Theory:-
There
are several tests are performed to determine the physical characteristics of
the aggregate to ensure its performance as intended for highway construction.
One of these tests is the Determination
of Clay Lumps in Aggregate.
Why the Determination of Clay Lumps in Aggregate is Important?
Excessive presence
clay lumps in a processed aggregate intended for use in a Portland Cement or
Hot Mix Asphalt may interfere with the bonding between the aggregate and
cementitious material. This will affect in spalling, raveling, or stripping and
create weak points and pop-outs if the material is incorporated into the
pavement or structure.
Determination of Clay Lumps in Aggregate, IS: 2386 (Part-2)–1963
Hi friends, you are welcomed in the
world of Civil Allied Gyan. Read definition,
apparatus, IS code, test procedure, formula, result and lab report of Determination of Clay Lumps in Aggregate as
per IS 2386-2-1963.
IS
Code for Determination
of Clay Lumps:-
IS: 2386 (Part-2)–1963,
Estimation of deleterious materials and organic impurities in aggregate.
Apparatus Required For Determination of Clay Lumps:-
The apparatus shall consist of the following:
- Balance – A balance or scale sensitive to within 0.1 percent of the weight of the sample to be weighed.
- Containers – Containers of a size and shape that will permit the spreading of the sample on the bottom in a thin layer.
- Sieves – Sieves conforming to IS: 460-1962, Specification for Test Sieves (Revised).
Sampling the Test Specimen:-
- Test samples will be obtained by quartering or by the use of a sampler, from a representative sample selected from the material to be tested.
- Test samples will be handled in such a manner as to avoid breaking up clay lumps which may be present in it.
- Test samples will be dried to constant weight at a temperature not exceeding 110 °C.
- The samples of fine aggregate will consist of particles coarser than 1.18 mm IS Sieve and will weigh not less than 100 g.
- The samples of coarse aggregate will be separated into different sizes using 4·75 mm, 10 mm, 20 mm and 40 mm IS Sieves.
- The weight of the samples for different sizes will be not less than those indicated below:
Size of Particles making up the sample (in mm) |
Weight of sample min. (in g) |
Over 4.75 to
10 |
1000 |
Over 10 to
20 |
2000 |
Over 20 to
40 |
3000 |
Over 40 |
5000 |
In the case of
mixtures of fine aggregates and coarse aggregates, the material will be separated
into two sizes on 4.75 mm IS Sieve.
The samples of fine and coarse aggregates will be prepared as described under above paragraph of sampling.
Procedure for Determination of Clay Lumps:-
- Spread the sample in a thin layer on a bottom of container and examine for clay lumps.
- Break the sample particles with fingers if does, that particles will be classified as clay lumps.
- After all discernible clay lumps have been broken, remove the residue from the clay lumps by the use of IS Sieves indicated below:
Size of Particles Making up the Sample (in mm) |
Size of Sieve for Sieving Residue of Clay Lumps |
Fine
aggregate (retained on 1.18 mm lS Sieve) |
850 Micron |
Over 4.75 mm
to 10 mm |
2.36 mm |
Over 10 mm
to 20 mm |
4.75 mm |
Over 20 mm
to 40 mm |
4.75 mm |
Over 40 mm |
4.75 mm |
Calculation:-
The percentage of
clay lumps in aggregates shall be calculated in accordance with the following
formula:
Formula to Calculate Clay
Lumps in Aggregates:-
Where
L = percentage of
clay lumps,
W = weight of sample,
and
R = weight of sample
after removal of clay lumps.
Reporting
of Results:-
The percentage of
clay lumps in the aggregate shall be reported to the nearest 0.1 percent.
Object:-
This method of test (IS:
2386 (Part-2)–1963) covers the procedure for the approximate determination of
clay lumps in the routine examination of aggregates.
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