Structural analysis of flexible pavements has been and still is currently performed using a multi-layer elastic theory. However, for thinly surfaced pavements subjected to light to medium volumes of traffic, the importance of non-linear stress-strain behaviour of unbound granular materials (UGM’s) requires the use of more sophisticated numerical models for structural design and analysis of such...

An existing permanent deformation (PD) model for the unbound granular materials (UGMs) in pavements, developed based on multistage (MS) repeated load triaxial (RLT) tests, was modified to better suit field conditions and software applications. The calibrated a few UGMs with series of moisture contents (w) using MS (to include stress-history effect) RLT tests validated by predicting PD under dif...

Resilient modulus and California Bearing Ratio (CBR) in unbound granular materials are the key technical characteristics of layers in a flexible pavement design. Among the factors affecting these two parameters, the aggregate gradation is the most important. Using particle size distribution curve developed by AASHTO, together with other considerations mentioned in the related regulations have y...

In this study, a comprehensive laboratory testing program was designed to study the resilience characteristics of unbound granular materials (aggregate base coarse) using repeated load triaxial test (RLTT). During experimental program, resilient modulus material examined different moisture content levels, gradation Fuller’s equation, and stress levels. The results show that content, gradation, ...

Unbound granular pavement layers show a characteristic increase in moduli from the subgrade to the surface. The ratio of moduli between successive layers provides a direct and effective measure of pavement quality that makes due allowance for site conditions and seasonal effects beyond a contractor’s control. The modular ratio is therefore an effective indicator for performance-based specificat...