LAB REPORT 1

Sieve analysis

1.0 Introduction

Soil can be defined as naturally occurring soft or loose sediments forming the

earth crust. Soil also formed as a result of the weathering of rocks or from the

decomposition of plants. Soil is formed from different materials such as gravel ,

sand, silt, clay or a mixture of these materials. Soil is normally classified based on its

properties and characteristics.

1.1 Types of soil

Soil type can be identified according to their characteristic such as

group, properties and size of particles as shown in table below.

Group Soil properties Soil size

(mm)

Soil type

Course-

grained

Non-cohesive

soil

0.06 – 2.0

2.0 - 60

Sand

Gravel

Fine-grained Cohesive soil < 0.002

0.002 – 0.06

Clay

Silt

Organic Organic soil <0.002 Peat soil

Coarse-grained soil such as sand and gravels are rock sediments

transported by weathering agents such as water, wind and others. The action

of these agents causes the soil to be rounded. The particle of fine-grained soil

such as clay and organic soil are flaky. Some shapes of soil particle are

angular, prism, flaky and round.

1.2 Properties of soil

There are three properties of soil that is cohesive soil, non-cohesive

soil and organic soil.

1.2.1 Cohesive soil

Cohesive soil contains clay minerals and posses plasticity.

Cohesive soil is formed from flaky fine particles with high cohesive force.

In moist condition, the soil particles stick to each other due to this

cohesive force. Cohesive soil has low permeability and has ability to retain

water for longer time. In dry condition, the cohesive soil form hard solid

particles. Some examples of cohesive soil are clay and silt.

1.2.2 Non-cohesive soil

Non-cohesive means the soil has no shear strength if no

confinement. Non-cohesive soil has particles which are rounded, angular

or prismatic. The texture of the soil is hard and rough, and the bond

between particles is loose. Its stability depends on the friction between the

particles. The soil has high permeability and in rainy condition, water

quickly seeps among soil particles. As a result, non-cohesive soil cannot

retain water. Some examples of non-cohesive soil are sand and gravel.

1.2.3 Organic soil

Organic soil is formed as a result of the decomposition of

organic materials, plants and decaying organism. The soil is also

formed from the formation of humus due to the reaction of bacteria

and fungus which decay the organic waste. Humus is a biochemical

element which causes organic soil to change color into grey and dark.

Organic soil has low density and low bearing capacity because

of its loose particle packing and brittle but is able to retain water with

very high moisture content. The soil also has high plastic limit, liquid

limit, acidic, soft and compressible. It is not suitable for supporting

load. An example of organic soil is peat soil.

1.3 Sieve analysis

Sieve analysis is the process of determining the size of soil particles by

passing the soil sample through a number of different sieves having different

opening (hole sizes). Sieve analyses provide more accurate result for coarse-grained

soil. Sieve analysis can be conducted by using dry or wet sieving. The aim of

performing dry sieve analysis test is to determine the particle size of a sample of soil.

2.0 Procedure

2.1 Fine aggregate

Firstly, the sieve must been cleaned with brush and arrange the sieves

from larger size placed on top. Then, dry sample have been taken and

weighted it into 500g. After that, placed the sample on the top sieve and

placed the sieve onto the shaking machine and shake it for two minute.

Lastly, the weights of soil passing through each sieve have been determined

and the percentages of soil passing through each sieve have been calculated.

2.2 Coarse aggregate

Firstly, the sieve must been cleaned with brush and arrange the sieves

from larger size placed on top. Then, dry sample have been taken and

weighted it into 3000g. After that, placed the sample on the top sieve and

placed the sieve onto the shaking machine and shake it for two minute.

Lastly, the weights of soil passing through each sieve have been determined

and the percentages of soil passing through each sieve have been calculated.