Concrete Technolgy

2. Cement test can be divided into
two types
 Field Tests
 Laboratory Tests
2

3.  There should not be lumps and colour should
be greenish grey.
 Should give cool feeling.
 Should give smooth feeling when taken
between fingers.
 Cement particle should float for some time
before sinking
3

4.  Fineness Test
 Standard Consistency Test
 Setting Time Test
 Compressive Strength Test
 Soundness Test
 Tensile Strength Test
4

5.  Measurement of mean size of grains in
cement.
 Strength in cement depends on cement
fineness.
 Finer cement – quicker action with water –
early strength.
 Shrinkage and cracking of cement increase
with fineness of cement.
5

6.  Sieve Test
 Air-permeability Test
6

7.  Weigh 100 grams of cement and take it on IS
sieve No. 9 (90 micron).
 Remove the air set lumps by fingers.
 Sieve the given sample for 15 minutes.
 Weigh the residue left on sieve which should
be < 10% for ordinary cement.
7

8. 8

9.  More recent method in India.
 Fineness is determined in terms specific
surface of cement.
 Specific surface expressed in cm2/gm or
m2/kg.
 Specific surface cement < 2250 cm2/gm.
9

10.  To determine the percentage of water
required for preparing cement paste.
 Done by Vicat apparatus.
 Percentage of water required is 25 to 35%.
10

11. 11

12.  Weigh approximately 400g of cement and mix
with weighed quantity of cement.
 Fill the paste in Vicat mould.
 Lower the plunger till it touches the cement
surface.
 Release the plunger allowing it to sink into paste.
 Repeat the procedure till the gauge shows 5mm
to 7mm.
12

13.  To detect the deterioration of cement due to
storage.
 Done using Vicat apparatus.
 Prepare cement paste and fill the Vicat
mould.
 Start the stop watch the moment water is
added to cement.
13

14.  Place the block under rod bearing the needle.
 Lower the needle so that its touches the
surface.
 Release the needle – penetrates the paste.
 Repeat the procedure till 5mm+or- 0.5mm
from the bottom of the mould.
14

15.  Replace the needle
 When the needle creates impression but
attachment fails to do so.
 Then cement is considered as final set.
15

16.  To determine the compressive strength.
 Cement (1) + sand (3) for cement mortor.
 Compressive Strength=11.5 N/mm2 (3days )
and 17.5 N/mm2 (7days )
16

17.  Mixture of cement and standard sand in 1:3 in China dish.
 Mix it by adding water – uniform colour.
 Place the mould over vibrating machine and held by clamps.
 Fill the mould with paste and compact using vibrating machine.
 Keep the mould in water of temerature 27±2o C for 24 hours.
 Remove cube from mould and submerge it in water.
 Test the cubes 3and 7 days (3 cubes each).
17

18.  To detect – uncombined lime an magnesia –
expansion of cement.
 Le-chatelier apparatus is used.
 Expansion < 10% for portland cement.

18

19. 19

20. 20
 Place the apparatus on the glass plate
Fill it with cement paste
Place it in water having temerature 27±2o C for 1 day
Measure the distance separating indicator(d1)
Again submerge the apparatus in same water and bring it boiling
point
Remove the mould and cool and measure the distance (d2)
(d1-d2) gives the expansion of cement.