete easier to finish. For the high cement contents used in the production of high-
strength concrete, coarse sand with an FM around 3.0 produces concrete with the best
workability and highest compressive strength.
Fineness Modulus