CONSISTENCY TEST FOR CEMENT
object
Standard consistency of a cement paste
is defined as that consistency which will permit a vicat plunger having 10 mm
dia and 50 mm length to penetrate to a depth of 33-35 mm from top of the mould.
APPARATUS
MEASURING INSTRUMENTS
NAME
|
CAPACITY / RANGE / SIZE
|
ACCURACY
/ LEAST COUNT
|
Vicat
apparatus
|
Should be made
as per IS:5513
|
—
|
Balance
|
1000 g
|
1 g
|
Measuring
cylinder
|
100 ml
|
1 ml
|
OTHER ACCESSORIES
Tray, glass
plate
|
Fig:-Showing Vicat Apparatus
ENVIRONMENTAL CONDITION
Temperature
|
27 ± 20 C
|
Humidity
|
65 ± 5 %
|
PROCEDURE
1.
Take
400 g of cement and place it in the enameled tray.
2.
Mix
about 25% water by weight of dry cement thoroughly to get a cement paste. Total
time taken to obtain thoroughly mixed water cement paste i.e. “Gauging time”
should not be more than 3 to 5 minutes.
3.
Fill
the vicat mould, resting upon a glass plate, with this cement paste.
4.
After
filling the mould completely, smoothen the surface of the paste, making it
level with top of the mould.
5.
Place
the whole assembly(i.e. mould + cement paste + glass plate) under the rod
bearing plunger.
6.
Lower
the plunger gently so as to touch the surface of the test block and quickly
release the plunger allowing it to sink into the paste.
7.
Measure
the depth of penetration and record it.
8.
Prepare
trial pastes with varying percentages of water content and follow the steps (2
to 7) as described above, until the depth of penetration becomes 33 to 35
mm.
Table:-Observation table for
Normal Consistency
S.No.
|
Wt of cement in gm |
% Water added
|
Water added in cc |
Penetration of plunger in mm.
|
Normal consistency(P)
|
1
|
400
|
26
|
104
|
17
|
|
2
|
400
|
28
|
112
|
20
|
30
|
3
|
400
|
30
|
120
|
33
|
|
CALCULATION
Calculate percentage of water (P) by
weight of dry cement required to prepare cement paste of standard consistency
by following formula, and express it to the first place of decimal.
Where,
W=Quantity of water added
C=Quantity of cement used
PRECAUTIONS
§ Gauging time
should be strictly observed
§ Room temperature
should be well maintained as per test requirement.
§ All
apparatus used should be clean.
§ The experiment
should be performed away from vibrations and other disturbances.
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