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Lab 1-Field Identification Tests

This lab focuses on simple field identification tests to determine the composition and characteristics of soil, specifically differentiating between silt and clay. There are four tests: 1) the dispersion test where soil is mixed with water and the rate of settlement of sand, silt, and clay layers is observed, 2) the shaking test where water retention on soil indicates silt or clay content, 3) the plasticity test where ability to roll soil into a thread indicates clay, and 4) the dry strength test where force needed to crush dry soil indicates clay content. These simple tests use common tools like containers and hands to enable classification of soils in the field prior to excavation.

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3K views2 pages

Lab 1-Field Identification Tests

This lab focuses on simple field identification tests to determine the composition and characteristics of soil, specifically differentiating between silt and clay. There are four tests: 1) the dispersion test where soil is mixed with water and the rate of settlement of sand, silt, and clay layers is observed, 2) the shaking test where water retention on soil indicates silt or clay content, 3) the plasticity test where ability to roll soil into a thread indicates clay, and 4) the dry strength test where force needed to crush dry soil indicates clay content. These simple tests use common tools like containers and hands to enable classification of soils in the field prior to excavation.

Uploaded by

Hazem
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PDF, TXT or read online on Scribd
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CIVE 430

Soil Mechanics & Lab

Lab #1
Field Identification Tests
Purpose: During this lab you will learn about
Field Identification tests to determine the type of soil

Overview:

This lab consists of four simple tests that enable us to determine roughly, the composition and
characteristics of the soil, mainly to differentiate between silt and clay. The information that
interests us is the composition of sand, silt, and clay present in the soil. This composition
clarifies the soil characteristics that the engineer needs before excavating the site. All these tests
are done in the field using simple tools like transparent container and a stirring rod.

1- Dispersion Test
Apparatus:

Transparent Container
Stirring rod
Procedure:
Fill approximately the soil to be tested up to a 100 ml in a graduated cylinder/transparent
container.
Add water to the soil make sure that the amount of water is more than the amount of soil
approximately to the 500ml mark.
Mix the sample using the stirring rod or by shaking to ensure that the sample is in
suspension
Allow the sample to settle and note the rate of settlement of the sample
After 24hrs, mark the settlement of each precipitated layer and measure its thickness
Determine the ratio of each soil type
Results: After we mix the content of the transparent container, we can see sand particles that start
to settle down. Silt particles settle slower than the sand since their size is smaller and it takes
more time for them to settle. Clay particles will settle after a longer time since their size is so
small that gravitational forces dont have a major effect in the settling process. After about 24
hours we will have three layers that could be differentiated by eye. The first layer from the
bottom is the sand, the second is silt, and the third is clay. To be precise, check the height of the
three layers, in order to determine the composition of the soil
CIVE 430
Soil Mechanics & Lab

2- Shaking Test
Apparatus:

None
Procedure:
Put a small quantity of soil on the palm of your hand and add water to it
Mix until the created sample is homogenous and is mud like
Place the sample in an open palm to get a thin layer of mud and tap the back of the hand
Squeeze the hand and then stretch it
Results: After we tap on our hand, we see how much water will reach the top of the mud layer.
The more the water that reaches the top layer, the soil contains silt and sand. The less the water
that reaches the top, the soil contains more clay. This is due to the lower particle size of the clay
that exhibits more friction and entraps the water inside

3- Plasticity Test
Apparatus:

None
Procedure:
Put a small quantity of soil on the palm of your hand and add water to it till a paste in
formed
Roll the sample into a 3mm thread
Results: If the sample can be rolled easily while drying without losing its plasticity then the main
constituent of the soil is clay. On the other hand, if the sample is non plastic, it would break
before it can be threaded and the soil is mainly silt (low plasticity).

4- Dry Strength Test


Apparatus:

None
Procedure:
Prepare a soil sample that has water already added to it and allow it to dry by air
When dry, break the sample apart and take a smaller fragment.
Crush the fragment between your thumb and forefinger
Results: The stronger the force needed to crush the sample, the more the soil contains clay. The
weaker it is against crushing, the more sand and silt it contains

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