Theory:
Bulking
is the increasing volume of fine aggregate in a loosely feel state, When it is
moist due to present of moisture film around the partical there is no bulking.
When the sand is dry or when it is fully saturated in with the water fine sand
bulks more than coarse sand. Sand value may increase 20 % to 30 % as the
moisture increase from 0 to 4 % to 5 %.
Application:
The
quantity of sand to be added in each batch is consider in saturated surface day
condition. In practice on actual work site and sand may be weight either
accuracy itself due to rain or due washing to remove clay etc. volume of sand
to be plot in each batch as therefor to be increase depending on bulking. If
this allows not made the concrete mix will be under sanded at so brush it will
consume more cement proportinaly its water cement ratio will change so it
compressive strength will be affected.
Items
Required:
1. Cylindrical container
2. Steel rule
3. Steel rod
4. Tray
5. Weight of 500 gms
Procedure:
1. Sufficient quantity of
moist sand is loosely feel upto 2/3 height of consider and level the top
surface of sand.
2. A steel rule pushed vertically
through sand at the middle of portion going to the bottom of container. The
height of sand is recorded.
3. Sand from the container was
removed and feel it into the another container of same diameter.
4. Feel the first container ½
full with water and about ½ sand was put back and rodded with the steel rod of
6 mm dia. and reduce the volume to minimum.
5. The remaining sand is added
and rodded as above level. The top surface of sand and its depth or height is
measured at the middle with the steel rule.
Precaution:
1. The height of sample before
feel with in water and after should be taken accurately.
2. Care should be taken while
transferring the sample to another container.
Observation:
1. Height of sand when moist
(h) = 400 cm
2. Height of sand when
saturated (h1) = 300 cm
Conclusion:
Percentage
bulking = (h-h1/h1) X 100 %
Observation
Table:
INITIAL VOL.
OF SAND
|
VOL. OF WATER
ADDED
|
TOTAL VOLUME
|
% OF WATER
CONTENT
|
HEIGHT OF
SAND
|
% OF BULKING
|
300
|
10 ml
|
310
|
3.33
|
325
|
8.3
|
300
|
20 ml
|
320
|
6.66
|
330
|
10.0
|
300
|
30 ml
|
330
|
10.0
|
370
|
23.3
|
300
|
40 ml
|
340
|
13.33
|
400
|
33.3
|
300
|
50 ml
|
350
|
16.66
|
385
|
28.3
|
300
|
60 ml
|
360
|
20
|
365
|
21.6
|
300
|
70 ml
|
370
|
23.33
|
345
|
15.0
|
300
|
80 ml
|
380
|
26.66
|
325
|
8.33
|
300
|
90 ml
|
390
|
30
|
310
|
3.3
|
300
|
100 ml
|
400
|
33.33
|
300
|
0
|
Result:
The
percentage bulking of given sample of fine aggregate sand is found = 33.3 %
