Determine Particle Size Distribution of Soil by Sieving

To Determine Particle Size Distribution of Soil by Sieving

When analyzing soil, a common technique is to use a set of sieves to separate the material into different sizes. The soil is placed on top of the sieves and shaken, causing the smaller particles to fall through and the larger particles to be retained. The material that remains on each sieve is then weighed to determine the amount of material in each size category.

To express the results of this analysis, the percentage of material retained on each sieve is calculated. This percentage indicates the proportion of the original soil sample that falls into each size range. By analyzing the percentages of material in each size category, scientists and researchers can gain insight into the properties and characteristics of the soil being studied.

Where 

The given context refers to a formula used to calculate the cumulative percentage of material retained on a specific sieve in a soil sample. The formula uses two variables: the mass of soil retained on sieve ‘n’ and the total mass of the sample.

The cumulative percentage of material retained refers to the proportion of the soil sample that is larger than a particular sieve size. In other words, it is the amount of soil that is too large to pass through the sieve.

To calculate this percentage, the formula uses the mass of soil that is retained on a specific sieve size (denoted by ‘n’) and divides it by the total mass of the sample. The result is then multiplied by 100 to get the percentage.

Therefore, the formula for calculating the cumulative percentage of material retained can be expressed as M_n/M x 100, where M_n is the mass of soil retained on sieve ‘n’ and M is the total mass of the sample.

C_n = P₁ + P₂ + P₃ + . . . . . . . . . +P_n

Where P₁, P₂ etc are the percentages retained on sieve 1, 2 etc which are coarser than sieve ‘n’. The percentage finer than the sieve ‘n’

Equipment for Particle Size Distribution

The equipment list includes two sets of sieves, one comprising of fine sieves with different mesh sizes ranging from 2mm to 75 microns and the other set comprising of coarse sieves with mesh sizes ranging from 100mm to 4.75mm. A weighing balance with an accuracy of 0.1% of the mass of the sample is also part of the equipment list. Additionally, an oven, mechanical shaker, trays, mortar with a rubber covered pestle, brushes, and a riffler are included.

The fine sieves are designed for separating smaller particles from the sample, while the coarse sieves are used for separating larger particles. The weighing balance is important for measuring the mass of the sample accurately, and the oven can be used for drying the sample or for heating it to a specific temperature. The mechanical shaker helps in sieving the sample effectively, and trays can be used to collect the different particle sizes separated by the sieves.

The mortar and pestle are used for grinding the sample before sieving, and the brushes are useful for cleaning the sieves and trays after use. The riffler, on the other hand, is used for dividing the sample into smaller portions for testing. Overall, this set of equipment is suitable for conducting particle size analysis and testing in various industries such as food, pharmaceuticals, and construction.

Part-I: Coarse Sieve Analysis of Soil

The procedure for conducting a coarse and fine sieve analysis on soil samples involves several steps. Firstly, a required quantity of the sample is taken and passed through a 4.75mm IS sieve. The portion of soil retained on the sieve is used for the coarse sieve analysis (Part-I), while the part that passes through the sieve is used for the fine sieve analysis (Part-II).

The second step involves sieving the sample through a set of coarse sieves by hand. During this process, the sieve is agitated to ensure that the sample rolls in an irregular motion over the sieve. Care should be taken not to break the individual particles, and the material retained on the sieve may be rubbed with the rubber pestle in the mortar if necessary. The quantity of material taken for sieving on each sieve should not exceed the specified value.

After sieving, the mass of the material retained on each sieve is determined, and the percentage of soil retained on each sieve is calculated based on the total mass of the sample taken in step one. Finally, the percentage passing through each sieve is determined.

Part-II: Fine Sieve Analysis of Soil

To analyze soil samples, a portion of the soil that passes through a 4.75 mm IS sieve is taken and oven-dried at a temperature of 105 to 1100C. The dried soil is then weighed to an accuracy of 0.1% of the total mass. The soil sample is then sieved through a nest of fine sieves, with the sieves being agitated to ensure the sample rolls in an irregular motion over the sieves. It is important to ensure that no particles are pushed through the sieve during this process.

The material retained on each sieve is collected in a mortar and rubbed with a rubble pestle. However, individual particles should not be broken during this process. The material is then reserved through the nest of sieves, and a minimum of 10 minutes of shaking is required if a mechanical shaker is used. The soil fraction retained on each sieve is collected in a separate container and weighed.

Finally, the percentage retained, cumulative percentage retained, and percentage finer are determined based on the total mass taken in step (1). This process is essential for analyzing soil samples accurately and understanding their characteristics. It ensures that the soil is separated into different fractions based on particle size, which is crucial for determining soil properties such as permeability, porosity, and fertility.

Data Sheet for Sieve Analysis

The given context provides information about the total mass of dry soil, the mass of soil retained on a 4.75mm sieve, and the mass of soil passing through the 4.75mm sieve. The total mass of dry soil is not specified, and therefore, it is left blank. The mass of soil retained on the 4.75mm sieve is given, while the mass of soil passing through the 4.75mm sieve is also provided.

To summarize, the context presents data related to the quantity of soil and its distribution based on the size of particles. It specifies the mass of soil retained on a particular sieve and the mass of soil that has passed through it. These details are critical in soil analysis and can help in determining the characteristics of soil, such as its composition and texture.

Observations			Calculations
IS Sieve	Size of opening	Mass of soil retained	Percentage retained	Cumulative % retained	% finer
Coarse Fraction (Part-I)
100 m	100 mm
80 mm	80 mm
40 mm	40 mm
20 mm	20 mm
10 mm	10 mm
4.75 mm	4.75 mm
Fine Fraction (Part-II)
2 mm	2 mm
1 mm	1 mm
600	0.600 mm
425	0.425 mm
300	0.300 mm
212	0.212 mm
150	0.150 mm
75	0.075 mm
	–

Result:

The information provided in the last column, which represents the percentage of particles that are finer than a given size, can be used to construct a particle size distribution curve. To do so, the particle size values should be plotted on the abscissa (x-axis) using a logarithmic scale, and the percentage finer should be plotted on the ordinate (y-axis). This will allow for a visualization of the distribution of particle sizes in the sample being analyzed. By using a logarithmic scale, the data can be more easily represented and compared across a wide range of particle sizes. The resulting particle size distribution curve can provide valuable insights into the characteristics of the sample being studied, such as the presence of fine or coarse particles and the overall particle size range.

Fig: Particle size distribution on semi log graph

Fig: Grading of soils

[Note:

The passage is discussing different methods for analyzing soil samples that contain a significant amount of clay particles. It mentions that wet sieve analysis is one option, but another method involves adding water with sodium hexametaphosphate to the soil fraction before conducting step (7) of the analysis process. This mixture should be stirred thoroughly and left to soak before washing the specimen on a 75 mesh sieve. The purpose of adding the sodium hexametaphosphate is to help disperse the clay particles and prevent them from clogging the sieve during the washing process. This alternative method may be used instead of the wet sieve analysis for soil samples that contain clay particles.

To ensure that the soil sample is free of impurities and to determine the particle size distribution, a series of steps must be followed. First, the soil sample is weighed and placed onto a sieve. Water is then poured onto the soil and the sieve is agitated until the water passing through it is clear. The remaining fraction of soil on the sieve is then dried in an oven. Once the soil is dry, it is sieved again through a nest of sieves to further determine the particle size distribution. The mass of the material retained on the sieve is equal to the original mass of the soil before washing minus the dry mass of the soil retained on the 75-micron sieve. These steps are essential to accurately analyze the particle size distribution of the soil sample.

sieve after washing.]