CE 39007 – Concrete Lab
Mondays/Thursdays/Fridays
Instructors:
Nirjhar Dhang (CE, Monday)
Sudhirkumar Barai (CE, Monday)
S K Bhattacharyya (CE, Thursday)
Biswanath Banerjee (CE, Thursday)
Sushanta Chakrabarti (CE, Friday)
A George (ARP, Friday)
Experiment 4 - Aggregates
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75 % of Volume of Concrete
Classification of Aggregates
-Fine aggregate
-Coarse Aggregate
IS:383 Definition
Fine Aggregate –
aggregates which passes through 4.75 mm IS Sieve
Coarse Aggregate –
aggregates which stays in 4.75 mm IS Sieve
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Properties of Aggregate
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Particle shape
Surface texture
Strength of aggregate
Specific gravity
Bulk density
Water absorption and surface moisture
Bulking of sand
Deleterious substances in aggregates
Soundness of aggregate
Alkali-aggregate reaction
Experiment 4.A –
Sieve Analysis of CA and FA

Sieves –
A set of 5 sieves 450 mm diameter –
80,40,20,12.5, 4.75 mm and
5 sieves 200 mm diameter –
2.36, 1.18 mm and 600,300 and 150 micron.
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Fineness Modulus of CA
Fineness Modulus of FA
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Fineness Modulus
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Represents the massed average size of the sieve on which
material is retained, the sieve being counted from the finest
Example – FM = 3 => the third sieve 600 micron is the average
size
Limits –
For Fine sand
2.2 to 2.6
F Medium
For
M di
sand
d
2 6 tto 2
2.6
2.9
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For Coarse sand
2.9 to 3.2
FM > 3.2
Not Acceptable
Grading Curves
Compare the graphs with standard grading curves
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Grading of Fine Aggregates
IS Sieve
Designation
Percentage passing for
Zone 1
Zone 2
Zone 3
Zone 4
10 mm
100
100
100
100
4.75 mm
90-100
90-100
90-100
95-100
Zone 2: Normal sand
2.36 mm
60-95
75-100
85-100
95-100
Zone 3: Fine sand
1.18 mm
30-70
55-90
75-100
90-100
Zone 4: Very fine sand
600 micron
15-34
35-59
60-79
80-100
300 micron
5-20
8-30
12-40
15-50
150 micron
0-10
0-10
0-10
0-15
Zone 1: Coarse sand
Experiment 4.B –
Bulking of Fine Aggregate
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Presence of moisture content  aggregates bulk in volume
The moisture particles form a thin film around the aggregates
and exert surface tension  leads to bulk in volume
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Experiment 4.C –
Aggregate Crushing Value for CA
Strength of the bulk of
aggregate by direct method
is impossible
- Compressive strength of
prepared samples of parent
rock
- Aggregate crushing value
etc.
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Experiment 4.C –
Aggregate Crushing Value for CA
•
Explicit relation between Compressive Strength and
Aggregate is NOT AVAILABLE
•
Lower the Crushing Value -> Higher the Compressive
Strength
•
Crushing value > 30% for Road/Pavement
Crushing Value > 45% for Structural work
•
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Experiment 4.D –
Absorption of Aggregates
• Determination of
percentage of absorption
of the aggregates
• % Absorption
Experiment 4.E –
Bulk Density of Aggregates
•
The ratio of Loose bulk density/ Compacted bulk density should
be between 0.87 to 0.96
•
Bulk Density
Cement
1440 kg/m3
Sand
1440 kg/m3 to 1600 kg/m3
CA
1600 kg/m3 to 1880 kg/m3
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Any questions on
Courtesy: http://en.wikipedia.org/wiki/File:10mm-aggregate.jpg
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