Development of a Design Guide for Ultra Thin Whitetopping (UTW)

Download Final Report

CAIT project no.: FHWA NJ 2001 018

Fiscal Year: 1996/1997

Status: Final

Rutgers-CAIT Author(s): Nenad Gucunski

External Author(s): Nicholas Vitillo, NJDOT



Concrete overlay of deteriorated asphalt pavements (whitetopping) has been a viable alternative to improve the pavement’s structural integrity for over six decades. The thickness of such overlay usually exceeds five inches. In the last few years, however, a newer technology has emerged which is commonly known as Ultra Thin Whitetopping (UTW). UTW is a construction technique, which involves placement of a thinner (than normal) thickness ranging from 2 to 4 inches. The application of UTW has been targeted to restore/rehabilitate deteriorated asphalt pavements with fatigue and/or rutting distress.

Study of UTW was initiated by the construction of the first experimental project on an access road to a landfill in Louisville, Kentucky in 1991. This rather successful project was complemented by a series of experimental projects by many state and local agencies. There have been more than 170 UTW projects constructed from the early 1990’s and many investigators published papers/articles on the performance of these experimental projects. As a natural outcome of experimental observations, a need for a thorough and comprehensive (theoretical) understanding of UTW system is felt amongst researchers and experimentalists. In order to gain an insight into the contribution of the many variables in a UTW pavements system (i.e., thickness of UTW, AC and base layers; stiffness moduli of UTW, AC and base layers; size of UTW panels; UTW-AC interface; load transfer; etc.), there have been a few research endeavors.

The intent of this research study is to identify and address important factors that contribute to the performance of the UTW pavement system. It is also the goal of this research to present an interim design procedure fine tuned by further observation of UTW pavement systems.