Weekly lab report on Standard consistency, initial and final sitting times of cement paste.

1. Submitted by: HAFIZULLAH SADAT
Date Submitted: Mar.20, 2018
Instructor: PRO.SHASHANK BISHNOI

2. 1
Introduction
hen water is mixed with cement, it starts
hydration. Excessive addition of water in
cement results an increase in Water cement ratio
& ultimately cement loses its strength when it
hardens. If less water is added than required,
Cement isn’t properly hydrated and results in loss
of strength.
NORMAL CONSISTENCY TEST
Test objectives
The Consistency of cement test is performed to
determine the amount of water content that is to be
added in cement to attain Standard consistency or
normal consistency of cement.
Test apparatus and materials
 Vicatt’s apparatus
 Balance
 Measuring cylinder
 400 cement
 Water (by trail)
 Trowels
 Vicat mould
Figure -01 Vicatt’s apparatus with plunger
Vicatt’s Apparatus
Is used to find out the consistency, initial setting
time and final setting time of the cement. In the
normal consistency test we have to find out the
amount of water to be added to the cement to form
a cement paste of normal consistency.
Vicatt’s apparatus consists of an arrangement to
hold the plunger of 10 mm diameter and two other
needles with 1mm dia. And an enlarged 5 mm
hollow cylindrical base, which are made to freely
fall into a mould filled with the cement paste and
the amount of penetration of the needles of plunder
can be noted using the vertical graduations from 0
mm to 50 mm.
Test Procedure
In order to obtain the amount of water to attain the
standard consistency or normal consistency, the
following procedure was followed during test:
The finding of standard amount of water was
started with trails, different trials were done:
Trail 1: (29% water), 400 gr cement was taken and
place in bowel, by assuming the standard
consistency of water as 29%, the same quantity of
water( 116 gr) was added and mixed with cement.
W
Figure -02 apparatus during test

3. 2
The paste was mixed thoroughly within 3-5
minutes, then the paste was filled in Vicat mould
correctly and excess paste which was remained on
Vicat mould was taken off by using trowel.
Then, the Vicat mould was placed on the steel
plate in such a manner that the surface of Vicat
mould was touched by plunger gently, and the
plunger was released and allowed to sink into the
test mould, the penetration of the plunger was
noted down from the bottom of the mould, which
is indicated on the scale, the value of penetration
which was recorded in first trail was 13mm.
The same procedure was repeated by adding
different % of water until the reading was in
between 5-7mm (according to IS Code) on the
Vicat apparatus scale.
Calculations
As mentioned before obtaining standard
consistency of cement paste is obtained through
trails, in this test method different trails were done,
the recorded values have been shown in the
following table:
Trail
No.
Wat.
(gr)
Cem.
(gr)
Wat.
%
Pene.
(mm)
1 116 400 29 13
2 122 400 30.5 11
3 124 400 31 6
Table -01 test penetration values
Analysis and Conclusion
By adding different percentage of water the
penetration depth of plunger was increased,
starting from 29% as initial amount of water the
penetration depth was 13mm, and followed by
another trail with 30.5% of water the depth was
gotten decreased to 11mm, by continuing this
procedure the final amount of water in terms of %
which was added 31 % and the penetration depth
was 6 mm which is in between 5-7 mm.
So the amount of water require for standard
consistency of cement paste is around 31% of
weigh of cement.
SETTING TIME MEASUREMENT
Once the normal consistency is determined, than
by using the taken specification of that paste from
consistency test, the initial and final setting times
can be measured.
1. Initial setting time
Test objectives
The initial setting time can be defined as “time
taken by paste to stiffen to such an extent that the
Vicatt’s needle is not permitted to move down
through the paste through 25 mm.”
Test apparatus and materials
 Vicatt’s apparatus
 Conical ring
 400 cement
 Water (from consistency test)
 Flat Trowels
Figure -03 Vicatt’s apparatus with needle

4. 3
Test Procedure
As water amount was determined in previous test
(Consistency test) which was 31%. In this test new
fresh cement paste was prepared using the pre-
determined amount of water and cement of the
standard consistency, in addition to that 1.5 %
calcium chloride was added as an accelerator
admixture and mixed thoroughly, then the Vicat
mould (steel ring) was placed on the steel plate.
1 mm diameter needle was used and the sample
was penetrated with this needle by leaving it to
free fall, and then the Vicat scale ruler was read.
The specimen was allowed to remain in the moist
cabinet or moist room for 30 min after molding
without being disturbed, and then the penetration
of the 1-mm needle was determined at this time
and every 15 min thereafter until a penetration of
25 mm or less was obtained. The elapsed time
from mixing the water with dry cement till this
moment is called initial setting time.
Calculations
Round
No.
Time
(h:min)
Penetration
(mm)
1 1:20 3
2 1:22 6
3 1:24 8
4 1:25 10
Table -02 sitting times
Result
As it is revealed from the above table that the
penetration depth is various as time passing, thus
the desired initial setting time can be determined
as mentioned in the IS code that the “time taken by
paste to stiffen to such an extent that the Vicatt’s
needle is not permitted to move down through the
paste through 5 mm.” is initial setting time, from
above table this time is almost 1hr and 22 min.
2. Final setting time
Test objectives
The final setting time is the time from the mixing
of the water to the time when this needle just
makes the impression on the surface of the cement
but do not penetrate into it. Generally the final
setting time of cement (OPC) is 10 hrs. To 12 hrs.
Test apparatus and materials
Same apparatus and materials are used in this test,
because this the test for initial setting time is
followed by this test, the only thing that should be
changed is the Vicatt’s apparatus needle for final
setting time which is an enlarged 5 mm hollow
cylindrical base as shown the following figure.
Figure -04 apparatus’s needles

5. 4
Steps for final setting time tests
Foe calculating the final setting time of cement
paste, set the 5 mm. diameter needles on the lower
end of the rod.
Now again repeat the above steps for noting the
final setting time of cement.
Penetrate the sample by needle every 15 minutes
till only the needle makes an impression on the
paste surface but the cutting edge fails to.
The final setting time will be noted when the
needle if released doesn’t sink visibly and leaves
no impression on the surface of the paste.
Found by the formula:
Conclusion
To measure the setting times of cement, we have
to do our tests on cement of standard consistency.
Normal consistency of standard cement can be
gained by using the W C ratio and depending on
27%- 32%.
The higher rate of water the more initial setting
time needed.
BLAIN PERMEABILITY TEST
Test objectives
The fineness of cement is measured as specific
surface. Specific surface is expressed as the total
surface area in square meters of all the cement
particles in one kilogram of cement. The higher the
Specific surface is, the finer cement will be.
Test apparatus
 Blain Apparatus
 Permeability Cell
 Perforated disc
 Plunger
 Manometer
Test Procedure
Place the perforated disc on the ledge at the
bottom of the cell and place on it a new filter paper
disc. Place the weighed quantity of cement, m1, in
the cell. Place a second new filter paper disc on the
levelled cement. Insert the plunger and press it
gently but firmly until the lower face of the cap is
in contact with the cell. Slowly withdraw the
Figure -05 Blain’s permeability apparatus

6. 5
plunger, rotate it through 90 ° and press once again
the bed is now compacted and ready for the
permeability test.
Test is performed on the Blaine apparatus it is
practically manometer in the U-tube form. One
arm of the manometer is provided at the top with
conical socket to form an airtight fit with the
conical surface of the cell. The same arm has four
etched lines M1 to M4 and T-joint, which lead to
an airtight stopcock beyond which is attached
aspiration rubber bulb.
Manometer is filled to the level of the lowest
etched line with non-volatile, non-hygroscopic
liquid of low viscosity and density (such as
dibutylphthalate or light mineral oil).
Insert the conical surface of the cell into the socket
at the top of the manometer.
Open the stopcock and with gentle aspiration raise
the level of the manometer liquid to that of the
highest etched line. Close the stopcock and the
manometer liquid will begins to flow. Start the
timer as the liquid reaches the second etched line
and stop it when the liquid reaches the third etched
line. Record the time, t, and the temperature, T.
The procedure repeats three times
Calculate three values of the specific surface and
the mean of them
Calculations
Principle of air permeability method is in
observing the time taken for a fixed quantity of air
to flow through compacted cement bed of
specified dimension and porosity. Under
standardized conditions the specific surface of
cement is proportional to √ 𝑡 where t is the time for
given quantity of air to flow through the
compacted cement bed.
The number and size range of individual pores in
the specified bed are determined by the cement
Particle size distribution which also determined
the time for the specified air flow.
A bed of cement is prepared in special
permeability cell and have exact porosity e = 0,500
weight a quantity of cement.
The weight of the cement is calculated from:
m1 = 0,500 × ρ × V ……….1 [g]
Where ρ is the density of the cement [g.cm-3
]
V volume of the cement bed [cm3
]
Specific surface S is expressed as:
𝑺 =
𝑲
𝝆
𝒙
√ 𝒆 𝟑
(𝟏−𝒆)
𝒙
√𝒕
𝟎.𝟏𝜼
……………..…….2 [Cm2
.g-1
]
Where
K is the apparatus constant
e porosity of the bed
t the measured time [s]
ρ density of cement [g.cm-3
]
η the viscosity of air at the test .
Temperature taken from Table.
Table -03 standard Air viscosity table

7. 6
The apparatus constant is determinate by
measuring permeability of reference cement of
known specific surface. The procedure repeats
three times for three samples of cement bed. For
each sample is calculated constant K from
formula:
𝑲 = 𝑺 𝟎 𝒙 𝛒 𝟎
𝒙
(𝟏−𝒆)
√ 𝒆 𝟑
𝒙
√𝟎.𝟏𝜼 𝟎
√ 𝒕 𝟎
…………….3
Where
S0 is the specific surface of the reference
cement [cm2.g-1
]
ρ0 density of the reference cement [g.cm-3
]
t0 measured time [s]
η0 air viscosity at the test temperature [Pa.s]
With the specified porosity of e = 0,500
𝑲 = 𝟏. 𝟒𝟏𝟒𝒙𝑺 𝟎 𝒙 𝛒 𝟎
𝒙
√𝟎.𝟏𝜼 𝟎
√ 𝒕 𝟎
………..….4
The mean of three values of K is the constant K for
the apparatus.
Alternatively, the S value can be computed though
simple formula:
𝑺 = 𝟓𝟖√ 𝒕 ………………..5 [Cm2
.kg-1
]
Where t is the time for given quantity of air to flow
through the compacted cement bed. And computed
by sec. in this test the (t) was 2.6 sec, by
considering this value of (t) the specific surface
can be calculated as follow:
𝑺 = 𝟓𝟖√ 𝒕 = 𝟓𝟔√𝟐. 𝟔 = 𝟗𝟑. 𝟓𝟐 Cm2
/ kg
Result
The resulting value, called the Blaine fineness, is
today expressed in units of m2/kg, although in
previous times it was expressed in cm2/g. The
Blaine fineness of OPC usually ranges from 300 –
500 m2/kg (3000 – 5000 cm2/g).
As we see here the obtained value for specific
surface area is smaller than standard values, this is
just due some slight difference in test method and
material.
Since those slandered material which was used in
tests as a reference material was also not good
defined, because no value of ρ0, t0, η0, S0 was
known to us.