Strength Evaluation of Flexible Pavement of Runway Using Benkelman Beam Deflection Technique for Surat Airport Project
Dr. N. C. Shah, Professor, Civil Engineering Department, Sardar Vallabhbhai National Institute of Technology, (SVNIT) Ichchhnath, Surat

Introduction
The performance of flexible pavements is closely related to the elastic deflection of pavement under the wheel loads. The deformation or elastic deflection under a given load depends upon surgrade soil type, its moisture content and compaction, the thickness and quality of the pavement courses, drainage conditions, pavement surface temperature etc.
The Benkelman Beam Deflection Method is thus widely used for Evaluation of Structural Capacity of Existing Flexible Pavements and also for Estimation and Design of Overlays for Strengthening of any weak pavement for Highways.

This method may probably provide relative idea of Structural Capacity of Existing Flexible Pavements of Runway of Surat Airport Project in three different sections as specified below for confirmation of the PCN values obtained in these sections:
- For widening portion of Runway from ch.0 to ch.1400m at cross ch.from 15 m to 22.5m on both side.
- From ch.1400 m to ch.1585 m for full width of Runway.
- From ch.1585 m to ch.2100 m for full width of Runway.
The results were obtained in terms of Characteristic Deflection in mm and shall mean that higher the Characteristic Deflection, weaker is the pavement structure.