Effect of resilient modulus of undisturbed subgrade soils on pavement rutting

Abstract

This paper presents the results from a test program to characterise resilient modulus (MR) of subgrade soils for different geographic regions in South Carolina. For this study, Shelby tube samples of subgrade soils were collected from existing pavements in different regions: SC-93 in Pickens county (Upstate Area), US-521 in Georgetown county (Coastal Plain), and US-321 in Orangeburg county (Coastal Plain, near the fall line). Resilient modulus model parameters were obtained using both the bulk stress model and the generalised constitutive resilient modulus model. Statistical analysis was performed to develop MR estimation models for undisturbed soils using soils index properties. A correlation between laboratory measured MR with the modulus from Falling Weight Deflectometer tests was also developed. Finally, the effects of MR on subgrade rutting were studied using MEPDG. Results showed that the developed models offer higher reliability than the universal Long-Term Pavement Performance models in estimating the resilient modulus of undisturbed soils and predicting subgrade rutting for South Carolina.