Modelling of Permanent Deformation on Flexible Pavement Using Accelerated Pavement Testing

Abstract

The two major distresses encountered on flexible pavement under Indian conditions are fracture (cracking) and longitudinal permanent deformation (rutting) which affects the serviceability of pavement. Accelerated Pavement Testing Facility (APTF) is a tool which is a vital link for testing and measuring full-scale field behaviour of cracking and rutting of pavement at in-situ conditions. Recently, CSIR-Central Road Research Institute (CRRI) in India has procured a linear Heavy Vehicle Simulator (HVS) type of APTF which is presently being used for finding out the cracking and rutting behaviour of a flexible pavement consisting Dense Bituminous Concrete (DBC) as wearing course and Dense Bituminous Macadam (DBM) as binder course apart from the conventional granular layers above sub-grade. The present paper deals with the development of a statistical model and its approach for pavement rutting under numerous passes (bi-directional) for the layer specifications which are (i) 40 mm DBC (ii) 120 mm DBM (iii) 250 mm Wet Mix Macadam (WMM) and (iv) 300 mm Granular Sub-base (GSB) above the Sub- grade, which is an Indian Specification widely used for 30 Million Standard Axles (MSA) at 5% CBR. The statistical model has been developed by observing / recording pavement surface profile using Laser Profilometer (off board) for every 5,000 passes upto 50,000 passes, thereafter at every 10,000 passes upto 175,000 passes and then at every 25,000 passes upto 275,000 passes. The details of methodology adopted, load applied, temperature and material properties have also been given in the paper.