Goldschmidt theory suggests that the plasticity in soil is due to electro-magnetic charges. Let's understand this theory in detail.

Explanation:
The plasticity of soil refers to its ability to change shape and stay in that shape without cracking or breaking. This property is critical in construction and engineering projects as it helps in determining the stability of structures built on the soil. Goldschmidt, a German mineralogist, proposed a theory that explains the plasticity of soil. According to him, the plasticity of soil is due to the electro-magnetic charges present on the soil particles.

When water is added to the soil, the water molecules surround the soil particles and create a thin film. This film creates a repulsive force between the particles and makes them move apart, resulting in the plasticity of the soil. The electro-magnetic charges present on the soil particles play a vital role in creating this repulsive force.

The presence of clay particles in the soil increases the plasticity of the soil. Clay particles have a high surface area and contain a net negative charge. Due to this negative charge, they attract positively charged ions present in the water, which form a layer around the clay particles. This layer creates a repulsive force between the particles, making them move apart and resulting in the plasticity of the soil.

Conclusion:
In conclusion, Goldschmidt theory suggests that the plasticity in soil is due to electro-magnetic charges. The electro-magnetic charges create a repulsive force between the soil particles, making them move apart and resulting in the plasticity of the soil. Understanding the plasticity of soil is crucial in construction and engineering projects, and Goldschmidt theory provides a useful framework for understanding this property.