5.2.2. Dry Sieve Analysis

Dry sieve analysis is carried out on particles coarser than 75 micron. Samples (with fines removed) are dried and shaken through a set of sieves of descending size.

Dry sieve analysis is a method used to determine the particle size distribution of soil particles that are larger than 75 microns. In this process, the soil sample is first dried to eliminate moisture. Then, the sample is shaken through a series of sieves, each with progressively smaller openings, allowing particles to be sorted based on their size.

Imagine you have a box of different sized marbles, and you want to separate them by size. You use several colanders with holes of different sizes. When you pour the marbles into the largest colander, the bigger ones stay while the smaller ones fall through. You then repeat this process with smaller colanders until all the marbles are sorted. This is essentially how dry sieve analysis works with soil particles.

The weight retained in each sieve is measured. The cumulative percentage quantities finer than the sieve sizes (passing each given sieve size) are then determined.

Once the soil has passed through the sieves, the next step is to measure the weight of soil retained on each sieve. This weight allows for the calculation of the cumulative percentage of soil particles that are finer than the sieve sizes. This cumulative data helps to form a complete picture of the soil's particle size distribution.

Think of a baking process where you sift flour to remove lumps. As you sift, the fine flour falls through while the lumps get caught on the screen. By measuring how much flour is left on the screen after each sifting, you can see how much fine flour has passed through, helping you understand the quality of your flour after sifting.

The resulting data is presented as a distribution curve with grain size along x-axis (log scale) and percentage passing along y-axis (arithmetic scale).

After the measurements are completed, the data collected from the sieve analysis is plotted on a graph known as the distribution curve. The x-axis represents the particle size on a logarithmic scale, while the y-axis shows the cumulative percentage of particles passing through the sieves on a standard arithmetic scale. This curve visually represents how the sizes of particles are distributed within the soil sample.

Imagine you're tracking the scores of students in a class on a test. You might plot their scores on a graph where the scores (ranging from 0-100) are on the horizontal axis, and the number of students who received those scores is on the vertical axis. This helps you visualize how students performed overall, just as the distribution curve helps visualize particle sizes in soil.

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