Failure Of Road Pavement

In the case of most structures, failure hardly needs defining - it happens suddenly, it is
very obvious, and it marks the end of the structure’s useful life.

Consider a suspended concrete slab. Simply support this at each end and then apply an
increasing load at the centre. Eventually the concrete snaps and we have a “catastrophic”
failure.

Whilst some pavement failures happen suddenly, in most situations a pavement gradually
deteriorates. Perhaps a more typical example is a barge board on a house. If the board is left
unpainted, gradually the paint deteriorates and cracks to the extent that it has to be scraped
back and repainted. If the board is further left unattended, the board will eventually rot away
and will be difficult and expensive to replace, in that some other components will also have to
be removed and replaced.

To settle on a definition, let us refer to the term “pavement failure” as when the
deterioration of a section of pavement reduces its serviceability and/or future usefulness such
that remedial action is necessary.

Most primary failures result from weakness at one of three points in a pavement. These are:

(a) Surface Failures:

Potholes, ageing, etc., which are generally shown by sharp edges or firm
pavement without general distortion.

(b) Base Failures:

                           Insufficient strength caused by bad design, overloading, or material change due to
moisture or weathering. This failure is characterized by plastic deformation of the pavement.
In advanced stages it may also be accompanied by crocodile cracking, followed by leaching of
fine materials as deterioration increases.

(c) Bond Failures:

Normally  occur  between  bitumen  bound  layers,  between  bound  layers  or
between a bitumen bound layer and the base course.

1.4 Study Methodology:

1. Remove unsuitable material.

2. Install any necessary under drains.

3. Replace base with a well-graded aggregate.

4. Compact aggregate.

5. Prime area.

6. Replace surface using Asphalt Concrete