Rutting in Flexible Pavement: An approach of evaluation with Accelerated Pavement Testing Facility

Majority of roads in India are constructed of flexible pavements, wherein, the bulk of distress is in the form of either cracking (fatigue) or rutting (permanent deformation). Rutting is the longitudinal depression in the wheel path in bituminous pavements, which can be attributed to excessive consolidation, formed by an accumulation of permanent deformations caused by repeated heavy loads, or lateral movement of the material, caused by shear failure of the bituminous concrete layer, or a combination of both mechanisms. There are countries facing functional constraints on their flexible road pavements due to rutting and trying to resolve this failure. Rutting in pavement is a serious mode of distress beside fatigue in bituminous pavement in high temperature areas including India and may lead to premature failure in pavements and results in early and costly rehabilitation. In addition, rutting in pavements causes hydroplaning, severe physiological and safety concern for users. Premature distress and associated problems in pavement result in an economic burden on tax payer. Hence, this problems needs to be properly addressed through evaluation and mitigation measures so that the occurrence and resulting impacts are minimised. In order to study the pavement failure modes and to minimise them so as to get good serviceability from the huge road assets the country is having, the actual response of pavement structure needs to be monitored. This necessitates a systematic assessment and performance evaluation of pavement with known design and influencing factors. An array of response measuring instruments, under measurable loading conditions is required to accrue objective indicators. Evaluation strategies use performance monitoring through laboratory and field evaluation, while the field evaluation itself can be accomplished by monitoring in-service pavements or smaller replicate test strips using an 'Accelerated Pavement Testing' protocol. CSIR-CRRI has recently procured and established a national facility of Accelerated Pavement Testing. Through this, the in-field loading on pavements, and design traffic, tyre pressure can be simulated. A systematic study was initiated on the permanent deformation development involving a flexible pavement designed as per Indian practice. The paper brings out the details of this evaluation study and also features the capabilities and applications of Indian APTF in the issue. (C) 2013 The Authors. Published by Elsevier Ltd.