A Comparative Evaluation of the Structural Performance of Papua New Guinea River Gravel Using the Repeat Load Triaxial (RLT)- a Performance-Based Test

Abstract

Roads in Papua New Guinea (PNG) do not appear to perform to design expectations. Premature pavement failure followed by rapid deterioration seems to be the current trend in PNG’s road systems. Most roads in PNG are built using river gravel as unbound granular material (UGM) for pavement. The use of river gravels is believed to be one of the causes of early pavement failure in PNG even though it complies with the current specifications. The present method of characterizing the unbound granular pavement base materials which are the most critical component of the pavement layer is inadequate. The current empirical characterization and specification of pavement materials are ineffective in that the tests employed do not take into account the real in-service performance of the pavement under cyclic traffic loading. Recent development and advancement in pavement engineering have revealed that the relevant materials’ characteristic parameters should undergo testing through more representative performance-based tests. These new tests offer more insight into the physical behavior for fair characterization by simulating the in-service conditions of the pavement materials under cyclic traffic loadings. In this study, four samples of common PNG base course materials including river gravel were tested in New Zealand using the Repeat Load Triaxial (RLT) testing apparatus (a performance-based test). The results showed that the river gravels were extremely moisture-sensitive compared to coronous and limestone. Thus, the study concluded that the use of River Gravel as UGM is one of the leading causes of premature pavement failure that contributes to poor road performances in PNG.

Keywords: Unbound, Granular Materials, Pavement, Base Materials, Performance-Based Tests