PQC stands for Pavement Quality Concrete. It is a type of concrete mix specifically designed for use in pavement construction. The purpose of using PQC is to ensure the durability, strength, and smoothness of the pavement surface, providing a safe and comfortable driving experience for road users. Here is a detailed explanation of the answer:

1. Pavement Quality Concrete (PQC):
- PQC is a high-performance concrete mix used for constructing rigid pavements, such as highways, runways, and industrial roads.
- It is designed to withstand heavy traffic loads, resist cracking, and provide a long service life.
- PQC has superior strength, durability, and abrasion resistance compared to conventional concrete mixes.

2. Importance of PQC in Pavement Construction:
- Pavements are subjected to dynamic loads from vehicles, temperature variations, and environmental factors, which can cause distress and deterioration over time.
- PQC helps in minimizing the effects of these factors and provides a stable and long-lasting pavement structure.
- It ensures a smooth riding surface, reducing vehicle wear and tear, as well as driver discomfort.

3. Key Properties of PQC:
- Strength: PQC has a high compressive strength, which enables it to withstand heavy loads without significant deformation or failure.
- Durability: PQC is designed to resist the effects of freeze-thaw cycles, chemical attack, abrasion, and other forms of deterioration.
- Workability: PQC has a good workability, allowing it to be easily placed, compacted, and finished to achieve the desired surface characteristics.
- Smoothness: PQC provides a smooth and even surface, minimizing vibrations, noise, and discomfort for road users.

4. Design and Construction of PQC:
- PQC mix design involves selecting the appropriate aggregates, cementitious materials, admixtures, and water-cement ratio to achieve the desired strength and durability.
- The concrete is typically batched and mixed in a central plant, ensuring consistent quality and uniformity.
- PQC is placed and compacted using specialized equipment, such as slipform pavers or fixed-forms, to achieve the desired pavement thickness and shape.
- Proper curing and finishing techniques are employed to enhance the concrete's properties and surface characteristics.

In conclusion, PQC (Pavement Quality Concrete) is specifically designed for use in pavement construction, offering superior strength, durability, and smoothness. It plays a critical role in ensuring the long-term performance and safety of rigid pavements.