OBJECT: - To determine (A) Fineness modulus, (B)
Gradding of a given sample of (i) Coarse aggregate (ii) Fine
aggregate.
APPARATUS:-(1) 1.S. sieves for grading determination:
i) For C.A.: 80mm, 63mm, 50mm. 40mm, 31.5mm, 25mm,
20mm. 16mm. 12.5mm, 10mm, 6.3mm. 4.7mm.
ii) For F.A.3.35mm, 2.36mm, 1.18mm. 600 micron, 300
micron, 150micron, 75 micron.
(2) 1.S. Sieve for
Fineness modules determination:
i) For C.A.- 150mm, 75mm, 40mm. 20mm,
10mm, 4.75mm, 2.36mm. 1.18mm, 600 micron, 300 micron. 150 micron.
ii) For F.A.-4.75mm, 2.36mm, 1.18mm, 600 micron, 300
micron, 150micron..
(3) BALANCE: The balance or scale shall be such that it is readable and accurate to o.1 percent of the weight of test
sample.
EXTRACTS FROM L.S. 2386 (PART I)-1963)
1. The sample shall be brought to an air
dry condition before weighing and sieving. This may be achieved either by
drying at room temperature of by heating at a temperature of 100 C to 110 C.
The air dry sample shall be weighed and sieved successively on the appropriate
sieves starting with the largest care shall be taken to ensure that the sieves
are clean before use.
2. Each sieve shall be shaken separately
over a lean tray until not more than a trace passes, but in any case for a
period of not less two minutes. The shaking shall done with a varied motion.
backwards and forwards, left to right, circular clockwise and anti-clockwise
and with frequent jarring, so that the material is kept moving over the sieve
surface in frequently changing direction. Material shall not be forced through
the sieve by Hanel pressure, but on sieve coarser than 20 mm pressing of
particles is permitted lumps of fine material, if present, may be broken by
gentle pressure with fingers against the side of the sieve. Light brushing with
a soft brush on the underside of the sieve may be used to clear the sieve
openings.
3. Light brushing with a fine camel hair
brush may be used on the 150 micron, and 75 micron I.S. sieves to prevent
aggregation of powder and blinding of aperture. stiff or worn out brushes shall
not be used for this purpose and pressure shall not be applied to the surface
of the sieve to force particle a through the mesh.
(i) On completion of sieving the material
retained on each sieve together with any material cleaned from the mesh shall
be weighed.
In the event of a scum forming on the
surface of the test block, use the underside of the block for the
determination.
OBSERVATIONS: (i) Weight of cement 400 gms
(ii) Weight of
water 0.85 PX 400 gms
(P-percentage of water required to make a
cement paste of Standard consistency).
(a)
Initial
Setting Time
|
S.No. |
Time elapsed from the instant of adding
water |
Penetration from the bottom |
Remark |
|
|
|
|
|
(b) Initial and Final Setting
Time using NaOH
|
.S.No. |
Time elapsed from the instant of
adding water |
Penetration from the bottom (initial setting) |
Nature of Impression (Final setting time) |
Remark |
|
|
|
|
|
|
NOTE:
RESULTS:
Dote (.) occurs only when final setting
occurs. Before this, nature of impression is a dot surrounded by a circle (0)
(a) Initial Setting Time.......
(b) (i) Initial Setting Time using NaOH.
(ii) Final Setting time using NaOH
.DISCUSSION: Cover the following points
(i)
Importance
of the test, with reference to chemical Composition of cement and its
hydrolysis properties.
(ii)
Normal
results expected
(iii)
Use of additives to change setting time and
its importance
(iv)
Use
of retarders.
(v)
Reasons
of deviation of actual results from expected results
Note: LEAVE THE APPLIANCES USED BY YOU AND
THEIR SURROUNDING RECORD YOUR OBSERVATIONS IN THE JOURNAL & GET THEM BY
YOUR TEACHER.
Note 1:- For many routine purposes
mechanical sieving is advantageous but it this method is used, care should be
taken to ensure that the sieving is complete. Note 2:- The following
alternative procedure is permissible where it is required to determine only the
cumulative percentage figures.
The weighted sample shall be passed
through the largest of the appropriate sieve as described above. The fraction
which passes the sieve shall be weighed. than passed through the next smaller
sieve; the fraction which passes shall be weighed and so on.
The cumulative weight passing each sieve
shall be calculated as a percentage of the total sample weight.
Note 3:- If sieve is carried out with a
nest of sieves on a machine not less than 10 minutes sieving will be required
for each test.
Note 4:- Use mechanical sieving and
alternative procedure given in note 2 for the test in laboratory.
GRADING OF AGGREGATES:
1. COARSE AGGREGATES:- Coarse aggregates
shall be supplied in the nominal size given in Table 3. For any one of the
nominal size, the proportion of other sizes as determined by the method
described above shall also be in accordance with Table III.
TABLE III COARSE AGGREGATE
4. In order to prevent binding of the
sieve apertures by overloading, the amount of aggregate placed on each sieve
shall be such that the weight of the aggregate retained on the sieve at
completion of the operation is not greater than the value given for that sieve.
TABLE I Maximum weight to be retained at
the completion of sieving
Coarse aggregates
Fine aggregates
|
I.S. sieve |
Maximum weight for |
1.S. sieve |
Maximum weight for 20 cm dia
sieve |
|
|
|
45 cm dia sieve Kg. |
30 cm dia sieve Kg. |
|
|
|
50 mm |
10 |
4.5 |
|
|
|
40 mm |
08 |
3.5 |
2.36 mm |
200 |
|
31.5mm or 25mm |
06 |
2.5 |
1.18 mm |
100 |
|
20 mm |
04 |
2.0 |
|
|
|
16 mm or 12.5 mm |
03 |
1.5 |
600 micron |
75 |
|
10 mm |
02 |
1.5 |
300 micron |
50 |
|
6.3 mm |
1.5 |
0.75 |
|
|
|
4.75 mm |
1.0 |
0.50 |
150 micron |
40 |
|
3.35 mm |
|
0.30 |
75 micron |
25 |
TABLE II Minimum weight of sample for
sieve Analysis
|
Maximum
Size present in Substantial proportions |
Minimum Weight for sample to be
taken for sieving. |
|
Mm |
Kg |
|
63 |
50 |
|
50 |
35 |
|
40 or 31.5 |
15 |
|
25 |
05 |
|
20 or 16 |
02 |
|
10 |
01 |
|
6.3 |
0.5 |
|
4.75 |
0.2 |
|
2.36 |
0.1 |
In Table I Sample weights given in Table
II will thus normally required in several operations on each sieve.
2. Fine Aggregates: - The grading of fine
aggregates, when determined is described above shall be within the limit given
in Table 4 and shall be described as fine aggregate. Grading ones 1. II. III
& IV. Where the grading falls outside the limit of any particular grading
some of sieve other than 600-micron I.S. sieve by a total amount not exceeding
5 percent, it shall be regarded as falling within that grading zone. This
tolerance shall not be applied to percentage passing the 600 micron I.S. sieve
or to percentage passing any other sieve size on the coarse limit of Grading
Zone I or the finer limit of grading Zone IV.
3. All in Aggregates or Mixed Coarse and
Fine Aggregates: - The weight of sample available shall not be less than the
weight given in Table V. The sample for sieving (see Table V) shall be prepared
from the larger sample either by Quartering or by means of a sample divider
(use it in the laboratory).
REPORTING OF RESULTS: The results shall be
calculated and reported as:
(a) The commutative percentage by weight
of the total sample passing of the sieve to the nearest whole number.
(b) The percentage by weight of the total
sample passing on sieve and retained on the next smaller sieves to the nearest
0.1 percent.
(c) The result of sieve analysis may be
recorded graphically on the chart for recording sieve analysis.
It is recommended that cumulative
percentage figures should be used for comparison with specification requirement
or for reporting results graphically.
RESULTS:
(a) Fineness modulus of coarse aggregate ………………….
(b) Fineness modulus of fine aggregate……………..
DISCUSSION:- Cover the following points:
(i)
Importance of the Test.
(ii) Normal results expected
(iii) Reasons of Deviation of actual
results from expected results.
NOTE: -
1. LEAVE THE APPLIANCES USED BY YOU AND
THEIR SURROUNDINGS CLEAN.
2. RECORD YOUR OBSERVATIONS IN THE JOURNAL
& GET THEM VERIFIED BY YOUR TEACHER.
TABLE IV FINE AGGREGATE
|
LS.
Sieve Designation |
Percentage
passing for |
|||
|
Grading Zone I |
Grading Zone II |
Grading Zone III |
Grading Zone IV |
|
|
10mm |
100 |
100 |
100 |
100 |
|
4.75mm |
90-100 |
90-100 |
90-100 |
95-100 |
|
2.36mm |
60-95 |
75-100 |
85-100 |
95-100 |
|
1.18mm |
30-70 |
55-90 |
75-100 |
90-100 |
|
600micron |
15-34 |
35-59 |
60-79 |
80-100 |
|
300micron |
5-20 |
8-30 |
12-40 |
15-50 |
|
150micron |
0-10 |
0-10 |
0-10 |
0-15 |
TABLE V MINIMUM WEIGHTS FOR
SAMPLING
|
Maximum
size present in Substantial proportions (mm) |
Minimum
weight of sample dispatched for testing. (Kg) |
|
63 |
10 |
|
50 |
10 |
|
40 |
50 |
|
25 |
50 |
|
20 |
25 |
|
16 |
25 |
|
12.5 |
12 |
|
10 |
6 |
|
6.3 |
03 |
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