Impact of Moisture Content on Resilient Modulus Predictions for Unbound Granular Materials Using Stress-Dependent Constitutive Models
摘要
Unbound granular materials are the main construction materials used in the base and subbase layers of road pavements to provide structural support to the upper layers and ensure adequate response to traffic loads. These materials exhibit elastoplastic behavior, characterized by both resilient and non-recoverable deformation properties. However, in pavement design, the resilient modulus (Mr) is used as the main indicator of their mechanical response. This parameter is unique for each sample of unbound materials, as it is influenced by various factors including stress level, dry density, aggregate gradation, moisture content, grain shape, and aggregate type. In addition to stress level, moisture content is also considered to have a significant influence on Mr, but it seems to be ignored when using constitutive models to predict Mr for pavement design. Therefore, this paper investigates the effect of the moisture content of the unbound base/subbase layer on the determination of the resilient modulus using different constitutive models. First, laboratory tests were conducted on samples of unbound granular materials to estimate their Mr values at five different moisture contents. Then, three different constitutive models were selected and used to predict the Mr value for each moisture content. Finally, the laboratory-derived Mr values are compared with the model-based Mr values after regression analysis to provide valuable insight into the predictability of each selected constitutive model with respect to moisture content variation.