Silt test

silt test concrete

1. 1



CODE & SUBJECT : DCC 2042 – CONCRETE AND
BRICWORK
TITLE : SILT TEST
LECTURER’S NAME : PUAN HUSNA BINTI MAT SALLEH
KELAS : DKA1B

NAME

REGISTRATION NO.

MUHAMAD AKMAL BIN MOHAMAD SHARIF

03DKA16F2030

AINUNYASMINE BINTI HASLAN

03DKA16F2023

NIRANDOAL A/L CHENG

03DKA16F2029

NUR AIDA BINTI ZAINOL ABIDIN

03DKA16F2027

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BILL TITLES PAGE NUMBER
1 Objevtive 1
2 Theory 1
3 Apparatus 2-3
4 Procedure 4-8
5 Result 9
6 Discussion 9
7 Conclusion 10

3. 3

OBJECTIVE
The silt test is carried out to determine the amount of silt, clay or other fine dust that may
be present in a sand sample. The presence of such in a sand used in concrete will reduce
the strength of the hardened concrete if exceeds a permitted limit. The permitted limit is
8 percent.
THEORY
There are two types of harmful substances preset in fine aggregates i.e. organic matter
produced by decay of vegetable matter and/or clay and silt, which form coating thus
preventing a good bond between cement and the aggregates. If present in large
quantities, result in the increase water-cement ratio and finally affecting the strength of
concrete.
Field test is generally conducted in order to determine the volumetric percentage of silt in
natural sand for percentage up to 6%, otherwise more detailed test as prescribed by
standard code are required to be conducted.

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EQUIPMENT AND APPRATUS
1. Sample of sand

2. Salt solution

3. Graduated cylinder

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PROCEDURE
1. 200 ml of sand has been poured into the graduated cylinder.

2. Continue to add salt solution up the 250ml mark.


3. Shake well covering the top of the graduated cylinder with your hand.

4. Allow to settle for three hours.
5. Measure the heights of both sand and silt respectively.
6. Calculate the amount of silt as a percentage of the amount of sand.

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ANALYSIS
Calculating the percentage using the following formula:
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×100=�������??????�� �� ��??????� �������
RESULT

6
150
×100=4%

DISCUSSION
The sand can be used in any project because it have silt not more than 8%.If we use sand
with silt more than 8%, the concrete will weak and cannot use it for any project. This is
because the silt will weaken the bond between aggregates and cement paste.
We use the salt in this test is for separate the water with the sand to measure the silt layer
on the top of the sand. If we don’t use the salt, we could not measure it as the water did
not float or separate with the sand.

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CONCLLUSION
Silt is created by a variety of physical processes capable of splitting the generally sand-
sized quartz crystals of primary rocks by exploiting deficiencies in their lattice. These
involve chemical weathering of rock and regulate, and a number of physical weathering
processes such as frost shattering and haloclasty. The main process is abrasion through
transport, including fluvial combinations, Aeolian attrition and glacial grinding. It is in semi-
arid environments that substantial quantities of silt are produced. Silt is sometimes known
as "rock flour" or "stone dust", especially when produced by glacial action. Mineralogical,
silt is composed mainly of quartz and feldspar. Sedimentary rock composed mainly of silt
is known as siltstone.
If the sand contains more than 6% silt, you would have to use more cement and the
concrete would shrink more during the hardening process, causing cracks in the product.
Silt and clay are not as strong as typical aggregates. They can absorb water and their
properties can change because of it. In fresh concrete, I would think that silt and clay
would interfere with the bonding of aggregates to cement. In hardened concrete, if the silt
and clay come in contact with water in air voids, they can shrink or swell, either building
internal pressure (swelling) or leaving larger voids and weakening the concrete
(shrinking).