What Is Flexible Pavement?

 

What Is Flexible Pavement?

Flexible pavement consists of a surface layer of bitumen-bound aggregate (asphalt concrete), several lower layers of appropriate quality aggregate and the sub grade beneath. The layers enable the pavement to “bend”, reducing damage and the need for repairs over time.

Functions of a Flexible Pavement

Flexible pavements serve three functions, and in order to achieve these effectively, several layers are required:

·         The initial (visible) function of flexible pavements is to provide a surface that is safe, smooth and durable enough for the traffic anticipated to be using it, over the design life.

·         The second key function is to distribute loads from the vehicle tyres onto a wider area underneath (subgrade – see later), so that the subgrade does not deform under repeated loading.

·         Lastly, it is important to protect the lower pavement layers and subgrade from any of the weakening effects of water.

Layers of a Flexible Pavement

The structure of flexible pavement is typically made up of the following layers:

 The various layers of a flexible pavement can be divided into two overlapping sections:

Pavement section

The foundation section.

The foundation section of a flexible pavement comprises the subgrade and subbase with possibly a capping layer between, whilst the pavement section includes the subbase, the base, the binder course and the surface course layers.

A flexible pavement's foundation section may have either a single layer or double layer above the subgrade, comprising either a subbase and capping layer or simply the subbase.

 The Advantages of Flexible Pavement

Thanks to the various layers of flexible pavement, it offers the following advantages:

·         With flexible pavement, the subgrade beneath is less likely to deform than with rigid pavement.

·         Repairs are easy and inexpensive with flexible pavement.

·         The installation process does not require joints and materials are cheaper.

·         Its short curation time (typically less than 24 hours) makes for quick installations, reducing traffic disruption.

·         Black ice is less likely to form on the surface of flexible pavement.

·         Water is unable to rise up through the lower layers, preventing the pavement from becoming weakened.