The most suitable material for the central impervious core of a zoned embankment type dam is clay.

Explanation:

Zoned embankment type dams are constructed using different types of materials in different zones or layers. These zones are designed to perform specific functions and ensure the stability and safety of the dam structure. The central impervious core is one of the key zones in the dam and is responsible for preventing water seepage.

Here are the reasons why clay is the most suitable material for the central impervious core of a zoned embankment type dam:

1. Impermeability:
Clay has low permeability, which means it has a very low rate of water flow through its particles. This property makes it an ideal material for the impervious core of the dam. It helps to prevent the seepage of water through the dam body and ensures that the water is retained within the reservoir.

2. Plasticity and Cohesion:
Clay possesses high plasticity and cohesion, which means it can be easily molded and compacted into a stable structure. These properties are crucial for constructing a strong and stable impervious core. The compacted clay layer forms a barrier to the flow of water and maintains the integrity of the dam structure.

3. Self-healing Capability:
Clay has the ability to self-heal small cracks or fissures that may occur due to settlement or external factors. When clay comes into contact with water, it absorbs the moisture and expands, filling the gaps or cracks and restoring its impermeability. This self-healing capability further enhances the effectiveness of the impervious core in preventing water seepage.

4. Availability and Cost:
Clay is widely available in nature, making it a cost-effective choice for constructing the central impervious core. It can be easily sourced from nearby locations, reducing transportation costs. Additionally, the cost of clay is relatively lower compared to other materials, making it economically viable for large-scale dam construction projects.

In conclusion, clay is the most suitable material for the central impervious core of a zoned embankment type dam due to its impermeability, plasticity, cohesion, self-healing capability, and cost-effectiveness. These properties ensure the stability and long-term functionality of the dam, preventing water seepage and protecting the surrounding environment and infrastructure.