Pavement Overlay Design using Falling Weight Deflectometer

Pavement evaluation is a technique of assessing the condition of a pavement, both structurally and surface characteristics. Pavements which have been subjected to traffic, deform elastically under load which depends on type subgrade soil and its compaction level, pavement thickness and its composition, drainage conditions, pavement surface temperature and wheel load. There are number of different types of pavement deflection testing equipment which are being used all over the world. The most common types are Benkelman Beam Deflection (BBD), Falling Weight Deflectometer (FWD) and Dynamic Cone Penetrometer. BBD test widely used method in which rebound deflection is measured on static loading and there by evaluating strength of the pavement. However with limitations and practical difficulties of BBD, FWD was chosen for the study. The deflections of the pavement are recorded due to the dynamic loading and studied for further strength determination. A 4-lane National Highway has been selected and tested for residual strength and it is designed for overlay as per IRC:115-2014 & IRC:37-2012 using FWD equipment and with the assistance of KGPBACK and IIT PAVE software’s. An overlay of 50 mm on one direction and 100 mm on opposite direction was recommended to meet the functional and structural requirement respectively.