DLC stands for Dry Lean Concrete, and PQC stands for Pavement Quality Concrete. In rigid pavements, Dry Lean Concrete (DLC) is used as a bottom layer, and Pavement Quality Concrete (PQC) is used as a top layer.
Understanding DLC and PQC in Pavement Construction
Rigid pavements are a common type of road or airport runway construction known for their strength and durability. They differ significantly from flexible pavements (like asphalt) in how they distribute loads. According to the provided reference, the structure of a typical rigid pavement includes specific layers made from different types of concrete.
Dry Lean Concrete (DLC)
- Role: As per the reference, DLC serves as the bottom layer in rigid pavements.
- Composition: Dry Lean Concrete is typically a mix with a relatively low cement content compared to PQC, and often has a drier consistency. This "lean" mix means it uses less cement and sometimes a higher proportion of aggregate.
- Function: The primary purpose of the DLC layer is to provide a stable, uniform, and strong base for the PQC layer above it. It helps in distributing loads to the subgrade and prevents pumping (the ejection of soil and water from beneath the pavement). It also acts as a barrier layer.
Pavement Quality Concrete (PQC)
- Role: The reference states that PQC is the top layer in rigid pavements.
- Composition: Pavement Quality Concrete is a high-strength concrete specifically designed for the wearing surface of pavements. It has a higher cement content and carefully selected aggregates to ensure durability, strength, and resistance to traffic loads, abrasion, and environmental factors.
- Function: The PQC layer is the structural slab that directly bears the traffic loads and is exposed to the elements. It is designed to withstand the critical conditions of stress in the rigid pavement structure.
Layer Structure Summary
Here's a simple breakdown based on the reference:
| Layer | Material | Position in Rigid Pavement | Primary Role Based on Context |
|---|---|---|---|
| Top | Pavement Quality Concrete (PQC) | Upper Layer | Wearing surface, bears traffic loads |
| Bottom | Dry Lean Concrete (DLC) | Lower Layer | Base layer for PQC, load distribution |
This two-layer concrete system (DLC below, PQC above) is a standard approach in building robust rigid pavements capable of handling heavy traffic loads over long periods.
