Kathmandu University Civil Labs
SIEVE ANALYSIS OF AGGREGATES
APPARATUS REQUIRED:
1) Set of Sieves
2) Weighing machine
3) Vibrator
THEORY:
Aggregate retained on 4.75mm size sieve is called as coarse aggregate and particles passed through
4.75mm size sieve is called as fine aggregate. The operation of dividing the sample of aggregate into
fraction, each fraction consisting of particles of similar size is called as sieve analysis.
The mass of the aggregates retained in each sieve is used to get the percentage finer, which is plotted
against sieve size or particle size in the semi-log graph. This graph is known as particle size distribution
curve. From this curve, grain size and finally the type of soil is determined. Or in the other word
classification of soil is done.
The recommended sieves for the sieve analysis of aggregates are as follows.
80mm or 75mm
40 or 37.5mm
20mm
10mm
4.75mm
2mm
1mm
600 micron
325 micron
150 micron
75 micron
PROCEDURE:
1. Dry sample (5kg) of aggregate is taken.
2. A series of sieve is arranged in descending orders with pan at bottom.
3. The sample is placed in top of sieve of stack and covered with lid.
4. Then the assembly of sieve is sieved up to 10 minutes at uniform rate and the weight of fraction
of aggregates retained in each sieve was weighed separately and dust collected on pan was
weighed.
5. The total weight is added up which should not be less than 99.55% in initial sample.
6. The calculations are done and the graph is plotted taking sieve size along X-axis and % finer
along Y-axis on semi log graph.
Figure :
OBSERVATIONS AND CALCULATIONS:
Weight of the sample aggregate (W) = 5 kg
S.No. Sieve Size(mm) Wt. retained,W1
(gm)
% Wt. retained
W1*100/W
Cumulative %
wt. retained
X
% finer
(W-W1)*100/W
or (100-X)
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
Pan
∑
From the graph,
D60 = ......... mm
D30 = ......... mm
D10 = ......... mm
Where,
D60 is the particle size corresponding to 60% finer.
D30 is the particle size corresponding to 30% finer.
D10 is the particle size corresponding to 10% finer.
1. Coefficient of uniformity Cu = D60/D10
2. Coefficient of curvature Cc = (D30
2
)/(D10*D60)
CONCLUSION:
Visit the above-mentioned drive link for clarity.
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