Both silt and clay are types of fine-grained soil produced by the chemical and physical breakdown of rock minerals. They are both used in construction, but what is the difference between the two? In this article, we will jot down what makes clay and silt different. Keep reading to find out.

First, let us discuss what clay and silt are.

What is Silt?

Silt is a granular material with a particle size between sand and clay, ranging from 0.002 to 0.006 mm. It is scarce in plasticity, making it difficult to mould silt into a particular shape.

What is Clay?

Clay is a fine-grained natural soil material with a clay mineral. These particles are smaller than 0.002 mm, being the finest among all soil particles. It has plasticity and can be pressed into any shape you want.

How are Silt and Clay Different?

There are several factors that differ silt from clay, including:

1. Particle Size

The particle size of clay is the finest of all soil particles. Clay is fine-grained soil with a particle size of less than 0.002 mm. On the other hand, silt has a particle size of 0.002 to 0.006 mm.

2. Plasticity

Clay is easy to shape in any way you desire, as it has more plasticity than silt. Comparatively, silt has less plasticity, which means you cannot mould it into a particular shape of your liking.

3. Water Holding Capacity
Water holding capacity is described as the ability of a soil texture to hold water physically against gravity. When it comes to water holding capacity, clay takes the lead. Clay has comparatively more water holding capacity than silt.

4. Surface Area

Since clay particles are smaller in size, they have more surface area than silt particles.

5. Nature of Particles

Clay particles are sticky in nature. In comparison, silt comprises non-sticky, uniform, and smooth-to-touch particles.

6. Dry Strength

The dry strength of a soil is its strength when it is dry, determined with the help of the crushing test. Clay has greater dry strength than silt.

7. Retaining Plant Nutrients

Clay can retain the plant nutrients in the soil well. In contrast, silt has inadequate or limited retention of plant nutrients.

8. Permeability

This property of soil tells how water and air can move through it. Silt has more permeability than clay, allowing water and air to move through it easily.

9. Density

The soil density is important and is of two types; particle density and bulk density. The bulk density of soil gives insight into the soil’s ability to function for structural support and more. Silt particles have more gaps between them, which means their density is less than that of clay, which is closely packed.

What’s the Takeaway?

In conclusion, silt and clay have many differences. The main difference between them is the size of their particles. They also differ in plasticity, water holding capacity, surface area, nature, dry strength, retention of plant nutrients, permeability, and density. WM Trucking & Excavations can help if you are looking for fill materials or excavations. Contact us at 936-372-1399.