Put plastic sheeting below all the aggregates (fine
& coarse) so as to prevent direct contact of the aggregates with the soil
below and contamination with mud.
Erect a permanent or temporary partition in between
the stocked aggregates.
This will prevent the mixing of the aggregates.
1) CHECKLIST FOR SAND (FINE AGGREGATES) REQUIREMENT
Fine aggregate � Aggregate most of which passes 4.75 mm I.S. sieve.
Fine aggregate should be river sand
I.S. 383-1970 has specified four distinct zones for
fine aggregates.
IS SEIVE
|
Grading
Zone 1
|
Grading
Zone 2
|
Grading
Zone 3
|
Grading
Zone 4
|
10 mm
|
100
|
100
|
100
|
100
|
4.75 mm
|
90-100
|
90-100
|
90-100
|
95-100
|
2.36 mm
|
60-95
|
75-100
|
85-100
|
95-100
|
1.18 mm
|
30-70
|
55-90
|
75-100
|
90-100
|
600 micron
|
15-34
|
35-59
|
60-79
|
80-100
|
300 micron
|
5-20
|
8-30
|
12-40
|
15-50
|
150 micron
|
0-20
|
0-10
|
0-10
|
0-15
|
COARSEST
SAND
|
FINEST
SAND
|
|||
LESS WATER
FOR SAME
WORKABILITY
|
MORE WATER
FOR SAME
WORKABILITY
|
|||
SEGREGATION
AND
BLEEDING
|
HIGH
COHESION
|
We therefore select a medium sand from
Zone 2, so as to satisfy the two extremes.
Such sand should have Fineness Modulus of 2.6 -2.9.
Fineness Modulus
|
Above 3.2
|
2.9 to 3.2
|
2.6 to 2.9
|
2.2 to 2.6
|
Below 2.2
|
Type of sand
|
Very coarse
|
Coarse
|
Medium
|
Fine
|
Very fine
|
Fine aggregate should be sieved on a square sieve
of size 4.75 mm to remove coarser aggregates or impurities.
Fine aggregate should be free from clay lumps,
silt, organic and inorganic impurities.
Percentage of clay in fine aggregate should not
exceed one percent by weight.
Also percentage of silt (material finer than 75
microns) should not exceed 3 percent by weight.
However silt test can be checked by volume as well
as it is much simple and faster and gives an indication of silt in the fine
aggregates.
Silt content should not exceed 8% by volume in 3
hours.
2) CHECKLIST FOR COARSE AGGREGATE REQUIREMENT
Coarse aggregate � Aggregate most of which is retained on 4.75 mm
I.S. sieve.
Remedios factors for deciding the maximum size of
the aggregate in a given stock.
(Generally used for mix design calculations)
Aggregates passing 10 mm
IS.Sieve
Maximum size of aggregate
0 � 25
%
20 mm
25-75
%
15 mm
75-100
%
10 mm
Aggregates passing 20 mm
IS.Sieve
Maximum
size of aggregate
0 � 25
%
40 mm
25-75
%
30 mm
75-100
%
20 mm
As far as possible avoid flaky and elongated
aggregates.
The maximum size of the aggregate should not be
greater than one fourth of the minimum thickness of the member.
For thin members like pardis the size of the
aggregates should be restricted to maximum size of 10 mm.
